AD is a treatment for organic and naturally biodegradable materials, including:
- Waste from food processing and supermarkets.
- Household and business food waste collection.
- Farmyard manure and crops.
These materials are blended to form a feedstock and fed into a large, sealed tank (a digester). The tank doesn’t contain oxygen, but is instead filled with naturally occurring micro-organisms and bacteria. This mixture is heated and gently stirred for several days enabling the bacteria to break down the feedstock. During this process, the material emits a gas known as biogas which is extracted and sent to a storage dome. From here, the gas is sent to generate renewable gas and electric energy.
AD outputs include:
Biogas is cleaned and pressurised before being exported into the national gas network. This network supplies the local neighbourhood, meaning that houses and businesses near the plant are able to receive green energy gas.
Biogas is directed to an engine used to generate electricity. The electricity is exported to the National Grid. The engine also emits heat which can be captured and put to use so that nothing is wasted.
Once the gas has been extracted from the process, a liquid material remains. This is known as digestate and it is rich in nutrients. It can be used as a direct replacement for artificial or manufactured fertilisers. It is taken directly from the site and spread on fields to enhance sustainable crop production.