I insert the filler hose fitting into the fuel filler neck and turn it half a turn to seal the connection. A click of the toggle switch - and the blinking LED on the gas pump with a huge inscription h3 indicates that refueling has started. A minute - and the tank is full, you can go!
Elegant body contours, ultra-low suspension, low-profile slicks give off a real racing breed. Through the transparent cover, an intricate network of pipelines and cables is visible. I've already seen a similar solution somewhere... Oh yes, on the Audi R8 the engine is also visible through the rear window. But on Audi it is traditional gasoline, and this car runs on hydrogen. Like the BMW Hydrogen 7, but unlike the latter, there is no internal combustion engine. The only moving parts are the steering gear and the electric motor rotor. And the energy for it is provided by a fuel cell. This car was produced by the Singaporean company Horizon Fuel Cell Technologies, specializing in the development and production of fuel cells. In 2009, the British company Riversimple already introduced an urban hydrogen car powered by Horizon Fuel Cell Technologies fuel cells. It was developed in collaboration with Oxford and Cranfield Universities. But Horizon H-racer 2.0 is a solo development.
The fuel cell consists of two porous electrodes coated with a layer of catalyst and separated by a proton exchange membrane. Hydrogen at the anode catalyst is converted into protons and electrons, which travel through the anode and an external electrical circuit to the cathode, where hydrogen and oxygen recombine to form water.
"Go!" - the editor-in-chief nudges me with his elbow in Gagarin style. But not so fast: first you need to “warm up” the fuel cell at part load. I switch the toggle switch to “warm up” mode and wait for the allotted time. Then, just in case, I top up the tank until it’s full. Now let's go: the car, the engine humming smoothly, moves forward. The dynamics are impressive, although, by the way, what else can you expect from an electric car - the torque is constant at any speed. Although not for long - a full tank of hydrogen lasts only a few minutes (Horizon promises to release a new version in the near future, in which hydrogen is not stored as a gas under pressure, but is retained by a porous material in the adsorber). And, frankly speaking, it is not very controlled - there are only two buttons on the remote control. But in any case, it’s a pity that this is only a radio-controlled toy, which cost us $150. We wouldn't mind driving a real car with fuel cells for power.
The tank, an elastic rubber container inside a rigid casing, stretches when refueling and works as a fuel pump, “squeezing” hydrogen into the fuel cell. In order not to “overfill” the tank, one of the fittings is connected with a plastic tube to the emergency pressure relief valve.
Gas station
Do it yourself
The Horizon H-racer 2.0 machine is supplied as a kit for large-scale assembly (do-it-yourself type), you can buy it, for example, on Amazon. However, assembling it is not difficult - just put the fuel cell in place and secure it with screws, connect the hoses to the hydrogen tank, fuel cell, filler neck and emergency valve, and all that remains is to put the upper part of the body in place, not forgetting the front and rear bumpers. The kit includes a filling station that produces hydrogen by electrolysis of water. It is powered by two AA batteries, and if you want the energy to be completely “clean”, by solar panels (they are also included in the kit).
www.popmech.ru
How to make a fuel cell with your own hands?
Of course, the simplest solution to the problem of ensuring the constant operation of fuel-free systems is to purchase a ready-made secondary energy source on a hydraulic or any other basis, but in this case it will certainly not be possible to avoid additional costs, and in this process it is quite difficult to consider any idea for flight of creative thought. In addition, making a fuel cell with your own hands is not at all as difficult as you might think at first glance, and even the most inexperienced craftsman can cope with the task if desired. In addition, a more than pleasant bonus will be the low cost of creating this element, because despite all its benefits and importance, you can absolutely easily make do with the means you already have at hand.
In this case, the only nuance that must be taken into account before completing the task is that you can make an extremely low-power device with your own hands, and the implementation of more advanced and complex installations should still be left to qualified specialists. As for the order of work and the sequence of actions, the first step is to complete the body, for which it is best to use thick-walled plexiglass (at least 5 centimeters). For gluing the walls of the case and installing internal partitions, for which it is best to use thinner plexiglass (3 millimeters is enough), ideally use two-composite glue, although if you really want, you can do high-quality soldering yourself, using the following proportions: per 100 grams of chloroform - 6 grams shavings from the same plexiglass.
In this case, the process must be carried out exclusively under a hood. In order to equip the case with the so-called drain system, it is necessary to carefully drill a through hole in its front wall, the diameter of which will exactly match the dimensions of the rubber plug, which serves as a kind of gasket between the case and the glass drain tube. As for the size of the tube itself, ideally its width should be five to six millimeters, although it all depends on the type of structure being designed. It is more likely to say that the old gas mask listed in the list of necessary elements for making a fuel cell will cause some surprise among potential readers of this article. Meanwhile, the entire benefit of this device lies in the activated carbon located in the compartments of its respirator, which can later be used as electrodes.
Since we are talking about a powdery consistency, to improve the design you will need nylon stockings, from which you can easily make a bag and put the coal in it, otherwise it will simply spill out of the hole. As for the distribution function, the concentration of fuel occurs in the first chamber, while the oxygen necessary for the normal functioning of the fuel cell, on the contrary, will circulate in the last, fifth compartment. The electrolyte itself, located between the electrodes, should be soaked in a special solution (gasoline with paraffin in a ratio of 125 to 2 milliliters), and this must be done before placing the air electrolyte in the fourth compartment. To ensure proper conductivity, copper plates with pre-soldered wires are laid on top of the coal, through which electricity will be transmitted from the electrodes.
This design stage can be safely considered the final stage, after which the finished device is charged, for which an electrolyte will be needed. In order to prepare it, you need to mix ethyl alcohol with distilled water in equal parts and begin gradually introducing caustic potassium at the rate of 70 grams per glass of liquid. The first test of the manufactured device involves simultaneously filling the first (fuel liquid) and third (electrolyte made from ethyl alcohol and caustic potassium) containers of the plexiglass housing.
uznay-kak.ru
Hydrogen fuel cells | LAVENT
I have long wanted to tell you about another direction of the Alfaintek company. This is the development, sale and service of hydrogen fuel cells. I would like to immediately explain the situation with these fuel cells in Russia.
Due to the fairly high cost and the complete lack of hydrogen stations for charging these fuel cells, their sale in Russia is not expected. Nevertheless, in Europe, especially in Finland, these fuel cells are gaining popularity every year. What's the secret? Let's get a look. 
This device is environmentally friendly, easy to use and effective. It comes to the aid of a person where he needs electrical energy. You can take it with you on the road, on a hike, or use it in your country house or apartment as an autonomous source of electricity.
Electricity in a fuel cell is generated by a chemical reaction of hydrogen from the tank with metal hydride and oxygen from the air. The cylinder is not explosive and can be stored in your closet for years, waiting in the wings. This is perhaps one of the main advantages of this hydrogen storage technology. It is the storage of hydrogen that is one of the main problems in the development of hydrogen fuel. Unique new lightweight fuel cells that convert hydrogen into conventional electricity safely, quietly and emission-free.
This type of electricity can be used in places where there is no central electricity, or as an emergency power source.
Unlike conventional batteries, which need to be charged and disconnected from the electrical consumer during the charging process, a fuel cell works as a “smart” device. This technology provides uninterrupted power throughout the entire period of use thanks to the unique power saving function when changing the fuel container, which allows the user to never turn off the consumer. In a closed case, fuel cells can be stored for several years without losing the volume of hydrogen and reducing their power.
The fuel cell is designed for scientists and researchers, law enforcement, emergency responders, boat and marina owners, and anyone else who needs a reliable power source in case of emergency. 
You can get 12 volts or 220 volts and then you will have enough energy to run your TV, stereo, refrigerator, coffee maker, kettle, vacuum cleaner, drill, microstove and other electrical appliances.
Hydrocell fuel cells can be sold as a single unit or in batteries of 2-4 cells. Two or four elements can be combined to either increase power or increase amperage. 
OPERATING TIME OF HOUSEHOLD APPLIANCES WITH FUEL CELLS
| Electrical appliances | Operating time per day (min.) | Required power per day (Wh) | Operating time with fuel cells |
|||
| Electric kettle | ||||||
| Coffee maker | ||||||
| Microslab | ||||||
| TV | ||||||
| 1 light bulb 60W | ||||||
| 1 light bulb 75W | ||||||
| 3 bulbs 60W | ||||||
| Computer laptop | ||||||
| Fridge | ||||||
| Energy saving lamp | ||||||
* - continuous operation
Fuel cells are fully charged at special hydrogen stations. But what if you travel far from them and there is no way to recharge? Especially for such cases, Alfaintek specialists have developed cylinders for storing hydrogen, with which fuel cells will work much longer.
Two types of cylinders are available: NS-MN200 and NS-MN1200. The assembled NS-MN200 is slightly larger than a Coca-Cola can, it holds 230 liters of hydrogen, which corresponds to 40Ah (12V), and weighs only 2.5 kg .The metal hydride cylinder NS-MH1200 holds 1200 liters of hydrogen, which corresponds to 220Ah (12V). The weight of the cylinder is 11 kg.
The metal hydride technique is a safe and easy way to store, transport and use hydrogen. When stored as a metal hydride, hydrogen is in the form of a chemical compound rather than a gaseous form. This method makes it possible to obtain a sufficiently high energy density. The advantage of using metal hydride is that the pressure inside the cylinder is only 2-4 bar. The cylinder is not explosive and can be stored for years without reducing the volume of the substance. Since the hydrogen is stored as a metal hydride, the purity of the hydrogen obtained from the cylinder is very high at 99.999%. Metal hydride hydrogen storage cylinders can be used not only with HC 100,200,400 fuel cells, but also in other cases where pure hydrogen is needed. The cylinders can be easily connected to a fuel cell or other device using a quick-connect connector and flexible hose.
It is a pity that these fuel cells are not sold in Russia. But among our population there are so many people who need them. Well, we'll wait and see, and you'll see, we'll have some. In the meantime, we will buy energy-saving light bulbs imposed by the state.
P.S. It looks like the topic has finally faded into oblivion. So many years after this article was written, nothing has come of it. Maybe I’m not looking everywhere, of course, but what catches my eye is not at all pleasing. The technology and idea are good, but they haven’t found any development yet.
lavent.ru
The fuel cell is a future that starts today!
The beginning of the 21st century considers ecology as one of the most important global challenges. And the first thing that should be paid attention to in the current conditions is the search and use of alternative energy sources. They are the ones who are able to prevent pollution of our environment, as well as completely abandon the continuously rising prices of hydrocarbon-based fuels.
Already today, energy sources such as solar cells and wind turbines have found application. But, unfortunately, their disadvantage is associated with dependence on the weather, as well as on the season and time of day. For this reason, their use in astronautics, aircraft and automotive industries is gradually being abandoned, and for stationary use they are equipped with secondary power sources - batteries.
However, the best solution is a fuel cell, since it does not require constant energy recharging. This is a device that is capable of processing and converting various types of fuel (gasoline, alcohol, hydrogen, etc.) directly into electrical energy.
A fuel cell works on the following principle: fuel is supplied from the outside, which is oxidized by oxygen, and the energy released is converted into electricity. This principle of operation ensures almost eternal operation.
Since the end of the 19th century, scientists have studied the fuel cell itself and constantly developed new modifications of it. So, today, depending on operating conditions, there are alkaline or alkaline (AFC), direct borohydrate (DBFC), electro-galvanic (EGFC), direct methanol (DMFC), zinc-air (ZAFC), microbial (MFC), models based on formic acid (DFAFC) and metal hydrides (MHFC) are also known.
One of the most promising is the hydrogen fuel cell. The use of hydrogen in power plants is accompanied by a significant release of energy, and the exhaust from such a device is pure water vapor or drinking water, which does not pose any threat to the environment.
The successful testing of fuel cells of this type on spacecraft has recently aroused considerable interest among manufacturers of electronics and various equipment. Thus, the PolyFuel company presented a miniature hydrogen fuel cell for laptops. But the too high cost of such a device and the difficulties in unhindered refueling limit its industrial production and wide distribution. Honda has also been producing automotive fuel cells for over 10 years. However, this type of transport does not go on sale, but only for the official use of company employees. The cars are under the supervision of engineers.
Many people wonder whether it is possible to assemble a fuel cell with their own hands. After all, a significant advantage of a homemade device will be a minor investment, in contrast to an industrial model. For the miniature model, you will need 30 cm of platinum-coated nickel wire, a small piece of plastic or wood, a 9-volt battery clip and the battery itself, clear adhesive tape, a glass of water and a voltmeter. Such a device will allow you to see and understand the essence of the work, but, of course, it will not be possible to generate electricity for the car.
fb.ru
Hydrogen fuel cells: a little history | Hydrogen
Nowadays, the problem of shortage of traditional energy resources and the deterioration of the planet’s ecology as a whole due to their use is particularly acute. That is why, recently, significant financial resources and intellectual resources have been spent on the development of potentially promising substitutes for hydrocarbon fuels. Hydrogen may become such a substitute in the very near future, since its use in power plants is accompanied by the release of a large amount of energy, and the exhaust is water vapor, that is, it does not pose a danger to the environment.
Despite some technical difficulties that still exist in the implementation of hydrogen-based fuel cells, many car manufacturers have appreciated the promise of the technology and are already actively developing prototypes of production cars capable of using hydrogen as the main fuel. Back in two thousand and eleven, Daimler AG presented conceptual Mercedes-Benz models with hydrogen power plants. In addition, the Korean company Hyndayi has officially announced that it no longer intends to develop electric cars, but will concentrate all its efforts on developing an affordable hydrogen car.
Despite the fact that the very idea of using hydrogen as a fuel is not wild for many, most have no idea how fuel cells using hydrogen work and what is so remarkable about them.
To understand the importance of the technology, we suggest looking at the history of hydrogen fuel cells.
The first person to describe the potential of using hydrogen in a fuel cell was a German, Christian Friedrich. Back in 1838, he published his work in a famous scientific journal of the time.
The very next year, a prototype of a workable hydrogen battery was created by a judge from Uhls, Sir William Robert Grove. However, the power of the device was too small even by the standards of that time, so its practical use was out of the question.
As for the term “fuel cell,” it owes its existence to scientists Ludwig Mond and Charles Langer, who in 1889 attempted to create a fuel cell operating on air and coke oven gas. According to other sources, the term was first used by William White Jaques, who first decided to use phosphoric acid in an electrolyte.
In the 1920s, a number of studies were carried out in Germany, which resulted in the discovery of solid oxide fuel cells and ways to use the carbonate cycle. It is noteworthy that these technologies are effectively used in our time.
In 1932, engineer Francis T Bacon began work on directly researching hydrogen-based fuel cells. Before him, scientists used an established scheme - porous platinum electrodes were placed in sulfuric acid. The obvious disadvantage of such a scheme lies, first of all, in its unjustified high cost due to the use of platinum. In addition, the use of caustic sulfuric acid posed a threat to the health, and sometimes even the life, of researchers. Bacon decided to optimize the circuit and replaced platinum with nickel, and used an alkaline composition as the electrolyte.
Thanks to productive work to improve his technology, Bacon already in 1959 presented to the general public his original hydrogen fuel cell, which produced 5 kW and could power a welding machine. He called the presented device “Bacon Cell”.
In October of the same year, a unique tractor was created that ran on hydrogen and produced twenty horsepower.
In the sixties of the twentieth century, the American company General Electric developed the scheme developed by Bacon and applied it to the Apollo and NASA Gemini space programs. Experts from NASA came to the conclusion that using a nuclear reactor is too expensive, technically difficult and unsafe. In addition, we had to abandon the use of batteries together with solar panels due to their large dimensions. The solution to the problem was hydrogen fuel cells, which are capable of supplying the spacecraft with energy and its crew with clean water.
The first bus using hydrogen as fuel was built back in 1993. And prototypes of passenger cars powered by hydrogen fuel cells were presented already in 1997 by such global automobile brands as Toyota and Daimler Benz.
It’s a little strange that a promising environmentally friendly fuel, sold fifteen years ago in a car, has not yet become widespread. There are many reasons for this, the main ones, perhaps, are political and the demands for creating the appropriate infrastructure. Let's hope that hydrogen will still have its say and become a significant competitor to electric cars.(odnaknopka)
energycraft.org
Created 07/14/2012 20:44 Author: Alexey NorkinOur material society without energy cannot not only develop, but even exist at all. Where does the energy come from? Until recently, people used only one way to obtain it; we fought with nature, burning the obtained trophies in the furnaces of first home hearths, then steam locomotives and powerful thermal power plants.
There are no labels on the kilowatt-hours consumed by the modern average person that would indicate how many years nature worked so that civilized man could enjoy the benefits of technology, and how many years she still has to work to smooth out the damage caused to her by such a civilization. However, there is a growing understanding in society that sooner or later the illusory idyll will end. Increasingly, people are inventing ways to provide energy for their needs with minimal damage to nature.
Hydrogen fuel cells are the Holy Grail of clean energy. They process hydrogen, one of the common elements of the periodic table, and release only water, the most common substance on the planet. The rosy picture is spoiled by people's lack of access to hydrogen as a substance. There is a lot of it, but only in a bound state, and extracting it is much more difficult than pumping oil out of the depths or digging up coal.
One of the options for clean and environmentally friendly production of hydrogen is microbial fuel cells (MTB), which use microorganisms to decompose water into oxygen and hydrogen. Not everything is smooth here either. Microbes do an excellent job of producing clean fuel, but to achieve the efficiency required in practice, MTB requires a catalyst that accelerates one of the chemical reactions of the process.
This catalyst is the precious metal platinum, the cost of which makes the use of MTB economically unjustified and practically impossible.
Scientists from the University of Wisconsin-Milwaukee have found a replacement for the expensive catalyst. Instead of platinum, they proposed using cheap nanorods made from a combination of carbon, nitrogen and iron. The new catalyst consists of graphite rods with nitrogen embedded in the surface layer and iron carbide cores. During three months of testing the new product, the catalyst demonstrated capabilities higher than those of platinum. The operation of nanorods turned out to be more stable and controllable.
And most importantly, the brainchild of university scientists is much cheaper. Thus, the cost of platinum catalysts is approximately 60% of the cost of MTB, while the cost of nanorods is within 5% of their current price.
According to the creator of catalytic nanorods, Professor Junhong Chen: “Fuel cells are capable of directly converting fuel into electricity. Together, electrical energy from renewable sources can be delivered where it is needed in a clean, efficient and sustainable manner.”
Professor Chen and his team of researchers are now studying the exact characteristics of the catalyst. Their goal is to give their invention a practical focus, to make it suitable for mass production and use.
Based on materials from Gizmag
www.facepla.net
Hydrogen fuel cells and energy systems
A water-powered car may soon become a reality and hydrogen fuel cells will be installed in many homes...
Hydrogen fuel cell technology is not new. It began in 1776, when Henry Cavendish first discovered hydrogen while dissolving metals in dilute acids. The first hydrogen fuel cell was invented already in 1839 by William Grove. Since then, hydrogen fuel cells have been gradually improved and are now installed in space shuttles, supplying them with energy and serving as a source of water. Today, hydrogen fuel cell technology is on the verge of reaching the mass market, in cars, homes and portable devices.
In a hydrogen fuel cell, chemical energy (in the form of hydrogen and oxygen) is converted directly (without combustion) into electrical energy. A fuel cell consists of a cathode, electrodes and an anode. Hydrogen is fed to the anode, where it is separated into protons and electrons. Protons and electrons have different routes to the cathode. Protons move through the electrode to the cathode, and electrons pass around the fuel cells to get to the cathode. This movement creates subsequently usable electrical energy. On the other side, hydrogen protons and electrons combine with oxygen to form water.
