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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 being poured into fuel cell research today as pollution issues persist. environment, increasing emissions of greenhouse gases generated during the combustion of organic fuel, the reserves of which are also not infinite.

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 ethyl alcohol(simpler, 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, you need to soak it with a solution of paraffin in gasoline (ratio of 2 grams of paraffin to half a glass of gasoline) before filling the fourth chamber with carbon for the air electrolyte. 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 must 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 problem concerns only finding inexpensive and effective way obtaining hydrogen. Enormous funds invested in the development of hydrogen generators and fuel cells cannot but bear fruit, so a technological breakthrough and their actual use in Everyday life, 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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A fuel cell is a device that efficiently produces direct current and heat from hydrogen-rich fuel by electrically chemical reaction.

A fuel cell is similar to a battery in that it produces direct current through a chemical reaction. Again, like a battery, a 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 can continuously produce electricity as long as they have a supply of fuel and air. The correct term to describe a functioning fuel cell is a system of cells, since it requires some auxiliary systems to function properly.

How does an electrolyzer work?

Light enters the solar cell, producing electricity. An electrolyzer uses this electrical energy to separate water into oxygen and hydrogen. The hydrogen is then fed into a fuel cell, which produces electricity and lights the lamp. This is how a very simple electrolyzer makes hydrogen gas from water.

Why do fuel cells take so long?

In a real electrolyzer, performance is greatly improved by using a solid polymer membrane as the electrolyte, which allows ions to move through it. When the power is turned on, water is split into positively charged hydrogen ions and negatively charged oxygen ions. The positive hydrogen ions are attracted to the negative end and recombine in pairs to form hydrogen gas. Likewise, negative oxygen ions are drawn to the positive terminal and recombine in pairs to form oxygen gas.

The battery connects the positive terminal to the negative terminal through an electrolyte.
In a simple laboratory experiment, the electrolyte may be pure water.

Photo: Maybe before hydrogen pumps like this become commonplace.

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.

Four decades later, there are virtually no fuel cell vehicles on our streets. various reasons. Firstly, the world is focused on producing gasoline engines per million, so they are naturally much cheaper, better tested and more reliable. There are also huge savings on petroleum based to support gasoline engines: there are garages everywhere, Can service gasoline cars and gas stations around the world to supply them with fuel. In contrast, hardly anyone knows anything about fuel cells in cars, and there are virtually no gas stations that supply pressurized hydrogen. The “hydrogen economy” is a distant dream.

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 cell operation are water in the form of steam and a small amount of carbon dioxide, which is not emitted at all if pure hydrogen is used as fuel. Fuel cells are assembled into assemblies and then into individual functional modules.

Fuel cells with hydroxy exchange membranes

It's easy to see how a world full of hydrogen cars could work. We have many electrolyzer plants around the world creating hydrogen gas from water. Now gases take up much more space than liquids or solids, so we need to turn hydrogen gas into liquid hydrogen, which will make it easier to transport and store by compressing it to high pressure. hydrogen to gas stations where people could pump it into their cars, which would be powered by fuel cells instead of conventional gasoline engines.

Operating principle of fuel cells

Fuel cells produce electricity and heat through an electrochemical reaction using an electrolyte, a cathode, and an anode.

The anode and cathode are separated by an electrolyte that conducts protons. Once hydrogen is supplied to the anode and oxygen is supplied to the cathode, a chemical reaction begins, resulting in the generation of electric current, heat and water. 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).

Producing hydrogen by electrolysis uses energy - and quite a lot of it: we have to use electricity to split water. If we use typical solar cells to provide this electricity, they can be about 10 percent efficient, while an electrolyzer can be 75 percent efficient, giving a pitiful overall efficiency of just 5 percent. That's a pretty bad start - and it's just the beginning!

We also take the energy that transports hydrogen and compress it so that cars can carry enough in their tanks to go anywhere. This is a real problem because hydrogen's energy density is only about a fifth that of gasoline. In other words, you need five times as much to get this far. Another problem is that hydrogen is difficult to store for long periods of time because its extremely tiny molecules leak easily from most containers, and because hydrogen is flammable, leaks can cause terrible explosions.

Below is the corresponding reaction:

Reaction at the anode: 2H2 => 4H+ + 4e-
Reaction at the cathode: O2 + 4H+ + 4e- => 2H2O
General reaction of the element: 2H2 + O2 => 2H2O

Types of fuel 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.

And then, of course, there's all the downside at the opposite end of the process, where a fuel cell car turns hydrogen back into electricity to power the electric motors that drive its wheels. Hydrogen is not a miracle energy source; It's just an energy carrier, like a rechargeable battery, and it's a pretty inefficient energy carrier with a whole bunch of practical defects.

Professor David Mackay Sustainable energy without hot air. Hydrogen is not a fuel itself, but simply a way of transporting fuel produced by some other process. So it's better to compare it with batteries than with gasoline. All told, hydrogen cars today are significantly less efficient than the best battery-powered electric cars and are often less efficient than conventional gasoline or diesel engines! We could use solar panels to electrolyze water "for free", but we could just as easily store the same energy in batteries and use them to power our cars.

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.

Fuel cell cars sound promising, but if batteries are truly superior, hydrogen could prove to be a costly distraction from the important business of switching the world from fossil fuels to renewables.

Until oil gets much more expensive, there will be little or no incentive for motorists to switch to fuel cell vehicles. Even then, there are competing technologies that can stop fuel cell cars. We can stick with internal combustion engines, but power them using biofuels. Or it might be more efficient to build electric cars with on-board batteries that you charge at home. Or maybe a massive shift to hybrid cars powered by gasoline engines and electric motors will keep the world's oil supply going long enough for us to come up with a whole new technology - maybe even nuclear cars!

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.

