23 May 07

A new compound of lithium could result in fuel cell powered cars that can drive over 300 miles before needing to refuel. The compound, developed by scientists at the Universities of Oxford and Birmingham and the Rutherford Appleton Laboratory, promises to solve the tricky problem of how to store hydrogen on board cars without exceeding size and weight limits.

Prototype fuel cell powered vehicles produce carbon-free electricity by harnessing electrochemical reactions between hydrogen and oxygen. However, it would take a fuel tank the size of a double-decker bus to store enough hydrogen gas for a 300-mile journey. Carrying hydrogen as a compressed gas in cylinders or as a liquid in tanks is also impractical because of size and weight implications.

The new approach uses a process in which atoms of hydrogen gas are absorbed into the crystal structure of a material and then released. A variety of lithium hydride developed by scientists from the UK Sustainable Hydrogen Energy Consortium (UK-SHEC) appears to be an ideal material for this purpose.

'We tested thousands of compounds in search of a light, readily available material which would enable this process to take place rapidly and safely at the right temperature,' said UK-SHEC's Project Co-ordinator, Professor Peter Edwards in the Department of Chemistry at Oxford University. 'This could be a major step towards the breakthrough that the fuel cell industry and the transport sector have been waiting for.'

Professor Bill David from the ISIS Facility at the Rutherford Appleton Laboratory, a Visiting Professor at Oxford University, said: 'The combination of rapid materials synthesis and the rapid structural characterisation capabilities at the ISIS neutron source and the ESRF and Diamond synchrotron sources is crucial to the UK playing a leading role in discovery and development of novel hydrogen storage materials.'

The UK-SHEC team hope that their work will help see mass-market fuel cell cars go on sale within the next decade. UK-SHEC is funded by the SUPERGEN (Sustainable Power Generation and Supply) initiative managed and led by the Engineering and Physical Sciences Research Council (EPSRC).