Electrolyzers are one way to extract hydrogen from water. The process is basically the opposite of what happens with a hydrogen fuel cell. The electrolyzer consists of an anode, an electrochemical cell and a cathode. Water and voltage are applied to the anode, which splits the water into hydrogen and oxygen. Hydrogen passes through the electrochemical cell to the cathode and oxygen is supplied directly to the cathode. From there, hydrogen and oxygen can be extracted and stored. During times when electricity is not required to be produced, the accumulated gas can be removed from the storage facility and passed back through the fuel cell.
This system uses hydrogen as fuel, which is probably why there are many myths about its safety. After the explosion of the Hindenburg, many people far from science and even some scientists began to believe that the use of hydrogen is very dangerous. However, recent research has shown that the cause of this tragedy was related to the type of material that was used in the construction, and not to the hydrogen that was pumped inside. After testing the safety of hydrogen storage, it was found that storing hydrogen in fuel cells is safer than storing gasoline in a car fuel tank.
How much do modern hydrogen fuel cells cost? Companies currently offer hydrogen fuel systems that produce power for about $3,000 per kilowatt. Marketing research has established that when the cost drops to $1,500 per kilowatt, consumers in the mass energy market will be ready to switch to this type of fuel.
Hydrogen fuel cell vehicles are still more expensive than internal combustion engine vehicles, but manufacturers are exploring ways to bring the price to comparable levels. In some remote areas where there are no power lines, using hydrogen as a fuel or powering the home independently may be more economical right now than, for example, building infrastructure for traditional energy sources.
Why are hydrogen fuel cells still not widely used? At the moment, their high cost is the main problem for the spread of hydrogen fuel cells. Hydrogen fuel systems simply do not have mass demand at the moment. However, science does not stand still and in the near future a car running on water may become a real reality.
www.tesla-tehnika.biz
Ecology of knowledge. Science and technology: Mobile electronics are improving every year, becoming more widespread and accessible: PDAs, laptops, mobile and digital devices, photo frames, etc. They are all replenished all the time
DIY fuel cell at home
Mobile electronics are improving every year, becoming more widespread and accessible: PDAs, laptops, mobile and digital devices, photo frames, etc. All of them are constantly updated with new functions, larger monitors, wireless communications, stronger processors, while decreasing in size . Power technologies, unlike semiconductor technology, are not advancing by leaps and bounds.
The existing batteries and accumulators to power the achievements of the industry are becoming insufficient, so the issue of alternative sources is very acute. Fuel cells are by far the most promising area. The principle of their operation was discovered back in 1839 by William Grove, who generated electricity by changing the electrolysis of water.
What are fuel cells?
Video: Documentary, fuel cells for transport: past, present, future
Fuel cells are of interest to car manufacturers, and spaceship designers are also interested in them. In 1965, they were even tested by America on the Gemini 5 spacecraft launched into space, and later on Apollo. Millions of dollars are still being invested in fuel cell research today, when there are problems associated with environmental pollution and increasing emissions of greenhouse gases generated during the combustion of fossil fuels, the reserves of which are also not endless.
A fuel cell, often called an electrochemical generator, operates in the manner described below.
Being, like accumulators and batteries, a galvanic element, but with the difference that the active substances are stored in it separately. They are supplied to the electrodes as they are used. Natural fuel or any substance obtained from it burns on the negative electrode, which can be gaseous (hydrogen, for example, and carbon monoxide) or liquid, like alcohols. Oxygen usually reacts at the positive electrode.
But the seemingly simple principle of operation is not easy to translate into reality.
DIY fuel cell
Unfortunately, we do not have photographs of what this fuel element should look like, we rely on your imagination.
You can make a low-power fuel cell with your own hands even in a school laboratory. You need to stock up on an old gas mask, several pieces of plexiglass, alkali and an aqueous solution of ethyl alcohol (more simply, vodka), which will serve as “fuel” for the fuel cell.
First of all, you need a housing for the fuel cell, which is best made from plexiglass, at least five millimeters thick. The internal partitions (there are five compartments inside) can be made a little thinner - 3 cm. To glue plexiglass, use glue of the following composition: six grams of plexiglass shavings are dissolved in one hundred grams of chloroform or dichloroethane (work is done under a hood).
Now you need to drill a hole in the outer wall, into which you need to insert a glass drain tube with a diameter of 5-6 centimeters through a rubber stopper.
Everyone knows that in the periodic table the most active metals are in the lower left corner, and highly active metalloids are in the upper right corner of the table, i.e. the ability to donate electrons increases from top to bottom and from right to left. Elements that can, under certain conditions, manifest themselves as metals or metalloids are in the center of the table.
Now we pour activated carbon from the gas mask into the second and fourth compartments (between the first partition and the second, as well as the third and fourth), which will act as electrodes. To prevent coal from spilling out through the holes, you can place it in nylon fabric (women's nylon stockings are suitable).
The fuel will circulate in the first chamber, and in the fifth there should be an oxygen supplier - air. There will be an electrolyte between the electrodes, and in order to prevent it from leaking into the air chamber, before pouring coal into the fourth chamber for the air electrolyte, you need to soak it with a solution of paraffin in gasoline (ratio of 2 grams of paraffin to half a glass of gasoline). On the layer of coal you need to place (by slightly pressing) copper plates to which the wires are soldered. Through them, the current will be diverted from the electrodes.
All that remains is to charge the element. For this you need vodka, which needs to be diluted with water 1:1. Then carefully add three hundred to three hundred fifty grams of caustic potassium. For the electrolyte, 70 grams of potassium hydroxide is dissolved in 200 grams of water.
The fuel cell is ready for testing. Now you need to simultaneously pour fuel into the first chamber and electrolyte into the third. A voltmeter connected to the electrodes should show from 07 volts to 0.9. To ensure continuous operation of the element, it is necessary to remove spent fuel (drain into a glass) and add new fuel (through a rubber tube). The feed rate is adjusted by squeezing the tube. This is what the operation of a fuel cell looks like under laboratory conditions, the power of which is understandably low.
To ensure greater power, scientists have been working on this problem for a long time. The active steel in development houses methanol and ethanol fuel cells. But, unfortunately, they have not yet been put into practice.
Why the fuel cell is chosen as an alternative power source
A fuel cell was chosen as an alternative power source, since the end product of hydrogen combustion in it is water. The only problem is finding an inexpensive and efficient way to produce hydrogen. Enormous funds invested in the development of hydrogen generators and fuel cells cannot but bear fruit, so a technological breakthrough and their real use in everyday life is only a matter of time.
Already today, the monsters of the automotive industry: General Motors, Honda, Draimler Coyler, Ballard, are demonstrating buses and cars that run on fuel cells, the power of which reaches 50 kW. But the problems associated with their safety, reliability, and cost have not yet been resolved. As already mentioned, unlike traditional power sources - batteries and accumulators, in this case the oxidizer and fuel are supplied from the outside, and the fuel cell is only an intermediary in the ongoing reaction of burning fuel and converting the released energy into electricity. “Combustion” occurs only if the element supplies current to the load, like a diesel electric generator, but without a generator and a diesel engine, and also without noise, smoke and overheating. At the same time, the efficiency is much higher, since there are no intermediate mechanisms.
Great hopes are placed on the use of nanotechnology and nanomaterials, which will help miniaturize fuel cells while increasing their power. There have been reports that ultra-efficient catalysts have been created, as well as designs for fuel cells that do not have membranes. In them, fuel (methane, for example) is supplied to the element along with the oxidizer. Interesting solutions use oxygen dissolved in air as an oxidizer, and organic impurities that accumulate in polluted waters are used as fuel. These are so-called biofuel elements.
Fuel cells, according to experts, may enter the mass market in the coming years. published
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Description:
This article examines in more detail their design, classification, advantages and disadvantages, scope of application, effectiveness, history of creation and modern prospects for use.
Using fuel cells to power buildings
Part 1
This article examines in more detail the principle of operation of fuel cells, their design, classification, advantages and disadvantages, scope of application, efficiency, history of creation and modern prospects for use. In the second part of the article, which will be published in the next issue of the ABOK magazine, provides examples of facilities where various types of fuel cells were used as sources of heat and power supply (or only power supply).
Water can be stored even in both directions in both compressed and liquefied form, but this is also slush, both of which are caused by significant technical problems. This is due to high pressures and extremely low temperatures due to liquefaction. For this reason, for example, a water fuel dispenser stand must be designed differently than we are used to; the end of the filling line connects the robotic arm to a valve on the car. Connecting and filling is quite dangerous, and therefore it is best if it happens without human presence.
Introduction
Fuel cells are a very efficient, reliable, durable and environmentally friendly way to generate energy.
Initially used only in the space industry, fuel cells are now increasingly used in a variety of areas - as stationary power plants, heat and power supplies for buildings, vehicle engines, power supplies for laptops and mobile phones. Some of these devices are laboratory prototypes, some are undergoing pre-production testing or are used for demonstration purposes, but many models are mass-produced and used in commercial projects.
Such a device is in a test run at the airport in Munich, try driving here with individual cars and buses. A high kilogram of mileage is cool, but in practice it is just as important as how many kilograms it will cost, and how much space in the car a strong, insulated fuel tank will take up. Some other problems with water: - create a complex air bath - problem with garages, auto repair shops, etc. - thanks to a small molecule that penetrates every bottleneck, screws and valves - compression and liquefaction require significant energy expenditure.
A fuel cell (electrochemical generator) is a device that converts the chemical energy of fuel (hydrogen) into electrical energy directly through an electrochemical reaction, in contrast to traditional technologies that use the combustion of solid, liquid and gaseous fuels. Direct electrochemical conversion of fuel is very effective and attractive from an environmental point of view, since the operation process produces a minimal amount of pollutants and there is no strong noise or vibration.
The special pressures, compression and set of necessary safety measures have a very good value in the assessment at the end of the water, compared to liquid hydrocarbon fuels, which are produced using lightweight, non-pressurized containers. Therefore, perhaps very urgent circumstances may contribute to his truly flattering pleasure.
In the near future, car manufacturers are still looking for cheaper and relatively less dangerous liquid fuels. The hot melt may be methanol, which can be extracted relatively easily. Its main and only problem is toxicity, on the other hand, like water, methane can be used both in internal combustion engines and in a certain type of fuel chain. It also has some advantages in internal combustion engines, including in terms of emissions.
From a practical point of view, a fuel cell resembles a conventional voltaic battery. The difference is that the battery is initially charged, i.e. filled with “fuel”. During operation, “fuel” is consumed and the battery is discharged. Unlike a battery, a fuel cell uses fuel supplied from an external source to produce electrical energy (Fig. 1).
In this regard, the water can rise to relatively unexpected and yet capable competition. The fuel cell is a source of current generated by an electrochemical reaction. Unlike all our known batteries, it receives reagents and discharges waste constantly, so unlike a battery, it is virtually inexhaustible. Although there are many different types, the following diagram of a hydrogen fuel cell helps us understand how it works.
The fuel is supplied to the positive electrode, where it is oxidized. O2 oxygen enters the negative electrode and can be reduced.
It was even possible to develop a fuel cell that directly burned coal. Since the work of scientists from the Lawrence Livermore Laboratory, which was able to test a fuel cell that directly converts coal into electricity, could be a very important milestone in the development of energy, we will stop at a few words. Coal soil up to 1 micron in size is mixed at 750-850 ° C with molten lithium, sodium or potassium carbonate.
To produce electrical energy, not only pure hydrogen can be used, but also other hydrogen-containing raw materials, for example, natural gas, ammonia, methanol or gasoline. Ordinary air is used as a source of oxygen, also necessary for the reaction.
When using pure hydrogen as a fuel, the reaction products, in addition to electrical energy, are heat and water (or water vapor), i.e., gases that cause air pollution or cause the greenhouse effect are not emitted into the atmosphere. If a hydrogen-containing feedstock, such as natural gas, is used as a fuel, other gases such as carbon and nitrogen oxides will be a by-product of the reaction, but the amount is much lower than when burning the same amount of natural gas.
Then everything is done in the standard way according to the above diagram: oxygen in the air reacts with carbon to carbon dioxide, and energy is released in the form of electricity. Although we know of several different types of fuel cells, they all work according to the principle described. This is a kind of controlled combustion. When we mix hydrogen with oxygen, we get a fission mixture that explodes to form water. Energy is released in the form of heat. A hydrogen fuel cell has the same reaction, the product is also water, but the energy is released as electricity.
The process of chemically converting fuel to produce hydrogen is called reforming, and the corresponding device is called a reformer.
Advantages and disadvantages of fuel cells
Fuel cells are more energy efficient than internal combustion engines because there is no thermodynamic energy efficiency limitation for fuel cells. The efficiency of fuel cells is 50%, while the efficiency of internal combustion engines is 12-15%, and the efficiency of steam turbine power plants does not exceed 40%. By using heat and water, the efficiency of fuel cells is further increased.
The big advantage of a fuel cell is that it produces electricity from fuel one way or another directly, without an intermediate thermal plant, so emissions are lower and efficiency is higher. It reaches 70%, while as a standard we achieve 40% conversion of coal to electricity. Why don't we build giant fuel cells instead of power plants? A fuel cell is a rather complex device that operates at high temperatures, so the requirements for electrode materials and the electrolyte itself are high.
Unlike, for example, internal combustion engines, the efficiency of fuel cells remains very high even when they are not operating at full power. In addition, the power of fuel cells can be increased by simply adding individual units, while the efficiency does not change, i.e. large installations are just as efficient as small ones. These circumstances make it possible to very flexibly select the composition of equipment in accordance with the wishes of the customer and ultimately lead to a reduction in equipment costs.
Electrolytes include, for example, ion exchange membranes or conductive ceramic materials, or rather expensive materials, or phosphoric acid, sodium hydroxide or molten alkali metal carbonates, which are very aggressive to alter tissue. It was this difficulty that, after the initial enthusiasm in the twentieth century, fuel cells, outside of the space program, were not more significant.
Interest then waned again when it became clear that wider use was beyond the capabilities of the technology at the time. However, over the past thirty years, development has not stopped, new materials and concepts have appeared, and our priorities have changed - we now pay much more attention to protecting the environment than then. Therefore, we are experiencing something of a renaissance in fuel cells, which are increasingly being used in many areas. There are 200 such devices around the world. For example, they serve as a backup device where network failure could cause serious problems - for example, in hospitals or military establishments.
An important advantage of fuel cells is their environmental friendliness. Fuel cell emissions are so low that in some areas of the United States, their operation does not require special approval from government air quality regulators.
Fuel cells can be placed directly in a building, reducing losses during energy transportation, and the heat generated as a result of the reaction can be used to supply heat or hot water to the building. Autonomous sources of heat and electricity can be very beneficial in remote areas and in regions characterized by a shortage of electricity and its high cost, but at the same time there are reserves of hydrogen-containing raw materials (oil, natural gas).
They are used in very remote locations where it is easier to transport fuel than to stretch the cable. They may also start competing with power plants. This is the most powerful module installed in the world.
Almost every major automaker is working on a fuel cell electric vehicle project. It appears to be a much more promising concept than a conventional battery electric car because it doesn't require a long charging time and the infrastructure change required is not as extensive.
The advantages of fuel cells are also the availability of fuel, reliability (there are no moving parts in a fuel cell), durability and ease of operation.
One of the main disadvantages of fuel cells today is their relatively high cost, but this disadvantage can soon be overcome - more and more companies are producing commercial samples of fuel cells, they are constantly being improved, and their cost is decreasing.
The growing importance of fuel cells is also illustrated by the fact that the Bush administration has recently rethought its approach to automobile development, and the funds it spent on developing cars with the best possible mileage are now transferred to fuel cell projects. Development financing does not simply remain in the hands of the state.
Of course, the new drive concept is not limited to passenger cars, but we can also find it in mass transit. Fuel cell buses carry passengers on the streets of several cities. Along with car drives, there are a number of smaller ones on the market, such as powered computers, video cameras and mobile phones. In the picture we see a fuel cell to power the traffic alarm.
The most effective way is to use pure hydrogen as a fuel, but this will require the creation of a special infrastructure for its production and transportation. Currently, all commercial models use natural gas and similar fuels. Motor vehicles can use regular gasoline, which will allow maintaining the existing developed network of gas stations. However, the use of such fuel leads to harmful emissions into the atmosphere (albeit very low) and complicates (and therefore increases the cost of) the fuel cell. In the future, the possibility of using environmentally friendly renewable energy sources (for example, solar or wind energy) to decompose water into hydrogen and oxygen using electrolysis, and then converting the resulting fuel in a fuel cell, is being considered. Such combined plants, operating in a closed cycle, can represent a completely environmentally friendly, reliable, durable and efficient source of energy.
Worth mentioning is the use of fuel cells in landfills, where they can burn off gas emissions and help improve the environment in addition to producing electricity. Several test facilities are currently operational, and an extensive installation program of these facilities is being prepared at 150 test sites across the United States. Fuel cells are simply useful devices, and we're sure to see them more and more often.
Chemists have developed a catalyst that could replace expensive platinum in fuel cells. Instead, he uses about two hundred thousand cheap iron. Fuel cells convert chemical energy into electrical energy. Electrons in different molecules have different energies. The energy difference between one molecule and another can be used as a source of energy. Just find a reaction in which electrons move from higher to lower. Such reactions are the main source of energy for living organisms.
Another feature of fuel cells is that they are most efficient when using both electrical and thermal energy simultaneously. However, not every facility has the opportunity to use thermal energy. If fuel cells are used only to generate electrical energy, their efficiency decreases, although it exceeds the efficiency of “traditional” installations.
The best known is respiration, which converts sugars into carbon dioxide and water. In a hydrogen fuel cell, two-atom hydrogen molecules combine with oxygen to form water. The energy difference between the electrons in hydrogen and water is used to generate electricity. Hydrogen cells are probably the most commonly used to drive cars today. Their massive expansion also prevents small hooking.
In order for an energetically rich reaction to take place, a catalyst is needed. Catalysts are molecules that increase the likelihood of a reaction occurring. Without a catalyst, it could also work, but less often or more slowly. Hydrogen cells use precious platinum as a catalyst.
History and modern use of fuel cells
The principle of operation of fuel cells was discovered in 1839. The English scientist William Robert Grove (1811-1896) discovered that the process of electrolysis - the decomposition of water into hydrogen and oxygen through electric current - is reversible, i.e. hydrogen and oxygen can be combined into water molecules without combustion, but with the release of heat and electric current. Grove called the device in which such a reaction was possible a “gas battery,” which was the first fuel cell.
The same reaction that occurs in hydrogen cells also occurs in living cells. Enzymes are relatively large molecules made up of amino acids that can be combined like Lego bricks. Each enzyme has a so-called active site, where the reaction is accelerated. Molecules other than amino acids are also often present at the active site.
In the case of hydrogen acid, this is iron. A team of chemists, led by Morris Bullock of the US Department of Energy's Pacific Laboratory, was able to mimic the reaction at the hydrogenation active site. Like an enzyme, hydrogenation is sufficient for platinum with iron. It can split 0.66 to 2 hydrogen molecules per second. The difference in voltage ranges from 160 to 220 thousand volts. Both are comparable to current platinum catalysts used in hydrogen cells. The reaction is carried out at room temperature.
The active development of technologies for the use of fuel cells began after the Second World War, and it is associated with the aerospace industry. At this time, a search was underway for an effective and reliable, but at the same time quite compact, source of energy. In the 1960s, NASA (National Aeronautics and Space Administration, NASA) specialists chose fuel cells as a power source for the spacecraft of the Apollo (manned flights to the Moon), Apollo-Soyuz, Gemini and Skylab programs. . The Apollo spacecraft used three 1.5 kW (2.2 kW peak) plants using cryogenic hydrogen and oxygen to produce electricity, heat and water. The mass of each installation was 113 kg. These three cells operated in parallel, but the energy generated by one unit was sufficient for a safe return. Over the course of 18 flights, the fuel cells operated for a total of 10,000 hours without any failures. Currently, fuel cells are used in the Space Shuttle, which uses three 12 W units to generate all the electrical energy on board the spacecraft (Fig. 2). The water obtained as a result of the electrochemical reaction is used for drinking water and also for cooling equipment.
