A British bus company believes it may have a secret weapon to cut pollution emissions — sheep urine in the engine.

The Stagecoach company has fitted a bus in Winchester with a tank of sheep urine. The waste is sprayed into exhaust fumes to reduce emissions of harmful nitrous oxides.

It is a novel way of reducing pollution but we believe it will work, Andrew Dyer, managing director of Stagecoach South, said. 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 bus carried its first passengers last month.

The urine is collected by the fertilizer industry from farmyard waste and refined into pure urea, which is then sold to be used in the new engine. 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.

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