It's a mechanical problem that's troubled scientists since Archimedes and the ancient Greeks but now an electrician has come up with a new invention that could help save consumers thousands of pounds in energy bills. Scotsman Ian Gilmartin, 60, and his friend Bob Cattley, 58, both from Kendal, Cumbria have invented a mini-waterwheel capable of supplying enough electricity to power a house - for free. The contraption is designed to be used in small rivers or streams - ideal for potentially thousands of homes across Britain. It is the first off-the-shelf waterwheel system which can generate a good supply of...