One kilogram of iron costs 0.5 CZK. Therefore, iron is 200 thousand times cheaper than platinum. In the future, fuel cells may be cheaper. Expensive platinum is not the only reason why they should not be used, at least not on a large scale. Handling it is difficult and dangerous.
If hydrogen chambers were to be used in bulk to drive cars, they would have to build the same infrastructure as gasoline and diesel. In addition, copper is needed to produce the electric motors that power hydrogen-powered cars. However, this does not mean that fuel cells are useless. When there's oil, maybe we have no choice but to run on hydrogen.
In our country, work was also carried out on the creation of fuel cells for use in astronautics. For example, fuel cells were used to power the Soviet Buran reusable spacecraft.
Development of methods for the commercial use of fuel cells began in the mid-1960s. These developments were partially funded by government organizations.
Currently, the development of technologies for the use of fuel cells is proceeding in several directions. This is the creation of stationary power plants on fuel cells (both for centralized and decentralized energy supply), power plants for vehicles (samples of cars and buses on fuel cells have been created, including in our country) (Fig. 3), and also power supplies for various mobile devices (laptop computers, mobile phones, etc.) (Fig. 4).
Examples of the use of fuel cells in various fields are given in Table. 1.
One of the first commercial fuel cell models designed for autonomous heat and power supply to buildings was the PC25 Model A manufactured by ONSI Corporation (now United Technologies, Inc.). This fuel cell with a rated power of 200 kW is a type of cell with an electrolyte based on phosphoric acid (Phosphoric Acid Fuel Cells, PAFC). The number “25” in the model name means the serial number of the design. Most previous models were experimental or test units, such as the 12.5 kW "PC11" model introduced in the 1970s. The new models increased the power extracted from an individual fuel cell, and also reduced the cost per kilowatt of energy produced. Currently, one of the most efficient commercial models is the PC25 Model C fuel cell. Like Model A, this is a fully automatic 200 kW PAFC fuel cell designed for on-site installation as a self-contained source of heat and power. Such a fuel cell can be installed outside a building. Externally, it is a parallelepiped 5.5 m long, 3 m wide and high, weighing 18,140 kg. The difference from previous models is an improved reformer and a higher current density.
| Table 1 Field of application of fuel cells |
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In some types of fuel cells, the chemical process can be reversed: by applying a potential difference to the electrodes, water can be broken down into hydrogen and oxygen, which collect on the porous electrodes. When a load is connected, such a regenerative fuel cell will begin to produce electrical energy.
A promising direction for the use of fuel cells is their use in conjunction with renewable energy sources, for example, photovoltaic panels or wind power plants. This technology allows us to completely avoid air pollution. A similar system is planned to be created, for example, at the Adam Joseph Lewis Training Center in Oberlin (see ABOK, 2002, No. 5, p. 10). Currently, solar panels are used as one of the energy sources in this building. Together with NASA specialists, a project has been developed for using photovoltaic panels to produce hydrogen and oxygen from water by electrolysis. The hydrogen is then used in fuel cells to produce electrical energy and. This will allow the building to maintain the functionality of all systems during cloudy days and at night.
Operating principle of fuel cells
Let's consider the principle of operation of a fuel cell using the example of a simple element with a proton exchange membrane (Proton Exchange Membrane, PEM). Such a cell consists of a polymer membrane placed between an anode (positive electrode) and a cathode (negative electrode) along with anode and cathode catalysts. The polymer membrane is used as an electrolyte. The diagram of the PEM element is shown in Fig. 5.
A proton exchange membrane (PEM) is a thin (about 2-7 sheets of paper thick) solid organic compound. This membrane functions as an electrolyte: it separates a substance into positively and negatively charged ions in the presence of water.
An oxidation process occurs at the anode, and a reduction process occurs at the cathode. The anode and cathode in a PEM cell are made of a porous material, which is a mixture of carbon and platinum particles. Platinum acts as a catalyst that promotes the dissociation reaction. The anode and cathode are made porous for the free passage of hydrogen and oxygen through them, respectively.
The anode and cathode are placed between two metal plates, which supply hydrogen and oxygen to the anode and cathode, and remove heat and water, as well as electrical energy.
Hydrogen molecules pass through channels in the plate to the anode, where the molecules are decomposed into individual atoms (Fig. 6).
Figure 5. () Schematic of a fuel cell with a proton exchange membrane (PEM cell) |
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Figure 6. () Hydrogen molecules pass through channels in the plate to the anode, where the molecules decompose into individual atoms |
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Figure 7. () As a result of chemisorption in the presence of a catalyst, hydrogen atoms are converted into protons |
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Figure 8. () Positively charged hydrogen ions diffuse through the membrane to the cathode, and a flow of electrons is directed to the cathode through an external electrical circuit to which the load is connected |
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Figure 9. () Oxygen supplied to the cathode, in the presence of a catalyst, enters into a chemical reaction with hydrogen ions from the proton exchange membrane and electrons from the external electrical circuit. As a result of a chemical reaction, water is formed |
Then, as a result of chemisorption in the presence of a catalyst, hydrogen atoms, each giving up one electron e –, are converted into positively charged hydrogen ions H +, i.e. protons (Fig. 7).
Positively charged hydrogen ions (protons) diffuse through the membrane to the cathode, and the flow of electrons is directed to the cathode through an external electrical circuit to which the load (consumer of electrical energy) is connected (Fig. 8).
Oxygen supplied to the cathode, in the presence of a catalyst, enters into a chemical reaction with hydrogen ions (protons) from the proton exchange membrane and electrons from the external electrical circuit (Fig. 9). As a result of a chemical reaction, water is formed.
The chemical reaction in other types of fuel cells (for example, with an acid electrolyte, which uses a solution of orthophosphoric acid H 3 PO 4) is absolutely identical to the chemical reaction in a fuel cell with a proton exchange membrane.
In any fuel cell, some of the energy from a chemical reaction is released as heat.
The flow of electrons in an external circuit is a direct current that is used to do work. Opening the external circuit or stopping the movement of hydrogen ions stops the chemical reaction.
The amount of electrical energy produced by a fuel cell depends on the type of fuel cell, geometric dimensions, temperature, gas pressure. A separate fuel cell provides an EMF of less than 1.16 V. The size of fuel cells can be increased, but in practice several elements connected into batteries are used (Fig. 10).
Fuel cell design
Let's look at the design of a fuel cell using the PC25 Model C as an example. The fuel cell diagram is shown in Fig. eleven.
The PC25 Model C fuel cell consists of three main parts: the fuel processor, the actual power generation section and the voltage converter.
The main part of the fuel cell, the power generation section, is a battery composed of 256 individual fuel cells. The fuel cell electrodes contain a platinum catalyst. These cells produce a constant electrical current of 1,400 amperes at 155 volts. The battery dimensions are approximately 2.9 m in length and 0.9 m in width and height.
Since the electrochemical process takes place at a temperature of 177 °C, it is necessary to heat the battery at the time of start-up and remove heat from it during operation. To achieve this, the fuel cell includes a separate water circuit, and the battery is equipped with special cooling plates.
The fuel processor converts natural gas into hydrogen needed for an electrochemical reaction. This process is called reforming. The main element of the fuel processor is the reformer. In the reformer, natural gas (or other hydrogen-containing fuel) reacts with water vapor at high temperature (900 °C) and high pressure in the presence of a nickel catalyst. In this case, the following chemical reactions occur:
CH 4 (methane) + H 2 O 3H 2 + CO
(the reaction is endothermic, with heat absorption);
CO + H 2 O H 2 + CO 2
(the reaction is exothermic, releasing heat).
The overall reaction is expressed by the equation:
CH 4 (methane) + 2H 2 O 4H 2 + CO 2
(the reaction is endothermic, with heat absorption).
To provide the high temperature required to convert natural gas, a portion of the spent fuel from the fuel cell stack is directed to a burner, which maintains the required reformer temperature.
The steam required for reforming is generated from condensate generated during operation of the fuel cell. This uses the heat removed from the battery of fuel cells (Fig. 12).
The fuel cell stack produces an intermittent direct current that is low voltage and high current. A voltage converter is used to convert it to industrial standard AC current. In addition, the voltage converter unit includes various control devices and safety interlock circuits that allow the fuel cell to be turned off in the event of various failures.
In such a fuel cell, approximately 40% of the fuel energy can be converted into electrical energy. Approximately the same amount, about 40% of the fuel energy, can be converted into thermal energy, which is then used as a heat source for heating, hot water supply and similar purposes. Thus, the total efficiency of such an installation can reach 80%.
An important advantage of such a source of heat and electricity is the possibility of its automatic operation. For maintenance, the owners of the facility where the fuel cell is installed do not need to maintain specially trained personnel - periodic maintenance can be carried out by employees of the operating organization.
Types of fuel cells
Currently, several types of fuel cells are known, differing in the composition of the electrolyte used. The following four types are most widespread (Table 2):
1. Fuel cells with a proton exchange membrane (Proton Exchange Membrane Fuel Cells, PEMFC).
2. Fuel cells based on orthophosphoric acid (Phosphoric Acid Fuel Cells, PAFC).
3. Fuel cells based on molten carbonate (Molten Carbonate Fuel Cells, MCFC).
4. Solid Oxide Fuel Cells (SOFC). Currently, the largest fleet of fuel cells is based on PAFC technology.
One of the key characteristics of different types of fuel cells is operating temperature. In many ways, it is the temperature that determines the area of application of fuel cells. For example, high temperatures are critical for laptops, so proton exchange membrane fuel cells with low operating temperatures are being developed for this market segment.
For autonomous power supply of buildings, fuel cells of high installed power are required, and at the same time there is the possibility of using thermal energy, so other types of fuel cells can be used for these purposes.
Proton exchange membrane fuel cells (PEMFC)
These fuel cells operate at relatively low operating temperatures (60-160 °C). They have a high power density, allow you to quickly adjust the output power, and can be turned on quickly. The disadvantage of this type of element is the high requirements for fuel quality, since contaminated fuel can damage the membrane. The rated power of this type of fuel cells is 1-100 kW.
Proton exchange membrane fuel cells were originally developed by General Electric in the 1960s for NASA. This type of fuel cell uses a solid-state polymer electrolyte called a Proton Exchange Membrane (PEM). Protons can move through the proton exchange membrane, but electrons cannot pass through it, resulting in a potential difference between the cathode and anode. Because of their simplicity and reliability, such fuel cells were used as a power source on the manned Gemini spacecraft.
This type of fuel cell is used as a power source for a wide range of different devices, including prototypes and prototypes, from mobile phones to buses and stationary power systems. The low operating temperature allows such cells to be used to power various types of complex electronic devices. Their use is less effective as a source of heat and electricity supply to public and industrial buildings, where large volumes of thermal energy are required. At the same time, such elements are promising as an autonomous source of power supply for small residential buildings such as cottages built in regions with a hot climate.
| table 2 Types of fuel cells |
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Phosphoric Acid Fuel Cells (PAFC)
Tests of fuel cells of this type were carried out already in the early 1970s. Operating temperature range - 150-200 °C. The main area of application is autonomous sources of heat and electricity supply of medium power (about 200 kW).
These fuel cells use a phosphoric acid solution as the electrolyte. The electrodes are made of paper coated with carbon in which a platinum catalyst is dispersed.
The electrical efficiency of PAFC fuel cells is 37-42%. However, since these fuel cells operate at a fairly high temperature, it is possible to use the steam generated as a result of operation. In this case, the overall efficiency can reach 80%.
To produce energy, hydrogen-containing feedstock must be converted into pure hydrogen through a reforming process. For example, if gasoline is used as fuel, it is necessary to remove sulfur-containing compounds, since sulfur can damage the platinum catalyst.
PAFC fuel cells were the first commercial fuel cells to be used economically. The most common model was the 200 kW PC25 fuel cell manufactured by ONSI Corporation (now United Technologies, Inc.) (Fig. 13). For example, these elements are used as a source of thermal and electrical energy in the police station in Central Park in New York or as an additional source of energy in the Conde Nast Building & Four Times Square. The largest installation of this type is being tested as an 11 MW power plant located in Japan.
Phosphoric acid fuel cells are also used as an energy source in vehicles. For example, in 1994, H-Power Corp., Georgetown University and the US Department of Energy equipped a bus with a 50 kW power plant.
Molten Carbonate Fuel Cells (MCFC)
Fuel cells of this type operate at very high temperatures - 600-700 °C. These operating temperatures allow the fuel to be used directly in the cell itself, without the use of a separate reformer. This process was called “internal reform”. It makes it possible to significantly simplify the design of the fuel cell.
Fuel cells based on molten carbonate require a significant start-up time and do not allow for prompt adjustment of output power, so their main area of application is large stationary sources of thermal and electrical energy. However, they are characterized by high fuel conversion efficiency - 60% electrical efficiency and up to 85% overall efficiency.
In this type of fuel cell, the electrolyte consists of potassium carbonate and lithium carbonate salts heated to approximately 650 °C. Under these conditions, the salts are in a molten state, forming an electrolyte. At the anode, hydrogen reacts with CO 3 ions, forming water, carbon dioxide and releasing electrons, which are sent to the external circuit, and at the cathode, oxygen interacts with carbon dioxide and electrons from the external circuit, again forming CO 3 ions.
Laboratory samples of fuel cells of this type were created in the late 1950s by Dutch scientists G. H. J. Broers and J. A. A. Ketelaar. In the 1960s, engineer Francis T. Bacon, a descendant of the famous English writer and scientist of the 17th century, worked with these cells, which is why MCFC fuel cells are sometimes called Bacon cells. In the NASA Apollo, Apollo-Soyuz, and Scylab programs, these fuel cells were used as a source of energy supply (Fig. 14). During these same years, the US military department tested several samples of MCFC fuel cells produced by Texas Instruments, which used military grade gasoline as fuel. In the mid-1970s, the US Department of Energy began research to create a stationary molten carbonate fuel cell suitable for practical applications. In the 1990s, a number of commercial installations with rated power up to 250 kW were introduced, for example at the US Naval Air Station Miramar in California. In 1996, FuelCell Energy, Inc. launched a pre-production 2 MW plant in Santa Clara, California.
Solid-state oxide fuel cells (SOFC)
Solid-state oxide fuel cells are simple in design and operate at very high temperatures - 700-1,000 °C. Such high temperatures allow the use of relatively “dirty”, unrefined fuel. The same features as those of fuel cells based on molten carbonate determine a similar field of application - large stationary sources of thermal and electrical energy.
Solid oxide fuel cells are structurally different from fuel cells based on PAFC and MCFC technologies. The anode, cathode and electrolyte are made of special grades of ceramics. The most commonly used electrolyte is a mixture of zirconium oxide and calcium oxide, but other oxides can also be used. The electrolyte forms a crystal lattice coated on both sides with porous electrode material. Structurally, such elements are made in the form of tubes or flat boards, which makes it possible to use technologies widely used in the electronics industry in their production. As a result, solid-state oxide fuel cells can operate at very high temperatures, making them advantageous for producing both electrical and thermal energy.
At high operating temperatures, oxygen ions are formed at the cathode, which migrate through the crystal lattice to the anode, where they interact with hydrogen ions, forming water and releasing free electrons. In this case, hydrogen is separated from natural gas directly in the cell, i.e. there is no need for a separate reformer.
The theoretical foundations for the creation of solid-state oxide fuel cells were laid in the late 1930s, when Swiss scientists Emil Bauer and H. Preis experimented with zirconium, yttrium, cerium, lanthanum and tungsten, using them as electrolytes.
The first prototypes of such fuel cells were created in the late 1950s by a number of American and Dutch companies. Most of these companies soon abandoned further research due to technological difficulties, but one of them, Westinghouse Electric Corp. (now Siemens Westinghouse Power Corporation), continued work. The company is currently accepting pre-orders for a commercial model of a tubular solid-state oxide fuel cell, expected to be available this year (Figure 15). The market segment of such elements is stationary installations for the production of thermal and electrical energy with a capacity of 250 kW to 5 MW.
SOFC fuel cells have demonstrated very high reliability. For example, a prototype fuel cell manufactured by Siemens Westinghouse has achieved 16,600 hours of operation and continues to operate, making it the longest continuous fuel cell life in the world.
The high-temperature, high-pressure operating mode of SOFC fuel cells allows for the creation of hybrid plants in which fuel cell emissions drive gas turbines used to generate electrical power. The first such hybrid installation is operating in Irvine, California. The rated power of this installation is 220 kW, of which 200 kW from the fuel cell and 20 kW from the microturbine generator.
Fuel cell is an electrochemical device similar to a galvanic cell, but differs from it in that the substances for the electrochemical reaction are supplied to it from the outside - in contrast to the limited amount of energy stored in a galvanic cell or battery.
Rice. 1. Some fuel cells
Fuel cells convert the chemical energy of fuel into electricity, bypassing ineffective combustion processes that occur with large losses. They convert hydrogen and oxygen into electricity through a chemical reaction. As a result of this process, water is formed and a large amount of heat is released. A fuel cell is very similar to a battery that can be charged and then use the stored electrical energy. The inventor of the fuel cell is considered to be William R. Grove, who invented it back in 1839. This fuel cell used a sulfuric acid solution as an electrolyte and hydrogen as a fuel, which was combined with oxygen in an oxidizing agent. Until recently, fuel cells were used only in laboratories and on spacecraft.
Unlike other power generators, such as internal combustion engines or turbines powered by gas, coal, fuel oil, etc., fuel cells do not burn fuel. This means no noisy high-pressure rotors, no loud exhaust noise, no vibrations. Fuel cells produce electricity through a silent electrochemical reaction. Another feature of fuel cells is that they convert the chemical energy of the fuel directly into electricity, heat and water.
Fuel cells are highly efficient and do not produce large amounts of greenhouse gases such as carbon dioxide, methane and nitrous oxide. The only emissions from fuel cells are water in the form of steam and a small amount of carbon dioxide, which is not released at all if pure hydrogen is used as fuel. Fuel cells are assembled into assemblies and then into individual functional modules.
Fuel cells have no moving parts (at least not within the cell itself) and therefore do not obey Carnot's law. That is, they will have greater than 50% efficiency and are especially effective at low loads. Thus, fuel cell vehicles can become (and have already proven to be) more fuel efficient than conventional vehicles in real-world driving conditions.
The fuel cell produces a constant voltage electric current that can be used to drive the electric motor, lighting, and other electrical systems in the vehicle.
There are several types of fuel cells, differing in the chemical processes used. Fuel cells are usually classified by the type of electrolyte they use.
Some types of fuel cells are promising for power plant propulsion, while others are promising for portable devices or to drive cars.
1. Alkaline fuel cells (ALFC)
Alkaline fuel cell- This is one of the very first elements developed. Alkaline fuel cells (AFC) are one of the most studied technologies, used since the mid-60s of the twentieth century by NASA in the Apollo and Space Shuttle programs. On board these spacecraft, fuel cells produce electrical energy and potable water.
Alkaline fuel cells are one of the most efficient elements used to generate electricity, with power generation efficiency reaching up to 70%.
Alkaline fuel cells use an electrolyte, an aqueous solution of potassium hydroxide, contained in a porous, stabilized matrix. The potassium hydroxide concentration may vary depending on the operating temperature of the fuel cell, which ranges from 65°C to 220°C. The charge carrier in SHTE is the hydroxyl ion (OH-), moving from the cathode to the anode, where it reacts with hydrogen, producing water and electrons. The water produced at the anode moves back to the cathode, again generating hydroxyl ions there. As a result of this series of reactions taking place in the fuel cell, electricity and, as a by-product, heat are produced:
Reaction at the anode: 2H2 + 4OH- => 4H2O + 4e
Reaction at the cathode: O2 + 2H2O + 4e- => 4OH
General reaction of the system: 2H2 + O2 => 2H2O
The advantage of SHTE is that these fuel cells are the cheapest to produce, since the catalyst needed on the electrodes can be any of the substances that are cheaper than those used as catalysts for other fuel cells. In addition, SHTEs operate at relatively low temperatures and are among the most efficient.
