Forget the tiger - put sheep urine in your tank

A British bus company is testing a new secret weapon that it hopes will help forward its push to cut its polluting emissions - sheep urine.

Stagecoach has fitted a bus in Winchester with a tank containing the animal waste, which is sprayed into exhaust fumes to reduce emissions of harmful nitrous oxides.

Andrew Dyer, managing director of Stagecoach South, said: "It is a novel way of reducing pollution but we believe it will work. There is nothing to worry about - we won't be asking passengers to leave a sample and we won't be carrying a resident sheep at the back of the bus."

The urine is collected by the fertiliser industry from farmyard waste and refined into pure urea, which is then sold on to be used in the green engine technology. Ammonia from the urea reacts with nitrous oxides in the exhaust fumes and converts them to nitrogen gas and water, which is released as steam.