KEY POINTS:
Britain has opened its first hydrogen filling-station. Researchers there will be assessing alternative fuel vehicles in search of greener motoring.
Is hydrogen the answer? The hydrogen fuel-cell is revolutionary. It supersedes the internal combustion engine and does away with fossil fuels. Some of the world's leading energy and motor companies are developing alternatives to the conventional car. If the world wants hydrogen it will have to invest in it, scrapping existing technology, factories, refineries, infrastructure and know-how. Consumers would have to pay for the leap forward.
What's so good about hydrogen?
It is green at the point of use. Hydrogen fuel-cell vehicles emit no carbon dioxide, nitrous oxide or carcinogenic particles. All that emerges from the exhaust is water vapour. The hydrogen fuel, stored in pressurised tanks, is used to create a chemical reaction using catalysts. It is quiet, and performance is acceptable for many purposes; in any case it is early days yet.
Do hydrogen fuel cells work?
Californian and South Korean authorities have tested fleets of Honda and Hyundai fuel-cell cars satisfactorily. Mercedes-Benz and General Motors are two other companies who've produced running, everyday fuel-cell models (Mercedes A-Class and a Vauxhall Zafira, respectively). The Honda FCX Clarity, a "proper" executive fuel-cell car, will be available for lease in the United States this summer.
So what's the snag?
The greenness of hydrogen does depend on how much energy is inefficiently expended in generating it and moving it around. If, at one extreme, a much more efficient method of making hydrogen could be discovered, and if the energy used in its manufacture and transport was sustainable (like from a power station using solar energy), then it might well be the greenest option. At worst, there isn't much advance on fossil fuels.
How about just using hydrogen as fuel?
Simply replacing fossil fuels with hydrogen in a conventional internal combustion engine can be done. BMW's Hydrogen 7 is almost as quiet and refined as its petrol-powered cousin. But it needs a huge tank for (unpressurised) hydrogen, and that tank of fuel can evaporate in as little as 10 days.
Are biofuels any use?
This technology is also controversial. In theory, biofuels are carbon neutral, as the carbon dioxide used in producing them is "absorbed" by the plants grown to create the biofuel. So-called first generation biofuels do suffer from drawbacks. First, they can displace food crops. Second, they can reduce biodiversity, as witnessed in the Indonesian rain forest, where palm oil crops for biodiesel have done much damage. Third, critics point to the energy expended in producing and transporting the biofuels, the artificial fertilisers used, the subsidies to grow them in Europe and the United States, and so on. More defensible are second, third and fourth generation biofuels, which become progressively greener, though none are commercially available.
Why aren't there more hybrids?
Toyota's Prius leads the field, although Honda, Ford and General Motors are also on the scene. Using power wasted, for example, in braking, and recycling that via an electric motor to supplement a petrol engine is a clever one. But many manufacturers say small, efficient diesel engines are just as effective and a lot cheaper to make, with no batteries to dispose of.
What happened to the electric car?
The motor-show concept Chevrolet Volt (a "plug-in" hybrid) promises much, and GM are committed to making it. Electric cars can be extremely green, but again much depends on how their power is generated.
What should motorists do?
Drive more carefully; downsize; use public transport more. There's an argument for keeping an old car on the road for longer, thus saving the resources and energy used in producing a new one. Modern cars are much greener than their predecessors. Ford and Volkswagen are tuning existing models to return exceptional economy and low emissions - the VW Polo "Bluemotion" is an outstanding example. But manufacturers do tend to price their green or diesel cars on the high side.
- INDEPENDENT