One of the characteristic features of SHTE is its high sensitivity to CO2, which may be contained in fuel or air. CO2 reacts with the electrolyte, quickly poisons it, and greatly reduces the efficiency of the fuel cell. Therefore, the use of SHTE is limited to enclosed spaces, such as space and underwater vehicles; they operate on pure hydrogen and oxygen.
2. Molten carbonate fuel cells (MCFC)
Fuel cells with molten carbonate electrolyte are high temperature fuel cells. The high operating temperature allows the direct use of natural gas without a fuel processor and low calorific value fuel gas from industrial processes and other sources. This process was developed in the mid-60s of the twentieth century. Since then, production technology, performance and reliability have been improved.
The operation of RCFC differs from other fuel cells. These cells use an electrolyte made from a mixture of molten carbonate salts. Currently, two types of mixtures are used: lithium carbonate and potassium carbonate or lithium carbonate and sodium carbonate. To melt carbonate salts and achieve a high degree of ion mobility in the electrolyte, fuel cells with molten carbonate electrolyte operate at high temperatures (650°C). Efficiency varies between 60-80%.
When heated to a temperature of 650°C, the salts become a conductor for carbonate ions (CO32-). These ions pass from the cathode to the anode, where they combine with hydrogen to form water, carbon dioxide and free electrons. These electrons are sent through an external electrical circuit back to the cathode, generating electric current and heat as a by-product.
Reaction at the anode: CO32- + H2 => H2O + CO2 + 2e
Reaction at the cathode: CO2 + 1/2O2 + 2e- => CO32-
General reaction of the element: H2(g) + 1/2O2(g) + CO2(cathode) => H2O(g) + CO2(anode)
The high operating temperatures of molten carbonate electrolyte fuel cells have certain advantages. The advantage is the ability to use standard materials (stainless steel sheets and nickel catalyst on the electrodes). The waste heat can be used to produce high pressure steam. High reaction temperatures in the electrolyte also have their advantages. The use of high temperatures requires a long time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. These characteristics allow the use of fuel cell installations with molten carbonate electrolyte under constant power conditions. High temperatures prevent damage to the fuel cell by carbon monoxide, “poisoning,” etc.
Fuel cells with molten carbonate electrolyte are suitable for use in large stationary installations. Thermal power plants with an electrical output power of 2.8 MW are commercially produced. Installations with output power up to 100 MW are being developed.
3. Phosphoric acid fuel cells (PAFC)
Fuel cells based on phosphoric (orthophosphoric) acid became the first fuel cells for commercial use. This process was developed in the mid-60s of the twentieth century, tests have been carried out since the 70s of the twentieth century. The result was increased stability and performance and reduced cost.
Phosphoric (orthophosphoric) acid fuel cells use an electrolyte based on orthophosphoric acid (H3PO4) at concentrations up to 100%. The ionic conductivity of phosphoric acid is low at low temperatures, so these fuel cells are used at temperatures up to 150-220 °C.
The charge carrier in fuel cells of this type is hydrogen (H+, proton). A similar process occurs in proton exchange membrane fuel cells (PEMFCs), in which hydrogen supplied to the anode is split into protons and electrons. Protons travel through the electrolyte and combine with oxygen from the air at the cathode to form water. The electrons are sent through an external electrical circuit, thereby generating an electric current. Below are reactions that generate electric current and heat.
Reaction at the anode: 2H2 => 4H+ + 4e
Reaction at the cathode: O2(g) + 4H+ + 4e- => 2H2O
General reaction of the element: 2H2 + O2 => 2H2O
The efficiency of fuel cells based on phosphoric (orthophosphoric) acid is more than 40% when generating electrical energy. With combined production of heat and electricity, the overall efficiency is about 85%. In addition, given operating temperatures, waste heat can be used to heat water and generate atmospheric pressure steam.
The high performance of thermal power plants using fuel cells based on phosphoric (orthophosphoric) acid in the combined production of thermal and electrical energy is one of the advantages of this type of fuel cells. The units use carbon monoxide with a concentration of about 1.5%, which significantly expands the choice of fuel. Simple design, low degree of electrolyte volatility and increased stability are also advantages of such fuel cells.
Thermal power plants with electrical output power of up to 400 kW are commercially produced. Installations with a capacity of 11 MW have passed appropriate tests. Installations with output power up to 100 MW are being developed.
4. Proton exchange membrane fuel cells (PEMFC)
Proton exchange membrane fuel cells are considered the best type of fuel cells for generating power for vehicles, which can replace gasoline and diesel internal combustion engines. These fuel cells were first used by NASA for the Gemini program. Installations based on MOPFC with power from 1 W to 2 kW have been developed and demonstrated.
The electrolyte in these fuel cells is a solid polymer membrane (a thin film of plastic). When saturated with water, this polymer allows protons to pass through but does not conduct electrons.
The fuel is hydrogen, and the charge carrier is a hydrogen ion (proton). At the anode, the hydrogen molecule is split into a hydrogen ion (proton) and electrons. Hydrogen ions pass through the electrolyte to the cathode, and electrons move around the outer circle and produce electrical energy. Oxygen, which is taken from the air, is supplied to the cathode and combines with electrons and hydrogen ions to form water. The following reactions occur at the electrodes: Reaction at the anode: 2H2 + 4OH- => 4H2O + 4eReaction at the cathode: O2 + 2H2O + 4e- => 4OH Overall cell reaction: 2H2 + O2 => 2H2O Compared to other types of fuel cells, fuel cells with a proton exchange membrane produce more energy for a given volume or weight of the fuel cell. This feature allows them to be compact and lightweight. In addition, the operating temperature is less than 100°C, which allows you to quickly start operation. These characteristics, as well as the ability to quickly change energy output, are just a few that make these fuel cells a prime candidate for use in vehicles.
Another advantage is that the electrolyte is a solid rather than a liquid. It is easier to retain gases at the cathode and anode using a solid electrolyte, so such fuel cells are cheaper to produce. With a solid electrolyte, there are no orientation issues and fewer corrosion problems, increasing the longevity of the cell and its components.
5. Solid oxide fuel cells (SOFC)
Solid oxide fuel cells are the highest operating temperature fuel cells. The operating temperature can vary from 600°C to 1000°C, allowing the use of different types of fuel without special pre-treatment. To handle such high temperatures, the electrolyte used is a thin solid metal oxide on a ceramic base, often an alloy of yttrium and zirconium, which is a conductor of oxygen ions (O2-). The technology of using solid oxide fuel cells has been developing since the late 50s of the twentieth century and has two configurations: planar and tubular.
The solid electrolyte provides a sealed transition of gas from one electrode to another, while liquid electrolytes are located in a porous substrate. The charge carrier in fuel cells of this type is the oxygen ion (O2-). At the cathode, oxygen molecules from the air are separated into an oxygen ion and four electrons. Oxygen ions pass through the electrolyte and combine with hydrogen, creating four free electrons. The electrons are sent through an external electrical circuit, generating electric current and waste heat.
Reaction at the anode: 2H2 + 2O2- => 2H2O + 4e
Reaction at the cathode: O2 + 4e- => 2O2-
General reaction of the element: 2H2 + O2 => 2H2O
The efficiency of electrical energy production is the highest of all fuel cells - about 60%. In addition, high operating temperatures allow for the combined production of thermal and electrical energy to generate high-pressure steam. Combining a high-temperature fuel cell with a turbine makes it possible to create a hybrid fuel cell to increase the efficiency of generating electrical energy by up to 70%.
Solid oxide fuel cells operate at very high temperatures (600°C-1000°C), resulting in significant time required to reach optimal operating conditions and a slower system response to changes in energy consumption. At such high operating temperatures, no converter is required to recover hydrogen from the fuel, allowing the thermal power plant to operate with relatively impure fuels resulting from gasification of coal or waste gases, etc. The fuel cell is also excellent for high power applications, including industrial and large central power plants. Modules with an electrical output power of 100 kW are commercially produced.
6. Direct methanol oxidation fuel cells (DOMFC)
Direct methanol oxidation fuel cells They are successfully used in the field of powering mobile phones, laptops, as well as to create portable power sources, which is what the future use of such elements is aimed at.
The design of fuel cells with direct oxidation of methanol is similar to the design of fuel cells with a proton exchange membrane (MEPFC), i.e. A polymer is used as an electrolyte, and a hydrogen ion (proton) is used as a charge carrier. But liquid methanol (CH3OH) oxidizes in the presence of water at the anode, releasing CO2, hydrogen ions and electrons, which are sent through an external electrical circuit, thereby generating an electric current. Hydrogen ions pass through the electrolyte and react with oxygen from the air and electrons from the external circuit to form water at the anode.
Reaction at the anode: CH3OH + H2O => CO2 + 6H+ + 6eReaction at the cathode: 3/2O2 + 6H+ + 6e- => 3H2O General reaction of the element: CH3OH + 3/2O2 => CO2 + 2H2O The development of such fuel cells has been carried out since the beginning of the 90s s of the twentieth century and their specific power and efficiency were increased to 40%.
These elements were tested in the temperature range of 50-120°C. Because of their low operating temperatures and the absence of the need for a converter, such fuel cells are a prime candidate for use in mobile phones and other consumer products, as well as in car engines. Their advantage is also their small size.
7. Polymer electrolyte fuel cells (PEFC)
In the case of polymer electrolyte fuel cells, the polymer membrane consists of polymer fibers with water regions in which conduction water ions H2O+ (proton, red) attaches to a water molecule. Water molecules pose a problem due to slow ion exchange. Therefore, a high concentration of water is required both in the fuel and at the outlet electrodes, which limits the operating temperature to 100°C.
8. Solid acid fuel cells (SFC)
In solid acid fuel cells, the electrolyte (CsHSO4) does not contain water. The operating temperature is therefore 100-300°C. The rotation of the SO42 oxyanions allows the protons (red) to move as shown in the figure. Typically, a solid acid fuel cell is a sandwich in which a very thin layer of solid acid compound is sandwiched between two electrodes that are tightly pressed together to ensure good contact. When heated, the organic component evaporates, exiting through the pores in the electrodes, maintaining the ability of multiple contacts between the fuel (or oxygen at the other end of the element), the electrolyte and the electrodes.
9. Comparison of the most important characteristics of fuel cells
Fuel cell type | Operating temperature | Power generation efficiency | Fuel type | Scope of application |
Medium and large installations |
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Pure hydrogen | installations |
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Pure hydrogen | Small installations |
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Most hydrocarbon fuels | Small, medium and large installations |
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Portable installations |
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Pure hydrogen | Space researched |
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Pure hydrogen | Small installations |
10. Use of fuel cells in cars
A fuel cell is an electrochemical energy conversion device that converts hydrogen and oxygen into electricity through a chemical reaction. As a result of this process, water is formed and a large amount of heat is released. A fuel cell is very similar to a battery that can be charged and then use the stored electrical energy.
William R. Grove is considered the inventor of the fuel cell, who invented it back in 1839. In this fuel cell, a solution of sulfuric acid was used as an electrolyte, and hydrogen was used as a fuel, which was combined with oxygen in an oxidizing agent. It should be noted that until recently, fuel cells were used only in laboratories and on spacecraft.
In the future, fuel cells will be able to compete with many other energy conversion systems (including gas turbines in power plants), internal combustion engines in cars and electric batteries in portable devices. Internal combustion engines burn fuel and use the pressure created by the expansion of combustion gases to perform mechanical work. Batteries store electrical energy, then convert it into chemical energy, which can be converted back into electrical energy if necessary. Fuel cells are potentially very efficient. Back in 1824, the French scientist Carnot proved that the compression-expansion cycles of an internal combustion engine cannot ensure an efficiency of conversion of thermal energy (which is the chemical energy of burning fuel) into mechanical energy above 50%. A fuel cell has no moving parts (at least not within the cell itself) and therefore they do not obey Carnot's law. Naturally, they will have greater than 50% efficiency and are especially effective at low loads. Thus, fuel cell vehicles are poised to become (and have already proven to be) more fuel efficient than conventional vehicles in real-world driving conditions.
The fuel cell produces a constant voltage electric current that can be used to drive the electric motor, lighting, and other electrical systems in the vehicle. There are several types of fuel cells, differing in the chemical processes used. Fuel cells are usually classified by the type of electrolyte they use. Some types of fuel cells are promising for power plant propulsion, while others may be useful for small portable devices or for powering cars.
The alkaline fuel cell is one of the very first cells developed. They have been used in the US space program since the 1960s. Such fuel cells are very susceptible to contamination and therefore require very pure hydrogen and oxygen. They are also very expensive, meaning this type of fuel cell will likely not see widespread use in automobiles.
Fuel cells based on phosphoric acid can find application in stationary low-power installations. They operate at fairly high temperatures and therefore take a long time to warm up, which also makes them ineffective for use in cars.
Solid oxide fuel cells are better suited for large stationary power generators that could supply power to factories or communities. This type of fuel cell operates at very high temperatures (around 1000 °C). The high operating temperature creates certain problems, but on the other hand there is an advantage - the steam produced by the fuel cell can be sent to turbines to generate more electricity. Overall, this improves the overall efficiency of the system.
One of the most promising systems is the proton exchange membrane fuel cell (PEMFC - Protone Exchange Membrane Fuel Cell). Currently, this type of fuel cell is the most promising because it can power cars, buses and other vehicles.
Chemical processes in a fuel cell
Fuel cells use an electrochemical process to combine hydrogen with oxygen obtained from the air. Like batteries, fuel cells use electrodes (solid electrical conductors) in an electrolyte (an electrically conductive medium). When hydrogen molecules come into contact with the negative electrode (anode), the latter are separated into protons and electrons. Protons pass through a proton exchange membrane (POEM) to the positive electrode (cathode) of the fuel cell, producing electricity. A chemical combination of hydrogen and oxygen molecules occurs to form water as a byproduct of this reaction. The only type of emissions from a fuel cell is water vapor.
The electricity produced by fuel cells can be used in a vehicle's electric powertrain (consisting of an electrical power converter and an AC induction motor) to provide mechanical energy to propel the vehicle. The job of an electric power converter is to convert the direct current produced by the fuel cells into alternating current that runs the vehicle's traction motor.
Diagram of a fuel cell with a proton exchange membrane:
1 - anode;
2 - proton exchange membrane (PEM);
3 - catalyst (red);
4 - cathode
Proton exchange membrane fuel cell (PEMFC) uses one of the simplest reactions of any fuel cell.
Single cell fuel cell
Let's look at how a fuel cell works. The anode, the negative terminal of the fuel cell, conducts electrons that are freed from hydrogen molecules so that they can be used in the external electrical circuit. To do this, channels are engraved in it, distributing hydrogen evenly over the entire surface of the catalyst. The cathode (positive pole of the fuel cell) has etched channels that distribute oxygen across the surface of the catalyst. It also conducts electrons back from the outer loop (circuit) to the catalyst, where they can combine with hydrogen ions and oxygen to form water. The electrolyte is a proton exchange membrane. This is a special material that is similar to ordinary plastic, but has the ability to allow positively charged ions to pass through and block the passage of electrons.
A catalyst is a special material that facilitates the reaction between oxygen and hydrogen. The catalyst is usually made from platinum powder applied in a very thin layer to carbon paper or cloth. The catalyst must be rough and porous so that its surface can come into maximum contact with hydrogen and oxygen. The platinum-coated side of the catalyst is in front of the proton exchange membrane (PEM).
Hydrogen gas (H2) is supplied to the fuel cell under pressure from the anode. When an H2 molecule comes into contact with platinum on the catalyst, it splits into two parts, two ions (H+) and two electrons (e–). The electrons are conducted through the anode, where they pass through an external loop (circuit) doing useful work (such as driving an electric motor) and return at the cathode side of the fuel cell.
Meanwhile, on the cathode side of the fuel cell, oxygen gas (O 2 ) is forced through the catalyst, where it forms two oxygen atoms. Each of these atoms has a strong negative charge, which attracts two H+ ions across the membrane, where they combine with an oxygen atom and two electrons from the outer circuit to form a water molecule (H 2 O).
This reaction in a single fuel cell produces approximately 0.7 W of power. To raise power to the required level, many individual fuel cells must be combined to form a fuel cell stack.
POM fuel cells operate at relatively low temperatures (around 80°C), meaning they can be quickly brought up to operating temperature and do not require expensive cooling systems. Continuous improvements in the technologies and materials used in these cells have brought their power closer to the point where a battery of such fuel cells, occupying a small part of the trunk of a car, can provide the energy needed to drive the car.
Over the past years, most of the world's leading automobile manufacturers have been investing heavily in the development of vehicle designs that use fuel cells. Many have already demonstrated fuel cell vehicles with satisfactory power and performance characteristics, although they were quite expensive.
The improvement of the designs of such cars is very intensive.
Fuel cell vehicle uses a power plant located under the vehicle's floor
The NECAR V is based on a Mercedes-Benz A-class car, with the entire power plant, along with fuel cells, located under the floor of the car. This design solution makes it possible to accommodate four passengers and luggage in the car. Here, not hydrogen, but methanol is used as fuel for the car. Methanol, using a reformer (a device that converts methanol into hydrogen), is converted into hydrogen necessary to power the fuel cell. Using a reformer on board a car makes it possible to use almost any hydrocarbons as fuel, which allows you to refuel a fuel cell car using the existing network of gas stations. In theory, fuel cells produce nothing but electricity and water. Converting fuel (gasoline or methanol) into hydrogen required for a fuel cell somewhat reduces the environmental appeal of such a car.
Honda, which has been involved in fuel cells since 1989, produced a small batch of Honda FCX-V4 vehicles in 2003 with Ballard membrane-type proton exchange fuel cells. These fuel cells generate 78 kW of electrical power, and traction electric motors with a power of 60 kW and a torque of 272 Nm are used to drive the drive wheels. A fuel cell car, compared to a traditional car, has a weight of approximately 40% less, which ensures it has excellent dynamics, and the supply of compressed hydrogen allows it to run up to 355 km.
The Honda FCX uses electric energy generated by fuel cells to drive.
The Honda FCX is the world's first fuel cell vehicle to receive government certification in the United States. The car is certified according to ZEV - Zero Emission Vehicle standards. Honda is not going to sell these cars yet, but is leasing about 30 cars per unit. California and Tokyo, where hydrogen refueling infrastructure already exists.
General Motors' Hy Wire concept vehicle has a fuel cell powertrain
General Motors is conducting extensive research into the development and creation of fuel cell vehicles.
Hy Wire car chassis
The GM Hy Wire concept car was issued 26 patents. The basis of the car is a functional platform 150 mm thick. Inside the platform are hydrogen tanks, a fuel cell powertrain and vehicle control systems using the latest drive-by-wire technologies. The Hy Wire vehicle's chassis is a thin platform that encloses all of the vehicle's major structural elements: hydrogen tanks, fuel cells, batteries, electric motors and control systems. This approach to design makes it possible to change car bodies during operation. The company is also testing prototype Opel fuel cell cars and designing a plant for the production of fuel cells.
Design of a "safe" liquefied hydrogen fuel tank:
1 - filling device;
2 - external tank;
3 - supports;
4 - level sensor;
5 - internal tank;
6 - filling line;
7 - insulation and vacuum;
8 - heater;
9 - mounting box
BMW pays a lot of attention to the problem of using hydrogen as a fuel for cars. Together with Magna Steyer, renowned for its work on the use of liquefied hydrogen in space exploration, BMW has developed a fuel tank for liquefied hydrogen that can be used in cars.
Tests have confirmed the safety of using a liquid hydrogen fuel tank
The company conducted a series of tests for the safety of the structure using standard methods and confirmed its reliability.
