UK chemists seek hydrogen store
October 18, 2004
UK scientists think they have taken a major step forward in making hydrogen a practical replacement for petrol.
Hydrogen has zero greenhouse emissions when "burned" in the novel car engines now under development - but being a gas it is expensive to compress or liquefy.
Now, Newcastle and Liverpool University teams have shown how to store large quantities in super-porous materials based on carbon and nickel.
They describe their work in the journal Science.
The teams say it is proof of concept research which requires many more years of active study. But their approach adds yet another possible solution to the hydrogen storage problem.
'Window' shut
Whilst hydrogen's energy content on a mass-for-mass basis is better than petrol, it has difficulty competing with fossil fuels because it is a gas.
An uncompressed 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.
Scientists are now trying to get around this. The options include metal alloys that can be persuaded to absorb up to 1,000 times their own volume of hydrogen; and minuscule cylinders of carbon atoms, known as nanotubes, that are more efficient still.
But both of these solutions have their drawbacks, and now the teams from Newcastle and Liverpool Universities have come forward with another approach.
They have investigated a number of synthetic materials including a blue solid containing carbon, nickel, nitrogen and a little oxygen which together form a crystalline "tongue and groove" structure.
Within this lattice there are tiny gaps that are millionths of a millimetre in size where the hydrogen can sit. What is more, these pores are protected by "windows" that "close" once the hydrogen is inside.
Further information is available on the BBC News site.
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