Nobody knows what the future holds, but one thing is certain: oil will play a much smaller role in it. The sooner we embrace alternatives - electric cars, biofuels, fuel cells or something else, the better. There are also test videos of some of today's hydrogen fuel cell vehicles. Stations capable of producing hydrogen, like this one in Warsaw, are growing in Europe, North America and Asia. You'd have to be completely uninterested in cars or any other type of transportation not to recognize that cars are undergoing a major transition.

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%.

They no longer run solely on internal combustion engines and burn petroleum-based fuels. Nowadays, consumers typically buy cars that run partially or entirely on electricity. There are various forces behind this colossal shift. For example, electric vehicles reduce emissions of pollutants that degrade local air quality, as well as carbon dioxide emissions, which raise significant concerns about climate change.

Another reason to favor electric vehicles is National security. Sufficient oil reserves are found only in certain regions of the world. Therefore, countries that do not have these natural resources, will remain in the political and economic situation, if they continue to use vehicles that burn gasoline or diesel.

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.

The latter reason stems from the fact that exploitable sources of oil are slowly running out. Once society reaches a point where production cannot keep up with demand, prices will skyrocket. So it's no surprise that the transition to electric vehicles is accelerating.

Use of fuel cells in cars

Electric vehicles can be divided into three groups. The most common today, of course, are hybrids, which combine batteries, electric motors and internal combustion engines. Although these vehicles have many advantages, particularly high efficiency, all but hybrid hybrids end up using all their energy from petroleum fuels.

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. 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.

Hybrid and battery electric vehicles are common enough now that I don't need to say much about how they work. Fuel cell electric vehicles are still rare, so let me describe how they work in more detail.

Instead of relying on combustion to drive pistons, which then drive an electric generator, as in a hybrid car, a fuel cell car uses electrochemistry to directly generate electricity. This is done by taking compressed hydrogen gas stored on board and combining it with oxygen from the air. The products of the reaction are electricity to power the vehicle and water, which is discharged through the exhaust pipe along with nitrogen, which enters the fuel cell with air.

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.

Since no combustion occurs, high temperatures are avoided and nitrogen oxides, fog-causing pollutants from conventional vehicles, are not produced. And since there is no fuel to fuel at the beginning, no hydrocarbons, carbon monoxide or carbon dioxide are emitted from the tailpipe.

In addition, a fuel cell electric vehicle is extremely efficient, more than three times more efficient than a modern gasoline vehicle. Its range and refueling times are comparable to those of conventional cars, its fuel can be produced in a variety of ways, and its transmission produces virtually no vibration.

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).

Sounds attractive, doesn't it? You may be wondering how you can start driving. If you are in right place, now you can.

There are currently several dozen hydrogen refueling stations operating in Europe, and a program called Hydrogen Mobility in Europe is making efforts to increase this number.

And both use regenerative braking, a key energy-saving attribute of electric vehicles. Where they differ fundamentally from each other is the power source, the time required to recharge or refuel, the range and the ability to increase the size of the vehicle. Let's first consider the source of electricity.

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 (H3PO4) at concentrations 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.

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. In addition, CO2 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.

Reaction at the anode: 2H2 + 4OH- => 4H2O + 4e-
Reaction at the cathode: O2 + 2H2O + 4e- => 4OH-
General reaction of the element: 2H2 + O2 => 2H2O

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, a solid electrolyte does not pose the same orientation challenges and 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 (O2-). 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 (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 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 direct methanol oxidation fuel cells 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 (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+ + 6e-
Reaction at the cathode: 3/2O2 + 6H+ + 6e- => 3H2O
General reaction of the element: CH3OH + 3/2O2 => CO2 + 2H2O

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 temperature range 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 elements used to generate electricity, with power generation efficiency reaching up to 70%.

Alkaline fuel cells use an electrolyte, i.e. water solution 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 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 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 must run on pure hydrogen and oxygen. Moreover, molecules such as CO, H2O 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 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)

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 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 elements), the electrolyte and the electrodes. published

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

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Fuel cell- what it is? When and how did he appear? Why is it needed and why do they talk about them so often nowadays? What are its applications, characteristics and properties? Unstoppable progress requires answers to all these questions!

What is a fuel cell?

Fuel cell- is a chemical current source or electrochemical generator; it is a device for converting chemical energy into electrical energy. In modern life, chemical power sources are used everywhere and are batteries for mobile phones, laptops, PDAs, as well as batteries in cars, uninterruptible power supplies, etc. The next stage in the development of this area will be the widespread distribution of fuel cells and this is an irrefutable fact.

History of fuel cells

The history of fuel cells is another story about how the properties of matter, once discovered on Earth, found wide application far in space, and at the turn of the millennium returned from heaven to Earth.

It all started in 1839, when the German chemist Christian Schönbein published the principles of the fuel cell in the Philosophical Journal. In the same year, an Englishman and Oxford graduate, William Robert Grove, designed a galvanic cell, later called the Grove galvanic cell, which is also recognized as the first fuel cell. The name “fuel cell” was given to the invention in the year of its anniversary - in 1889. Ludwig Mond and Karl Langer are the authors of the term.

A little earlier, in 1874, Jules Verne, in his novel The Mysterious Island, predicted the current energy situation, writing that “Water will one day be used as fuel, the hydrogen and oxygen of which it is composed will be used.”

Meanwhile, new power supply technology was gradually improved, and since the 50s of the 20th century, not a year has passed without the announcement of the latest inventions in this area. In 1958, the first tractor powered by fuel cells appeared in the United States, in 1959. a 5kW power supply for a welding machine was released, etc. In the 70s, hydrogen technology took off into space: airplanes and rocket engines powered by hydrogen appeared. In the 60s, RSC Energia developed fuel cells for the Soviet lunar program. The Buran program also could not do without them: alkaline 10 kW fuel cells were developed. And towards the end of the century, fuel cells crossed zero altitude above sea level - based on them, power supply German submarine. Returning to Earth, the first locomotive was put into operation in the United States in 2009. Naturally, on fuel cells.