In 2002, at the motor show in Frankfurt am Main (Germany), the Mini Cooper Hydrogen, which uses liquefied hydrogen as fuel, was shown. The fuel tank of this car takes up the same space as a regular gas tank. Hydrogen in this car is not used for fuel cells, but as fuel for the internal combustion engine.
The world's first production car with a fuel cell instead of a battery
In 2003, BMW announced the production of the first production car with a fuel cell, the BMW 750 hL. A fuel cell battery is used instead of a traditional battery. This car has a 12-cylinder internal combustion engine running on hydrogen, and the fuel cell serves as an alternative to a conventional battery, allowing the air conditioner and other electrical consumers to operate when the car is parked for long periods without the engine running.
Hydrogen filling is carried out by a robot, the driver is not involved in this process
The same BMW company has also developed robotic refueling dispensers that provide fast and safe refueling of cars with liquefied hydrogen.
The emergence in recent years of a large number of developments aimed at creating cars using alternative fuels and alternative powertrains suggests that the internal combustion engines, which have dominated cars for the past century, will eventually give way to cleaner, more efficient and silent designs. Their widespread adoption is currently constrained not by technical, but rather by economic and social problems. For their widespread use, it is necessary to create a certain infrastructure for the development of the production of alternative fuels, the creation and distribution of new gas stations and to overcome a number of psychological barriers. The use of hydrogen as a vehicle fuel will require addressing storage, delivery and distribution issues, with serious safety measures in place.
Hydrogen is theoretically available in unlimited quantities, but its production is very energy intensive. In addition, to convert cars to run on hydrogen fuel, it is necessary to make two big changes to the power system: first, switching its operation from gasoline to methanol, and then, over some time, to hydrogen. It will be some time before this issue is resolved.
Horizon: Zero Dawn | 2017-03-14
In Horizon: Zero Dawn you can find 5 fuel cells to complete the quest Ancient Arsenal for which they give Shield Weaver- the best armor set in the game.
Horizon: Zero Dawn - where to find fuel cells
You will find your first power supply early in the game. You have to go to Ruin, which Aloy remembers from childhood. This point is marked on the map with a green marker, and you need to head towards it. You can enter the ruins through a small hole in the ground. Your task is to go down to the first level.
It is almost impossible to get lost in the ruins, but be extremely careful. Sometimes you will have to go down the stairs, find doors and break stalactites.
The fuel cell is on the table and has a green icon. 
The second element can be found after completing the mission "Heart of Nora". Early on you will find a door with a switch, use it, unlock the door and continue on your way. Turn right, and then follow the door that is ahead.
After this, you will find a holo-lock, which you will not be able to open. To the left of it you can see a hole with candles inside. Move in this direction and soon you will find an element lying on the ground. 
The third element can be found during the mission "Master's Limit". One of the mission tasks will be to climb a tall building. And once at the top, you will receive a new assignment - to find information in Faro's office.
When you reach the right place, do not follow forward. Turn around and climb the wall ahead. Once you find a fuel cell, you can put it in your inventory and continue completing the task. 
Fourth fuel cell
The fourth element can be found during the mission "Treasure of Death". After you solve the holo-lock problem, go to the third floor, follow the stairs and you will soon find the right place. On the left in the corridor there will be a door with a holo-lock. Inside this room is the fuel cell. 
The fifth element can be found during the mission "Fallen Mountain". At a certain moment you will find yourself in a huge cave, after which you should not go down to the very bottom. Turn around and you will see a rock in front of you that you need to climb. At the top you will see a tunnel with a purple glow, go into it and follow it to the very end. The power cell will be waiting for you on the shelf. 
Very soon (more precisely, at the beginning of her fascinating adventure), the main character will stumble upon the Forerunner bunker, which is located very close to the lands of the Nora tribe. Inside this ancient bunker, behind a powerful and high-tech door, there will be armor that from a distance looks not only decent, but also very attractive. The armor is called "Shield Weaver" and it is actually the best equipment in the game. Therefore, a lot of questions immediately arise: “How to find and obtain the Shield Weaver armor?”, “Where to find fuel?”, “How to open the bunker doors?” and many other questions related to the same topic. So, in order to open the bunker doors and get the coveted armor, you need to find five fuel cells, which in turn will be scattered throughout the game world. Below I will tell you where and how to find fuel cells to solve puzzles during the search and in the Ancient Arsenal.
: The presented guide not only has a detailed text walkthrough, but also screenshots are attached to each fuel cell, and there is a video at the end. All this was created in order to facilitate your search, so if some point in the text passage is not clear, then I recommend watching the screenshots and video.
. First fuel - "Mother's Heart"
Where and how to find the first fuel cell - fuel location.
So, Aloy will be able to find the very first fuel cell (or, more simply put, fuel) long before entering the open world on the assignment “The Womb of the Mother.” The point is that after the “Initiation” task (which, by the way, also relates to the storyline), the main character will find herself in a place called “Mother’s Heart,” which is a sacred place for the Nora tribe and the abode of the Matriarchs.
As soon as the girl gets out of bed, sequentially go through several rooms (rooms), where in one of them you will come across a sealed door that you simply cannot open. At this moment, I strongly recommend that you look around, because next to the heroine (or near the doors - whichever is more convenient) there is a ventilation shaft, decorated with burning candles (in general, this is where you need to go).
After you pass a certain part of the way along the ventilation shaft, the heroine will find herself behind a locked door. Look at the floor next to the wall block and candles of mysterious purpose - the first fuel cell lies in this place.
: Be sure to remember that if you do not pick up the first fuel cell before entering the open world, then after that you will only be able to get to this location in the later stages of the passage. But to be more precise, after completing the mission “Heart of Nora,” so I recommend picking up the fuel now.
. Second fuel - "Ruins"
Where and how to find the second fuel cell - fuel location.
The first thing you need to know when searching for the second fuel: the main character was already in this location when she fell into ruins a long time ago as a child (at the very beginning of the game). So after completing the “Initiation” task, you will have to remember your deep childhood and go down to this place one more time to get the second fuel cell.
Below are several pictures (screenshots). The first picture shows the entrance to the ruins (in red). Inside the ruins, you will need to get to the first level - this is the lower right area, which will be highlighted in purple on the map. In addition, there will also be a door that the girl can open with her spear.
As soon as Aloy passes through the doors, go up the stairs and turn to the right at the first opportunity: in her deep youth, Aloy could not crawl through the stalactites, but now she has useful “toys” that can cope with any task. So, take out your spear and use it to break the stalactites. Soon the path will be clear, so all that remains is to take the fuel cell that lies on the table and go for the next one. If any moment of the passage is not clear, then screenshots are attached below in order.
. Third fuel - "Master's Limit"
Where and how to find the third fuel cell - fuel location.
It's time to head north. During the quest “Master's Limit,” Aloy will have to carefully explore and study the giant ruins of the Forerunners. So in these ruins on the twelfth level the next, third fuel cell will be hidden.
Therefore, you will have to climb not only to the upper level of these ruins, but also climb a little higher there. Don't waste precious time and climb higher along the surviving part of the building. Climb up until you find yourself on a small platform open to all winds. Then everything is simple, because at the top there will be a third element of fuel: no puzzles, no riddles or secrets. So take the fuel, go down and move on.
. Fourth fuel - “Treasure of Death”
Where and how to find the fourth fuel cell - fuel location.
The good news is that this fuel cell is also located in the northern part of the Horizon: Zero Dawn map, but it is a little closer to the lands of the Nora tribe. The main character will again find herself in this part of the map during the next story mission. But before getting to the penultimate fuel cell, Aloy will need to restore the power supply to the sealed door, which is located on the third level of the location. Moreover, to do this you will need to solve a small and not too complex puzzle. The puzzle involves blocks and regulators (there are two blocks of four regulators on the level below the doors). So, to begin with, I recommend that you deal with the left block of regulators: the first regulator should be raised (look) up, the second - to the right, the third - to the left, the fourth - down.
After that, go to the block on the right side. Do not touch the first two regulators, but the third and fourth regulators will need to be turned down. Therefore, go up one level - here is the last block of regulators. The correct order would be: 1 - up, 2 - down, 3 - left, 4 - right.
Once you do everything correctly, the controls will change color from white to turquoise. Thus, power supply will be restored. Therefore, go back to the doors and open it. Outside the doors, the heroine will be “greeted” by the penultimate fuel cell, so she can go for the next, last fuel.
. Fifth fuel - "GAIA Prime"
Where and how to find the fifth fuel cell - fuel location.
Finally the last fuel cell. And again, it can only be obtained during the passage of the storyline. This time the main character will have to go to the ruins called “GAIA Prime”. This is where you need to pay special attention when you find yourself near the third level. The point is that at a certain moment the girl will face an attractive abyss into which she can descend using a rope, although she should not go there.
Before the abyss, you should turn to the left and first explore a cave hidden from view: you can get into it if you carefully go down the mountainside. Go inside and then move forward until the very end. In the last room in the room on the right side there will be a shelf on which the last fuel cell finally lies. Together with him, you can now safely return back to the bunker and open all the locks to get luxurious equipment.
. How to get into the Ancient Arsenal?
Well, now all that remains is to return to the Ancient Arsenal to receive the long-awaited reward. If you don’t remember the corridors of the arsenal, then look at the screenshots below, which will help you remember the whole path.
When you get to the right place and go down, insert the fuel cells into the empty cells. This will cause the regulators to light up, so there is a new puzzle to solve to open the doors. So, the first regulator should be directed up, the second - to the right, the third - down, the fourth - to the left, the fifth - up. Once you do everything right, doors will open, but it's far from over.
Next you have to unlock the lock (or fastenings) of the armor - this is another simple puzzle related to the regulators, in which you have to use the remaining fuel cells. The first knob should be turned to the right, the second to the left, the third to up, the fourth to the right, the fifth to the left again.
Finally, after all this long torment, it will be possible to take the armor. “Shield Weaver” is a very good piece of equipment that makes the main character virtually invulnerable for a while. The most important thing is to constantly monitor the color of the armor: if the armor flickers white, then everything is in order. If it's red, the shield is gone.
They operate the spacecraft of the US National Aeronautics and Space Administration (NASA). They provide power to the computers of the First National Bank in Omaha. They are used on some public city buses in Chicago.
These are all fuel cells. Fuel cells are electrochemical devices that produce electricity without combustion - chemically, in much the same way as batteries. The only difference is that they use different chemicals, hydrogen and oxygen, and the product of the chemical reaction is water. Natural gas can also be used, but when using hydrocarbon fuels, of course, a certain level of carbon dioxide emissions is inevitable.
Because fuel cells can operate with high efficiency and no harmful emissions, they hold great promise as a sustainable energy source that will help reduce emissions of greenhouse gases and other pollutants. The main obstacle to widespread use of fuel cells is their high cost compared to other devices that generate electricity or propel vehicles.
History of development
The first fuel cells were demonstrated by Sir William Groves in 1839. Groves showed that the process of electrolysis - the splitting of water into hydrogen and oxygen under the influence of an electric current - is reversible. That is, hydrogen and oxygen can be combined chemically to form electricity.
After this was demonstrated, many scientists rushed to study fuel cells with zeal, but the invention of the internal combustion engine and the development of oil reserve infrastructure in the second half of the nineteenth century left the development of fuel cells far behind. The development of fuel cells was further hampered by their high cost.
A surge in the development of fuel cells occurred in the 50s, when NASA turned to them in connection with the need for a compact electric generator for space flights. The investment was made and the Apollo and Gemini flights were powered by fuel cells. Spacecraft also run on fuel cells.
Fuel cells are still largely an experimental technology, but several companies are already selling them on the commercial market. In the last nearly ten years alone, significant advances have been made in commercial fuel cell technology.
How does a fuel cell work?
Fuel cells are similar to batteries - they produce electricity through a chemical reaction. In contrast, internal combustion engines burn fuel and thus produce heat, which is then converted into mechanical energy. Unless the heat from the exhaust gases is used in some way (for example, for heating or air conditioning), then the efficiency of the internal combustion engine can be said to be quite low. For example, the efficiency of fuel cells when used in a vehicle, a project currently under development, is expected to be more than twice the efficiency of today's typical gasoline engines used in automobiles.
Although both batteries and fuel cells produce electricity chemically, they perform two very different functions. Batteries are stored energy devices: the electricity they produce is the result of a chemical reaction of a substance that is already inside them. Fuel cells do not store energy, but rather convert some of the energy from externally supplied fuel into electricity. In this respect, a fuel cell is more like a conventional power plant.
There are several different types of fuel cells. The simplest fuel cell consists of a special membrane known as an electrolyte. Powdered electrodes are applied on both sides of the membrane. This design - an electrolyte surrounded by two electrodes - is a separate element. Hydrogen goes to one side (anode), and oxygen (air) to the other (cathode). Different chemical reactions occur at each electrode.
At the anode, hydrogen breaks down into a mixture of protons and electrons. In some fuel cells, the electrodes are surrounded by a catalyst, usually made of platinum or other noble metals, which promotes the dissociation reaction:
2H2 ==> 4H+ + 4e-.
H2 = diatomic hydrogen molecule, form, in
in which hydrogen is present in the form of a gas;
H+ = ionized hydrogen, i.e. proton;
e- = electron.
The operation of a fuel cell is based on the fact that the electrolyte allows protons to pass through it (towards the cathode), but electrons do not. Electrons move to the cathode along an external conductive circuit. This movement of electrons is an electrical current that can be used to drive an external device connected to the fuel cell, such as an electric motor or light bulb. This device is usually called a "load".
At the cathode side of the fuel cell, protons (that have passed through the electrolyte) and electrons (that have passed through the external load) are “recombined” and react with the oxygen supplied to the cathode to form water, H2O:
4H+ + 4e- + O2 ==> 2H2O.
The total reaction in a fuel cell is written as follows:
2H2 + O2 ==> 2H2O.
In their work, fuel cells use hydrogen fuel and oxygen from the air. Hydrogen can be supplied directly or by separating it from an external fuel source such as natural gas, gasoline or methanol. In the case of an external source, it must be chemically converted to extract the hydrogen. This process is called "reforming". Hydrogen can also be produced from ammonia, alternative resources such as gas from city landfills and wastewater treatment plants, and through water electrolysis, which uses electricity to break water into hydrogen and oxygen. Currently, most fuel cell technologies used in transportation use methanol.
Various means have been developed to reform fuels to produce hydrogen for fuel cells. The US Department of Energy has developed a fuel unit inside a gasoline reformer to supply hydrogen to a self-contained fuel cell. Researchers from the Pacific Northwest National Laboratory in the US have demonstrated a compact fuel reformer one-tenth the size of a power supply. American utility Northwest Power Systems and Sandia National Laboratories have demonstrated a fuel reformer that converts diesel fuel into hydrogen for fuel cells.
Individually, the fuel cells produce about 0.7-1.0V each. To increase the voltage, the elements are assembled into a “cascade”, i.e. serial connection. To create more current, sets of cascaded elements are connected in parallel. If you combine fuel cell cascades with a fuel system, an air supply and cooling system, and a control system, you get a fuel cell engine. This engine can power a vehicle, a stationary power plant, or a portable electric generator6. Fuel cell engines come in different sizes depending on the application, the type of fuel cell and the fuel used. For example, each of the four separate 200 kW stationary power plants installed at a bank in Omaha is approximately the size of a truck trailer.
Applications
Fuel cells can be used in both stationary and mobile devices. In response to tightening emissions regulations in the United States, automakers including DaimlerChrysler, Toyota, Ford, General Motors, Volkswagen, Honda and Nissan have begun experimenting with and demonstrating fuel cell-powered vehicles. The first commercial fuel cell vehicles are expected to hit the road in 2004 or 2005.
A major milestone in the development of fuel cell technology was the June 1993 demonstration of Ballard Power System's experimental 32-foot city bus powered by a 90-kilowatt hydrogen fuel cell engine. Since then, many different types and different generations of fuel cell passenger vehicles have been developed and put into service, running on different types of fuel. Since late 1996, three hydrogen fuel cell golf carts have been in use in Palm Desert, California. On the roads of Chicago, Illinois; Vancouver, British Columbia; and Oslo, Norway, city buses powered by fuel cells are being tested. Taxis powered by alkaline fuel cells are being tested on the streets of London.
Stationary installations using fuel cell technology are also being demonstrated, but they are not yet widely used commercially. First National Bank of Omaha in Nebraska uses a fuel cell system to power its computers because the system is more reliable than the old system, which ran off the main grid with backup battery power. The world's largest commercial fuel cell system, rated at 1.2 MW, will soon be installed at a mail processing center in Alaska. Fuel cell-powered portable laptop computers, control systems used in wastewater treatment plants and vending machines are also being tested and demonstrated.
"Pros and cons"
Fuel cells have a number of advantages. While modern internal combustion engines are only 12-15% efficient, fuel cells are 50% efficient. The efficiency of fuel cells can remain quite high even when they are not used at full rated power, which is a serious advantage compared to gasoline engines.
The modular design of fuel cells means that the power of a fuel cell power plant can be increased simply by adding more stages. This ensures that capacity underutilization is minimized, allowing for better matching of supply and demand. Since the efficiency of a fuel cell stack is determined by the performance of the individual cells, small fuel cell power plants operate as efficiently as large ones. Additionally, waste heat from stationary fuel cell systems can be used for water and space heating, further increasing energy efficiency.
There are virtually no harmful emissions when using fuel cells. When an engine runs on pure hydrogen, only heat and pure water vapor are produced as by-products. So on spaceships, astronauts drink water, which is formed as a result of the operation of onboard fuel cells. The composition of emissions depends on the nature of the hydrogen source. Methanol produces zero nitrogen oxide and carbon monoxide emissions and only small hydrocarbon emissions. Emissions increase as you move from hydrogen to methanol and gasoline, although even with gasoline, emissions will remain fairly low. In any case, replacing today's traditional internal combustion engines with fuel cells would lead to an overall reduction in CO2 and nitrogen oxide emissions.
The use of fuel cells provides flexibility to the energy infrastructure, creating additional opportunities for decentralized electricity production. The multiplicity of decentralized energy sources makes it possible to reduce losses during electricity transmission and develop energy markets (which is especially important for remote and rural areas with no access to power lines). With the help of fuel cells, individual residents or neighborhoods can provide most of their own electricity and thus significantly increase energy efficiency.
Fuel cells offer high quality energy and increased reliability. They are durable, have no moving parts, and produce a constant amount of energy.
However, fuel cell technology needs to be further improved to improve performance, reduce costs, and thus make fuel cells competitive with other energy technologies. It should be noted that when the cost characteristics of energy technologies are considered, comparisons should be made based on all component technology characteristics, including capital operating costs, pollutant emissions, energy quality, durability, decommissioning and flexibility.
Although hydrogen gas is the best fuel, the infrastructure or transport base for it does not yet exist. In the near future, existing fossil fuel supply systems (gas stations, etc.) could be used to provide power plants with sources of hydrogen in the form of gasoline, methanol or natural gas. This would eliminate the need for dedicated hydrogen filling stations, but would require each vehicle to have a fossil fuel-to-hydrogen converter ("reformer") installed. The disadvantage of this approach is that it uses fossil fuels and thus results in carbon dioxide emissions. Methanol, the current leading candidate, produces fewer emissions than gasoline, but would require a larger container in the vehicle because it takes up twice the space for the same energy content.
Unlike fossil fuel supply systems, solar and wind systems (using electricity to create hydrogen and oxygen from water) and direct photoconversion systems (using semiconductor materials or enzymes to produce hydrogen) could provide hydrogen supply without a reforming step, and thus Thus, emissions of harmful substances that are observed when using methanol or gasoline fuel cells could be avoided. The hydrogen could be stored and converted into electricity in the fuel cell as needed. Looking ahead, pairing fuel cells with these kinds of renewable energy sources is likely to be an effective strategy for providing a productive, environmentally smart, and versatile source of energy.
