According to Dr Paul Stonehart, president of the American company Stonehart Associates, a new polymer material developed by his company allows fuel cells to compete alongside coal, oil, gas and nuclear fission for widespread electricity generation.
'The material has opened up a big door; it allows us to say commercialisation (of fuel cells) is here now,' says Dr Stonehart.
The material developed by Stonehart, to be manufactured in the US by Du Pont, is a perfluorinated sulphonic acid polymer, and is the key component of a new type of fuel cell.
These cells are currently used in small-scale specialised applications, such as military vehicles and submarines, where the need for a compact, lightweight energy source outweighs cost considerations. Fuel cells have been used on American space missions since 1962, when Nasa adopted them for the Gemini programme.
Dr Stonehart believes that he can cut the current costs of polymer fuel cells by about 80 per cent by using the material developed by his company, which should make them economically attractive for all scales of commercial electricity generation.
Power outputs could range from a few kilowatts, enough for a small factory or an electric car, to the megawatt scale of power stations serving towns and even cities.
'The only question is whether the manufacturing technology is amenable to automation. The answer is yes,' says Dr Stonehart.
Fuel cells work like batteries, producing electricity directly from the electrochemical reaction of hydrogen with oxygen from the air. But unlike a battery, they do not have to be recharged or thrown away, as the hydrogen fuel is fed in continuously. Methanol or natural gas can also be used.
Because the fuel is not burnt in air there are no undesirable nitrogen oxides or sulphur dioxide emissions. The only by- products are water and heat, which can be harnessed usefully in, for example, combined heat and power schemes in which recovered heat provides additional energy, usually in the form of steam.
The commercial drive towards fuel-cell technology, in the US at least, is coming from environmental legislation. The state of California, for example, will require 2 per cent of all new vehicles to have zero emissions of sulphur dioxide and nitrogen oxides by 1998. That will increase to 5 per cent by the beginning of the next century. Polymer fuel cells have been seized upon by the vehicle industry as one possible means to that end.
The first prototype buses using polymer electrode fuel cells are now on the road in California. Dr Stonehart thinks that commercial electric vehicles will run on batteries recharged by fuel cells.
'The fuel cell is really a range extender,' he says. 'The battery is there to give overtaking and acceleration where you need a big spike, whereas the fuel cell is there to provide range.' He believes the fuel most likely to be adopted is methanol because it is a liquid.
Another plus is that waste heat from the fuel cell can be used to heat the bus. General Motors aims to have the first passenger cars using a polymer fuel cell run on methanol in operation in the US by 1997.
A major advantage of fuel cells is that they are modular and can be stacked together to provide enough electricity to power anything from homes or cars to multi-megawatt power plants.
In Tokyo an 11 MW fuel-cell system, currently the largest such power station in the world, supplies 4,000 homes with electricity. Modularity, however, makes them more suitable as smaller stand-alone generating units, typically used for hospitals, factories or blocks of flats.
Although fuel cells were invented in Britain by Sir William Grove at the Royal Institution in London in 1839, it is the US and Japan that now lead the field in their research and development. In the UK, however, ICI, Rolls- Royce, British Gas and the precious-metal supplier Johnson Matthey all have extensive fuel- cell development programmes, funded in part by the Department of Trade and Industry.
The efficiency of a fuel cell in converting fuel to useful energy can reach more than 80 per cent, so they produce less carbon dioxide per unit of electricity generated than conventional sources. Dr Stonehart believes that it is this, combined with a lack of other emissions, that will make fuel cells more attractive as environmental legislation continues to tighten over the next decade.
'We still don't know the impact of legislation. The relative costs will come down quickly when money has to be spent cleaning up emissions,' says Dr Stonehart.
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