In all the wonderful history of fuel cells, the interesting thing is that the wheel still remains an invention of mankind that has no analogues in nature. The fact is that in their design and principle of operation, fuel cells are similar to a biological cell, which, in essence, is a miniature hydrogen-oxygen fuel cell. As a result, man once again invented something that nature has been using for millions of years.

Operating principle of fuel cells

The principle of operation of fuel cells is obvious even from the school chemistry curriculum, and it was precisely this that was laid down in the experiments of William Grove in 1839. The thing is that the process of water electrolysis (water dissociation) is reversible. Just as it is true that when an electric current is passed through water, the latter is split into hydrogen and oxygen, so the reverse is also true: hydrogen and oxygen can be combined to produce water and electricity. In Grove's experiment, two electrodes were placed in a chamber into which limited portions of pure hydrogen and oxygen were supplied under pressure. Due to the small volumes of gas, as well as due to the chemical properties of the carbon electrodes, a slow reaction occurred in the chamber with the release of heat, water and, most importantly, the formation of a potential difference between the electrodes.

The simplest fuel cell consists of a special membrane used as an electrolyte, on both sides of which powdered electrodes are applied. Hydrogen goes to one side (anode), and oxygen (air) goes 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, that promotes the dissociation reaction:

2H 2 → 4H + + 4e -

where H 2 is a diatomic hydrogen molecule (the form in which hydrogen is present as a gas); H + - ionized hydrogen (proton); e - - electron.

At the cathode side of the fuel cell, protons (that have passed through the electrolyte) and electrons (that have passed through the external load) recombine and react with the oxygen supplied to the cathode to form water:

4H + + 4e - + O 2 → 2H 2 O

Total reaction in a fuel cell it is written like this:

2H 2 + O 2 → 2H 2 O

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 (a load, such as a light bulb):

Fuel cells use hydrogen fuel and oxygen to operate. The easiest way is with oxygen - it is taken from the air. Hydrogen can be supplied directly from a certain container or by separating it from fuel (natural gas, gasoline or methyl alcohol - methanol). In the case of an external source, it must be chemically converted to extract the hydrogen. Currently, most fuel cell technologies being developed for portable devices use methanol.

Characteristics of fuel cells

Fuel cells are analogous to existing batteries in the sense that in both cases electrical energy is obtained from chemical energy. But there are also fundamental differences:

they only work as long as the fuel and oxidizer are supplied from an external source (i.e. they cannot store electrical energy),

the chemical composition of the electrolyte does not change during operation (the fuel cell does not need to be recharged),

they are completely independent of electricity (while conventional batteries store energy from the mains).

Each fuel cell creates voltage 1V. Higher voltage is achieved by connecting them in series. An increase in power (current) is realized through a parallel connection of cascades of series-connected fuel cells.

In fuel cells there is no strict limitation on efficiency, like that of heat engines (the efficiency of the Carnot cycle is the highest possible efficiency among all heat engines with the same minimum and maximum temperatures).

High efficiency achieved through the direct conversion of fuel energy into electricity. When diesel generator sets burn fuel first, the resulting steam or gas rotates a turbine or internal combustion engine shaft, which in turn rotates an electric generator. The result is an efficiency of a maximum of 42%, but more often it is about 35-38%. Moreover, due to the many links, as well as due to thermodynamic limitations on the maximum efficiency of heat engines, the existing efficiency is unlikely to be raised higher. For existing fuel cells Efficiency is 60-80%,

Efficiency almost does not depend on load factor,

Capacity is several times higher than in existing batteries,

Complete no environmentally harmful emissions. Only pure water vapor and thermal energy are released (unlike diesel generators, which have polluting exhausts and require their removal).

Types of fuel cells

Fuel cells classified according to the following characteristics:

according to the fuel used,

by operating pressure and temperature,

according to the nature of the application.

In general, the following are distinguished: types of fuel cells:

Solid-oxide fuel cells (SOFC);

Fuel cell with a proton-exchange membrane fuel cell (PEMFC);

Reversible Fuel Cell (RFC);

Direct-methanol fuel cell (DMFC);

Molten-carbonate fuel cells (MCFC);

Phosphoric-acid fuel cells (PAFC);

Alkaline fuel cells (AFC).

One type of fuel cell that operates at normal temperatures and pressures using hydrogen and oxygen is the ion exchange membrane cell. The resulting water does not dissolve the solid electrolyte, flows down and is easily removed.

Fuel cell problems

The main problem of fuel cells is related to the need to have “packaged” hydrogen, which could be freely purchased. Obviously, the problem should be solved over time, but for now the situation raises a slight smile: what comes first - the chicken or the egg? Fuel cells are not yet developed enough to build hydrogen factories, but their progress is unthinkable without these factories. Here we note the problem of the hydrogen source. Currently, hydrogen is produced from natural gas, but rising energy costs will also increase the price of hydrogen. At the same time, in hydrogen from natural gas, the presence of CO and H 2 S (hydrogen sulfide) is inevitable, which poison the catalyst.

Common platinum catalysts use a very expensive and irreplaceable metal - platinum. However, this problem is planned to be solved by using catalysts based on enzymes, which are a cheap and easily produced substance.

The heat generated is also a problem. Efficiency will increase sharply if the generated heat is directed into a useful channel - to produce thermal energy for the heating system, to use it as waste heat in absorption refrigeration machines and so on.

Methanol Fuel Cells (DMFC): Real Applications

The greatest practical interest today is direct fuel cells based on methanol (Direct Methanol Fuel Cell, DMFC). The Portege M100 laptop running on a DMFC fuel cell looks like this:

A typical DMFC cell circuit contains, in addition to the anode, cathode and membrane, several additional components: a fuel cartridge, a methanol sensor, a fuel circulation pump, an air pump, a heat exchanger, etc.

The operating time of, for example, a laptop compared to batteries is planned to be increased 4 times (up to 20 hours), a mobile phone - up to 100 hours in active mode and up to six months in standby mode. Recharging will be carried out by adding a portion of liquid methanol.

