Wessex Water produces bio-gas at its sewage treatment works at Avonmouth in Bristol, where around 75 million cubic metres of sewage waste is treated and 35,000 tonnes of food waste, collected from households, supermarkets and food manufacturers, is recycled.
Through a process known as anaerobic digestion, 17million cubic metres of biomethane a year are generated. Some of the gas is injected into the national gas grid network to power homes, but a new venture is to use it to power a bus in Bristol (the no. 2 service from Cribbs Causeway to Stockwood).
The 40-seater Bio-Bus is produces fewer emissions than traditional diesel engines. On a full tank of gas the bus can travel 300 km - which takes the annual waste of 5 people to produce. The tank is filled at a specialist gas refuelling plant at Bristol sewage treatment works.
As well as producing bio-gas for national grid and bus fuel, the treatment plant also produces nutrient-rich fertiliser offering farmers a safe and sustainable alternative to inorganic chemicals.
Feature in Wessex Water Magazine, spring/summer 2015
