Discovery Is A Step Towards Pollution-free Cars

A team from the Universities of Newcastle upon Tyne and Liverpool in the UK, who report their findings in the prestigious academic journal, Science, have found a safe way of storing and releasing hydrogen to produce energy. They do this using nanoporous materials, which have tiny pores that are one hundred-thousandth (100,000th) the thickness of a sheet of paper.

Hydrogen has been investigated for a long time as a replacement for petrol, amid worries over the long-term availability of fossil fuels. It is also an environmentally-friendly alternative, as it produces only water rather than the 'greenhouse gas', carbon dioxide. However, scientists and others have been baffled for a long time about how to store the substance - which is a gas and so contains less energy in a given volume than the liquid petrol - safely and efficiently.

In his January 2003 State of the Union Address, President Bush announced the Hydrogen Fuel Initiative - "so that America can lead the world in developing clean, hydrogen-powered automobiles." Hydrogen storage technology - the ability to carry enough hydrogen on-board a vehicle to enable 300-mile vehicle range - is critical to the success of the President's initiative. The UK Government is also very keen to exploit the hydrogen economy.

At the present time, no existing hydrogen storage technology meets the challenging performance required to make hydrogen-powered automobiles competitive with traditional vehicles. New and innovative ideas are needed.

The Liverpool and Newcastle researchers have found a workable method of injecting the gas at high pressure into the tiny pores - of ten to the minus nine metres in size - in specially-designed materials to give a dense form of hydrogen. They then reduce the pressure within the material in order to store the captured hydrogen safely. Heat can be applied to release the hydrogen as energy, on which a car could potentially run.

Professor Mark Thomas, of Newcastle University's Northern Carbon Research Laboratories in the School of Natural Sciences, a member of the research team, said:

"This is a proof of principle that we can trap hydrogen gas in a porous material and release it when required. However, if developed further, this method would have the potential to be applied to powering cars or any generator supplying power. Although hydrogen-powered cars are likely to be decades away, our discovery brings this concept a step towards becoming reality.

"Now that we have a mechanism that works, we can go on to design and build better porous framework materials for storing hydrogen, which may also be useful in industries that use gas separation techniques."

Professor Matt Rosseinsky, of the University of Liverpool's Department of Chemistry, said "Our new porous materials can capture hydrogen gas within their channels, like a molecular cat-flap.

"After allowing the hydrogen molecule - the 'cat' - in, the structure closes shut behind it. The important point is that the hydrogen is loaded into the materials at high pressure but stored in them at a much lower pressure - a unique behaviour. This basic scientific discovery may have significant ramifications for hydrogen storage and other technologies that rely on the controlled entrapment and release of small molecules."

The study was part-funded by the Carbon Trust.