The main task is to find options for using a methanol solution with its highest concentration. The problem is that methanol is a fairly strong poison, lethal in doses of several tens of grams. But the concentration of methanol directly affects the duration of operation. If previously a 3-10% methanol solution was used, then mobile phones and PDAs using a 50% solution have already appeared, and in 2008, in laboratory conditions, specialists from MTI MicroFuel Cells and, a little later, Toshiba obtained fuel cells operating on pure methanol.

Fuel cells are the future!

Finally, the obvious future of fuel cells is evidenced by the fact that the international organization IEC (International Electrotechnical Commission), which determines industrial standards for electronic devices, has already announced the creation of a working group to develop an international standard for miniature fuel cells.

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 power factories or settlements. 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. Happening chemical compound molecules of hydrogen and oxygen to form water as a by-product 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 a power converter is to convert the direct electrical current produced by the fuel cells into alternating current, on which the vehicle's traction motor operates.

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 most simple reactions 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 cylinders, a fuel cell power plant and vehicle control systems using the latest technology electronic control by wire. The chassis of the Hy Wire vehicle is a thin platform that houses all the main elements of the vehicle's structure: 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.
Appearance in last years large quantity developments aimed at creating cars using alternative fuels and alternative powertrains indicate that the internal combustion engines, which have dominated automobiles for the past century, will eventually give way to cleaner, more efficient and quieter 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 a period of 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 world. open world on the assignment “The Womb of the Mother”. The point is that after the task “Initiation” (which, by the way, also applies to 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”. At this point it is necessary to pay attention 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 do two things: 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.

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 operation. different types 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 features for decentralized power generation. 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 become self-sufficient for the most part electricity and thus significantly increase the efficiency of its use.

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, hydrogen sources in the form of gasoline, methanol or natural gas could be used to provide power plants with existing systems fossil fuel supplies (gas stations, etc.). 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)

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)

Phosphoric acid fuel cells (PAFC)

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 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.

Proton exchange membrane fuel cells (PEMFCs)

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.

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

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

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

One of characteristic features SHTE – 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)

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

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.

Special pressures, compression and a set of necessary safety measures have very good value in the assessment at the end of 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., no polluting gases are released into the atmosphere air environment or causing the greenhouse effect. 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. Emissions of pollutants into the atmosphere from fuel cell operation are so low that in some areas of the United States their operation does not require special permission from government agencies, controlling air quality.

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 required. 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 have been used to supply energy Soviet ship reusable "Buran".

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 of 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

Region applications	Nominal power	Examples of using
Stationary installations	5–250 kW and higher	Autonomous sources of heat and power supply for residential, public and industrial buildings, uninterruptible power supplies, backup and emergency power supply sources
Portable installations	1–50 kW	Road signs, freight and refrigerated railroad trucks, wheelchairs, golf carts, spaceships and satellites
Mobile installations	25–150 kW	Cars (prototypes were created, for example, by DaimlerCrysler, FIAT, Ford, General Motors, Honda, Hyundai, Nissan, Toyota, Volkswagen, VAZ), buses ( e.g. "MAN", "Neoplan", "Renault") and other vehicles, warships and submarines
Microdevices	1–500 W	Mobile phones, laptops, personal digital assistants (PDAs), various consumer electronic devices, modern military devices

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. It is planned to create a similar system, for example, in training center Adam Joseph Lewis at 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)
	Figure 6. () Hydrogen molecules pass through channels in the plate to the anode, where the molecules decompose into individual atoms
	Figure 7. () As a result of chemisorption in the presence of a catalyst, hydrogen atoms are converted into protons
	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
	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

Item type	Workers temperature, °C	Efficiency output electrical energy),%	Total Efficiency, %
Fuel cells with proton exchange membrane (PEMFC)	60–160	30–35	50–70
Fuel cells based on phosphorus (phosphoric) acid (PAFC)	150–200	35	70–80
Fuel cells based molten carbonate (MCFC)	600–700	45–50	70–80
Solid oxide fuel cells (SOFC)	700–1 000	50–60	70–80

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 a 17th century scientist, which is why MCFC fuel cells are sometimes called Baconian cells. In NASA's 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 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.

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.

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.

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.

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 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.

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)

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

Characteristics of fuel cells

Fuel cell type	Operating temperature	Power generation efficiency	Fuel type	Scope of application
				Medium and large installations
			Pure hydrogen	installations
			Pure hydrogen	Small installations
			Most hydrocarbon fuels	Small, medium and large installations
				Portable installations
			Pure hydrogen	Space researched
			Pure hydrogen	Small installations

10. Use of fuel cells in cars

Story

The first element was made, it seems, from the lead of a Russian (this is important) simple pencil, and the body was a beer stopper. All this was heated on the kitchen stove. The electrolyte was Digger pipe cleaner powder, which is NaOH according to the label. Since I managed to get some current, I thought that perhaps such an element could really work. The tin cans started leaking at the seams (the solder was corroded by the alkali), and I don’t even remember what the results were. For a more serious experience, I bought a stainless steel juggernaut. However, nothing worked out with her. Not only was the voltage only 0.5 volts, it was also directed in the wrong direction. It also turned out that coals from pencils really like to crumble into their component parts. Apparently, they are not made from a solid graphite crystal, but are glued together from dust. The same fate befell the rods from AA batteries. We also bought brushes from some electric motors, but the places where the supply wire enters the brush quickly became unusable. In addition, one pair of brushes turned out to contain copper or some other metal (this happens with brushes).

Scratching my head firmly, I decided that for reliability it would be better to make the vessel out of silver, and the coal using the technology described by Jaco, i.e., sintering. Silver costs moderate money (prices fluctuate, but somewhere around 10-20 rubles per gram). I've met tea that costs much more.

