British scientist Mike Rowe (Cardiff University) has made a significant advance in harnessing the energy of hot and warm waste water. In his laboratory he is using a bathful of dirty water (55°C) to power a colour TV and is certain that, on an industrial scale, his technology will provide large amounts of low-cost electricity. Professor Rowe’s breakthrough is the discovery that thermocouples, the devices which create electricity from temperature difference, need not be made from metals. Usable voltages can also be generated by cheaper ‘semi conductors’, made from materials such as germanium and silicon.

The new technology could also benefit the environment. Industry dumps large amounts of warm water into rivers, affecting the life cycles of river animals and fish.