Snezhinsk breakthrough

The first Russian power system based on a solid-oxide fuel cell is tested in Snezhinsk. By importance, this event is comparable with the first automobile construction.

The first Russian power system based on a solid-oxide fuel cell had been tested in the All-Russia Research Institute of Technical Physics (Russian Federal Nuclear Center, Snezhinsk, Chelyabinsk oblast). In this system, hydrogen is obtained from natural gas, and oxygen – from the air. For the first time, such a system has been built up of units (air pump, reformer, and fuel cell) that all are made in Russia at factories of the Ministry of Atomic Energy (Minatom). Almost ten-year-long work of Minatom specialists on creating the solid-oxide fuel cell has been successful. The testing team has acknowledged an important financial support of the ISTC that helped to solve key technical problems.

Viktor Emel’yanov, co-coordinator of the ISTC fuel cell construction initiative, has reported the following. The scientists launched an experimental system, which was operated several days and then turned off. But the main goal was attained: it has been revealed, which units are to be modified and how. The resource of the energy system functioning has been estimated in pilot experiments with separate fuel cells at 50 thousands of hours. Though the coast hasn’t been evaluated yet, it is expected to be acceptable. This event is comparable by importance with the first automobile construction. The experimental system power is 1 kW. This makes us sure that building 2.5 kW system under the ISTC project can be successfully accomplished.

Fuel cells and power systems on their basis are the key elements of hydrogen energetic, which is a promising way to reduce the consumption of fossil fuels and also to reduce or stop the air pollution by exhaust gases of vehicles and power industries. Hydrogen energetic in Russia is promoted by the alliance of Minaton, ISTC, and Gazprom under aforementioned project, plus the Norilsk Nickel Company and Russian Academy of Sciences under the complex program of research and experimental-construction works on hydrogen energetic and fuel cells signed in December of 2003.

A fuel cell creates electricity through an electrochemical process that combines hydrogen and oxygen. For this purpose, hydrogen atoms are driven to the hydrogen electrode, turned to ions, and transferred by an electrolyte to the oxygen electrode, where they join up with oxygen atoms to form water and leave the fuel cell. There are several kinds of electrolytes that determine the construction of a fuel cell and respective power system.

A solid-oxide fuel cell is a high-temperature fuel cell having an operating temperature of more than 800 degrees. At room temperature, this electrolyte does not conduct any ions. It is unsuitable for an automobile, but quite appropriate for generating electricity and heat for a severed cottage or supplementary equipment of transport means. The main advantage of this fuel cell is its adjustability to hydrocarbon fuels, primarily, natural gas. The decomposition of natural gas to hydrogen and carbon monoxide and dioxide results in the production of synthesis gas. Here carbon monoxide can serve as a fuel along with hydrogen due to the presence of oxygen anions in the electrolyte. But it would be a poison in alternative low-temperature fuel cells, where the electrolyte conducts hydrogen ions (protons). Solid-oxide fuel cells produce not only electricity, but also heat that can be used in heating of buildings as well as generating an additional power supply, e.g., with the use of gas or vapour turbine.

Solid-oxide electrolyte is usually made of zirconium oxide substances with the addition of alkaline-earth and rare-earth metals. There are two ways of obtaining electricity with the use of solid-oxide fuel cells, one of which is based on a tubular construction developed in Snezhinsk. That fuel cell consists of many modules. Each module is a tube about 1 cm in diameter and 25 cm long, consisting of the same material as the electrolyte, i.e., zirconium oxide, in which the electrodes are implanted: the hydrogen one is made up of nickel and zirconium oxide, and the oxygen one of lanthanum-strontium manganate. The tube is filled up with a porous insulator, in which a smaller metal tube is incorporated. By this tube synthesis gas is supplied to the fuel cell, and the electricity exits the fuel cell. A tube can be made also from the material of cathode. In this case, it is clad in electrolyte 20-30 cm thick, which is covered by the anode layer. Such a tube having the power density 550 mW/sq cm at the temperature of 950 degrees can produce the electric current of 0.55 V and 13 W. And these values do not change during 1.5 thousand hours of the operation test that has been conducted by the scientists.

An alternative idea is a planar fuel cell. In this case, the base is made of either a half-millimetre-thick plate of the same electrolyte carrying micron-deep layers of porous cathode and anode made of above-mentioned materials, or of a millimetre-thick anode plate with electrolyte and cathode layers. Such a plate up to 60 mm in diameter made of nickel/zirconium oxide with adjustable porosity and conductivity can be produced, for example, in the Institute of Physics and Power Engineering in Obninsk. That is commented by one of the members of the research team, N.I. Khramushin, as follows. The planar construction is more efficient and compact than the tubular one. Its use allows for obtaining a higher electric power density and decreasing power and heat losses. We have managed to obtain a maximal power density of 700 mW/sq cm at 950 degrees. Therefore, power systems based on such fuel cells will cost lower than tubular ones – the price for one kilowatt of power may drop to 400 dollars in case of a massive production.