IEER's recommendations are that local, federal, and state governments devote a portion of their transportation procurement budgets to fuel cell vehicles, as well as stationary fuel cell systems, to provide heat and power for some of their significant or new buildings. This will promote the development of vital technology and reduce greenhouse gas emissions.
Just as there are different types of internal combustion engines, there are different types of fuel cells - choosing the right type of fuel cell depends on its application.
Fuel cells are divided into high temperature and low temperature. Low temperature fuel cells require relatively pure hydrogen as fuel. This often means that fuel processing is required to convert the primary fuel (such as natural gas) into pure hydrogen. This process consumes additional energy and requires special equipment. High Temperature Fuel Cells do not need this additional procedure, as they can carry out the "internal conversion" of the fuel at elevated temperatures, meaning there is no need to invest in hydrogen infrastructure.
Molten carbonate fuel cells (MCFC)
Molten carbonate electrolyte fuel cells are high temperature fuel cells. The high operating temperature allows the direct use of natural gas without a fuel processor and low calorific value fuel gas from industrial processes and other sources. This process was developed in the mid-1960s. Since then, production technology, performance and reliability have been improved.
The operation of RCFC differs from other fuel cells. These cells use an electrolyte made from a mixture of molten carbonate salts. Currently, two types of mixtures are used: lithium carbonate and potassium carbonate or lithium carbonate and sodium carbonate. To melt carbonate salts and achieve a high degree of ion mobility in the electrolyte, fuel cells with molten carbonate electrolyte operate at high temperatures (650°C). Efficiency varies between 60-80%.
When heated to a temperature of 650°C, the salts become a conductor for carbonate ions (CO 3 2-). These ions pass from the cathode to the anode, where they combine with hydrogen to form water, carbon dioxide and free electrons. These electrons are sent through an external electrical circuit back to the cathode, generating electric current and heat as a by-product.
Reaction at the anode: CO 3 2- + H 2 => H 2 O + CO 2 + 2e -
Reaction at the cathode: CO 2 + 1/2 O 2 + 2e - => CO 3 2-
General reaction of the element: H 2 (g) + 1/2 O 2 (g) + CO 2 (cathode) => H 2 O (g) + CO 2 (anode)
The high operating temperatures of molten carbonate electrolyte fuel cells have certain advantages. At high temperatures, natural gas is internally reformed, eliminating the need for a fuel processor. In addition, advantages include the ability to use standard construction materials such as stainless steel sheets and nickel catalyst on the electrodes. The waste heat can be used to generate high pressure steam for a variety of industrial and commercial purposes.
High reaction temperatures in the electrolyte also have their advantages. The use of high temperatures requires significant time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. These characteristics allow the use of fuel cell installations with molten carbonate electrolyte under constant power conditions. High temperatures prevent damage to the fuel cell by carbon monoxide, "poisoning", etc.
Fuel cells with molten carbonate electrolyte are suitable for use in large stationary installations. Thermal power plants with an electrical output power of 2.8 MW are commercially produced. Installations with output power up to 100 MW are being developed.
Phosphoric acid fuel cells (PAFC)
Phosphoric (orthophosphoric) acid fuel cells were the first fuel cells for commercial use. The process was developed in the mid-1960s and has been tested since the 1970s. Since then, stability and performance have been increased and cost has been reduced.
Phosphoric (orthophosphoric) acid fuel cells use an electrolyte based on orthophosphoric acid (H 3 PO 4) with a concentration of up to 100%. The ionic conductivity of phosphoric acid is low at low temperatures, for this reason these fuel cells are used at temperatures up to 150–220°C.
The charge carrier in fuel cells of this type is hydrogen (H + , proton). A similar process occurs in proton exchange membrane fuel cells (PEMFCs), in which hydrogen supplied to the anode is split into protons and electrons. Protons travel through the electrolyte and combine with oxygen from the air at the cathode to form water. The electrons are sent through an external electrical circuit, thereby generating an electric current. Below are reactions that generate electric current and heat.
Reaction at the anode: 2H 2 => 4H + + 4e -
Reaction at the cathode: O 2 (g) + 4H + + 4e - => 2H 2 O
General reaction of the element: 2H 2 + O 2 => 2H 2 O
The efficiency of fuel cells based on phosphoric (orthophosphoric) acid is more than 40% when generating electrical energy. With combined production of heat and electricity, the overall efficiency is about 85%. In addition, given operating temperatures, waste heat can be used to heat water and generate atmospheric pressure steam.
The high performance of thermal power plants using fuel cells based on phosphoric (orthophosphoric) acid in the combined production of thermal and electrical energy is one of the advantages of this type of fuel cells. The units use carbon monoxide with a concentration of about 1.5%, which significantly expands the choice of fuel. In addition, CO 2 does not affect the electrolyte and the operation of the fuel cell; this type of cell works with reformed natural fuel. Simple design, low degree of electrolyte volatility and increased stability are also advantages of this type of fuel cell.
Thermal power plants with electrical output power of up to 400 kW are commercially produced. The 11 MW installations have passed the appropriate tests. Installations with output power up to 100 MW are being developed.
Proton exchange membrane fuel cells (PEMFCs)
Proton exchange membrane fuel cells are considered the best type of fuel cell for generating vehicle power, which can replace gasoline and diesel internal combustion engines. These fuel cells were first used by NASA for the Gemini program. Today, MOPFC installations with power from 1 W to 2 kW are being developed and demonstrated.
These fuel cells use a solid polymer membrane (a thin film of plastic) as the electrolyte. When saturated with water, this polymer allows protons to pass through but does not conduct electrons.
The fuel is hydrogen, and the charge carrier is a hydrogen ion (proton). At the anode, the hydrogen molecule is split into a hydrogen ion (proton) and electrons. Hydrogen ions pass through the electrolyte to the cathode, and electrons move around the outer circle and produce electrical energy. Oxygen, which is taken from the air, is supplied to the cathode and combines with electrons and hydrogen ions to form water. The following reactions occur at the electrodes:
Reaction at the anode: 2H 2 + 4OH - => 4H 2 O + 4e -
Reaction at the cathode: O 2 + 2H 2 O + 4e - => 4OH -
General reaction of the element: 2H 2 + O 2 => 2H 2 O
Compared to other types of fuel cells, proton exchange membrane fuel cells produce more energy for a given fuel cell volume or weight. This feature allows them to be compact and lightweight. In addition, the operating temperature is less than 100°C, which allows you to quickly start operating. These characteristics, as well as the ability to quickly change energy output, are just some of the features that make these fuel cells a prime candidate for use in vehicles.
Another advantage is that the electrolyte is a solid rather than a liquid. It is easier to retain gases at the cathode and anode using a solid electrolyte, and therefore such fuel cells are cheaper to produce. Compared to other electrolytes, solid electrolytes do not pose any orientation issues, fewer corrosion problems, resulting in greater longevity of the cell and its components.
Solid oxide fuel cells (SOFC)
Solid oxide fuel cells are the highest operating temperature fuel cells. The operating temperature can vary from 600°C to 1000°C, allowing the use of different types of fuel without special pre-treatment. To handle such high temperatures, the electrolyte used is a thin solid metal oxide on a ceramic base, often an alloy of yttrium and zirconium, which is a conductor of oxygen ions (O 2 -). Solid oxide fuel cell technology has been developing since the late 1950s. and has two configurations: flat and tubular.
The solid electrolyte provides a sealed transition of gas from one electrode to another, while liquid electrolytes are located in a porous substrate. The charge carrier in fuel cells of this type is the oxygen ion (O 2 -). At the cathode, oxygen molecules from the air are separated into an oxygen ion and four electrons. Oxygen ions pass through the electrolyte and combine with hydrogen, creating four free electrons. The electrons are sent through an external electrical circuit, generating electric current and waste heat.
Reaction at the anode: 2H 2 + 2O 2 - => 2H 2 O + 4e -
Reaction at the cathode: O 2 + 4e - => 2O 2 -
General reaction of the element: 2H 2 + O 2 => 2H 2 O
The efficiency of the produced electrical energy is the highest of all fuel cells - about 60%. In addition, high operating temperatures allow for the combined production of thermal and electrical energy to generate high-pressure steam. Combining a high-temperature fuel cell with a turbine makes it possible to create a hybrid fuel cell to increase the efficiency of generating electrical energy by up to 70%.
Solid oxide fuel cells operate at very high temperatures (600°C–1000°C), resulting in significant time to reach optimal operating conditions and a slower system response to changes in energy consumption. At such high operating temperatures, no converter is required to recover hydrogen from the fuel, allowing the thermal power plant to operate with relatively impure fuels resulting from gasification of coal or waste gases, etc. The fuel cell is also excellent for high power applications, including industrial and large central power plants. Modules with an electrical output power of 100 kW are commercially produced.
Direct methanol oxidation fuel cells (DOMFC)
The technology of using fuel cells with direct methanol oxidation is undergoing a period of active development. It has successfully proven itself in the field of powering mobile phones, laptops, as well as for creating portable power sources. This is what the future use of these elements is aimed at.
The design of fuel cells with direct oxidation of methanol is similar to fuel cells with a proton exchange membrane (MEPFC), i.e. A polymer is used as an electrolyte, and a hydrogen ion (proton) is used as a charge carrier. However, liquid methanol (CH 3 OH) oxidizes in the presence of water at the anode, releasing CO 2, hydrogen ions and electrons, which are sent through an external electrical circuit, thereby generating an electric current. Hydrogen ions pass through the electrolyte and react with oxygen from the air and electrons from the external circuit to form water at the anode.
Reaction at the anode: CH 3 OH + H 2 O => CO 2 + 6H + + 6e -
Reaction at the cathode: 3 / 2 O 2 + 6H + + 6e - => 3H 2 O
General reaction of the element: CH 3 OH + 3/2 O 2 => CO 2 + 2H 2 O
The development of these fuel cells began in the early 1990s. With the development of improved catalysts and other recent innovations, power density and efficiency have been increased to 40%.
These elements were tested in the temperature range of 50-120°C. With low operating temperatures and no need for a converter, direct methanol oxidation fuel cells are a prime candidate for applications in both mobile phones and other consumer products and automobile engines. The advantage of this type of fuel cells is their small size, due to the use of liquid fuel, and the absence of the need to use a converter.
Alkaline fuel cells (ALFC)
Alkaline fuel cells (AFC) are one of the most studied technologies, used since the mid-1960s. by NASA in the Apollo and Space Shuttle programs. On board these spacecraft, fuel cells produce electrical energy and potable water. Alkaline fuel cells are one of the most efficient cells used to generate electricity, with power generation efficiency reaching up to 70%.
Alkaline fuel cells use an electrolyte, an aqueous solution of potassium hydroxide, contained in a porous, stabilized matrix. The potassium hydroxide concentration may vary depending on the operating temperature of the fuel cell, which ranges from 65°C to 220°C. The charge carrier in SHTE is the hydroxyl ion (OH -), moving from the cathode to the anode, where it reacts with hydrogen, producing water and electrons. The water produced at the anode moves back to the cathode, again generating hydroxyl ions there. As a result of this series of reactions taking place in the fuel cell, electricity and, as a by-product, heat are produced:
Reaction at the anode: 2H 2 + 4OH - => 4H 2 O + 4e -
Reaction at the cathode: O 2 + 2H 2 O + 4e - => 4OH -
General reaction of the system: 2H 2 + O 2 => 2H 2 O
The advantage of SHTE is that these fuel cells are the cheapest to produce, since the catalyst required on the electrodes can be any of the substances that are cheaper than those used as catalysts for other fuel cells. In addition, SFCs operate at relatively low temperatures and are among the most efficient fuel cells - such characteristics can consequently contribute to faster power generation and high fuel efficiency.
One of the characteristic features of SHTE is its high sensitivity to CO 2, which may be contained in fuel or air. CO 2 reacts with the electrolyte, quickly poisons it, and greatly reduces the efficiency of the fuel cell. Therefore, the use of SHTE is limited to enclosed spaces, such as space and underwater vehicles, they must run on pure hydrogen and oxygen. Moreover, molecules such as CO, H 2 O and CH 4, which are safe for other fuel cells, and for some of them even act as fuel, are harmful to SHFC.
Polymer Electrolyte Fuel Cells (PEFC)
In the case of polymer electrolyte fuel cells, the polymer membrane consists of polymer fibers with water regions in which conduction water ions H2O+ (proton, red) attaches to a water molecule. Water molecules pose a problem due to slow ion exchange. Therefore, a high concentration of water is required both in the fuel and at the outlet electrodes, which limits the operating temperature to 100°C.
Solid acid fuel cells (SFC)
In solid acid fuel cells, the electrolyte (C s HSO 4) does not contain water. The operating temperature is therefore 100-300°C. The rotation of the oxy anions SO 4 2- allows the protons (red) to move as shown in the figure. Typically, a solid acid fuel cell is a sandwich in which a very thin layer of solid acid compound is sandwiched between two electrodes that are tightly pressed together to ensure good contact. When heated, the organic component evaporates, exiting through the pores in the electrodes, maintaining the ability of multiple contacts between the fuel (or oxygen at the other end of the element), the electrolyte and the electrodes.
| Fuel cell type | Working temperature | Power generation efficiency | Fuel type | Application area |
|---|---|---|---|---|
| RKTE | 550–700°C | 50-70% | Medium and large installations | |
| FCTE | 100–220°C | 35-40% | Pure hydrogen | Large installations |
| MOPTE | 30-100°C | 35-50% | Pure hydrogen | Small installations |
| SOFC | 450–1000°C | 45-70% | Most hydrocarbon fuels | Small, medium and large installations |
| PEMFC | 20-90°C | 20-30% | Methanol | Portable units |
| SHTE | 50–200°C | 40-65% | Pure hydrogen | Space research |
| PETE | 30-100°C | 35-50% | Pure hydrogen | Small installations |
You will no longer surprise anyone with either solar panels or wind turbines, which generate electricity in all regions of the world. But the output from these devices is not constant and it is necessary to install backup power sources or connect to the network to obtain electricity during the period when renewable energy sources do not generate electricity. However, there are plants developed in the 19th century that use “alternative” fuels to generate electricity, i.e. do not burn gas or petroleum products. Such installations are fuel cells.
HISTORY OF CREATION
Fuel cells (FC) or fuel cells were discovered back in 1838-1839 by William Grove (Grove, Grove), when he was studying the electrolysis of water.
Help: Electrolysis of water is the process of decomposition of water under the influence of electric current into hydrogen and oxygen molecules
Having disconnected the battery from the electrolytic cell, he was surprised to find that the electrodes began to absorb the released gas and generate current. The discovery of the process of electrochemical “cold” combustion of hydrogen was a significant event in the energy industry. He later created the Grove battery. This device had a platinum electrode immersed in nitric acid and a zinc electrode in zinc sulfate. It generated a current of 12 amperes and a voltage of 8 volts. Grow himself called this design "wet battery". He then created a battery using two platinum electrodes. One end of each electrode was in sulfuric acid, and the other ends were sealed in containers with hydrogen and oxygen. There was a stable current between the electrodes, and the amount of water inside the containers increased. Grow was able to decompose and improve the water in this device.
"Battery Grow"
(source: Royal Society of the National Museum of Natural History)
The term “fuel cell” (English “Fuel Cell”) appeared only in 1889 by L. Mond and
C. Langer, who tried to create a device for generating electricity from air and coal gas.
HOW IT WORKS?
A fuel cell is a relatively simple device. It has two electrodes: anode (negative electrode) and cathode (positive electrode). A chemical reaction occurs at the electrodes. To speed it up, the surface of the electrodes is coated with a catalyst. FCs are equipped with one more element - membrane. The conversion of the chemical energy of the fuel directly into electricity occurs thanks to the work of the membrane. It separates the two chambers of the element into which fuel and oxidizer are supplied. The membrane allows only protons, which are produced as a result of fuel splitting, to pass from one chamber to another at an electrode coated with a catalyst (electrons then travel through an external circuit). In the second chamber, protons combine with electrons (and oxygen atoms) to form water.
Working principle of a hydrogen fuel cell
At the chemical level, the process of converting fuel energy into electrical energy is similar to the conventional combustion process (oxidation).
During normal combustion in oxygen, oxidation of organic fuel occurs, and the chemical energy of the fuel is converted into thermal energy. Let's see what happens during the oxidation of hydrogen with oxygen in an electrolyte environment and in the presence of electrodes.
By supplying hydrogen to an electrode located in an alkaline environment, a chemical reaction occurs:
2H 2 + 4OH - → 4H 2 O + 4e -
As you can see, we get electrons that, passing through the external circuit, arrive at the opposite electrode, to which oxygen flows and where the reaction takes place:
4e- + O 2 + 2H 2 O → 4OH -
It can be seen that the resulting reaction 2H 2 + O 2 → H 2 O is the same as during normal combustion, but The fuel cell produces electric current and some heat.
TYPES OF FUEL CELLS
It is customary to classify fuel cells according to the type of electrolyte used for the reaction:
Note that fuel cells can also use coal, carbon monoxide, alcohols, hydrazine, and other organic substances as fuel, and air, hydrogen peroxide, chlorine, bromine, nitric acid, etc. as oxidizing agents.
FUEL CELL EFFICIENCY
A feature of fuel cells is no strict limitation on efficiency, like heat engines.
Help: EfficiencyCarnot cycle is the highest possible efficiency among all heat engines with the same minimum and maximum temperatures.
Therefore, the efficiency of fuel cells in theory can be higher than 100%. Many smiled and thought, “The perpetual motion machine has been invented.” No, here we should go back to the school chemistry course. The fuel cell is based on the conversion of chemical energy into electrical energy. This is where miracles happen. Certain chemical reactions as they occur can absorb heat from the environment.
Help: Endothermic reactions are chemical reactions accompanied by the absorption of heat. For endothermic reactions, changes in enthalpy and internal energy have positive values (Δ H >0, Δ U >0), thus the reaction products contain more energy than the starting components.
An example of such a reaction is the oxidation of hydrogen, which is used in most fuel cells. Therefore, theoretically, the efficiency can be more than 100%. But today, fuel cells heat up during operation and cannot absorb heat from the environment.
Help: This limitation is imposed by the second law of thermodynamics. The process of heat transfer from a “cold” body to a “hot” one is not possible.
Plus, there are losses associated with nonequilibrium processes. Such as: ohmic losses due to the specific conductivity of the electrolyte and electrodes, activation and concentration polarization, diffusion losses. As a result, part of the energy generated in fuel cells is converted into heat. Therefore, fuel cells are not perpetual motion machines and their efficiency is less than 100%. But their efficiency is greater than that of other machines. Today Fuel cell efficiency reaches 80%.
Reference: In the forties, the English engineer T. Bacon designed and built a battery of fuel cells with a total power of 6 kW and an efficiency of 80%, running on pure hydrogen and oxygen, but the power-to-weight ratio of the battery turned out to be too small - such elements were unsuitable for practical use and too expensive (source: http://www.powerinfo.ru/).
FUEL CELL PROBLEMS
Almost all fuel cells use hydrogen as fuel, so the logical question arises: “Where can I get it?”
It seems that a fuel cell was discovered as a result of electrolysis, so it is possible to use the hydrogen released as a result of electrolysis. But let's look at this process in more detail.
According to Faraday's law: the amount of a substance that is oxidized at the anode or reduced at the cathode is proportional to the amount of electricity passing through the electrolyte. This means that in order to get more hydrogen, you need to spend more electricity. Existing methods of water electrolysis operate with an efficiency of less than one. Then we use the resulting hydrogen in fuel cells, where the efficiency is also less than unity. Therefore, we will spend more energy than we can produce.
Of course, you can use hydrogen produced from natural gas. This method of producing hydrogen remains the cheapest and most popular. Currently, about 50% of the hydrogen produced worldwide comes from natural gas. But there is a problem with storing and transporting hydrogen. Hydrogen has a low density ( one liter of hydrogen weighs 0.0846 g), so to transport it over long distances it must be compressed. And these are additional energy and monetary costs. Also, don’t forget about safety.