It is known that silver is stable in NaOH melt, while iron gives ferrates, for example, Na2FeO4. Since iron generally has a variable valency, its ions can cause a “short circuit” in the element, at least in theory. Therefore, I decided to first check the case of silver, as it is simpler. First, a cupronickel silver-plated spoon was purchased, and when tested with brushes, it immediately turned out to be 0.9V of an open circuit with the required polarity, as well as a fairly large current. Subsequently (not practically, but theoretically) it turned out that silver can also dissolve in alkali in the presence of sodium peroxide Na2O2, which is formed in some quantities when air is blown through. Whether this happens in the element or whether under the protection of carbon the silver is safe, I do not know.

The spoon did not live long. The silver layer swelled and it stopped working. Cupronickel is unstable in alkali (like most materials existing in the world). After that, I made a special cup from a silver coin, which produced a record power of 0.176 watts.

All this was done in an ordinary city apartment, in the kitchen. I never got seriously burned, didn’t start a fire, and only once spilled molten lye on the stove (the enamel immediately corroded). The simplest tool was used. If you can find out the correct type of iron and the correct composition of the electrolyte, then every not-so-armless man can make such an element on his knee.

In 2008, several “correct types of iron” were identified. For example, food grade stainless steel, tin cans, electrical steels for magnetic circuits, as well as low-carbon steels - st1ps, st2ps. The less carbon, the better job. Stainless steel seems to work worse than pure iron (by the way, it is much more expensive). “Norwegian sheet” iron, also known as Swedish, is iron that was made using charcoal in Sweden using charcoal and contained no more than 0.04% carbon. Currently, such low carbon content can only be found in electrical steels. It is probably best to make cups by stamping from sheet electrical steel

Making a silver cup

In 2008, it turned out that the iron cup also works well, so I remove everything that touches the silver cup. It was interesting, but now no longer relevant.

You can try using graphite. But I didn't have time. I asked the driver for an overlay for the trolley bus horns, but this was already at the end of my experimental epic. You can also try brushes from motors, but they are often made with copper, which violates the purity of the experiment. I had two options for brushes, one turned out to be with copper. Pencils do not produce any results because they have a small surface area and are inconvenient to draw current from. Battery rods fall apart in alkali
(something happens to the binder). Generally speaking, graphite is the worst fuel for the element because... it is the most chemically resistant. Therefore, we make the electrode “honestly.” We take charcoal (I bought birch charcoal for barbecues at the supermarket), grind it as finely as possible (I ground it first in a porcelain mortar, then bought a coffee grinder). In industry, electrodes are made from several fractions of coal, mixing them with each other. Nothing prevents you from doing the same. The powder is fired to increase electrical conductivity: it must be heated for several minutes to the highest possible temperature (1000 or more). Naturally, without air access.

For this I made a forge from two tin cans nested inside each other. Pieces of dry clay are piled between them for thermal insulation. The bottom of both cans is punched so that there is room for air to blow. The inner can is filled with coals (which act as fuel), among them a metal box is placed - a “crucible”, I also rolled it out of tin from a tin can. Coal powder wrapped in a paper bag is stuffed into the box. There must be a gap between the bundle of coal and the walls of the “crucible”. It is covered with sand to prevent air from entering. The coals are ignited, then blown through holes in the bottom with an ordinary hairdryer. All this is quite a fire hazard - sparks fly. You need safety glasses, and you also need to make sure that there are no curtains, barrels of gasoline or other fire hazards nearby. It would be better, in a good way, to do such things somewhere on a green lawn during the rainy season (in the break between rains). Sorry, but I'm too lazy to draw this whole structure. I think you can guess without me.

Next, a certain amount of sugar is added to the burnt powder by eye (probably from a third to a half). This is the binder. Then - a little water (when my hands were dirty and too lazy to open the tap, I just spat in it and added beer instead of water, I don’t know how much it matters; it’s quite possible that organic matter is important. All this is thoroughly mixed in mortar. The result should be a plastic mass. From this mass you need to form an electrode. The better you compress it, the better. I took a plugged piece of tube and hammered the coal into the tube with a smaller tube, using a hammer. So that the product does not fall apart when removed from the tube , before stuffing, several paper rims were inserted into the pipe. The plug should be removable, and even better, if the pipe is sawn lengthwise and connected with clamps. Then after pressing, you can simply disconnect the clamps and get the coal blank safe and sound. In the case of a removable plug, you need will squeeze out the finished workpiece from
pipes (in this case it may fall apart). My coal had a diameter of 1.2-1.5 cm and a length of 4-5 cm.

The finished form is dried. To do this, I turned on the gas stove on a very low fire, placed an empty tin can upside down on it and put a coal on the bottom. Drying should be slow enough so that water vapor does not tear the workpiece. After all the water has evaporated, the sugar will begin to “boil.” It will turn into caramel and stick the pieces of coal together.

After cooling, you need to drill a longitudinal (along its axis of symmetry) round hole in the coal into which the discharge electrode will be inserted. The diameter of the hole - I don’t remember, I think it was 4 mm. With this procedure, everything may already be covered, because the structure is fragile. I first drilled with a 2 mm drill, then carefully (by hand) expanded it with 3 mm and 4 mm drills, or even a needle file, I don’t remember exactly. In principle, this hole can be made already at the molding stage. But this -
nuances.

After everything is dried and drilled, you need to fire it. The general idea is that with a fairly smooth increase in temperature, you need to subject the coal to strong and uniform heating without air access for some time (about 20 minutes). You need to heat it up gradually and cool it down too. Temperature - the higher the better. Preferably more than 1000. I had
orange (closer to white) heating of iron in a makeshift forge. Industrial electrodes are fired for many days, with a very smooth supply and removal of heat. After all, this is essentially ceramics, which is fragile. I cannot guarantee that the coal will not crack. I did everything by eye. Some coals cracked immediately upon use.

