"What's really exciting about driving? Perhaps the noise has nothing to do with it," he shouts. "Perhaps it's possible to make a car that's completely quiet, that drives like a sports car - makes you feel every bit of the road - but all you hear is a whoosh."

Morgan's plans to build a hydrogen-powered sports car were announced last week as a joint project with the research firm Qinetiq and a smattering of university groups. If all goes to plan, the team will deliver the hydrogen-powered LIFEcar within three years.

No one at Morgan or Qinetiq is pretending that LIFEcar will do anything to save the planet, but if the project proves that environmentally friendly cars needn't lack looks or performance, it might just encourage others to look more seriously at making them. "If it works, and people like it, it will show that hydrogen is a marketable possibility," says Morgan.

Projects such as LIFEcar raise the profile of environmentally friendly vehicles and encourage the development of the fuel cells and electric motors needed to power them. But some experts believe that hydrogen cars for the masses are such a distant prospect that effort should be focused on alternatives. "We need to explore and develop our options," says John Heywood, director of the Sloan Automotive Lab at MIT (Massachusetts Institute of Technology). "We need things we can do right away."

Hydrogen cars, if introduced in the right way, will certainly bring benefits, according to research. In the latest issue of Science, Mark Jacobson and colleagues at Stanford University calculated that if all the vehicles in the US were powered by hydrogen, the resulting drop in pollution - in the form of carbon monoxide, ozone and nitrogen oxides - would prevent between 3,000 and 6,000 deaths a year. "It could be done at a fuel cost that's comparable to the cost of gasoline - and less than the cost of gasoline when yoou consider the health effects," he says.

One problem facing a hydrogen economy is creating an efficient infrastructure. In a paper soon to be published in the journal Energy, a team led by Zhijia Huang at China's Anhui University assessed various means of generating hydrogen and making it available to drivers needing to fill up around Shanghai. They produced a "well-to-wheels" analysis of the energy efficiency and emissions of different hydrogen pathways, taking into account how the gas was made and distributed.

The researchers found that while eight out of 10 pathways led to big cuts in urban pollution emissions, six of the 10 methods consumed more energy and generated more greenhouse gases than the existing petrol-based infrastructure. The best way to generate hydrogen, they concluded, was to use natural gas; the worst was electrolysis to split water into hydrogen and oxygen.

Picking the most efficient way to make and distribute hydrogen isn't the only issue for hydrogen cars. According to a study carried out in 2003 by researchers at the California Institute of Technology and Nasa's jet propulsion laboratory, leaks could have a damaging effect on the atmosphere. The study, reported in Science, says inevitable gas leaks from hydrogen production facilities, transporting the fuel and the hydrogen cars themselves, would lead to a four- to eight-fold rise in the amount of the gas being pumped into the atmosphere by human activity. If the hydrogen accumulated in the stratosphere, as the team believe it would, the likely effect would be a 10% drop in ozone levels.

According to Heywood, we have a long wait before the impact of hydrogen cars will be known. He compares the introduction of hydrogen cars to the push for diesel in Europe in the early 1980s. "It was a fairly standard technology that needed only a bit of development, and it took around 25 years to achieve substantial market penetration," he says. "With hydrogen cars, the fuel cells are new, the batteries and some of the electronics are new and you have to build new factories, which takes time and money. When we looked at how long it was likely to take for fuel cells to be really marketable, we came up with around 50 years."

Heywood isn't opposed to projects such as LIFEcar, but believes interim technologies are needed to ease reliance on fossil fuels in the next half-century. "If you extrapolate the petroleum consumption going into transportation in this country, western Europe, China and India, it's clear the future's different from the past. The developing world is big enough and growing rapidly enough. It's going to strain supplies. Maybe eventually we have to wean ourselves off fossil fuels for cars. But it doesn't have to be all hydrogen or all battery cars to do it."

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