However, there is also a solution here - liquid hydrocarbon fuel can be used as a source of hydrogen. For example, ethyl or methyl alcohol. True, this requires a special additional device - a fuel converter, which at high temperatures (for methanol it will be about 240 ° C) converts alcohols into a mixture of gaseous H 2 and CO 2. But in this case, it is already more difficult to think about portability - such devices are good to use as stationary or car generators, but for compact mobile equipment you need something less bulky.
Catalyst
To enhance the reaction in the fuel cell, the anode surface is usually treated with a catalyst. Until recently, platinum was used as a catalyst. Therefore, the cost of the fuel cell was high. Secondly, platinum is a relatively rare metal. According to experts, with the industrial production of fuel cells, proven reserves of platinum will run out in 15-20 years. But scientists around the world are trying to replace platinum with other materials. By the way, some of them achieved good results. So Chinese scientists replaced platinum with calcium oxide (source: www.cheburek.net).
USING FUEL CELLS
The first fuel cell in automotive technology was tested in 1959. The Alice-Chambers tractor used 1008 batteries to operate. The fuel was a mixture of gases, mainly propane and oxygen.
Source: http://www.planetseed.com/
Since the mid-60s, at the height of the “space race,” spacecraft creators became interested in fuel cells. The work of thousands of scientists and engineers allowed us to reach a new level, and in 1965. fuel cells were tested in the United States on the Gemini 5 spacecraft, and later on the Apollo spacecraft for flights to the Moon and the Shuttle program. In the USSR, fuel cells were developed at NPO Kvant, also for use in space (source: http://www.powerinfo.ru/).
Since in a fuel cell the final product of hydrogen combustion is water, they are considered the cleanest in terms of environmental impact. Therefore, fuel cells began to gain popularity against the backdrop of general interest in the environment.
Already, car manufacturers such as Honda, Ford, Nissan and Mercedes-Benz have created cars powered by hydrogen fuel cells.
Mercedes-Benz - Ener-G-Force powered by hydrogen
When using hydrogen cars, the problem with hydrogen storage is solved. The construction of hydrogen gas stations will make it possible to refuel anywhere. Moreover, refueling a car with hydrogen is faster than charging an electric car at a gas station. But when implementing such projects, we encountered a problem similar to that of electric vehicles. People are ready to switch to a hydrogen car if there is infrastructure for them. And the construction of gas stations will begin if there are a sufficient number of consumers. Therefore, we again came to the dilemma of the egg and the chicken.
Fuel cells are widely used in mobile phones and laptops. The time has already passed when the phone was charged once a week. Now the phone is charged almost every day, and the laptop works for 3-4 hours without a network. Therefore, mobile technology manufacturers decided to synthesize a fuel cell with phones and laptops for charging and operation. For example, the Toshiba company in 2003. demonstrated a finished prototype of a methanol fuel cell. It produces a power of about 100 mW. One refill of 2 cubes of concentrated (99.5%) methanol is enough for 20 hours of operation of the MP3 player. Again, the same Toshiba demonstrated a cell for powering laptops measuring 275x75x40mm, allowing the computer to operate for 5 hours on a single charge.
But some manufacturers have gone further. The PowerTrekk company has released a charger of the same name. PowerTrekk is the world's first water charger. It is very easy to use. The PowerTrekk requires the addition of water to provide instant electricity via the USB cord. This fuel cell contains silicon powder and sodium silicide (NaSi) when mixed with water, the combination generates hydrogen. Hydrogen is mixed with air in the fuel cell itself, and it converts hydrogen into electricity through its membrane-proton exchange, without fans or pumps. You can buy such a portable charger for 149 € (
Fuel cells (electrochemical generators) represent a very efficient, durable, reliable and environmentally friendly method of generating energy. Initially, they were used only in the space industry, but today electrochemical generators are increasingly used in various fields: power supplies for mobile phones and laptops, vehicle engines, autonomous power sources for buildings, and stationary power plants. Some of these devices operate as laboratory prototypes, while others are used for demonstration purposes or are undergoing pre-production testing. However, many models are already used in commercial projects and are mass-produced.
Device
Fuel cells are electrochemical devices capable of providing a high conversion rate of existing chemical energy into electrical energy.
The fuel cell device includes three main parts:
- Power generation section;
- CPU;
- Voltage transformer.
The main part of the fuel cell is the power generation section, which is a battery made of individual fuel cells. A platinum catalyst is included in the structure of the fuel cell electrodes. Using these cells, a constant electric current is created.
One of these devices has the following characteristics: at a voltage of 155 volts, 1400 amperes are produced. The battery dimensions are 0.9 m in width and height, and 2.9 m in length. The electrochemical process in it is carried out at a temperature of 177 °C, which requires heating of the battery at the time of start-up, as well as heat removal during its operation. For this purpose, a separate water circuit is included in the fuel cell, and the battery is equipped with special cooling plates.
The fuel process converts natural gas into hydrogen, which is required for an electrochemical reaction. The main element of the fuel processor is the reformer. In it, natural gas (or other hydrogen-containing fuel) interacts at high pressure and high temperature (about 900 ° C) with water vapor under the action of a nickel catalyst.
To maintain the required temperature of the reformer there is a burner. The steam required for reforming is created from the condensate. An unstable direct current is generated in the fuel cell battery and a voltage converter is used to convert it.
Also in the voltage converter block there are:
- Control devices.
- Safety interlock circuits that shut down the fuel cell during various faults.
Operating principle
The simplest proton exchange membrane cell consists of a polymer membrane that is located between the anode and cathode, as well as the cathode and anode catalysts. The polymer membrane is used as an electrolyte.
- The proton exchange membrane looks like a thin solid organic compound of small thickness. This membrane works as an electrolyte; in the presence of water, it separates the substance into negatively and positively charged ions.
- Oxidation begins at the anode, and reduction occurs at the cathode. The cathode and anode in a PEM cell are made of porous material; it is a mixture of platinum and carbon particles. Platinum acts as a catalyst, which promotes the dissociation reaction. The cathode and anode are made porous so that oxygen and hydrogen pass through them freely.
- The anode and cathode are located between two metal plates, they supply oxygen and hydrogen to the cathode and anode, and remove electrical energy, heat and water.
- Through channels in the plate, hydrogen molecules enter the anode, where the molecules are decomposed into atoms.
- As a result of chemisorption under the influence of a catalyst, hydrogen atoms are converted into positively charged hydrogen ions H+, that is, protons.
- Protons diffuse to the cathode through the membrane, and a flow of electrons goes to the cathode through a special external electrical circuit. A load is connected to it, that is, a consumer of electrical energy.
- Oxygen, which is supplied to the cathode, upon exposure, enters into a chemical reaction with electrons from the external electrical circuit and hydrogen ions from the proton exchange membrane. As a result of this chemical reaction, water appears.
The chemical reaction that occurs in other types of fuel cells (for example, with an acidic electrolyte in the form of orthophosphoric acid H3PO4) is completely identical to the reaction of a device with a proton exchange membrane.
Kinds
Currently, several types of fuel cells are known, which differ in the composition of the electrolyte used:
- Fuel cells based on orthophosphoric or phosphoric acid (PAFC, Phosphoric Acid Fuel Cells).
- Devices with proton exchange membrane (PEMFC, Proton Exchange Membrane Fuel Cells).
- Solid oxide fuel cells (SOFC, Solid Oxide Fuel Cells).
- Electrochemical generators based on molten carbonate (MCFC, Molten Carbonate Fuel Cells).
Currently, electrochemical generators using PAFC technology have become more widespread.
Application
Today, fuel cells are used in the Space Shuttle, reusable spacecraft. They use 12 W units. They generate all the electricity on the spacecraft. The water that is formed during the electrochemical reaction is used for drinking, including for cooling equipment.
Electrochemical generators were also used to power the Soviet Buran, a reusable spacecraft.
Fuel cells are also used in the civilian sector.
- Stationary installations with a power of 5–250 kW and above. They are used as autonomous sources for heat and power supply to industrial, public and residential buildings, emergency and backup power supplies, and uninterruptible power supplies.
- Portable units with a power of 1–50 kW. They are used for space satellites and ships. Instances are created for golf carts, wheelchairs, railway and freight refrigerators, and road signs.
- Mobile installations with a power of 25–150 kW. They are beginning to be used in military ships and submarines, including cars and other vehicles. Prototypes have already been created by such automotive giants as Renault, Neoplan, Toyota, Volkswagen, Hyundai, Nissan, VAZ, General Motors, Honda, Ford and others.
- Microdevices with a power of 1–500 W. They find application in advanced handheld computers, laptops, consumer electronic devices, mobile phones, and modern military devices.
Peculiarities
- Some of the energy from the chemical reaction in each fuel cell is released as heat. Refrigeration required. In an external circuit, the flow of electrons creates a direct current that is used to do work. Stopping the movement of hydrogen ions or opening the external circuit leads to the stop of the chemical reaction.
- The amount of electricity that fuel cells create is determined by gas pressure, temperature, geometric dimensions, and type of fuel cell. To increase the amount of electricity produced by the reaction, fuel cells can be made larger, but in practice several cells are used, which are combined into batteries.
- The chemical process in some types of fuel cells can be reversed. That is, when a potential difference is applied to the electrodes, water can be decomposed into oxygen and hydrogen, which will be collected on the porous electrodes. When the load is turned on, such a fuel cell will generate electrical energy.
Prospects
Currently, electrochemical generators require large initial costs to be used as the main source of energy. With the introduction of more stable membranes with high conductivity, efficient and cheap catalysts, and alternative sources of hydrogen, fuel cells will become highly economically attractive and will be implemented everywhere.
- Cars will run on fuel cells; there will be no internal combustion engines at all. Water or solid-state hydrogen will be used as an energy source. Refueling will be simple and safe, and driving will be environmentally friendly - only water vapor will be produced.
- All buildings will have their own portable fuel cell power generators.
- Electrochemical generators will replace all batteries and will be installed in any electronics and household appliances.
Advantages and disadvantages
Each type of fuel cell has its own disadvantages and advantages. Some require high quality fuel, others have a complex design and require high operating temperatures.
In general, the following advantages of fuel cells can be noted:
- environmental safety;
- electrochemical generators do not need to be recharged;
- electrochemical generators can create energy constantly, they do not care about external conditions;
- flexibility in scale and portability.
Among the disadvantages are:
- technical difficulties with fuel storage and transportation;
- imperfect elements of the device: catalysts, membranes, and so on.
Fuel cell ( Fuel Cell) is a device that converts chemical energy into electrical energy. It is similar in principle to a conventional battery, but differs in that its operation requires a constant supply of substances from the outside for the electrochemical reaction to occur. Hydrogen and oxygen are supplied to the fuel cells, and the output is electricity, water and heat. Their advantages include environmental friendliness, reliability, durability and ease of operation. Unlike conventional batteries, electrochemical converters can operate virtually indefinitely as long as fuel is supplied. They don't have to be charged for hours until they're fully charged. Moreover, the cells themselves can charge the battery while the car is parked with the engine turned off.
The most widely used fuel cells in hydrogen vehicles are proton membrane fuel cells (PEMFCs) and solid oxide fuel cells (SOFCs).
A proton exchange membrane fuel cell works as follows. Between the anode and cathode there is a special membrane and a platinum-coated catalyst. Hydrogen is supplied to the anode, and oxygen (for example, from air) is supplied to the cathode. At the anode, hydrogen is decomposed into protons and electrons with the help of a catalyst. Hydrogen protons pass through the membrane and reach the cathode, and electrons are transferred to the external circuit (the membrane does not allow them to pass through). The potential difference thus obtained leads to the generation of electric current. On the cathode side, hydrogen protons are oxidized by oxygen. As a result, water vapor appears, which is the main element of car exhaust gases. Possessing high efficiency, PEM cells have one significant drawback - their operation requires pure hydrogen, the storage of which is a rather serious problem.
If such a catalyst is found that replaces expensive platinum in these cells, then a cheap fuel cell for generating electricity will immediately be created, which means the world will get rid of oil dependence.
Solid Oxide Cells
Solid oxide SOFC cells are much less demanding on fuel purity. In addition, thanks to the use of a POX reformer (Partial Oxidation), such cells can consume regular gasoline as fuel. The process of converting gasoline directly into electricity is as follows. In a special device - a reformer, at a temperature of about 800 ° C, gasoline evaporates and decomposes into its constituent elements.
This releases hydrogen and carbon dioxide. Further, also under the influence of temperature and using SOFC directly (consisting of a porous ceramic material based on zirconium oxide), hydrogen is oxidized by oxygen in the air. After obtaining hydrogen from gasoline, the process continues according to the scenario described above, with only one difference: the SOFC fuel cell, unlike devices operating on hydrogen, is less sensitive to impurities in the original fuel. So the quality of gasoline should not affect the performance of the fuel cell.
The high operating temperature of SOFC (650–800 degrees) is a significant drawback; the warm-up process takes about 20 minutes. But excess heat is not a problem, since it is completely removed by the remaining air and exhaust gases produced by the reformer and the fuel cell itself. This allows the SOFC system to be integrated into a vehicle as a separate device in a thermally insulated housing.
The modular structure allows you to achieve the required voltage by connecting a set of standard cells in series. And, perhaps most importantly from the point of view of the implementation of such devices, SOFC does not contain very expensive platinum-based electrodes. It is the high cost of these elements that is one of the obstacles in the development and dissemination of PEMFC technology.
Types of fuel cells
Currently, there are the following types of fuel cells:
- A.F.C.– Alkaline Fuel Cell (alkaline fuel cell);
- PAFC– Phosphoric Acid Fuel Cell (phosphoric acid fuel cell);
- PEMFC– Proton Exchange Membrane Fuel Cell (fuel cell with a proton exchange membrane);
- DMFC– Direct Methanol Fuel Cell (fuel cell with direct breakdown of methanol);
- MCFC– Molten Carbonate Fuel Cell (fuel cell of molten carbonate);
- SOFC– Solid Oxide Fuel Cell (solid oxide fuel cell).
Advantages of fuel cells/cells
A fuel cell/cell is a device that efficiently produces direct current and heat from hydrogen-rich fuel through an electrochemical reaction.
A fuel cell is similar to a battery in that it produces direct current through a chemical reaction. The fuel cell includes an anode, a cathode and an electrolyte. However, unlike batteries, fuel cells cannot store electrical energy and do not discharge or require electricity to recharge. Fuel cells/cells can continuously produce electricity as long as they have a supply of fuel and air.
Unlike other power generators, such as internal combustion engines or turbines powered by gas, coal, fuel oil, etc., fuel cells/cells do not burn fuel. This means no noisy high pressure rotors, no loud exhaust noise, no vibration. Fuel cells/cells produce electricity through a silent electrochemical reaction. Another feature of fuel cells/cells is that they convert the chemical energy of the fuel directly into electricity, heat and water.
Fuel cells are highly efficient and do not produce large amounts of greenhouse gases such as carbon dioxide, methane and nitrous oxide. The only emission products during operation are water in the form of steam and a small amount of carbon dioxide, which is not released at all if pure hydrogen is used as fuel. Fuel elements/cells are assembled into assemblies and then into individual functional modules.
History of development of fuel cells/cells
In the 1950s and 1960s, one of the most pressing challenges for fuel cells arose from the National Aeronautics and Space Administration's (NASA) need for energy sources for long-duration space missions. NASA's alkaline fuel cell uses hydrogen and oxygen as fuel by combining the two chemical elements in an electrochemical reaction. The output is three useful byproducts of the reaction in space flight - electricity to power the spacecraft, water for drinking and cooling systems, and heat to warm the astronauts.
The discovery of fuel cells dates back to the beginning of the 19th century. The first evidence of the effect of fuel cells was obtained in 1838.
In the late 1930s, work began on fuel cells with an alkaline electrolyte and by 1939 a cell using high-pressure nickel-plated electrodes was built. During the Second World War, fuel cells/cells were developed for British Navy submarines and in 1958 a fuel assembly consisting of alkaline fuel cells/cells with a diameter of just over 25 cm was introduced.
Interest increased in the 1950s and 1960s, and also in the 1980s, when the industrial world experienced a shortage of petroleum fuels. During the same period, world countries also became concerned about the problem of air pollution and considered ways to generate electricity in an environmentally friendly manner. Fuel cell technology is currently undergoing rapid development.
Operating principle of fuel cells/cells
Fuel cells/cells produce electricity and heat due to an electrochemical reaction taking place using an electrolyte, a cathode and an anode.
The anode and cathode are separated by an electrolyte that conducts protons. After hydrogen flows to the anode and oxygen to the cathode, a chemical reaction begins, as a result of which electric current, heat and water are generated.
At the anode catalyst, molecular hydrogen dissociates and loses electrons. Hydrogen ions (protons) are conducted through the electrolyte to the cathode, while electrons are passed through the electrolyte and travel through an external electrical circuit, creating a direct current that can be used to power equipment. At the cathode catalyst, an oxygen molecule combines with an electron (which is supplied from external communications) and an incoming proton, and forms water, which is the only reaction product (in the form of vapor and/or liquid).
Below is the corresponding reaction:
Reaction at the anode: 2H 2 => 4H+ + 4e -
Reaction at the cathode: O 2 + 4H+ + 4e - => 2H 2 O
General reaction of the element: 2H 2 + O 2 => 2H 2 O
Types and variety of fuel elements/cells
Just as there are different types of internal combustion engines, there are different types of fuel cells - choosing the right type of fuel cell depends on its application.
Fuel cells are divided into high temperature and low temperature. Low temperature fuel cells require relatively pure hydrogen as fuel. This often means that fuel processing is required to convert the primary fuel (such as natural gas) into pure hydrogen. This process consumes additional energy and requires special equipment. High temperature fuel cells do not need this additional procedure as they can "internally convert" the fuel at elevated temperatures, meaning there is no need to invest in hydrogen infrastructure.
Molten Carbonate Fuel Cells/Cells (MCFC)
Molten carbonate electrolyte fuel cells are high temperature fuel cells. The high operating temperature allows the direct use of natural gas without a fuel processor and low calorific value fuel gas from industrial processes and other sources.
The operation of RCFC differs from other fuel cells. These cells use an electrolyte made from a mixture of molten carbonate salts. Currently, two types of mixtures are used: lithium carbonate and potassium carbonate or lithium carbonate and sodium carbonate. To melt carbonate salts and achieve a high degree of ion mobility in the electrolyte, fuel cells with molten carbonate electrolyte operate at high temperatures (650°C). Efficiency varies between 60-80%.
When heated to a temperature of 650°C, the salts become a conductor for carbonate ions (CO 3 2-). These ions pass from the cathode to the anode, where they combine with hydrogen to form water, carbon dioxide and free electrons. These electrons are sent through an external electrical circuit back to the cathode, generating electric current and heat as a by-product.
Reaction at the anode: CO 3 2- + H 2 => H 2 O + CO 2 + 2e -
Reaction at the cathode: CO 2 + 1/2O 2 + 2e - => CO 3 2-
General reaction of the element: H 2 (g) + 1/2O 2 (g) + CO 2 (cathode) => H 2 O (g) + CO 2 (anode)
The high operating temperatures of molten carbonate electrolyte fuel cells have certain advantages. At high temperatures, natural gas is internally reformed, eliminating the need for a fuel processor. In addition, advantages include the ability to use standard construction materials such as stainless steel sheets and nickel catalyst on the electrodes. The waste heat can be used to generate high pressure steam for a variety of industrial and commercial purposes.
High reaction temperatures in the electrolyte also have their advantages. The use of high temperatures requires significant time to achieve optimal operating conditions, and the system responds more slowly to changes in energy consumption. These characteristics allow the use of fuel cell installations with molten carbonate electrolyte under constant power conditions. High temperatures prevent carbon monoxide from damaging the fuel cell.
