United Utilities is about to build a plant in Manchester that will turn humane waste into methane gas. It will be virtually indistinguishable from methane extracted from the North Sea.
The pilot biogas conversion plant is expected to provide enough gas for 5,000 homes by 2011. Other plants will follow throughout the country.
Sewage plants already use sewage as fuel, but mostly to burn it to generate electricity. But the developers of the new plant say this is not an efficient use of the gas.
Methane is produced as a natural process when microbes break down sewage sludge in a process known as ‘anerobic digestion’.
Most sewage plants burn raw methane to generate electricity. The new plant will clean up the gas by removing moisture, carbon dioxide and the traces of sulphides and other contaminants that give sewage its distinctive aroma. It will be just as safe as our drinking water, they say, which also goes through an intensive filtration process to remove contaminants. The pure methane produced will be clear and ordourless and. like our North Sea methane, will be given a ‘gas’ smell for safety reasons.
This will be the first time a renewable source has been used to supply gas to consumers and is another step towards reducing our carbon footprint.