Project feeds biomethane to gas grid

Enough biomethane gas to supply up to 200 homes is now being produced at the Didcot sewage works in Oxfordshire.

It is hoped that the Didcot project, which is a joint venture between Thames Water, British Gas and Scotia Gas Networks, will be the first of many similar developments. According to a study by National Grid, gas produced from sewage could account for at least 15 per cent of the domestic gas market by 2020.

Sewage arrives at the Didcot works from some of Thames Water’s 13.8 million customers to be treated and recycled back to the environment.

Sludge, the solid part of sewage, is then treated further in warmed-up vats in a process called anaerobic digestion, where bacteria break down biodegradable material, yielding biogas.

Impurities are then removed from the biomethane before it is fed into the gas grid. The whole process – from flushing a toilet to gas being piped to people’s homes – takes around 20 days.

Martin Baggs, chief executive of Thames Water, said: ’We already produce £15m a year of electricity by burning biogas from the 2.8 billion litres a day of sewage produced by our 13.8 million customers. Feeding this renewable gas directly into the gas grid is the logical next step in our energy from waste business.’

Baggs was speaking at a breakfast barbecue held at Didcot sewage works to celebrate the completion of the project. Bacon sandwiches were served to invited guests after being cooked on a grill powered by the very same biomethane that is now being fed into the gas grid.

The project took six months to complete and cost £2.5m.

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