Going nowhere fast

It's not often ethical living journalists find themselves in the BMW hospitality pavilion at Wentworth golf club, sipping champagne and watching Veejay Singh tee off just a few metres away. (Not often enough, actually.) But readers! There was a reason for all this bacchanalian living, honestly: BMW is introducing the public to its hydrogen-powered 7-Series car, and had offered me a chance to drive it. I'm sure you understand that it was irresistible, as, indeed, is the whole idea of hydrogen power, the near alchemical dream of getting cars to run on a fuel that can be made out of water.

In the hydrogen dream, we could create our own power and fuel our cars, with zero carbon emissions and complete fuel security. The homepage for a website called Hydrogen Highway asks you, in that American way, to "imagine ... a world where the only thing coming out of your car's exhaust pipe is water vapour", and it's exactly the sort of world I like to imagine. But is the dream too good to be true? Hydrogen cars appear to be having a bit of a Moment. Next week, a bunch of green petrolheads (yes, there really is such a thing: Dale Vince of Ecotricity and Kevin McCloud from Grand Designs both own up to loving cars, just hating the emissions) will be taking part in the Revolve eco-car rally between Brighton and London. This summer Honda will be allowing journalists to drive its FCX concept car, and General Motors, Ford, Hyundai, Toyota, Nissan and DaimlerChrysler are hard at work on their own versions - all to be unveiled, no doubt, with similar fanfare.

Although the filling infrastructure in this country is in a woeful state - the only existing hydrogen petrol pump in east London was shut down last year amid a hum of disquiet from locals - there's a fair buzz of activity attempting to rectify this: the Policy Studies Institute is mapping out various possibilities in a big study for the Department of Transport; last week's energy white paper refers to hydrogen as one of the future options for fuel; while the Welsh Assembly has been putting a fair bit of money into the H2Wales project ("towards a hydrogen economy") at Glamorgan University. Further afield, in California Governor Schwarzenegger is constructing his beloved Hydrogen Highway; in Germany they've actually got a few hydrogen pumps up and running; and in Japan, apparently, they're mad for the stuff. And here I am, in my BMW, having overcome the slight issue that it is about 10 times bigger than my own car, in order to cruise majestically through the leafy lanes of Surrey. What could possibly be wrong?

The jarring flaw is that no one even begins to agree on how to reach the Hydrogen Future. BMW, for example, has stuck with the combustion engine ("It is where our competence lies," says one BMW man), but most other car manufacturers believe the hydrogen fuel cell is the way forward.

This would be the end of the old internal combustion engine (ICE), and on to a far more efficient way of moving the wheels (the efficient power use of the fuel cell beats the ICE hands down). But that massive paradigm shift - changing from combustion engines to fuel cells throughout the global motor industry - is only problem number one. Before the hydrogen even reaches the car there is the far greater problem of how to produce it. At the moment most is made either by steam compression or electrolysis: both, particularly the latter, use considerable amounts of fossil fuels. In fact, BMW admits straightaway that the hydrogen car I'm driving in effect has a heavier carbon footprint than a normal car. The way round this, suggests BMW, is that the electricity used in this process could be generated renewably - wind power, solar power etc. At first, this appears to be a good prospect, especially as hydrogen can be stored once produced, so it is a useful way of dealing with the intermittence of renewable power.

The gleaming red stumbling block to this is the Tesla, the electric car launched last year that has single-handedly revived the fortunes of the electric car market by looking convincing and even sexy (Top Gear magazine's recent green issue loved it: apparently it accelerates like the best of them). Why would you use electricity to create hydrogen to fuel a car (the hydrogen is then converted back into electricity in the fuel cell, after all) if you can just use the electricity? The Tesla must give car execs who've staked their money on hydrogen some sleepless nights.

There are, however, other ways of making hydrogen, and these are being explored: biological production is the big hope in Wales, where they've managed to generate hydrogen using sewage. They're about to build a renewable hydrogen demonstration centre, which will include a pump, to see if they can do it on a larger scale. If this works, it really will be alchemy. But it is at such an experimental stage that you wouldn't want to bet your house on it. Anaerobic digestion (the methane from the waste is used this time) is another option, but the people within the hydrogen world that I talk to all disagree about efficiency and viability.

And an oil company insider tells me that very few people in their industry take hydrogen (or electricity for that matter) very seriously at all; it's just not considered a viable mainstream prospect. The majority of the industry believes that the future will lie in bio-fuels (which, as we are increasingly hearing, come with their own major pitfalls) and perceives hydrogen and electricity as having little more than novelty value. The huge task of changing the filling and manufacturing infrastructure, not just here, but throughout the developed and developing world, does seem unbelievably daunting.

Is there a difference in driving experience between the petrol and the hydrogen engine? One petrolhead I spoke to thought the petrol one was noticeably more powerful, but it's a distinction beyond me. All I can detect is a faint whine in the lower gears when we're using hydrogen, otherwise the BMW is as efficient and chairmanlike as you would expect. But when does BMW expect to have it on the road? Five to 10 years, it says, just as it has been saying since the first one it built in 1978. Like a mirage, the hydrogen economy seems so near, but keeps moving away whenever we get closer.