From the point of view of “green” energy, hydrogen fuel cells have an extremely high efficiency of 60%. For comparison: the efficiency of the best internal combustion engines is 35-40%. For solar power plants, the coefficient is only 15-20%, but is highly dependent on weather conditions. Efficiency of the best vanes wind power plants up to 40%, which is comparable to steam generators, but wind turbines also require suitable weather conditions and expensive maintenance.
As we can see, in terms of this parameter, hydrogen energy is the most attractive source of energy, but there are still a number of problems that prevent its mass use. The most important of them is the process of hydrogen production.
Mining problems
Hydrogen energy is environmentally friendly, but not autonomous. To operate, a fuel cell requires hydrogen, which is not found on Earth in its pure form. Hydrogen needs to be produced, but all currently existing methods are either very expensive or ineffective.The most effective method in terms of the volume of hydrogen produced per unit of energy expended is considered to be the method of steam reforming of natural gas. Methane is combined with water vapor at a pressure of 2 MPa (about 19 atmospheres, i.e. pressure at a depth of about 190 m) and a temperature of about 800 degrees, resulting in a converted gas with a hydrogen content of 55-75%. Steam reforming requires huge installations that can only be used in production.
A tube furnace for steam methane reforming is not the most ergonomic way to produce hydrogen. Source: CTK-Euro
A more convenient and simpler method is water electrolysis. When an electric current passes through the water being treated, a series of electrochemical reactions occur, resulting in the formation of hydrogen. A significant disadvantage of this method is the high energy consumption required to carry out the reaction. That is, a somewhat strange situation arises: to obtain hydrogen energy you need... energy. To avoid unnecessary costs during electrolysis and conserve valuable resources, some companies are striving to develop full cycle “electricity - hydrogen - electricity” systems, in which energy production becomes possible without external recharge. An example of such a system is the development of Toshiba H2One.
Mobile power station Toshiba H2One
We have developed the H2One mobile mini power station that converts water into hydrogen and hydrogen into energy. To maintain electrolysis it uses solar panels, and excess energy is stored in batteries and ensures operation of the system in the absence of sunlight. The resulting hydrogen is either directly supplied to the fuel cells or sent for storage in an integrated tank. In an hour, the H2One electrolyzer generates up to 2 m 3 of hydrogen, and provides output power of up to 55 kW. To produce 1 m 3 of hydrogen, the station requires up to 2.5 m 3 of water.While the H2One station is not capable of providing electricity to a large enterprise or an entire city, its energy will be quite sufficient for the functioning of small areas or organizations. Thanks to its portability, it can also be used as a temporary solution during natural disasters or emergency power outages. In addition, unlike a diesel generator, which requires fuel to function properly, a hydrogen power plant only requires water.
Currently, the Toshiba H2One is used in only a few cities in Japan - for example, it supplies electricity and hot water train station in Kawasaki city.
Installation of the H2One system in Kawasaki
Hydrogen future
Nowadays, hydrogen fuel cells provide energy for portable power banks, city buses with cars, and railway transport. (We will talk more about the use of hydrogen in the auto industry in our next post). Hydrogen fuel cells unexpectedly turned out to be great solution for quadcopters - with a mass similar to the battery, the hydrogen supply provides up to five times longer flight time. However, frost does not affect efficiency in any way. Experimental fuel cell drones produced by the Russian company AT Energy were used for filming at the Sochi Olympics.It has become known that at the upcoming Olympic Games in Tokyo, hydrogen will be used in cars, in the production of electricity and heat, and will also become the main source of energy for the Olympic village. For this purpose, by order of Toshiba Energy Systems & Solutions Corp. One of the world's largest hydrogen production stations is being built in the Japanese city of Namie. The station will consume up to 10 MW of energy obtained from “green” sources, generating up to 900 tons of hydrogen per year through electrolysis.
Hydrogen energy is our “reserve for the future,” when fossil fuels will have to be completely abandoned, and renewable energy sources will not be able to meet the needs of humanity. According to the Markets&Markets forecast, the volume of global hydrogen production, which currently stands at $115 billion, will grow to $154 billion by 2022. But mass implementation of the technology is unlikely to happen in the near future; a number of problems associated with the production and operation of special power plants still need to be resolved and their cost reduced . When technological barriers are overcome, hydrogen energy will reach a new level and may be as widespread as traditional or hydropower today.
Fuel cell ( Fuel Cell) is a device that converts chemical energy into electrical energy. It is similar in principle to a conventional battery, but differs in that its operation requires a constant supply of substances from the outside for the electrochemical reaction to occur. Hydrogen and oxygen are supplied to the fuel cells, and the output is electricity, water and heat. Their advantages include environmental friendliness, reliability, durability and ease of operation. Unlike conventional batteries, electrochemical converters can operate virtually indefinitely as long as fuel is supplied. They don't have to be charged for hours until they're fully charged. Moreover, the cells themselves can charge the battery while the car is parked with the engine turned off.
The most widely used fuel cells in hydrogen vehicles are proton membrane fuel cells (PEMFCs) and solid oxide fuel cells (SOFCs).
A proton exchange membrane fuel cell works as follows. Between the anode and cathode there is a special membrane and a platinum-coated catalyst. Hydrogen is supplied to the anode, and oxygen (for example, from air) is supplied to the cathode. At the anode, hydrogen is decomposed into protons and electrons with the help of a catalyst. Hydrogen protons pass through the membrane and reach the cathode, and electrons are transferred to the external circuit (the membrane does not allow them to pass through). The potential difference thus obtained leads to the generation of electric current. On the cathode side, hydrogen protons are oxidized by oxygen. As a result, water vapor appears, which is the main element exhaust gases car. Possessing high efficiency, PEM cells have one significant drawback - their operation requires pure hydrogen, the storage of which is a rather serious problem.
If such a catalyst is found that replaces expensive platinum in these cells, then a cheap fuel cell for generating electricity will immediately be created, which means the world will get rid of oil dependence.
Solid Oxide Cells
Solid oxide SOFC cells are much less demanding on fuel purity. In addition, thanks to the use of a POX reformer (Partial Oxidation), such cells can consume regular gasoline as fuel. The process of converting gasoline directly into electricity is as follows. In a special device - a reformer, at a temperature of about 800 ° C, gasoline evaporates and decomposes into its constituent elements.
This releases hydrogen and carbon dioxide. Further, also under the influence of temperature and using SOFC directly (consisting of porous ceramic material based on zirconium oxide), hydrogen is oxidized by oxygen in the air. After obtaining hydrogen from gasoline, the process continues according to the scenario described above, with only one difference: the SOFC fuel cell, unlike devices operating on hydrogen, is less sensitive to impurities in the original fuel. So the quality of gasoline should not affect the performance of the fuel cell.
The high operating temperature of SOFC (650–800 degrees) is a significant drawback; the warm-up process takes about 20 minutes. But excess heat is not a problem, since it is completely removed by the remaining air and exhaust gases produced by the reformer and the fuel cell itself. This allows the SOFC system to be integrated into a vehicle as a separate device in a thermally insulated housing.
