'Ice cages' can store hydrogen

One of the major obstacles towards the 'hydrogen economy' - generating power through fuel cells, rather than by burning fossil fuels - is how to store the hydrogen.

So far, the most practical options have been liquefying or compressing the hydrogen, but these require difficult to achieve low temperatures and high pressures. An alternative approach may lie in research from the University of Chicago, where David and Wendy Mao have developed a method of trapping hydrogen atoms within a microscopic cage of ice.

The Maos used a diamond anvil cell to form the hydrogen-water complex, called a hydrogen clathrate hydrate. It took pressures of 20,000- 30,000 atmospheres and temperatures of -132 degrees C to make the compound, but it is stable at atmospheric pressure and -195 degrees C, the temperature of liquid nitrogen.

'We thought that would be economically very feasible,' says Wendy Mao. 'Liquid hydrogen is easy and cheap to make.'

Diamond anvil cells are not the most practical of pieces of equipment, however - cost aside, they will only generate very small amounts of material. However, it may be possible to generate larger quantities of clathrates in gas pressure devices, the Maos say.

The Maos have applied for a patent on their hydrogen clathrate synthesis technique.