AD at Northwick Power

The AD plant at Northwick is located on a 2.5Ha site of a redundant quarry in the middle of Northwick Estate just under 1.5kM from the nearest private house. The plant can generate 6.0 megawatts of power, which is sufficient to supply up to 8,000 homes or 20,000 people plus a further 3MWe of gas pumped 1.8km to the nearest medium pressure gas main. The power is available 24 hours a day, 7 days a week.

The site is screened by woodland on all sides and benefits from the existing infrastructure of roads, on-site water and electricity, and available farmland for digestate spreading.

The food waste for the plant is sourced across central England. We are partnered with another AD Plant in Wiltshire Codford Biogas, giving us excellent coverage across the UK for all of our food waste clients in the southwest Gloucestershire area.

The plant was built by MT-Energie, who have built hundreds of AD plants across Europe; Northwick Power was the first plant in the UK. Virtually any waste product can be effectively processed by the plant to produce a strong, stable gas yield with a short retention time required in the digester tanks. Packaged waste can be processed and cleaned by the plant, with the non-digestible products (plastics, card etc.) being set aside for further recycling into RDF.

The plant has a large waste reception building where we have the capacity to unload multiple bulk trailers plus we have a dedicated liquid waste reception area and a unique concrete storage tank which will accept unpackaged ‘sloppy’ loads.

Processed feedstock is piped to the Hydrolysis Tank, a 2,400 m3 vessel where the digestion process begins. From here the feedstock is pasteurised, then enters one of three digesters totalling almost 9,000m*3. This is where the anaerobic reaction takes place, with billions of bacteria processing the calorific content of the feedstock and converting it into methane.

The methane is stored within the digestion tanks; from here it is piped into one of the three CHP generators and up to the Gas to grid plant. The electricity is exported through a private HV underground network to the Estates private renewables complex and 40MW 66kV transformer. Gas is piped to the local medium pressure network. Digested feedstock (digestate, or biofertiliser) is piped out of the digester into our on-site lagoon ready to spread onto the crops on the surrounding farmland.