The modular structure allows you to achieve the required voltage by connecting a set of standard cells in series. And, perhaps most importantly from the point of view of the implementation of such devices, SOFC does not contain very expensive platinum-based electrodes. It is the high cost of these elements that is one of the obstacles in the development and dissemination of PEMFC technology.
Types of fuel cells
Currently, there are the following types of fuel cells:
- A.F.C.– Alkaline Fuel Cell (alkaline fuel cell);
- PAFC– Phosphoric Acid Fuel Cell (phosphoric acid fuel cell);
- PEMFC– Proton Exchange Membrane Fuel Cell (fuel cell with a proton exchange membrane);
- DMFC– Direct Methanol Fuel Cell (fuel cell with direct breakdown of methanol);
- MCFC– Molten Carbonate Fuel Cell (fuel cell of molten carbonate);
- SOFC– Solid Oxide Fuel Cell (solid oxide fuel cell).
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 are associated with great prospects towards a sustainable source of energy that will help reduce emissions of greenhouse gases and other pollutants. The main obstacle to the widespread use of fuel cells is their high price Compared to other devices that generate electricity or propel vehicles.
History of development
The first fuel cells were demonstrated by Sir William Groves in 1839. Groves showed that the process of electrolysis - the splitting of water into hydrogen and oxygen under the influence of an electric current - is reversible. That is, hydrogen and oxygen can be combined chemically to form electricity.
After this was demonstrated, many scientists rushed to study fuel cells with zeal, but the invention of the internal combustion engine and the development of oil reserve infrastructure in the second half of the nineteenth century left the development of fuel cells far behind. The development of fuel cells was further hampered by their high cost.
A surge in the development of fuel cells occurred in the 50s, when NASA turned to them in connection with the need for a compact electric generator for space flights. The investment was made and the Apollo and Gemini flights were powered by fuel cells. Spacecraft also run on fuel cells.
Fuel cells are still largely an experimental technology, but several companies are already selling them on the commercial market. In the last nearly ten years alone, significant advances have been made in commercial fuel cell technology.
How does a fuel cell work?
Fuel cells are similar to batteries - they produce electricity through a chemical reaction. In contrast, internal combustion engines burn fuel and thus produce heat, which is then converted into mechanical energy. Unless the heat from the exhaust gases is used in some way (for example, for heating or air conditioning), then the efficiency of the internal combustion engine can be said to be quite low. For example, the efficiency of fuel cells when used in a vehicle, a project currently under development, is expected to be more than twice the efficiency of today's typical gasoline engines used in automobiles.
Although both batteries and fuel cells produce electricity chemically, they perform two very different functions. Batteries are stored energy devices: the electricity they produce is the result of a chemical reaction of a substance that is already inside them. Fuel cells do not store energy, but rather convert some of the energy from externally supplied fuel into electricity. In this respect, a fuel cell is more like a conventional power plant.
There are several various types fuel cells. The simplest fuel cell consists of a special membrane known as an electrolyte. Powdered electrodes are applied on both sides of the membrane. This design - an electrolyte surrounded by two electrodes - is a separate element. Hydrogen goes to one side (anode), and oxygen (air) to the other (cathode). Different chemical reactions occur at each electrode.
At the anode, hydrogen breaks down into a mixture of protons and electrons. In some fuel cells, the electrodes are surrounded by a catalyst, usually made of platinum or other noble metals, which promotes the dissociation reaction:
2H2 ==> 4H+ + 4e-.
H2 = diatomic hydrogen molecule, form, in
in which hydrogen is present in the form of a gas;
H+ = ionized hydrogen, i.e. proton;
e- = electron.
The operation of a fuel cell is based on the fact that the electrolyte allows protons to pass through it (towards the cathode), but electrons do not. Electrons move to the cathode along an external conductive circuit. This movement of electrons is an electrical current that can be used to drive an external device connected to the fuel cell, such as an electric motor or light bulb. This device is usually called a "load".
At the cathode side of the fuel cell, protons (that have passed through the electrolyte) and electrons (that have passed through the external load) are “recombined” and react with the oxygen supplied to the cathode to form water, H2O:
4H+ + 4e- + O2 ==> 2H2O.
The total reaction in a fuel cell is written as follows:
2H2 + O2 ==> 2H2O.
In their work, fuel cells use hydrogen fuel and oxygen from the air. Hydrogen can be supplied directly or by separating it from an external fuel source such as natural gas, gasoline or methanol. In the case of an external source, it must be chemically converted to extract the hydrogen. This process is called "reforming". Hydrogen can also be produced from ammonia, alternative resources such as gas from city landfills and from waste treatment plants Wastewater, as well as by water electrolysis, which uses electricity to split 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, the size of each of four separate 200 kW stationary power plants installed at a bank in Omaha is approximately equal to size 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 largest in the world commercial system A 1.2 MW fuel cell power plant will soon be installed at a postal 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 individual elements, 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 provide most of their own electricity and thus significantly increase energy efficiency.
Fuel cells offer energy High Quality and increased reliability. They are durable, have no moving parts, and produce a constant amount of energy.
However, fuel cell technology needs to be further improved to improve performance, reduce costs, and thus make fuel cells competitive with other energy technologies. It should be noted that when the cost characteristics of energy technologies are considered, comparisons should be made based on all component technology characteristics, including capital operating costs, pollutant emissions, energy quality, durability, decommissioning and flexibility.
Although hydrogen gas is the best fuel, the infrastructure or transport base for it does not yet exist. In the near future, existing fossil fuel supply systems (gas stations, etc.) could be used to provide power plants with sources of hydrogen in the form of gasoline, methanol or natural gas. This would eliminate the need for dedicated hydrogen filling stations, but would require each vehicle to have a fossil fuel-to-hydrogen converter ("reformer") installed. The disadvantage of this approach is that it uses fossil fuels and thus results in carbon dioxide emissions. Methanol, the current leading candidate, produces fewer emissions than gasoline, but would require a larger container in the vehicle because it takes up twice the space for the same energy content.
Unlike fossil fuel supply systems, solar and wind systems (using electricity to create hydrogen and oxygen from water) and direct photoconversion systems (using semiconductor materials or enzymes to produce hydrogen) could provide hydrogen supply without a reforming step, and thus Thus, emissions of harmful substances that are observed when using methanol or gasoline fuel cells could be avoided. The hydrogen could be stored and converted into electricity in the fuel cell as needed. Looking ahead, pairing fuel cells with these kinds of renewable energy sources is likely to be an effective strategy for providing a productive, environmentally smart, and versatile source of energy.
IEER's recommendations are that local, federal, and state governments devote a portion of their transportation procurement budgets to fuel cell vehicles, as well as stationary fuel cell systems, to provide heat and power for some of their significant or new buildings. This will contribute to the development of vital important technology and reducing greenhouse gas emissions.