So, the coal is ready. It should have as little resistance as possible. When measuring resistance, you should not touch the coal with the needles of the tester, but take two stranded wires, lean them against the sides of the coal (not against the ends of the rod, but simply along the diameter) and press firmly with your fingers (just so as not to crack), see the figure, in the figure the pink amorphous mass is fingers squeezing the wire strands.

If the resistance is 0.3-0.4 ohms (this was on the edge of the sensitivity of my tester), then this is a good coal. If it is more than 2-3 ohms, then it is bad (the power density will be small). If the coal is unsuccessful, you can repeat the firing.

After firing, we make a discharge electrode. This is a strip of silver or iron - 2008 length equal to twice or slightly less than the length of the coal,
width - two hole diameters. Thickness - let's say 0.5 mm. From it you need to roll up a cylinder whose outer diameter is equal to
hole diameter. But the cylinder will not work, because the width is too small; it will turn out to be a cylinder with a longitudinal slot. This slot is important to compensate for thermal expansion. If you make a full cylinder, the silver will burst the coal when heated.
We insert the “cylinder” into the coal. You need to make sure it fits tightly into the hole. There are two sides to this: too much force will break the coal; too little force will not make enough contact (this is very important). See picture.

This design was not born right away, it seems to me more perfect than those clamps that are drawn in Jaco’s patent. Firstly, with such a contact, the current flows not along, but along the radius of the cylindrical coal, which can significantly reduce electrical losses. Secondly, metals have a higher coefficient of thermal expansion than coal, so the contact of coal with the metal clamp weakens when heated. In my case, the contact strengthens or maintains its strength. Thirdly, if the discharge electrode is not made of silver, then carbon protects it from oxidation. Hurry up and give me a patent!

Now you can measure the resistance again; one of the poles will be the current-carrying electrode. By the way, my tester has 0.3 ohms - this is already the sensitivity limit, so it is better to pass a current of a known voltage and measure its strength.

Air supply

We take a steel rod from a large-capacity ballpoint pen. Preferably empty. We remove the block with the ball from it - what remains is just an iron tube. We carefully remove the remaining paste (I didn’t do this very well and the paste later became charred, which made life difficult). First, this is done with water, and then it is better to ignite the rod several times in the flame of the burner. The ink will pyrolyze, leaving behind carbon that can be scooped out.

Next, we find some other tube to connect this rod (it will be hot) with a PVC tube leading from the aquarium compressor, which is used to condition the fish. Everything should be fairly tight. We put an adjustable clamp on the PVC pipe, because even the weakest compressor produces too much air. Ideally, you need to make a silver, not a steel, tube, and I even succeeded, but I could not ensure a tight connection between the silver tube and the PVC line. The intermediate tubes strongly poisoned the air (due to the same thermal gaps), so in the end I settled on a steel rod. Of course, this problem can be solved, but you just had to spend time and effort on it and choose the appropriate handset for the situation. In general, in this part I deviated greatly from Jaco’s patent. I couldn’t make a rose like the one he painted (and to be honest, I didn’t look at its design well enough at the time).

Here it is worth making a short digression and discussing how Jaco misunderstood the work of his element. Obviously, oxygen goes into an ionic form somewhere at the cathode, according to the formula O2 + 4e- = 2O2-, or some similar reaction where oxygen is reduced and combines with something. That is, it is important to ensure triple contact of air, electrolyte and cathode. This can occur when air bubbles come into contact with the metal of the atomizer and the electrolyte. That is, the larger the total perimeter of all the holes of the atomizer, the greater the current should be. Also, if you make a cup with inclined edges, the triple contact surface can also increase, see fig.

Another option is when dissolved oxygen is reduced at the cathode. In this case, the triple contact area is not particularly important, but you just need to maximize the surface area of the bubbles to speed up the dissolution of oxygen. True, in this case it is not clear why dissolved oxygen does not oxidize coal directly, without an electrochemical reaction (working “bypass” the electrical circuit). Apparently, in this case, the catalytic properties of the cup material are important. Okay, that's all lyrics. In any case, you need to divide the stream into small bubbles. The attempts I have made to do this have not been particularly successful.

To do this, it was necessary to make thin holes, which caused a lot of problems.

Firstly, thin holes quickly become clogged, because... the iron corrodes, rust and coal residues (remember that there was once pen paste there) fall out of the rod and plug the holes.
Secondly, the holes are of unequal size and it is difficult to get air to flow simultaneously from all the holes.
Thirdly, if two holes are located nearby, then there is a bad tendency for the bubbles to merge before they break off.
Fourthly, the compressor supplies air unevenly and this also somehow affects the size of the bubbles (apparently, one bubble pops out at one push). All this can be easily observed by pouring water into a transparent jar and testing the sprayer in it. Of course, alkali has a different viscosity and surface tension coefficient, so you have to act at random. I was never able to overcome these problems and, on top of that, the problem of air leaks due to thermal gaps. Due to these leaks, the sprayer could not start working, since this requires overcoming surface tension forces. It was here that the shortcomings of the clamps became fully apparent. No matter how you tighten them, they still loosen when heated. As a result, I switched to a simple ballpoint pen atomizer, which gave only one stream of bubbles. Apparently, to do this in a normal way, you need to carefully get rid of leaks, supply air under significant pressure (more than that created by an aquarium compressor) and through small holes.

This part of the design is frankly poorly worked out...

Assembly

All. Let's put it all together. You need to install everything on the clamps so that
1. There was no short circuit through the supporting structure.
2. The coal did not touch the tube blowing air or the walls
cup. This will be difficult, since the gaps are small, the clamps are flimsy, and the alkali will gurgle when the element operates. The Archimedean force will also act, which will shift everything where it is not needed, and the surface tension force, attracting the coal to other objects. The silver will become soft when heated. Therefore, in the end, I held the coal with pliers by the end of the discharge electrode. It was bad. For normal operation, you still need to make a lid (apparently, only from porcelain - the clay soaks in alkali and loses strength, maybe you can use baked clay). The idea of how to make this lid is in Jaco's patent. The main thing is that it should hold the coal quite well, because... even with a slight misalignment it will touch the cup at the bottom. To do this, it must have a large height. I didn’t manage to find such a porcelain lid, nor did I manage to make a ceramic one from clay (everything I tried to make from clay quickly cracked, apparently I somehow fired it wrong). The only little trick is to use a metal cover and a layer of even poorly fired clay as thermal insulation. This path is also not so easy.

