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Fuel Cell Possibilities

The energy crisis that hit New Zealand recently pales into insignificance compared to the problems the country will face in the future. Hydroelectricity is dependent on the vagaries of the weather, and in all probability (unless the weather patterns change more dramatically, which is unlikely) will be solved in the short term. This country's rapidly depleting oil and gas reserves, however, are not soluble -- once they are gone, they cannot be replenished.

The general perception is that our oil and gas reserves will have been depleted by the turn of the century, at the current rate of use. This may not be the view of all the gas and electric utilities, but they all do agree that these reserves are rapidly depleting and more efficient use should be made of them.

Currently, gas fired power stations are only of the order of 30% efficient. Co-generation or the use of fuel cell systems allows for efficiencies in the order of 60 to 70%. This would cause a doubling of our natural resource lifetime.

A fuel cell is a device for converting the chemical energy of a fuel directly to electrical energy. In principle, a fuel cell can convert primary energy to electricity with greater efficiency than can be achieved with the conventional steam turbine or other forms of heat engines. It is generally accepted that seven major types of fuel cells are under active development, with the Solid Oxide fuel cell (SOFC) one of the most popular.

The SOFC system is operated at high temperatures, and in-situ reforming promises higher fuel electricity conversion efficiencies together with high grade heat for industrial applications.

During the late 1980s, development of the SOFC has been dominated by the US Westinghouse programme. The operating performance of 3kW SOFC modules by Osaka Gas and Tokyo Gas, in Japan, has been very successful, and these utilities are now collaborating with Westinghouse in the construction of 25kW units designed to operate on natural gas with internal reforming.

The US Department of Energy is supporting a five-year, $64 million development programme, with a view to demonstrating a 2MW plant in 1995.

European programmes have begun to come to fruition too, and it is felt that an Australasian programme is a must. The CSIRO in Melbourne, in conjunction with a number of other interested parties, now have a multi-million dollar programme, looking at using one of its natural resources, zirconium dioxide, as the electrolyte in a solid oxide fuel cell system.

There is, however, no large programme currently in place within New Zealand. A programme needs to be set up here to investigate the interacting influences of design, materials selection, processing route and performance for a range of different fuel cell types and configurations. A final goal should be to realise a working fuel cell system, using natural gas or coal gas as the fuel. Co-generation with thermal-cycle plant, coupled to use the high-grade exhaust heat, should also be explored.

Solid oxide fuel cell technology can still be said to be embryonic, but it is eminently suited to integration with complex and efficient plants, such as that envisaged by an "integrated energy facility".

Why, then, are the gas and electricity utilities in New Zealand not pursuing this option (or, dare I say it, any alternative option), either by a co-venture with Australia or by providing research and development monies here?

Nigel Sammes is a lecturer in Materials Science at the University of Waikato.