In modern life, chemical sources of current surround us everywhere: these are batteries in flashlights, batteries in mobile phones, hydrogen fuel cells, which are already used in some cars. The rapid development of electrochemical technologies may lead to the fact that in the near future, instead of machines, gasoline engines We will be surrounded only by electric cars, phones will no longer run out quickly, and every home will have its own fuel cell electric generator. One of the joint programs of the Ural Federal University and the Institute of High-Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences is devoted to increasing the efficiency of electrochemical storage devices and generators of electricity, in partnership with which we are publishing this article.
Today, there are many different types of batteries, which can become increasingly difficult to navigate. It is not obvious to everyone how a battery differs from a supercapacitor and why a hydrogen fuel cell can be used without fear of harming the environment. In this article we will talk about how chemical reactions are used to generate electricity, what is the difference between the main types of modern chemical current sources, and what prospects open up for electrochemical energy.
Chemistry as a source of electricity
First, let's figure out why chemical energy can be used to generate electricity at all. The thing is that during redox reactions, electrons are transferred between two different ions. If the two halves of a chemical reaction are spaced apart so that oxidation and reduction take place separately from each other, then it is possible to make sure that an electron that leaves one ion does not immediately get to the second, but first passes along a path predetermined for it. This reaction can be used as a source of electric current.
This concept was first implemented in the 18th century by the Italian physiologist Luigi Galvani. The action of a traditional galvanic cell is based on the reduction and oxidation reactions of metals with different activities. For example, a classic cell is a galvanic cell in which zinc is oxidized and copper is reduced. Reduction and oxidation reactions take place at the cathode and anode, respectively. And to prevent copper and zinc ions from entering “foreign territory”, where they can react with each other directly, a special membrane is usually placed between the anode and cathode. As a result, a potential difference arises between the electrodes. If you connect electrodes, for example, to a light bulb, then current begins to flow in the resulting electrical circuit and the light bulb lights up.
Galvanic cell diagram
Wikimedia commons
In addition to the materials of the anode and cathode, an important component of the chemical current source is the electrolyte, inside which the ions move and at the border of which all electrochemical reactions take place with the electrodes. In this case, the electrolyte does not have to be liquid - it can be either a polymer or ceramic material.
The main disadvantage of the galvanic cell is its limited operating time. As soon as the reaction completes (that is, the entire gradually dissolving anode is completely consumed), such an element will simply stop working.
AA alkaline batteries
Rechargeable
The first step towards expanding the capabilities of chemical current sources was the creation of a battery - a current source that can be recharged and therefore reused. To do this, scientists simply proposed using reversible chemical reactions. Having completely discharged the battery for the first time, using an external current source, the reaction that took place in it can be started in the opposite direction. This will restore it to its original state so that the battery can be used again after recharging.
Car lead acid battery
Today, many different types of batteries have been created, which differ in the type of chemical reaction that occurs in them. The most common types of batteries are lead-acid (or simply lead) batteries, which are based on the oxidation-reduction reaction of lead. Such devices have a fairly long service life, and their energy intensity is up to 60 watt-hours per kilogram. Even more popular in Lately are lithium-ion batteries based on the oxidation-reduction reaction of lithium. The energy intensity of modern lithium-ion batteries now exceeds 250 watt-hours per kilogram.
Li-ion battery for mobile phone
The main problems with lithium-ion batteries are their low efficiency at negative temperatures, rapid aging and increased explosion hazard. And due to the fact that lithium metal reacts very actively with water to form hydrogen gas and oxygen is released when the battery burns, spontaneous combustion of a lithium-ion battery is very difficult to use with traditional fire extinguishing methods. In order to increase the safety of such a battery and speed up its charging time, scientists propose a cathode material that prevents the formation of dendritic lithium structures, and add substances to the electrolyte that cause the formation of explosive structures and components that ignite in the early stages.
Solid electrolyte
As another less obvious way to increase the efficiency and safety of batteries, chemists have proposed not limiting chemical current sources to liquid electrolytes, but creating a completely solid-state current source. In such devices there are no liquid components at all, but a layered structure of a solid anode, a solid cathode and a solid electrolyte between them. The electrolyte simultaneously performs the function of a membrane. Charge carriers in a solid electrolyte can be various ions, depending on its composition and the reactions that take place at the anode and cathode. But they are always small enough ions that can move relatively freely throughout the crystal, for example H + protons, lithium ions Li + or oxygen ions O 2-.
Hydrogen fuel cells
The ability to recharge and special safety measures make batteries much more promising sources of current than conventional batteries, but still each battery contains a limited amount of reagents, and therefore a limited supply of energy, and each time the battery must be recharged to restore its functionality.
To make a battery “endless,” you can use as an energy source not the substances that are inside the cell, but fuel specially pumped through it. The best choice for such fuel is a substance that is as simple in composition as possible, environmentally friendly and available in abundance on Earth.
The most suitable substance of this type is hydrogen gas. Its oxidation by atmospheric oxygen to form water (according to the reaction 2H 2 + O 2 → 2H 2 O) is a simple redox reaction, and the transport of electrons between ions can also be used as a current source. The reaction that occurs is a kind of reverse reaction to the electrolysis of water (in which, under the influence of an electric current, water is decomposed into oxygen and hydrogen), and such a scheme was first proposed in the middle of the 19th century.
But despite the fact that the circuit looks quite simple, creating an efficiently operating device based on this principle is not at all a trivial task. To do this, it is necessary to separate the flows of oxygen and hydrogen in space, ensure the transport of the necessary ions through the electrolyte and reduce possible energy losses at all stages of work.
Schematic diagram hydrogen fuel cell operation
The circuit of a working hydrogen fuel cell is very similar to the circuit of a chemical current source, but contains additional channels for supplying fuel and oxidizer and removing reaction products and excess supplied gases. The electrodes in such an element are porous conductive catalysts. A gaseous fuel (hydrogen) is supplied to the anode, and an oxidizing agent (oxygen from the air) is supplied to the cathode, and at the boundary of each electrode with the electrolyte, its own half-reaction takes place (hydrogen oxidation and oxygen reduction, respectively). In this case, depending on the type of fuel cell and the type of electrolyte, the formation of water itself can occur either in the anode or in the cathode space.
Toyota hydrogen fuel cell
Joseph Brent / flickr
If the electrolyte is a proton-conducting polymer or ceramic membrane, an acid or alkali solution, then the charge carrier in the electrolyte is hydrogen ions. In this case, at the anode, molecular hydrogen is oxidized to hydrogen ions, which pass through the electrolyte and react with oxygen there. If the charge carrier is the oxygen ion O 2–, as in the case of a solid oxide electrolyte, then oxygen is reduced to an ion at the cathode, this ion passes through the electrolyte and oxidizes hydrogen at the anode to form water and free electrons.
In addition to the hydrogen oxidation reaction, it has been proposed to use other types of reactions for fuel cells. For example, instead of hydrogen, the reducing fuel can be methanol, which is oxidized by oxygen to carbon dioxide and water.
