A British company has developed the first tractor in the world to be completely powered by COW DUNG.The liquid methane gas-powered T7 vehicle is said to be first of its kind and could mark a turning point in efficient energy supply on UK farms.The pioneering 270bhp tractor runs on fuel captured from farmyard manure and is said to match the performance of standard diesel-powered versions.It works by collecting waste by-products from a herd as small as 100 cows into abiomethane storage units based on the farm.The gas – known as fugitive methane - is then treated, compressed and turned into the low emission fuel.