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Wednesday, 29 January, 2003, 12:21 GMT
The long road for hydrogen
Cabs, BBC

President George Bush has set course for the hydrogen economy.

In his State of the Union speech, he announced $1.2bn in research funding to help America "lead the world in developing clean, hydrogen-powered automobiles".

The greatest environmental progress will come about... through technology and innovation

President George Bush
"With a new national commitment", he said, "our scientists and engineers will overcome obstacles to taking these cars from laboratory to showroom - so that the first car driven by a child born today could be powered by hydrogen, and pollution-free."

The move is part of his promise to find a greener future without adopting what he regards as the damaging restraints proposed by the Kyoto Protocol to cut emissions of greenhouse gases.

But as his speech concedes, the "obstacles" in the way of a hydrogen economy are high.

To say that there are immense technical problems to be solved before the gas can be thought of as a practical, everyday fuel is perhaps an understatement.

Difficulties of production

As a natural resource, hydrogen is there in abundance. It is in the water that covers 70% of the surface of the planet. But splitting it from the oxygen requires energy - electricity. Using fossil-fuel-produced power to do this would be perverse.

Only Iceland has so far been able to make a serious move towards a hydrogen future because it has ample hydro and geothermal means to separate the gases.

If the US wants "clean" production of hydrogen, it will also have to change its electricity generation system to include more hydro, solar and wind stations.

Science is about pushing boundaries, however, and already researchers are looking at alternative separation technologies. Biotechnology could give us enhanced microbes that produce hydrogen as a byproduct.

Storage and distribution

Whilst its energy content on a mass-for-mass basis is better than petrol, hydrogen has difficulty competing with the fossil fuel because it is a gas.

Turbine, Auto
Wind power: Local production could overcome distribution problems
A hydrogen gas fuel tank that contained a store of energy equivalent to a petrol tank would be more than 3,000 times bigger than its conventional cousin. Compressing or liquefying the gas is expensive.

Only then can you think about how you might distribute the hydrogen across the US to filling stations. Alternative containment technologies are in development, of course. Metal alloys can be persuaded to absorb up to 1,000 times their own volume of hydrogen but they are heavy and some become brittle after repeated use.

Carbon nanotubes, tiny cylinders of carbon atoms, have an even greater storage capacity, but this wonder technology is years from finding its way into a fuel tank.

Future engines choice

To be truly green hydrogen must be burnt in pure oxygen; in air you produce all the same nitrogen oxide pollutants you get from petrol engines. No one is seriously considering using hydrogen in this way.

Instead, the motor manufacturers are developing hybrids vehicles - cars that have separate injection systems for a carbon fuel and a hydrogen fuel - that use fuel cells.

In what is essentially the reverse of electrolysis, hydrogen is reacted with air (oxygen) over a catalyst to produce water and electricity. Engines based on fuel cells are very efficient (up to 80%) because they produce very little heat.

There seems little doubt that given more time and money, these novel systems will provide very acceptable alternatives to the internal combustion engines that propel our cars at the moment.

PR battle and price

Those pictures of the Hindenburg ablaze as it came into land at Lakehurst in New Jersey in 1937 are a powerful reminder of how explosive hydrogen gas can be. That single event probably did more harm to the image of hydrogen as a fuel than any other.

It is an unfair blot, of course. Research has shown that it was the flammable, aluminium-powder-filled paint varnish that coated the infamous airship, not the hydrogen inside it, that started the fateful fire.

Hindenburg, AP
Hindenburg: The unfair slur
Nevertheless, motorists will want reassurance that their vehicles will not suddenly become rockets in a shunt.

Mr Bush referred in his speech to the factors that drive change. "In this century, the greatest environmental progress will come about, not through endless lawsuits or command and control regulations, but through technology and innovation," he said.

However, he omitted perhaps the most important driver of all: price. All the technologies mentioned above are bound to come down in cost, but when drivers can buy their carbon fuel for 40 cents a litre, as they can now, there is little prospect of them switching away.

The innovation will have to travel some way if today's newborns are to be faced with a realistic choice in the car showrooms in 16 years.

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