IN THE Grimms' fairy tale, Rumpelstiltskin could spin straw into gold. But for parched regions around the world, turning saltwater into fresh would be a more valuable talent.

One-third of the world's population is living without sufficient water and of the 1400 million cubic kilometres of water on the planet, 98 per cent is undrinkable seawater. Worldwide, underground aquifers are being sucked dry.

The problem is likely only to worsen as the global population grows, so countries are looking to desalination to turn saltwater into drinking water (New Scientist, 10 July 2004, p 22).

The US built its first large-scale desalination plant in Florida in 2003, and plans are afoot for another, as well as over a dozen new plants in California and three in Texas. Desalination is also being considered for landlocked states such as New Mexico, Nevada and Utah, where a decade of drought has caused surface water ...