Fuel cells with molten carbonate electrolyte are suitable for use in large stationary installations. Thermal power plants with an electrical output power of 3.0 MW are commercially produced. Installations with output power up to 110 MW are being developed.
Phosphoric acid fuel cells/cells (PAFC)
Phosphoric (orthophosphoric) acid fuel cells were the first fuel cells for commercial use.
Phosphoric (orthophosphoric) acid fuel cells use an electrolyte based on orthophosphoric acid (H 3 PO 4) with a concentration of up to 100%. The ionic conductivity of phosphoric acid is low at low temperatures, for this reason these fuel cells are used at temperatures up to 150–220°C.
The charge carrier in fuel cells of this type is hydrogen (H+, proton). A similar process occurs in fuel cells with a proton exchange membrane, in which hydrogen supplied to the anode is split into protons and electrons. Protons travel through the electrolyte and combine with oxygen from the air at the cathode to form water. The electrons are sent through an external electrical circuit, thereby generating an electric current. Below are reactions that generate electric current and heat.
Reaction at the anode: 2H 2 => 4H + + 4e -
Reaction at the cathode: O 2 (g) + 4H + + 4e - => 2 H 2 O
General reaction of the element: 2H 2 + O 2 => 2H 2 O
The efficiency of fuel cells based on phosphoric (orthophosphoric) acid is more than 40% when generating electrical energy. With combined production of heat and electricity, the overall efficiency is about 85%. In addition, given operating temperatures, waste heat can be used to heat water and generate atmospheric pressure steam.
The high performance of thermal power plants using fuel cells based on phosphoric (orthophosphoric) acid in the combined production of thermal and electrical energy is one of the advantages of this type of fuel cells. The units use carbon monoxide with a concentration of about 1.5%, which significantly expands the choice of fuel. In addition, CO 2 does not affect the electrolyte and the operation of the fuel cell; this type of cell works with reformed natural fuel. Simple design, low degree of electrolyte volatility and increased stability are also advantages of this type of fuel cell.
Thermal power plants with electrical output power of up to 500 kW are commercially produced. The 11 MW installations have passed the appropriate tests. Installations with output power up to 100 MW are being developed.
Solid Oxide Fuel Cells (SOFC)
Solid oxide fuel cells are the highest operating temperature fuel cells. The operating temperature can vary from 600°C to 1000°C, allowing the use of different types of fuel without special pre-treatment. To handle such high temperatures, the electrolyte used is a thin solid metal oxide on a ceramic base, often an alloy of yttrium and zirconium, which is a conductor of oxygen ions (O2-).
The solid electrolyte provides a sealed transition of gas from one electrode to another, while liquid electrolytes are located in a porous substrate. The charge carrier in fuel cells of this type is the oxygen ion (O 2-). At the cathode, oxygen molecules from the air are separated into an oxygen ion and four electrons. Oxygen ions pass through the electrolyte and combine with hydrogen, creating four free electrons. The electrons are sent through an external electrical circuit, generating electric current and waste heat.
Reaction at the anode: 2H 2 + 2O 2- => 2H 2 O + 4e -
Reaction at the cathode: O 2 + 4e - => 2O 2-
General reaction of the element: 2H 2 + O 2 => 2H 2 O
The efficiency of the produced electrical energy is the highest of all fuel cells - about 60-70%. High operating temperatures allow combined production of thermal and electrical energy to generate high pressure steam. Combining a high-temperature fuel cell with a turbine makes it possible to create a hybrid fuel cell to increase the efficiency of generating electrical energy by up to 75%.
Solid oxide fuel cells operate at very high temperatures (600°C–1000°C), resulting in significant time to reach optimal operating conditions and a slower system response to changes in energy consumption. At such high operating temperatures, no converter is required to recover hydrogen from the fuel, allowing the thermal power plant to operate with relatively impure fuels resulting from gasification of coal or waste gases, etc. The fuel cell is also excellent for high power applications, including industrial and large central power plants. Modules with an electrical output power of 100 kW are commercially produced.
Direct Methanol Oxidation Fuel Cells/Cells (DOMFC)
The technology of using fuel cells with direct methanol oxidation is undergoing a period of active development. It has successfully proven itself in the field of powering mobile phones, laptops, as well as for creating portable power sources. This is what the future use of these elements is aimed at.
The design of fuel cells with direct oxidation of methanol is similar to fuel cells with a proton exchange membrane (MEPFC), i.e. A polymer is used as an electrolyte, and a hydrogen ion (proton) is used as a charge carrier. However, liquid methanol (CH 3 OH) oxidizes in the presence of water at the anode, releasing CO 2, hydrogen ions and electrons, which are sent through an external electrical circuit, thereby generating an electric current. Hydrogen ions pass through the electrolyte and react with oxygen from the air and electrons from the external circuit to form water at the anode.
Reaction at the anode: CH 3 OH + H 2 O => CO 2 + 6H + + 6e -
Reaction at the cathode: 3/2O 2 + 6 H + + 6e - => 3H 2 O
General reaction of the element: CH 3 OH + 3/2O 2 => CO 2 + 2H 2 O
The advantage of this type of fuel cells is their small size, due to the use of liquid fuel, and the absence of the need to use a converter.
Alkaline fuel cells/cells (ALFC)
Alkaline fuel cells are one of the most efficient cells used to generate electricity, with power generation efficiency reaching up to 70%.
Alkaline fuel cells use an electrolyte, an aqueous solution of potassium hydroxide, contained in a porous, stabilized matrix. The potassium hydroxide concentration may vary depending on the operating temperature of the fuel cell, which ranges from 65°C to 220°C. The charge carrier in SHTE is the hydroxyl ion (OH -), moving from the cathode to the anode, where it reacts with hydrogen, producing water and electrons. The water produced at the anode moves back to the cathode, again generating hydroxyl ions there. As a result of this series of reactions taking place in the fuel cell, electricity and, as a by-product, heat are produced:
Reaction at the anode: 2H 2 + 4OH - => 4H 2 O + 4e -
Reaction at the cathode: O 2 + 2H 2 O + 4e - => 4 OH -
General reaction of the system: 2H 2 + O 2 => 2H 2 O
The advantage of SHTE is that these fuel cells are the cheapest to produce, since the catalyst required on the electrodes can be any of the substances that are cheaper than those used as catalysts for other fuel cells. SFCs operate at relatively low temperatures and are among the most efficient fuel cells - such characteristics can consequently contribute to faster power generation and high fuel efficiency.
One of the characteristic features of SHTE is its high sensitivity to CO 2, which may be contained in fuel or air. CO 2 reacts with the electrolyte, quickly poisons it, and greatly reduces the efficiency of the fuel cell. Therefore, the use of SHTE is limited to enclosed spaces, such as space and underwater vehicles, they must run on pure hydrogen and oxygen. Moreover, molecules such as CO, H 2 O and CH4, which are safe for other fuel cells, and even act as fuel for some of them, are harmful to SHFC.
Polymer Electrolyte Fuel Cells (PEFC)
In the case of polymer electrolyte fuel cells, the polymer membrane consists of polymer fibers with water regions in which there is conduction of water ions H2O+ (proton, red) attaches to a water molecule). Water molecules pose a problem due to slow ion exchange. Therefore, a high concentration of water is required both in the fuel and at the outlet electrodes, limiting the operating temperature to 100°C.
Solid acid fuel cells/cells (SFC)
In solid acid fuel cells, the electrolyte (CsHSO 4) does not contain water. The operating temperature is therefore 100-300°C. The rotation of the oxy anions SO 4 2- allows the protons (red) to move as shown in the figure. Typically, a solid acid fuel cell is a sandwich in which a very thin layer of solid acid compound is sandwiched between two electrodes that are tightly pressed together to ensure good contact. When heated, the organic component evaporates, exiting through the pores in the electrodes, maintaining the ability of multiple contacts between the fuel (or oxygen at the other end of the element), the electrolyte and the electrodes.
Various fuel cell modules. Fuel cell battery
- Fuel cell battery
- Other equipment operating at high temperatures (integrated steam generator, combustion chamber, heat balance changer)
- Heat resistant insulation
Fuel cell module
Comparative analysis of types and varieties of fuel cells
Innovative energy-efficient municipal heat and power plants are typically built on solid oxide fuel cells (SOFC), polymer electrolyte fuel cells (PEFC), phosphoric acid fuel cells (PAFC), proton exchange membrane fuel cells (PEMFC) and alkaline fuel cells (ALFC). . Typically have the following characteristics:
The most suitable should be considered solid oxide fuel cells (SOFC), which:
- operate at higher temperatures, reducing the need for expensive precious metals (such as platinum)
- can operate on various types of hydrocarbon fuels, mainly natural gas
- have a longer start-up time and are therefore better suited for long-term action
- demonstrate high power generation efficiency (up to 70%)
- Due to high operating temperatures, the units can be combined with heat transfer systems, bringing the overall system efficiency to 85%
- have virtually zero emissions, operate silently and have low operating requirements compared to existing power generation technologies
| Fuel cell type | Working temperature | Power generation efficiency | Fuel type | Application area |
|---|---|---|---|---|
| RKTE | 550–700°C | 50-70% | Medium and large installations | |
| FCTE | 100–220°C | 35-40% | Pure hydrogen | Large installations |
| MOPTE | 30-100°C | 35-50% | Pure hydrogen | Small installations |
| SOFC | 450–1000°C | 45-70% | Most hydrocarbon fuels | Small, medium and large installations |
| PEMFC | 20-90°C | 20-30% | Methanol | Portable |
| SHTE | 50–200°C | 40-70% | Pure hydrogen | Space research |
| PETE | 30-100°C | 35-50% | Pure hydrogen | Small installations |
Since small thermal power plants can be connected to a conventional gas supply network, fuel cells do not require a separate hydrogen supply system. When using small thermal power plants based on solid oxide fuel cells, the heat generated can be integrated into heat exchangers to heat water and ventilation air, increasing the overall efficiency of the system. This innovative technology is best suited to efficiently generate electricity without the need for expensive infrastructure and complex instrument integration.
Application of fuel cells/cells
Application of fuel cells/cells in telecommunication systems
Due to the rapid proliferation of wireless communication systems throughout the world, as well as the increasing socio-economic benefits of mobile phone technology, the need for reliable and cost-effective power backup has become critical. Electricity grid losses throughout the year due to bad weather conditions, natural disasters or limited grid capacity pose an ongoing challenge for grid operators.
Traditional telecom power backup solutions include batteries (valve-regulated lead-acid battery cell) for short-term backup power and diesel and propane generators for longer-term backup power. Batteries are a relatively cheap source of backup power for 1 - 2 hours. However, batteries are not suitable for longer-term backup power because they are expensive to maintain, become unreliable after long periods of use, are sensitive to temperatures, and are hazardous to the environment after disposal. Diesel and propane generators can provide long-term power backup. However, generators can be unreliable, require labor-intensive maintenance, and emit high levels of pollutants and greenhouse gases.
To overcome the limitations of traditional power backup solutions, innovative green fuel cell technology has been developed. Fuel cells are reliable, quiet, contain fewer moving parts than a generator, have a wider operating temperature range than a battery: from -40°C to +50°C and, as a result, provide extremely high levels of energy savings. In addition, the lifetime costs of such an installation are lower than those of a generator. Lower fuel cell costs result from just one maintenance visit per year and significantly higher plant productivity. At the end of the day, the fuel cell is a green technology solution with minimal environmental impact.
Fuel cell installations provide backup power for critical communications network infrastructures for wireless, permanent and broadband communications in the telecommunications system, ranging from 250 W to 15 kW, they offer many unrivaled innovative features:
- RELIABILITY– few moving parts and no discharge in standby mode
- ENERGY SAVING
- SILENCE– low noise level
- SUSTAINABILITY– operating range from -40°C to +50°C
- ADAPTABILITY– installation outdoors and indoors (container/protective container)
- HIGH POWER– up to 15 kW
- LOW MAINTENANCE REQUIREMENT– minimal annual maintenance
- ECONOMICAL- attractive total cost of ownership
- GREEN ENERGY– low emissions with minimal impact on the environment
The system senses the DC bus voltage at all times and smoothly accepts critical loads if the DC bus voltage drops below a user-defined set point. The system runs on hydrogen, which is supplied to the fuel cell stack in one of two ways - either from an industrial hydrogen source or from a liquid fuel of methanol and water, using an integrated reforming system.
Electricity is produced by the fuel cell stack in the form of direct current. The DC power is transferred to a converter, which converts the unregulated DC power coming from the fuel cell stack into high quality regulated DC power for the required loads. Fuel cell installations can provide backup power for many days as the duration is limited only by the amount of hydrogen or methanol/water fuel available.
Fuel cells offer superior energy savings, improved system reliability, more predictable performance in a wide range of climates, and reliable operational durability compared to industry standard valve-regulated lead-acid battery packs. Lifetime costs are also lower due to significantly lower maintenance and replacement requirements. Fuel cells offer environmental benefits to the end user as disposal costs and liability risks associated with lead-acid cells are a growing concern.
The performance of electric batteries can be adversely affected by a wide range of factors such as charge level, temperature, cycling, life and other variables. The energy provided will vary depending on these factors and is not easy to predict. The performance of a proton exchange membrane fuel cell (PEMFC) is relatively unaffected by these factors and can provide critical power as long as fuel is available. Increased predictability is an important benefit when moving to fuel cells for mission-critical backup power applications.
Fuel cells generate power only when fuel is supplied, similar to a gas turbine generator, but have no moving parts in the generation area. Therefore, unlike a generator, they are not subject to rapid wear and do not require constant maintenance and lubrication.
The fuel used to drive the extended duration fuel converter is a fuel mixture of methanol and water. Methanol is a widely available, commercially produced fuel that currently has many uses, including windshield washers, plastic bottles, engine additives, and emulsion paints, among others. Methanol is easily transported, can be mixed with water, has good biodegradability and does not contain sulfur. It has a low freezing point (-71°C) and does not decompose during long-term storage.
Application of fuel cells/cells in communication networks
Secure communications networks require reliable backup power solutions that can operate for hours or days in emergency situations if the power grid is no longer available.
With few moving parts and no standby power loss, innovative fuel cell technology offers an attractive solution to current backup power systems.
The most compelling argument for using fuel cell technology in communications networks is the increased overall reliability and safety. During events such as power outages, earthquakes, storms and hurricanes, it is important that systems continue to operate and are provided with reliable backup power over an extended period of time, regardless of temperature or the age of the backup power system.
The line of fuel cell-based power devices are ideal for supporting classified communications networks. Thanks to their energy-saving design principles, they provide environmentally friendly, reliable backup power with extended duration (up to several days) for use in the power range from 250 W to 15 kW.
Application of fuel cells/cells in data networks
Reliable power supply for data networks, such as high-speed data networks and fiber optic backbones, is of key importance throughout the world. The information transmitted over such networks contains critical data for institutions such as banks, airlines or medical centers. A power outage in such networks not only poses a danger to the transmitted information, but also, as a rule, leads to significant financial losses. Reliable, innovative fuel cell installations that provide backup power supply provide the reliability needed to ensure uninterrupted power supply.
Fuel cell units, powered by a liquid fuel mixture of methanol and water, provide reliable backup power with extended duration, up to several days. In addition, these units have significantly reduced maintenance requirements compared to generators and batteries, requiring only one maintenance visit per year.
Typical application site characteristics for using fuel cell installations in data networks:
- Applications with power consumption quantities from 100 W to 15 kW
- Applications with battery life requirements > 4 hours
- Repeaters in fiber optic systems (hierarchy of synchronous digital systems, high-speed Internet, voice over IP...)
- Network nodes for high-speed data transmission
- WiMAX transmission nodes
Fuel cell power backup installations offer numerous benefits for mission-critical data network infrastructures compared to traditional battery or diesel generators, allowing for increased on-site deployment options:
- Liquid fuel technology solves the problem of hydrogen placement and provides virtually unlimited backup power.
- Thanks to their quiet operation, low weight, resistance to temperature changes and virtually vibration-free operation, fuel cells can be installed outside buildings, in industrial buildings/containers or on rooftops.
- Preparations for the use of the system on site are quick and economical, and operating costs are low.
- The fuel is biodegradable and provides an environmentally friendly solution for urban environments.
Application of fuel cells/cells in security systems
The most carefully designed building security and communications systems are only as reliable as the power supply that supports them. While most systems include some type of uninterruptible power backup system for short-term power losses, they do not accommodate the longer-term power outages that can occur after natural disasters or terrorist attacks. This could be a critical issue for many corporate and government agencies.
Vital systems such as CCTV access monitoring and control systems (ID card readers, door lock devices, biometric identification technology, etc.), automatic fire alarm and fire extinguishing systems, elevator control systems and telecommunication networks, are at risk in the absence of a reliable, long-lasting alternative power supply.
Diesel generators make a lot of noise, are difficult to locate, and have well-known reliability and maintenance problems. In contrast, a fuel cell installation that provides backup power is quiet, reliable, produces zero or very low emissions, and can be easily installed on a rooftop or outside a building. It does not discharge or lose power in standby mode. It ensures the continued operation of critical systems, even after the facility ceases operations and the building is vacated.
Innovative fuel cell installations protect expensive investments in critical applications. They provide environmentally friendly, reliable backup power with extended duration (up to many days) for use in the power range from 250 W to 15 kW, combined with numerous unrivaled features and, especially, high levels of energy savings.
Fuel cell power backup installations offer numerous advantages for use in mission-critical applications such as security and building control systems over traditional battery-powered or diesel generator applications. Liquid fuel technology solves the problem of hydrogen placement and provides virtually unlimited backup power.
Application of fuel cells/cells in municipal heating and power generation
Solid oxide fuel cells (SOFCs) provide reliable, energy-efficient, and emission-free thermal power plants to generate electricity and heat from widely available natural gas and renewable fuel sources. These innovative installations are used in a variety of markets, from home power generation to remote power supply, as well as auxiliary power supplies.
Application of fuel cells/cells in distribution networks
Small thermal power plants are designed to operate in a distributed power generation network consisting of a large number of small generator sets instead of one centralized power plant.
The figure below shows the loss in efficiency of electricity generation when it is generated at a thermal power plant and transmitted to homes through the traditional power transmission networks currently in use. Efficiency losses in centralized generation include losses from the power plant, low-voltage and high-voltage transmission, and distribution losses.
The figure shows the results of the integration of small thermal power plants: electricity is generated with generation efficiency of up to 60% at the point of use. In addition to this, a household can use the heat generated by the fuel cells to heat water and space, which increases the overall efficiency of fuel energy processing and increases energy savings.
Use of fuel cells to protect the environment - utilization of associated petroleum gas
One of the most important tasks in the oil industry is the utilization of associated petroleum gas. Existing methods of utilizing associated petroleum gas have a lot of disadvantages, the main one being that they are not economically viable. Associated petroleum gas is burned, which causes enormous harm to the environment and human health.
Innovative thermal power plants using fuel cells using associated petroleum gas as fuel open the way to a radical and cost-effective solution to the problems of associated petroleum gas utilization.
- One of the main advantages of fuel cell installations is that they can operate reliably and stably on associated petroleum gas of variable composition. Due to the flameless chemical reaction that underlies the operation of the fuel cell, a decrease in the percentage of, for example, methane only causes a corresponding decrease in power output.
- Flexibility in relation to the electrical load of consumers, drop, load surge.
- For the installation and connection of thermal power plants on fuel cells, their implementation does not require capital costs, because The units can be easily installed on unprepared sites near fields, are easy to use, reliable and efficient.
- High automation and modern remote control do not require permanent presence of personnel at the installation.
- Simplicity and technical perfection of the design: the absence of moving parts, friction, and lubrication systems provides significant economic benefits from the operation of fuel cell installations.
- Water consumption: none at ambient temperatures up to +30 °C and negligible at higher temperatures.
- Water outlet: none.
- In addition, thermal power plants using fuel cells do not make noise, do not vibrate, do not produce harmful emissions into the atmosphere