In short, my element design was also worthless.

It’s also a good idea to prepare a tool that can be used to get a piece of coal that may fall off the electrode and fall into the alkali. A piece of coal may fall off and fall into the alkali, then there will be a short circuit. As such a tool, I had a bent steel clip, which I held with pliers. We connect the wires - one to the handle, the other to the outlet electrode. You can solder it, although I used two metal plates and screwed them together with screws (all from a children's metal construction set). The main thing is to understand that the entire structure operates at low voltage and all connections must be made well. We measure the resistance in the absence of electrolyte between the electrodes - we make sure that it is high (at least 20 Ohms). We measure the resistance of all connections and make sure that they are small. We assemble a circuit with a load. For example, a resistance of 1 Ohm and an ammeter connected in series. Testers have low ammeter resistance only in the mode of measuring units of amperes; it is advisable to find out this in advance. You can either turn on the ampere unit change mode (the current will be from 0.001 to 0.4 A), or instead of a series-connected ammeter, turn on a voltmeter in parallel (the voltage will be from 0.2 to 0.9 V). It is desirable to provide the ability to change the conditions during the experiment in order to measure the open circuit voltage, short circuit current and current with a 1 ohm load. It’s better if the resistance can also be changed: 0.5 ohm, 1 ohm and 2 ohm to find the one at which maximum power will be achieved.

We turn on the compressor from the aquarium and tighten the clamp so that the air flows barely (and, by the way, the functionality of the supply pipeline must be checked by immersing it in water. Since the density of the alkali is 2.7, it must be immersed to an appropriately large depth. Complete tightness is not necessary, The main thing is that even at such a depth something gurgles from the end of the tube.

Precautionary measures

Next comes work with molten alkali. How can I explain what alkali melt is? Have you gotten soap in your eyes? It's unpleasant, isn't it? So, melted NaOH is also soap, only heated to 400 degrees and hundreds of times more caustic.

Protective measures when working with molten alkali are strictly required!

First of all, Good safety glasses are strictly necessary. I am nearsighted, so I wore two glasses - plastic safety glasses on top, and glass underneath. Safety glasses should protect against splashes not only from the front, but also from the sides. I felt safe in such ammunition. Despite safety glasses, it is not recommended to bring your face close to the device.

In addition to your eyes, you also need to protect your hands. I did everything very carefully, so in the end I got the hang of it and worked in a T-shirt. This is useful, since the smallest splashes of alkali that sometimes fall on your hands give a burn that does not allow you to forget for several days what substance you are dealing with.

But, naturally, there were gloves on my hands. First, rubber household ones (not the thinnest ones), and on top of them - pimply rag pimples sticking out from the back of the palm. I moistened them with water so that I could handle hot objects. With such a pair of gloves, your hands are more or less protected. But you need to make sure that the outer gloves are never too wet. A drop of water falling into the electrolyte instantly boils, and the electrolyte splashes very nicely. If this happens (and this happened to me three times), problems with the respiratory system arise. In these cases, I immediately held my breath without completing the inhalation (kayak practice helps not to panic in such situations), and got out of the kitchen as quickly as possible.

In general, to protect the respiratory system, good ventilation is needed during the experiment. In my case it was just a draft (it was in the summer). But ideally it should be a hood or open air.

Since lye splashes are inevitable, everything in the immediate vicinity of the cup is covered in some degree of lye. If you handle it with bare hands, you may get burned. It is necessary to wash everything after completing the experiment, including gloves.

In case of a burn, I always had a container of water and a container of diluted vinegar nearby to neutralize the alkali in case of a severe burn. Fortunately, vinegar has never come in handy, and I can’t say whether it’s worth using at all. In case of a burn, immediately wash off the alkali with plenty of water. There is also folk remedy from burns - urine. It seems to help too.

Actually working with the element

Pour dry NaOH into a glass (I bought Digger for cleaning pipes). You can add MgO and other ingredients, such as CaCO3 (tooth powder or chalk) or MgCO3 (I had MgO from friends). Light the burner and heat it up. Since NaOH is extremely hygroscopic, this must be done immediately (and the bag with NaOH must be tightly closed). It would be a good idea to make sure that the glass is surrounded by heat on all sides - the current VERY strongly depends on temperature. That is, make an improvised combustion chamber and direct the burner flame into it (you also need to make sure that the cartridge at the burner does not explode, in my opinion these burners are quite poorly made from this point of view, as I already wrote, for this you need to hot gases did not fall on the canister, and it was better to keep it in its normal position, and not “upside down”).
Sometimes it turns out to be convenient to bring the flame of the burner from above, but this is after everything has melted. Then the discharge tube, the discharge electrode (and the carbon through it), and the top of the glass, where there are most air bubbles, are heated at the same time). If my memory serves me correctly, the greatest result was obtained in this way.

After some time, the alkali will begin to melt and its volume will decrease. You need to add powder so that the glass is 2/3 full in height (the alkali will flow away due to capillarity and splashing). The air supply pipe did not work well for me (due to thermal expansion, the gaps and leaks will increase, and due to good heat removal, the alkali in it can solidify). Sometimes the air stopped flowing altogether. To fix this I did the following:
1. Blowing (temporary gentle increase in air supply)
2. Rise. (the pressure will be less and the air will displace the column of alkali from
pipes)
3. Warming up (take it out of the cup and heat it with a burner so that the alkali inside the sprayer melts).

