Anaerobic digestion for Somerset
An anaerobic digestion plant for Somerset’s food waste has been at Walpole near Bridgwater since 2013; this being strategically located close to junction 23 of the M5. The facility is successfully processing all household food waste collected for recycling in Somerset. It also has additional capacity for food waste from commercial sources.
Anaerobic digestion (AD) was selected by SWP due to offering the greatest carbon and environmental benefits, allowing renewable energy generation and providing the best technology for recycling food waste into biogas and bio-fertiliser for use on local farms.
The plant is operated by our strategic partner and contractor, Viridor, who, following a procurement process, selected Monsal to provide the technology platform for the facility.
The plant cost about £10 million to construct and processes up to 30,000 tonnes of food waste per annum, 20,000 tonnes of which is provided by SWP. If demand in the future is sufficient, its planning consent allows the facility to be expanded by a further 15,000 tonnes pa.
During construction, 20 jobs were created and there are now six full-time positions managing it’s operation.
The facility saves Somerset council tax payers £200,000 a year over previous arrangements for recycling the county’s food waste. In addition, SWP have a profit share arrangement to allow tax payers to benefit from additional income above a base level earned from the sale of energy as well as the digestate.
Biogas produced is being used initially to generate electricity. The facility has a generating capacity of 1MW and generates about 9,500 MWh a year, with about a fifth of this used within the plant and nearly four-fifths (78%) exported to the grid, which is enough to power more than 1,700 homes.
Viridor continue to evaluate the potential to instead scrub or clean the biogas, either for injection directly into the national gas grid or use to power Somerset’s recycling and waste management vehicle fleets. This has even greater benefits in energy and environmental terms than generating electricity and so would make the process even more sustainable.