Fuel cell efficiency
Despite all the advantages of hydrogen fuel cells (such as environmental friendliness, virtually unlimited efficiency, compact size and high energy intensity), they also have a number of disadvantages. These include, first of all, the gradual aging of components and difficulties in storing hydrogen. It is precisely how to eliminate these shortcomings that scientists are working on today.
It is currently proposed to increase the efficiency of fuel cells by changing the composition of the electrolyte, the properties of the catalyst electrode, and the geometry of the system (which ensures the supply of fuel gases to the desired point and reduces side effects). To solve the problem of storing hydrogen gas, materials containing platinum are used, for saturation of which, for example, graphene membranes.
As a result, it is possible to increase the stability of the fuel cell and the lifetime of its individual components. Now the coefficient of conversion of chemical energy into electrical energy in such elements reaches 80 percent, and under certain conditions it can be even higher.
The enormous prospects for hydrogen energy are associated with the possibility of combining fuel cells into entire batteries, turning them into electric generators with high power. Already, electric generators running on hydrogen fuel cells have a power of up to several hundred kilowatts and are used as power sources for vehicles.
Alternative electrochemical storage
In addition to classical electrochemical current sources, more unusual systems are also used as energy storage devices. One of such systems is a supercapacitor (or ionistor) - a device in which charge separation and accumulation occurs due to the formation of a double layer near a charged surface. At the electrode-electrolyte interface in such a device, ions of different signs are lined up in two layers, the so-called “double electric layer,” forming a kind of very thin capacitor. The capacity of such a capacitor, that is, the amount of accumulated charge, will be determined by the specific surface area of the electrode material, therefore, it is advantageous to take porous materials with a maximum specific surface area as a material for supercapacitors.
Ionistors are record holders among charge-discharge chemical current sources in terms of charge speed, which is an undoubted advantage of this type of device. Unfortunately, they also hold the record for discharge speed. The energy density of ionistors is eight times less compared to lead batteries and 25 times less than lithium-ion batteries. Classic “double-layer” ionistors do not use an electrochemical reaction as their basis, and the term “capacitor” is most accurately applied to them. However, in those versions of ionistors that are based on an electrochemical reaction and charge accumulation extends into the depth of the electrode, it is possible to achieve higher discharge times while maintaining a fast charge rate. The efforts of supercapacitor developers are aimed at creating hybrid devices with batteries that combine the advantages of supercapacitors, primarily high charging speed, and the advantages of batteries - high energy intensity and long discharge time. Imagine in the near future a battery-ionistor that will charge in a couple of minutes and power a laptop or smartphone for a day or more!
Despite the fact that now the energy density of supercapacitors is still several times less than the energy density of batteries, they are used in consumer electronics and for engines of various vehicles, including the most.
* * *
Thus, today there are a large number of electrochemical devices, each of which is promising for its specific applications. To improve the efficiency of these devices, scientists need to solve a number of problems of both fundamental and technological nature. Most of these tasks are being carried out within the framework of one of the breakthrough projects at the Ural Federal University, so we asked Maxim Ananyev, director of the Institute of High-Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences, professor of the Department of Electrochemical Production Technology of the Institute of Chemical Technology of the Ural Federal University, to talk about the immediate plans and prospects for the development of modern fuel cells .
N+1: Are there any alternatives to the currently most popular lithium-ion batteries expected in the near future?
Maxim Ananyev: Modern efforts of battery developers are aimed at replacing the type of charge carrier in the electrolyte from lithium to sodium, potassium, and aluminum. As a result of replacing lithium, it will be possible to reduce the cost of the battery, although the weight and size characteristics will increase proportionally. In other words, with the same electrical characteristics, a sodium-ion battery will be larger and heavier compared to a lithium-ion battery.
In addition, one of the promising developing areas for improving batteries is the creation of hybrid chemical energy sources based on combining metal-ion batteries with an air electrode, as in fuel cells. In general, the direction of creating hybrid systems, as has already been shown with the example of supercapacitors, will apparently in the near future make it possible to see chemical energy sources on the market with high consumer characteristics.
Ural federal university Today, together with academic and industrial partners in Russia and the world, it is implementing six mega-projects that are focused on breakthrough areas of scientific research. One of such projects is “Advanced technologies of electrochemical energy from chemical design of new materials to new generation electrochemical devices for energy conservation and conversion.”
A group of scientists from the strategic academic unit (SAE) of the UrFU School of Natural Sciences and Mathematics, which includes Maxim Ananyev, is engaged in the design and development of new materials and technologies, including fuel cells, electrolytic cells, metal-graphene batteries, electrochemical energy storage systems and supercapacitors.
Research and scientific work are carried out in constant cooperation with the Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences and with the support of partners.
Which fuel cells are currently being developed and have the most potential?
One of the most promising types of fuel cells are proton-ceramic elements. They have advantages over polymer fuel cells with proton exchange membrane and solid oxide elements, since they can operate with a direct supply of hydrocarbon fuel. This significantly simplifies the design of a power plant based on proton-ceramic fuel cells and the control system, and therefore increases operational reliability. True, this type of fuel cell is currently historically less developed, but modern scientific research allows us to hope for the high potential of this technology in the future.
What problems related to fuel cells are currently being addressed at the Ural Federal University?
Now UrFU scientists, together with the Institute of High-Temperature Electrochemistry (IVTE) of the Ural Branch of the Russian Academy of Sciences, are working on the creation of highly efficient electrochemical devices and autonomous power generators for applications in distributed energy. The creation of power plants for distributed energy initially implies the development of hybrid systems based on an electricity generator and a storage device, which are batteries. At the same time, the fuel cell operates constantly, providing load during peak hours, and in idle mode it charges the battery, which can itself act as a reserve both in case of high energy consumption and in case of emergency situations.
The greatest successes of UrFU and IVTE chemists have been achieved in the development of solid-oxide and proton-ceramic fuel cells. Since 2016, in the Urals, together with the State Corporation Rosatom, the first in Russia production of power plants based on solid oxide fuel cells has been created. The development of Ural scientists has already passed “full-scale” tests at the gas pipeline cathodic protection station at the experimental site of Uraltransgaz LLC. The power plant with a rated power of 1.5 kilowatts worked for more than 10 thousand hours and showed the high potential for the use of such devices.
Within the framework of the joint laboratory of UrFU and IVTE, the development of electrochemical devices based on a proton-conducting ceramic membrane is underway. This will make it possible in the near future to reduce operating temperatures for solid-oxide fuel cells from 900 to 500 degrees Celsius and to abandon the preliminary reforming of hydrocarbon fuels, thus creating cost-effective electrochemical generators capable of operating in conditions of the developed gas supply infrastructure in Russia.
Alexander Dubov
Lately, the topic of fuel cells has been on everyone's lips. And this is not surprising; with the advent of this technology in the world of electronics, it has found a new birth. World leaders in the field of microelectronics are racing to present prototypes of their future products, which will integrate their own mini power plants. This should, on the one hand, weaken the connection of mobile devices to the “outlet”, and on the other hand, extend their battery life.
In addition, some of them work on the basis of ethanol, so the development of these technologies is of direct benefit to producers of alcoholic beverages - after a dozen years, queues of “IT specialists” will line up at the winery, standing for the next “dose” for their laptop.
We cannot stay away from the fuel cell “fever” that has gripped the Hi-Tech industry, and we will try to figure out what kind of beast this technology is, what it is eaten with, and when we can expect it to arrive in “public catering.” In this material we will look at the path traveled by fuel cells from the discovery of this technology to the present day. We will also try to assess the prospects for their implementation and development in the future.
How it was
The principle of a fuel cell was first described back in 1838 by Christian Friedrich Schonbein, and a year later the Philosophical Journal published his article on this topic. However, these were only theoretical studies. The first working fuel cell was produced in 1843 in the laboratory of the Welsh scientist Sir William Robert Grove. When creating it, the inventor used materials similar to those used in modern phosphoric acid batteries. Sir Grove's fuel cell was subsequently improved by W. Thomas Grub. In 1955, this chemist, working for the legendary General Electric company, used a sulfonated polystyrene ion-exchange membrane as the electrolyte in a fuel cell. Only three years later, his colleague Leonard Niedrach proposed a technology for placing platinum on a membrane, which acted as a catalyst in the process of hydrogen oxidation and oxygen absorption.
"Father" of fuel cells Christian Schönbein
These principles formed the basis of a new generation of fuel cells, called Grub-Nidrach cells after their creators. General Electric continued development in this direction, within which, with the assistance of NASA and aviation giant McDonnell Aircraft, the first commercial fuel cell was created. On new technology paid attention overseas. And already in 1959, the Briton Francis Thomas Bacon introduced a stationary fuel cell with a power of 5 kW. His patented developments were subsequently licensed by the Americans and used in NASA spacecraft in power and supply systems drinking water. In the same year, the American Harry Ihrig built the first fuel cell tractor (total power 15 kW). Potassium hydroxide was used as the electrolyte in the batteries, and compressed hydrogen and oxygen were used as reagents.
For the first time, the production of stationary fuel cells for commercial purposes was launched by the UTC Power company, which offered backup power supply systems for hospitals, universities and business centers. This company, a world leader in this field, still produces similar solutions with a power of up to 200 kW. It is also the main supplier of fuel cells for NASA. Its products have been widely used during space program Apollo and is still in demand as part of the Space Shuttle program. UTC Power also offers "commodity" fuel cells that are widely used in vehicles. She was the first to create a fuel cell that makes it possible to generate current at subzero temperatures through the use of a proton exchange membrane.
How it works
Researchers experimented with various substances as reagents. However, the basic principles of operation of fuel cells, despite significantly different operational characteristics, remain unchanged. Any fuel cell is a device for electrochemical energy conversion. It produces electricity from a certain amount of fuel (on the anode side) and an oxidizer (on the cathode side). The reaction occurs in the presence of an electrolyte (a substance containing free ions and behaving as an electrically conductive medium). In principle, in any such device there are certain reagents entering it and their reaction products, which are removed after the electrochemical reaction has occurred. Electrolyte in in this case serves only as a medium for the interaction of reagents and does not change in the fuel cell. Based on this scheme, an ideal fuel cell should operate as long as there is a supply of substances necessary for the reaction.
Fuel cells should not be confused with conventional batteries here. In the first case, to produce electricity, a certain “fuel” is consumed, which subsequently needs to be refueled again. In the case of galvanic cells, electricity is stored in a closed chemical system. In the case of batteries, applying current allows the reverse electrochemical reaction to occur and return the reactants to their original state (i.e. charge it). Possible various combinations fuel and oxidizer. For example, a hydrogen fuel cell uses hydrogen and oxygen (an oxidizer) as reactants. Hydrocarbonates and alcohols are often used as fuel, and air, chlorine and chlorine dioxide act as oxidants.
The catalysis reaction that takes place in a fuel cell knocks electrons and protons out of the fuel, and the moving electrons form an electrical current. Platinum or its alloys are usually used as a catalyst that accelerates the reaction in fuel cells. Another catalytic process returns electrons, combining them with protons and an oxidizing agent, resulting in reaction products (emissions). Typically, these emissions are simple substances: water and carbon dioxide.
In a traditional proton exchange membrane fuel cell (PEMFC), a polymer proton-conducting membrane separates the anode and cathode sides. From the cathode side, hydrogen diffuses to the anode catalyst, where electrons and protons are subsequently released from it. The protons then pass through the membrane to the cathode, and the electrons that are unable to follow the protons (the membrane is electrically isolated) are sent along the circuit external load(energy supply system). On the cathode catalyst side, oxygen reacts with protons passing through the membrane and electrons entering through the external load circuit. This reaction produces water (in the form of steam or liquid). For example, the reaction products in fuel cells using hydrocarbon fuels (methanol, diesel fuel) are water and carbon dioxide.
Fuel cells of almost all types suffer from electrical losses, caused both by the natural resistance of the contacts and elements of the fuel cell, and by electrical overvoltage (the additional energy required to carry out the initial reaction). In some cases, it is not possible to completely avoid these losses and sometimes “the game is not worth the candle,” but most often they can be reduced to an acceptable minimum. An option to solve this problem is to use sets of these devices, in which fuel cells, depending on the requirements for the power supply system, can be connected in parallel (higher current) or in series (higher voltage).
Types of fuel cells
There are a great many types of fuel cells, but we will try to briefly discuss the most common ones.
Alkaline Fuel Cells (AFC)
Alkaline or alkaline fuel cells, also called Bacon cells after their British "father", are one of the most well-developed fuel cell technologies. It was these devices that helped man set foot on the moon. In general, NASA has been using fuel cells of this type since the mid-60s of the last century. AFCs consume hydrogen and pure oxygen, producing potable water, heat and electricity. Largely due to the fact that this technology is well developed, it has one of the highest efficiency indicators among similar systems (potential about 70%).
However, this technology also has its drawbacks. Due to the specificity of using a liquid alkaline substance as an electrolyte, which does not block carbon dioxide, it is possible for potassium hydroxide (one of the options for the electrolyte used) to react with this component of ordinary air. The result can be a toxic compound called potassium carbonate. To avoid this, it is necessary to use either pure oxygen or purify the air from carbon dioxide. Naturally, this affects the cost of such devices. Even so, AFCs are the cheapest fuel cells available today to produce.
Direct borohydride fuel cells (DBFC)
This subtype of alkaline fuel cells uses sodium borohydride as fuel. However, unlike conventional hydrogen-based AFCs, this technology has one significant advantage - there is no risk of producing toxic compounds after contact with carbon dioxide. However, the product of its reaction is the substance borax, widely used in detergents and soap. Borax is relatively non-toxic.
DBFCs can be made even cheaper than traditional fuel cells because they do not require expensive platinum catalysts. In addition, they have greater energy density. It is estimated that the production of a kilogram of sodium borohydride costs $50, but if we organize its mass production and organize the processing of borax, then this level can be reduced by 50 times.
Metal Hydride Fuel Cells (MHFC)
This subclass of alkaline fuel cells is currently being actively studied. A special feature of these devices is the ability to chemically store hydrogen inside the fuel cell. The direct borohydride fuel cell has the same ability, but unlike it, the MHFC is filled with pure hydrogen.
Among distinctive characteristics These fuel cells can be distinguished as follows:
- ability to recharge from electrical energy;
- work at low temperatures- up to -20°C;
- long shelf life;
- fast "cold" start;
- the ability to work for some time without an external source of hydrogen (during a fuel change).
Despite the fact that many companies are working on creating mass MHFCs, the efficiency of prototypes is not high enough compared to competing technologies. One of best performance The current density for these fuel cells is 250 milliamps per square centimeter, while conventional PEMFC fuel cells provide a current density of 1 ampere per square centimeter.
Electro-galvanic fuel cells (EGFC)
The chemical reaction in EGFC involves potassium hydroxide and oxygen. This creates an electrical current between the lead anode and the gold-plated cathode. The voltage produced by an electro-galvanic fuel cell is directly proportional to the amount of oxygen. This feature has allowed EGFCs to find widespread use as oxygen concentration testing devices in scuba gear and medical equipment. But it is precisely because of this dependence that potassium hydroxide fuel cells have a very limited lifespan. efficient work(while the oxygen concentration is high).
The first certified devices for checking oxygen concentration at EGFC became widely available in 2005, but did not gain much popularity then. The significantly modified model, released two years later, was much more successful and even received a prize for “innovation” at specialized exhibition divers in Florida. They are currently used by organizations such as NOAA (National Oceanic and Atmospheric Administration) and DDRC (Diving Diseases Research Center).
Direct formic acid fuel cells (DFAFC)
These fuel cells are a subtype of PEMFC devices with direct formic acid injection. Thanks to your specific features These fuel cells have a high chance of becoming the primary means of powering portable electronics such as laptops, cell phones, etc. in the future.
Like methanol, formic acid is directly fed into the fuel cell without a special purification step. Storing this substance is also much safer than, for example, hydrogen, and it does not require any specific storage conditions: formic acid is a liquid at normal temperature. Moreover, this technology has two undeniable advantages over direct methanol fuel cells. First, unlike methanol, formic acid does not leak through the membrane. Therefore, the efficiency of DFAFC should, by definition, be higher. Secondly, in case of depressurization, formic acid is not so dangerous (methanol can cause blindness, and in high dosages, death).
Interestingly, until recently, many scientists did not consider this technology as having a practical future. The reason that prompted researchers to “put an end to formic acid” for many years was the high electrochemical overvoltage, which led to significant electrical losses. But recent experiments have shown that the reason for this inefficiency was the use of platinum as a catalyst, which has traditionally been widely used for this purpose in fuel cells. After scientists at the University of Illinois conducted a series of experiments with other materials, it was found that when using palladium as a catalyst, DFAFC performance was higher than that of equivalent straight methanol fuel cells. Currently, the rights to this technology are owned by the American company Tekion, which offers its line of Formira Power Pack products for microelectronics devices. This system is a "duplex" consisting of battery and the fuel cell itself. After the supply of reagents in the cartridge that charges the battery runs out, the user simply replaces it with a new one. Thus, it becomes completely independent from the “outlet”. According to the manufacturer's promises, the time between charges will double, despite the fact that the technology will cost only 10-15% more than conventional batteries. The only major obstacle to this technology may be that the company supports it mediocre and it can simply be “overwhelmed” by larger-scale competitors presenting their technologies, which may even be inferior to DFAFC in a number of parameters.
Direct Methanol Fuel Cells (DMFC)
These fuel cells are a subset of proton exchange membrane devices. They use methanol, which is fed into the fuel cell without additional purification. However, methyl alcohol is much easier to store and is not explosive (although it is flammable and can cause blindness). At the same time, methanol has a significantly higher energy capacity than compressed hydrogen.
However, due to the ability of methanol to leak through the membrane, the efficiency of DMFC at large fuel volumes is low. And although for this reason they are not suitable for transport and large installations, these devices are excellent as replacement batteries for mobile devices.
Treated Methanol Fuel Cells (RMFC)
Processed methanol fuel cells differ from DMFCs only in that they convert methanol into hydrogen and carbon dioxide before generating electricity. This happens in a special device called a fuel processor. After this preliminary stage (the reaction is carried out at temperatures above 250°C), the hydrogen undergoes an oxidation reaction, which results in the formation of water and the generation of electricity.
The use of methanol in RMFC is due to the fact that it is a natural carrier of hydrogen, and at a sufficiently low temperature (compared to other substances) it can be decomposed into hydrogen and carbon dioxide. Therefore, this technology is more advanced than DMFC. Treated methanol fuel cells allow for greater efficiency, compactness, and sub-zero operation.
Direct ethanol fuel cells (DEFC)
Another representative of the class of fuel cells with a proton exchange lattice. As the name suggests, ethanol enters the fuel cell without undergoing additional purification or decomposition into simpler substances. The first advantage of these devices is the use ethyl alcohol instead of toxic methanol. This means that you do not need to invest a lot of money in developing this fuel.
The energy density of alcohol is approximately 30% higher than that of methanol. In addition, it can be obtained in large quantities from biomass. In order to reduce the cost of ethanol fuel cells, the search for an alternative catalyst material is being actively pursued. Platinum, traditionally used in fuel cells for these purposes, is too expensive and is a significant obstacle to the mass adoption of these technologies. A solution to this problem could be catalysts made from a mixture of iron, copper and nickel, which demonstrate impressive results in experimental systems.
Zinc Air Fuel Cells (ZAFC)
ZAFC uses the oxidation of zinc with oxygen from the air to produce electrical energy. These fuel cells are inexpensive to produce and provide fairly high energy densities. They are currently used in hearing aids and experimental electric cars.
On the anode side there is a mixture of zinc particles with an electrolyte, and on the cathode side there is water and oxygen from the air, which react with each other and form hydroxyl (its molecule is an oxygen atom and a hydrogen atom, between which there is a covalent bond). As a result of the reaction of hydroxyl with the zinc mixture, electrons are released that go to the cathode. The maximum voltage produced by such fuel cells is 1.65 V, but, as a rule, this is artificially reduced to 1.4–1.35 V, limiting air access to the system. The end products of this electrochemical reaction are zinc oxide and water.
It is possible to use this technology both in batteries (without recharging) and in fuel cells. In the latter case, the chamber on the anode side is cleaned and filled again with zinc paste. In general, ZAFC technology has proven to be a simple and reliable battery. Their undeniable advantage is the ability to control the reaction only by regulating the air supply to the fuel cell. Many researchers are considering zinc-air fuel cells as the future main power source for electric vehicles.
Microbial Fuel Cells (MFC)
The idea of using bacteria for the benefit of humanity is not new, although the implementation of these ideas has only recently come to fruition. Currently, the commercial use of biotechnologies for the production of various products (for example, the production of hydrogen from biomass), the neutralization of harmful substances and the production of electricity is being actively studied. Microbial fuel cells, also called biological fuel cells, are a biological electrochemical system that produces electrical current through the use of bacteria. This technology is based on catabolism (the decomposition of a complex molecule into a simpler one with the release of energy) of substances such as glucose, acetate (acetic acid salt), butyrate (butyrate salt) or waste water. Due to their oxidation, electrons are released, which are transferred to the anode, after which the generated electric current flows through the conductor to the cathode.
Such fuel cells typically use mediators that improve the flow of electrons. The problem is that the substances that play the role of mediators are expensive and toxic. However, in the case of using electrochemically active bacteria, the need for mediators disappears. Such “mediator-free” microbial fuel cells began to be created quite recently and therefore not all of their properties have been well studied.
Despite the obstacles that MFC has yet to overcome, the technology has enormous potential. Firstly, finding “fuel” is not particularly difficult. Moreover, today the issue of wastewater treatment and disposal of many wastes is very acute. The use of this technology could solve both of these problems. Secondly, theoretically its effectiveness can be very high. The main problem for microbial fuel cell engineers is, and in fact essential element of this device, microbes. And while microbiologists, who receive numerous grants for research, are rejoicing, science fiction writers are also rubbing their hands, anticipating the success of books devoted to the consequences of the “release” of the wrong microorganisms. Naturally, there is a risk of developing something that would “digest” not only unnecessary waste, but also something valuable. Therefore, in principle, as is the case with any new biotechnologies, people are wary of the idea of carrying a box infested with bacteria in their pocket.
Application
Stationary domestic and industrial power plants
Fuel cells are widely used as energy sources in various autonomous systems, such as spaceships, remote weather stations, military installations, etc. The main advantage of such a power supply system is its extremely high reliability compared to other technologies. Due to the absence of moving parts and any mechanisms in fuel cells, the reliability of power supply systems can reach 99.99%. In addition, in the case of using hydrogen as a reagent, very low weight can be achieved, which in the case of space equipment is one of the most important criteria.
Recently, combined heat and power plants, widely used in residential buildings and offices. The peculiarity of these systems is that they constantly generate electricity, which, if not consumed immediately, is used to heat water and air. Despite the fact that the electrical efficiency of such installations is only 15-20%, this disadvantage is compensated by the fact that unused electricity is used to produce heat. In general, the energy efficiency of such combined systems is about 80%. One of the best reagents for such fuel cells is phosphoric acid. These installations provide energy efficiency of 90% (35-50% electricity and the rest thermal energy).
Transport
Energy systems based on fuel cells are also widely used in transport. By the way, the Germans were among the first to install fuel cells on vehicles. So the world's first commercial boat equipped with such an installation debuted eight years ago. This small ship, christened "Hydra" and designed to carry up to 22 passengers, was launched near the former capital of Germany in June 2000. Hydrogen (alkaline fuel cell) acts as an energy-carrying reagent. Thanks to the use of alkaline (alkaline) fuel cells, the installation is capable of generating current at temperatures down to –10°C and is not “afraid” of salt water. The Hydra boat, driven by a 5 kW electric motor, is capable of speeds of up to 6 knots (about 12 km/h).
Boat "Hydra"
Fuel cells (in particular hydrogen) have become much more widespread in ground transport. In general, hydrogen has been used as a fuel for automobile engines for quite a long time, and in principle, a conventional internal combustion engine can be quite easily converted to use this alternative type of fuel. However, traditional hydrogen combustion is less efficient than generating electricity through a chemical reaction between hydrogen and oxygen. And ideally, hydrogen, if it is used in fuel cells, will be absolutely safe for nature or, as they say, “friendly to the environment,” since the chemical reaction does not release carbon dioxide or other substances that contribute to the “greenhouse effect.”
True, here, as one might expect, there are several big “buts”. The fact is that many technologies for producing hydrogen from non-renewable resources (natural gas, coal, petroleum products) are not so harmless to environment, since their process releases large amounts of carbon dioxide. Theoretically, if you use renewable resources to obtain it, then there will be no harmful emissions at all. However, in this case the cost increases significantly. According to many experts, for these reasons, the potential of hydrogen as a substitute for gasoline or natural gas is very limited. Already there are less expensive alternatives and, most likely, first element fuel cells periodic table never manage to become a mass phenomenon on vehicles.
Car manufacturers are quite actively experimenting with hydrogen as an energy source. And the main reason for this is the rather tough position of the EU regarding harmful emissions into the atmosphere. Spurred by increasingly stringent restrictions in Europe, Daimler AG, Fiat and Ford Motor Company have presented their vision of the future of fuel cells in the automobile, equipping their base models with similar powertrains. Another European auto giant, Volkswagen, is currently preparing its fuel cell car. Japanese and South Korean companies are not far behind them. However, not everyone is betting on this technology. Many people prefer to modify internal combustion engines or combine them with electric motors powered by batteries. Toyota, Mazda and BMW followed this path. As for American companies, in addition to Ford with its Focus model, General Motors also presented several fuel cell cars. All these undertakings are actively encouraged by many states. For example, in the USA there is a law according to which a new hybrid car entering the market is exempt from taxes, which can amount to quite a decent amount, because as a rule, such cars are more expensive than their counterparts with traditional internal combustion engines. This makes hybrids even more attractive as a purchase. True, for now this law only applies to models entering the market until sales reach 60,000 cars, after which the benefit is automatically canceled.
Electronics
Recently, fuel cells have begun to find increasing use in laptops, mobile phones and other mobile electronic devices. The reason for this was the rapidly increasing gluttony of devices designed for long-term battery life. As a result of the use of large touch screens in phones, powerful audio capabilities and the introduction of support for Wi-Fi, Bluetooth and other high-frequency wireless communication protocols, the requirements for battery capacity have also changed. And, although batteries have come a long way since the days of the first cell phones, in terms of capacity and compactness (otherwise today fans would not be allowed into stadiums with these weapons with a communication function), they still cannot keep up with either the miniaturization of electronic circuits or the desire manufacturers to integrate everything into their products more features. Another significant drawback of current rechargeable batteries is their long charging time. Everything leads to the fact that the more capabilities a phone or pocket multimedia player has that are designed to increase the autonomy of its owner (wireless Internet, navigation systems, etc.), the more dependent on the “outlet” this device becomes.
There is nothing to say about laptops that are much smaller than those limited in maximum sizes. For quite some time now, a niche has been formed for ultra-efficient laptops that are not intended for autonomous operation at all, except for such transfer from one office to another. And even the most economical representatives of the laptop world can hardly provide a full day of battery life. Therefore, the issue of finding an alternative to traditional batteries, which would be no more expensive, but also much more efficient, is very urgent. And leading representatives of the industry have recently been working on solving this problem. Not long ago, commercial methanol fuel cells were introduced, mass deliveries of which could begin as early as next year.
The researchers chose methanol rather than hydrogen for some reasons. Storing methanol is much easier, since it does not require high pressure or special temperature conditions. Methyl alcohol is a liquid at temperatures between -97.0°C and 64.7°C. Moreover, the specific energy contained in the Nth volume of methanol is an order of magnitude greater than in the same volume of hydrogen under high pressure. Direct methanol fuel cell technology, widely used in mobile electronic devices, involves the use of methyl alcohol after simply filling the fuel cell tank, bypassing the catalytic conversion procedure (hence the name “direct methanol”). This is also a major advantage of this technology.
However, as one would expect, all these advantages had their disadvantages, which significantly limited the scope of its application. Due to the fact that this technology has not yet been fully developed, the problem of the low efficiency of such fuel cells caused by the “leakage” of methanol through the membrane material remains unresolved. Besides, they are not impressive dynamic characteristics. It is not easy to resolve and what to do with the carbon dioxide produced at the anode. Modern DMFC devices are not capable of generating large amounts of energy, but have a high energy capacity for a small volume of material. This means that although there is not much energy available yet, direct methanol fuel cells can produce it for a long time. Due to their low power, this does not allow them to find direct use in vehicles, but makes them almost ideal solution for mobile devices for which battery life is critical.
Latest Trends
Although fuel cells for vehicles have been produced for a long time, these solutions have not yet become widespread. There are many reasons for this. And the main ones are the economic inexpediency and the unwillingness of manufacturers to put the production of affordable fuel on stream. Attempts to speed up the natural process of transition to renewable energy sources, as could be expected, did not lead to anything good. Of course, the reason for the sharp increase in prices for agricultural products is hidden not in the fact that they began to be massively converted into biofuels, but in the fact that many countries in Africa and Asia are not able to produce enough products even to meet domestic demand for products.
It is obvious that abandoning the use of biofuels will not lead to a significant improvement in the situation on the global food market, but on the contrary, it may deal a blow to European and American farmers, who for the first time in many years have the opportunity to earn good money. But the ethical aspect of this issue cannot be discounted; it is unsightly to put “bread” in tanks when millions of people are starving. Therefore, in particular, European politicians will now have a cooler attitude towards biotechnology, which is already confirmed by the revision of the strategy for the transition to renewable energy sources.
In this situation, the most promising area of application for fuel cells should be microelectronics. This is where fuel cells have the best chance of gaining a foothold. First, people who buy cell phones are more willing to experiment than, say, car buyers. And secondly, they are ready to spend money and, as a rule, are not averse to “saving the world.” This can be confirmed by the stunning success of the red “Bono” version of the iPod Nano player, part of the money from the sales of which went to the accounts of the Red Cross.
"Bono" version of the Apple iPod Nano player
Among those who have turned their attention to fuel cells for portable electronics are companies that previously specialized in creating fuel cells and have now simply opened new area their applications, and leading microelectronics manufacturers. For example, recently MTI Micro, which repurposed its business to produce methanol fuel cells for mobile electronic devices, announced that it would begin mass production in 2009. She also presented the world's first GPS device using methanol fuel cells. According to representatives of this company, in the near future its products will completely replace traditional lithium ion batteries. True, at first they will not be cheap, but this problem accompanies any new technology.
For a company like Sony, which recently demonstrated its DMFC version of the device that powers the multimedia system, these technologies are new, but they are serious about not getting lost in the new promising market. In turn, Sharp went even further and, with the help of its fuel cell prototype, recently set a world record for the specific energy capacity of 0.3 W for one cubic centimeter of methyl alcohol. Even the governments of many countries agreed to the companies producing these fuel cells. Thus, airports in the USA, Canada, Great Britain, Japan and China, despite the toxicity and flammability of methanol, have lifted previously existing restrictions on its transportation in the aircraft cabin. Of course, this is only permissible for certified fuel cells with a capacity of no more than 200 ml. Nevertheless, this once again confirms the interest in these developments on the part of not only enthusiasts, but also states.
True, manufacturers are still trying to play it safe and offer fuel cells mainly as a backup power system. One such solution is a combination of a fuel cell and a battery: as long as there is fuel, it constantly charges the battery, and when it runs out, the user simply replaces the empty cartridge with a new container of methanol. Another popular direction is the creation chargers on fuel cells. They can be used on the go. At the same time, they can charge batteries very quickly. In other words, in the future, perhaps everyone will carry such a “socket” in their pocket. This approach may be especially relevant in the case of mobile phones. In turn, laptops may well acquire built-in fuel cells in the foreseeable future, which, if not completely replace charging from a wall outlet, will at least become a serious alternative to it.
Thus, according to the forecast of Germany's largest chemical company BASF, which recently announced the start of construction of its fuel cell development center in Japan, by 2010 the market for these devices will reach $1 billion. At the same time, its analysts predict the growth of the fuel cell market to $20 billion by 2020. By the way, in this center BASF plans to develop fuel cells for portable electronics (in particular laptops) and stationary energy systems. The location for this enterprise was not chosen by chance; the German company sees local companies as the main buyers of these technologies.
Instead of a conclusion
Of course, you shouldn’t expect fuel cells to replace the existing energy supply system. At least for the foreseeable future. This is a double-edged sword: portable power plants are of course more efficient, due to the absence of losses associated with the delivery of electricity to the consumer, but it is also worth considering that they can become a serious competitor to the centralized energy supply system only if a centralized fuel supply system for these installations is created. That is, the “socket” must ultimately be replaced by a certain pipe that supplies the necessary reagents to every home and every nook. And this is not quite the freedom and independence from external power sources that fuel cell manufacturers talk about.
These devices have undeniable advantage in the form of charging speed - I simply changed the cartridge with methanol (in extreme cases, uncorked a trophy Jack Daniel's) in the camera, and again skipped along the stairs of the Louvre. On the other hand, if, say, a regular phone charges in two hours and requires recharge every 2-3 days, then it is unlikely that the alternative in the form of changing the cartridge, sold only in specialized stores, even once every two weeks will be in great demand by the mass user. And, of course, while these are hidden in a safe hermetic container a couple of hundred milliliters of fuel will reach the end consumer, its price will have time to rise significantly. It will be possible to combat this rise in price only by the scale of production, but will this scale be in demand on the market? And until the optimal type of fuel is chosen, solving this problem will be very problematic.
On the other hand, a combination of traditional charging from an outlet, fuel cells and other alternative energy supply systems (for example, solar panels) can be a solution to the problem of diversifying power sources and switching to environmentally friendly types. However, fuel cells can find wide application in a certain group of electronic products. This is confirmed by the fact that Canon recently patented its own fuel cells for digital cameras and announced a strategy for introducing these technologies into its solutions. As for laptops, if fuel cells reach them in the near future, it will most likely be only as a backup power system. Now, for example, we are talking mainly only about external charging modules that are additionally connected to the laptop.
But these technologies have enormous development prospects in the long term. Particularly in light of the threat of an oil famine that may occur in the next few decades. In these conditions, what is more important is not even how cheap the production of fuel cells will be, but how independent the production of fuel for them will be from the petrochemical industry and whether it will be able to cover the need for it.