In general, the element begins to work well at a red-hot temperature (the alkali begins to glow). At the same time, foam begins to flow (this is CO2), and popping noises with flashes are heard (either this is hydrogen, or CO is burning out, I still don’t understand).
I was able to achieve a maximum power of 0.025 W/cm2 or 0.176 W total per element, with a load resistance of 1.1 Ohms. At the same time, I measured the current with an ammeter. It was also possible to measure the voltage drop across the load.

Electrolyte degeneration

A bad side reaction occurs in the element

NaOH+CO2=Na2CO3+H2O.

That is, after some time (tens of minutes) everything will harden (the melting point of soda - I don’t remember, but about 800). For some time this can be overcome by adding more alkali, but in the end it doesn’t matter - the electrolyte will harden. Regarding how to combat this, see other pages on this site, starting with the page about UTE. Generally speaking, you can use NaOH, despite this problem, which is what Jaco wrote about in his patent. Because there are ways to produce NaOH from Na2CO3. For example, displacement by quicklime according to the reaction Na2CO3+CaOH=2NaOH+CaCO3, after which CaCO3 can be calcined and CaO will be obtained again. True, this method is very energy-intensive and the overall efficiency of the element will drop very much, and the complexity will increase. Therefore, I think that you still need to look for a stable electrolyte composition, which was found in SARA. It is quite possible that this can be done by finding SARA patent applications in the US Patent Office database (http://www.uspto.gov), especially since over time they could have become already issued patents. But I haven’t gotten around to it yet. Actually, this idea itself appeared only during the preparation of these materials. Apparently, I'll do it soon.

Results, thoughts and conclusions

Here I may repeat myself a little. You can start not with silver, but right away with iron. When I tried to use a cheater
made of stainless steel, it turned out poorly for me. Now I understand that the first reason for this is the low temperature and the large gap between the electrodes. In his article, Jacques writes that poor performance with iron is due to the fact that oil burns to the iron and a second carbon electrode is formed, so you need to very carefully clean the iron from the slightest traces of oil, and also use iron
low carbon. Maybe so, but I still think there is another, more important reason. Iron is an element of variable valence. It dissolves and forms a "short circuit". This is also supported by the change in color. When using silver, the color of the electrolyte does not change (silver is the most resistant metal to the action of molten alkalis). At
When using iron, the electrolyte turns brown. When using silver, the open circuit voltage reaches 0.9V or higher. When using iron, it is significantly less (I don’t remember exactly, but no more than 0.6V). As for what kind of iron needs to be used for everything to work well, see other pages. A little more about water vapor, which SARA writes about. On the one hand, it is good for everyone (in theory): it does not allow iron to go into solution (the decomposition reaction of alkali metal ferrates is known hot water, something like Na2FeO4+H2O=2NaOH+Fe2O3) and seems to shift the equilibrium in a bad side reaction. I looked up the thermodynamics of the reaction NaOH+CO2=Na2CO3+H2O using the online program F*A*C*T (http://www.crct.polymtl.ca/FACT/index.php) At all temperatures, the equilibrium in it is very strongly shifted to the right, i.e., water is unlikely to significantly displace carbon dioxide from its compound with sodium oxide. It is possible that the situation changes in the NaOH-Na2CO3 alloy, or that a kind of aqueous solution is formed, but I don’t know how to find out. I think that in this case practice is the criterion of truth.

The main thing you may encounter when conducting experiments with steam is condensation. If somewhere along the way from the point where water enters the air main, the temperature of any wall drops below 100C, the water can condense and then, with the flow of air, enter the alkali in the form of a droplet. This is very dangerous and should be avoided at all costs. What is especially dangerous is that the temperature of the walls is not so easy to measure. I myself have not tried to do anything with steam.

In general, of course, you need to carry out such work not in an apartment, but at least in a country house, and immediately make a larger element. To do this, naturally, you will need a larger furnace for firing, a larger “stove” for heating the element, and more starting materials. But it will be much more convenient to work with all the details. This is especially true for the structure of the element itself, which I did not have a lid. Making a large lid is much easier than making a small one.

About silver. Silver, of course, is not that cheap. But if you make the silver electrode thin enough, then the silver cell can become cost-effective. For example, let’s say we managed to make an electrode with a thickness of 0.1 mm. Given the plasticity and malleability of silver, this will be easy (silver can be pulled through rollers into very thin foil, and I even wanted to do this, but there were no rollers). With a density of about 10 g/cm^3, one cubic centimeter of silver costs approximately 150 rubles. It will give 100 square centimeters of electrode surface. You can get 200cm^2 if you take two flat coals and place a silver plate between them. With a specific power of 0.025 W/cm^2 that I achieved, the power is 5 watts or 30 rubles per watt, or 30,000 rubles per kilowatt. Due to the simplicity of the design, you can expect that the remaining components of the kilowatt element (stove, air pump) will be significantly cheaper. The body can be made of porcelain, which is relatively resistant to alkali melt. The result will not be too expensive, even compared to low-power gasoline power plants. And solar panels with windmills and thermoelectric generators are resting far behind. To further reduce the price, you can try to make a vessel from silver-plated copper. In this case, the silver layer will be 100-1000 times thinner. True, my experiments with a cupronickel spoon ended unsuccessfully, so it is unclear how durable the silver coating will be. That is, even the use of silver opens up pretty good prospects. The only thing that could fail here is if the silver is not strong enough.

More about case materials. Allegedly, when the element is operating great importance have sodium peroxides, for example Na2O2, which should arise when air is blown into NaOH. At high temperatures, peroxide corrodes almost all substances. Experiments were carried out to measure weight loss with crucibles made of various materials containing molten sodium peroxide. Zirconium turned out to be the most resistant, followed by iron, then nickel, then porcelain. Silver did not make it into the top four. Unfortunately, I don’t remember exactly how stable silver is. It was also written there about the good resistance of Al2O3 and MgO. But the second place, which is occupied by iron, inspires optimism.

That's all, actually.