If most of the world’s largest car manufacturers are right, it’s no longer going to be something that goes pop in the science lab or sets fire to 1930s airships. It is the fuel of our future, with the potential to rival the invention of the the first car in 1886 in terms of its impact on personal transport.

The problem for car makers is how to harness the gas and how to make it commercially viable. Last week two cars that are at the respective poles of hydrogen car design were demonstrated to a small number of journalists.

Both will be available to the public — albeit in restricted ways — by 2008. However, having attended both events, I found it not only impossible to judge which technology will prevail, but it became clear that genuine mainstream public ownership is years and possibly decades away.

The first is the BMW Hydrogen 7, which the German company will offer to selected members of the public on a lease basis next year. It’s based on BMW’s flagship 760iL limousine and uses liquid hydrogen stored in a separate tank from the petrol as a supplementary fuel source.

Because the internal combustion engine can run on either fuel with little need for modification, you can switch between hydrogen and petrol by pressing a button on the steering wheel. While the car is a little less refined when running on hydrogen than petrol, this may not matter too much when you consider that when there’s petrol in the engine it emits 332 grams of CO2 for every kilometre it travels but when it’s powered by hydrogen that figure falls to 5.2g/km.

The problems, however, are both numerous and serious. Comparatively trivial issues include a decimation of space in the back and boot to make way for both tanks, the fact it will travel only 125 miles on its hydrogen tank, and that if you leave it standing too long the hydrogen, which needs to be maintained at –253C to keep it liquid, will all boil off.

And you can’t park it in an enclosed space like your garage for fear of gas escaping from the tank and becoming trapped in an explosive pocket.

More thorny issues include the fact that there are just seven places in Europe where you can fill it. In Britain the only hydrogen refuelling station, a BP garage in Essex designed to service buses that run on the fuel, might conceivably close in January when the pilot hydrogen bus scheme comes to an end.

There are environmental issues, too. Although the CO2 emissions are minuscule at the point of use, this hides the so-called “well to wheel” pollution. At present the only commercially viable way to manufacture hydrogen is to extract it from natural gas, a process that itself emits large amounts of CO2.

I spent the best part of a day tooling in and around Berlin in a Hydrogen 7 and found it little different to drive than any other 7-series, just a little slower. BMW is committed to building 100 next year and putting them out on six-month loans to various political, sporting and environmental types who, it hopes, will help spread the word. No price is quoted.

Meanwhile, far away on the coast of southern California, another car manufacturer is making another commitment. This time it is Honda, and while it won’t talk numbers either it says it will put its FCX concept car into production in 2008 and that it will be driven not just by people who can generate good PR, but by proper members of the public too.

The differences between the BMW and Honda approaches are great. Rather than burn the hydrogen in the engine, as the BMW does, the Honda uses a fuel-cell stack that harnesses electricity created as a side effect of the chemical reaction that occurs between hydrogen and oxygen when they form water.

Fuel cell cars are nothing new, but this is the first to break beyond the concept stage and enter production. Its users still won’t own them — they’ll all be leased — and the numbers are likely to be modest, but as Steve Ellis, Honda’s manager of fuel cell marketing in the US, told me: “No other technology we know of has the ability to eliminate the vehicle from the environmental equation.” And that’s big stuff.

Critically, Honda also has a way around the supply infrastructure problem that undermines the BMW proposition. While BMW’s hydrogen needs to be frozen, Honda’s fuel cell car runs on compressed hydrogen that can be generated from a station owned not by BP or Shell, but by you.

The idea is to have a compact station in your home — 30in x 14in x 14in — that takes natural gas from the public supply and makes hydrogen for your car. And the FCX will go almost three times further than the BMW — 355 miles currently — on one fill.

Both Honda and BMW know that ultimately the only way to have a completely clean hydrogen car is to extract the hydrogen not from natural gas but from renewable sources such as solar, hydroelectric and wind power, but such is the cost of this technology that it is probably decades before it offers a commercially realistic means of providing hydrogen.

For now, though, time alone will tell whether BMW is right to back adapting the internal combustion engine to run on hydrogen, or whether Honda’s fuel cell holds the key to our future. To my mind Honda’s approach is more thoughtful and has the greatest potential, but the BMW way is more pragmatic and easier to visualise today.

And there is also the distinct possibility that neither approach is right, not least because obtaining reliable, clean sources of hydrogen on a worldwide scale at a price the consumer can afford will be an immensely greater challenge than setting up a limited pilot scheme.

All I can say with relative certainty is that the way this game plays out over the next 20 years of so will change not just the face of the automotive landscape, but the future of personal transport around the world. No pressure, then.

VITAL STATISTICS

Model BMW Hydrogen 7
Top speed 143mph
Range 125 miles (+310 petrol)
Max power 260bhp
Gas storage 7.8kg at -253C



Model Honda FCX
Top speed 100mph
Range 355 miles
Max power 95bhp
Gas storage 171 litres @ 350bar

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