Financial Times, 8 June 2005 - As petrol prices havesoared in the US over the past two years, American drivers have taken their lead from Hollywood's trend-setters, ditching their big gas-guzzlers and switching in growing numbers to the latest petrol-electric hybrids.

The addition of a battery and electric motor to increase the fuel efficiency of cars has been widely touted as a way to reduce America's appetite for oil from an unstable Middle East until zero-emission hydrogen fuel cells are available at lower cost.

But now a competing technology, which enables ordinary internal combustion engines to run on hydrogen, will soon start to hit the road.

Enthusiasts say the hydrogen engine could help smooth the introduction of hydrogen as a fuel - a process that will require heavy investment in filling stations, hydrogen production and specialised components.

The hope is that hydrogen engines will provide a "bridging technology" to fuel cells, says Vance Zanardelli, Ford's chief engineer for hydrogen engines. "When the fuel cell is ready for prime time, the world needs to be ready for hydrogen," he adds.

Hydrogen engines work in the same way as petrol engines. Indeed, BMW and Ford, the leading exponents of the technology, believe the best hope of popularising it will be to produce an engine that runs on either fuel. Certainly, fuel cells will be cleaner. They produce only water, with no soot or smog-forming nitrogen oxides. But their costs are hundreds of times higher and they produce relatively little power. Fuel cell cars using electric motors will also have to be designed from scratch.

In contrast, internal combustion engines that run on petrol are a familiar, century-old technology and can be adapted for hydrogen relatively quickly.

Ford plans to deliver a 100-strong test fleet of hydrogen-powered minibuses to airports and other large customers next year. BMW, meanwhile, has pledged to be the first to start mass-producing hydrogen cars, with a version of its 7-Series saloon due on sale in three years.

"Once people see it on the road, they are much more likely to take it seriously," says Mr Zanardelli.

At the moment, Ford and BMW are almost alone in championing hydrogen engines. Most carmakers are concentrating on fuel cells. General Motors and Toyota, the world's two largest carmakers, are discussing setting up a joint venture to build fuel cells. Even Ford believes fuel cells will be the long-term answer.

GM has developed a hydrogen-powered version of its Hummer offroader using an internal combustion engine. But it has decided not to develop the technology further.

"We don't see it being a big enough interim step for us to explore," says GM. "We have decided that if hydrogen is widely available it is more efficient to convert it into electricity (in a fuel cell) rather than burn it (in an engine)."

Toyota estimates engines are only about 34 per cent efficient, whether they burn petrol or hydrogen. Fuel cells are closer to 60 per cent efficient. In addition, hydrogen takes up a lot more storage space. Even when converted to a liquid, it still produces less energy for a given volume than petrol.

"Long term, hydrogen is definitely the future," says Honda. "But we are going down the fuel cell route. We don't see any reason to compromise."

Some of hydrogen's dis-advantages are apparent in BMW's prototype dual-fuel 7-Series saloon. It can do 310 miles (500km) on a tank of petrol but only 125 miles on a tank of hydrogen. BMW says its production version will have a range of 190 miles.

Undeterred, advocates of hydrogen engines say the technology offers a quick and cheap way of breaking the Catch-22 facing hydrogen-powered cars. Drivers will not want hydrogen cars until there is a network of filling stations. But no company will invest in filling stations - and hydrogen production - until there is a critical mass of cars.

BMW believes a hydrogen engine can be developed more quickly and will be cheaper than fuel cells. It also says it has achieved efficiency levels of 50 per cent with hydrogen engines in the laboratory - close to the efficiency of fuel cells.

For performance-oriented BMW drivers, hydrogen engines also have the advantage of being able to provide close to 300 horsepower, enough to power its test vehicle to a top speed of 186mph.

After the celebrity flirtation with Toyota's dull but environmentally friendly Prius, a hydrogen BMW could provide the boy racers among the glitterati with a way to gain green credentials, too.

www.ft.com/autos

Copyright 2005 The Financial Times Limited
Financial Times (London, England)