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Anaerobic Digestion

How does Anaerobic Digestion work? Anaerobic digestion (AD) produces heat and electricity by burning the biogas produced from the digestion of organic materials such as manures, slurries, food waste and sewage sludge.

The nutrient-rich treated liquid (or digestate) from the process can be used as a fertiliser. AD can be carried out in a small scale system, for example located on a farm and operated by farmers, or serve businesses (or clusters of businesses) with large food waste arising. The composition of the biogas will depend on the specific waste materials used as feedstocks. Digestion of manure generally produces biogas that is 55-65% methane (i.e. natural gas).

Anaerobic digestion systems are best suited to businesses, such as livestock or food production enterprises, located away from population centres, producing organic waste products suitable for digestion, and with access to enough land to spread any digestate.

How you benefit

The majority of rural properties, due to their locations and often historic nature, will require bespoke renewable energy solutions.

Our specialists can appraise your property and provide advice on which technologies would be sensible for your circumstances and how they might work for you. We have been developing expertise in this field for many years, and as such we have developed a wealth of knowledge and contacts to enable us to provide accurate information and advice. Knight Frank deals with such a diverse range of properties that we have real hands on experience of how best to improve the environmental credentials, and the productivity, of any number of different buildings.



  • