Hydrogen engines were designed in the 1980s. Today, in many countries of Europe, USA, and Japan new scientific hydrogen power engineering programs are being implemented: buses are running on a new fuel, and in Iceland hydrogen fuel is used for motor boats, cars, home heating. The reason of transfer to alternative energy resources are the following: absence or lack of own organic raw materials and desire to solve environmental problems. And what can we say about Russia? This question was addressed to Yuri Kotov, RAS Corresponding Member, coordinator of the program "Hydrogen Power Engineering and Fuel Cells" of the RAS Ural branch, by Ye. Ponizovkina, Nauka Urala newspaper correspondent.

There is a lot of coal and oil in our country, but these raw materials are being extracted from deeper layers, consequently, the costs are increasing. Besides, harmful emissions of our industrial centers are damaging wild nature. That is why our scientists have to find new sources of energy. Our country has all possibilities to settle this problem: we have a significant theoretical base, and specialists who are able to develop and implement it. For example, Ural scientists created high-temperature fuel cells that are more efficient as compared with low-temperature alkaline and polymer ones: these new fuels cells possess higher efficiency coefficient, ecological cleanness, they are "omnivorous", i.e. can work on coal gasification products, waste wood, natural biogas, etc.

Autonomous production of electricity-waste free and ecologically clean (as it supplies only the required volumes of energy) - is based on such energy sources. Furthermore, it allows to avoid electric losses which are inevitable in case of long-distance power transmission lines feeding from big power plants; unfortunately, such facilities are not guaranteed from accidents affecting supplies of heat and electricity to large cities. Finally, local power supply is very

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convenient for remote regions and small towns and settlements.

Speaking about advantages of hydrogen facilities, we cannot ignore one essential disadvatage - extremely high cost. Russian scientists involved in the program "Hydrogen Power Engineering and Fuel Cells"* are to reduce these costs by 10 times at the minimum. Specialists of three institutes of the RAS Ural Branch-Institute of Electrophysics (head organiztion), Institute of Chemistry of Solids, and Institute of High-Temperature Electrochemistry-are actively working in this direction. Specialists of the Institute of High-Temperature Electrochemistry have been developing fuel cells for more than 50 years, so there has been formed a substantial theoretical base. At present, specialists of this institute are developing a full range of electrochemical devices: from electrolysers and converters for the production of hydrogen to fuel cells for the production of electricity and heat.

Let's explain: in case of high-temperature electrolysers external current is used for decomposition of water vapor into hydrogen and oxygen. This reaction can be used in practice, for example, "excess" of electric power appearing at nights, when power consumption is shrinking, can be directed to these devices. The result of this process is production of pure hydrogen (it is collected in special tanks) which is used for fuel cells, producing additional volumes of energy in daytime (for reduction of peak loads, inclusive). In solid oxide converters hydrogen is produced by way of electrochemical conversion of combustible gases - it is a more effective method and purity of the final product is much higher.

Specialists developing fuel cells are trying to improve their design in order to make them cheaper and reduce temperature of electrochemical process that will increase time of uninterrupted operation and decrease construction costs. Operational scheme of such sources of energy is as follows: hydrogen (fuel) and oxygen are constantly introduced to the different sides of a membrane made of solid oxide electrolyte. Hydrogen is oxidizing, oxygen ions are running through the membrane, electrons are moving in an external circuit; as a result electricity is produced. Scientists are trying to make the membrane as thin as possible to reduce operating temperature and, consequently, to prolong the service life of the device itself.

It is difficult to use the most common type of fuel-natural gas - in fuels cell due to many reasons. That is why it is necessary to transform (reform) it into a synthesis-gas - a mixture of carbon oxide and hydrogen. Specialists of the RAS Ural Branch Institute of Chemistry of Solids believe: electrocatalytic reactor of a membrane type is the most effective and promising way to carry out this process. The main component of this device is a gasproof ceramic membrane of mixed (oxygen ion and electron) structure. The membrane is covered with a catalyst, which integrates extraction of oxygen from air and oxidation itself into a single self-sustained process. Development efforts in this field are still at the level of laboratory experiments but the results are encouraging.

A film made of a nanopowder is an optimal electrolyte for a fuel cell. Specialists of the RAS Ural Branch Institute of Electrophysics are trying to solve this technical problem. At the present moment, thickness of electrolytes is 0.3 - 0.4 mm, that is why operating temperature of the whole device is 900 - 1050C. Transfer to films up to 10 mm thick will reduce operating temperature to 800C, increase service life of materials, decrease the cost of equipment and increase power to weight ratio. There are some ways to manufacture such nanopowder coatings: suspension made of a nanopowder is sprayed to an electrode bearing surface or rolled out into a thin film which is later reeled on an electrode; it is also possible to apply voltage to an electrode and powder particles stick to it themselves.

In accordance with the aforesaid program all studies and practical results (optimization and cheapening of processes in the fuel cells) shall be completed in three years. Scientists have already achieved results in many areas. But, as Yuri Kotov believes, it is too early to assess the results, as it is difficult to define what methods are the most effective.

Nauka Urala newspaper, No. 13, 2005

Prepared by Olga BAZANOVA

* See: V. Rusanov, "Hydrogen and Hydrogen Power Engineering", Science in Russia, No. 6, 2004. - Ed.

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