Food scraps could power an ultra-cheap bacteria-driven battery. ‘Microbial Fuel Cells,’ developed in the past, have proved inefficient and expensive. But Chris Melhuish and researchers at Bristol University, have come up with a simplified MFC that costs as little as $10($15.50) to make. It runs only on sugar cubes, since these produce almost no waste, but the aim is to move to carrot power. ‘It has to be able to use raw materials, rather than a refined fuel,’ says Melhuish. Inside a Walkman-size battery, a colony of E. coli bacteria produce enzymes that break down carbohydrates, releasing hydrogen atoms. The cell also contains chemicals that drive a series of reduction and oxidation reactions. To prove the MFC works, researchers are powering a small, light-sensitive robot. When a number of the cells are connected, they can running a 40W-bulb for 8hrs on about 50gms of sugar. In its current form, the team says its organic battery can produce eight times as much power as previous MFCs. But Melhuish wants to improve this, both scaling up and finding a better mix of redox chemicals. For more information contact: University of the West of England, Bristol, Coldharbour Lane, Bristol, UK BS16 1QY . Tel: (+44 or 0) 117 965 6261.