Coming soon - the car that won't choke you

Hydrogen vehicles are now a real possibility.

The good news for asthma sufferers is that slowly, ever so slowly, the emissions-free vehicle is coming to car showrooms.

Asthma campaign

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The good news for asthma sufferers is that slowly, ever so slowly, the emissions-free vehicle is coming to car showrooms.

Today, commercial cars are almost all powered by petrol or diesel; a select few run on liquid petroleum gas (LPG), which produces fewer emissions than other fossil fuels. More importantly, it produces fewer of the particulates that are implicated in asthma.

But that's only "fewer" – not none. But "zero-emission" cars are a reality – though not quite a commercial one yet. There is, however, an intensive effort now to shift cars to the "hydrogen economy".

That is one where cars would burn hydrogen – to produce just water vapour. But it requires a fundamental shift in the production systems of car companies, and in the demands of car buyers.

At the New York motor show at the end of this month, Ford will show off a version of the Focus car that uses fuel cells and an electric battery system, combining to give it a range of between 160 and 200 miles, while its top speed is governed at 80mph.

It's not nirvana for car drivers; but even this is a substantial step forward from what has gone before. The tank holds the hydrogen equivalent of four gallons of petrol, but gets far more mileage from it.

Ford and General Motors have been showing off electric cars for years, but those relying on batteries to store the charge were heavy, slow, short range and expensive. Now, the focus has switched to fuel cells. These were invented in Britain: they are electrochemical devices that convert the energy released when hydrogen and oxygen combine into electricity and heat. That is then output to an electric motor.

One complaint made against fuel cells is that they just shift the pollution to another generator. The hydrogen has to be extracted from water in the first place, and that requires electricity; and power stations pollute. But those backing the "hydrogen economy" point out that renewable energy sources such as wind and wave can generate electricity without emissions – making the zero-emission economy a possibility.

"The nice thing about fuel cells is that they're equally effective at generating small or large amounts of power," says Jack Frost, director of fuel cells at the metals specialists Johnson Matthey in London. "That makes them ideal for using in cities."