Pigs' urine could purify pollution
Andrew Dyer, managing director for Stagecoach South, told edie news it was also hoped the gadget would improve fuel efficiency.
"We're working on the new technology with Cummins, the heavy vehicle engine manufacturer, to achieve the new Euro 4 emissions levels due to come in in September next year," he said.
He said reports that the test bus was using sheep urine was false and the chemical was currently being produced synthetically.
"The technology to refine slurry and extract the urea is there," he said. "At the moment it's not economically viable but perhaps in the future it will be and that would be a big win for the environment."
He accepted the current synthetic production of the urea would have an environmental impact due to the energy and chemical processes used in its manufacture but said he had been reassured that the benefits hugely outweighed the costs.
"In terms of extracting it from the animal kingdom, I'm told pig's urine is the best source," he said.
"But I dread to think how they get it - I have visions of pigs walking round their pens with colostomy bags."
Mr Dyer said rumours passengers on the back seat would be asked for a urine sample were greatly exaggerated and there were no plans to install sheep cages on the roofs of the Stagecoach fleet.
"Behind the jokes there is a serious environmental project that could see us dramatically reduce the emissions from our buses," he said.
"Basically what happens is the ammonia from the urine reacts with the nitrous oxide in the exhaust fumes to neutralise it, turning it into nitrogen and water which is then released as steam.
"An extra chamber for the urea is fitted onto the exhaust manifold and a computer-controlled dose is injected straight in."
He said Stagecoach was also hopeful the device might help cut fuel bills.
Previous emissions scrubbers have helped clean up exhaust fumes but have made the vehicles more expensive to run, reducing fuel efficiency by over 15% said Mr Dyer.
"We've got no evidence yet but we believe this thing will not effect fuel consumption," he said.
"If all goes according to plan we will be installing it on other buses in the autumn and then Winchester will have the cleanest fleet in the UK."
By Sam Bond
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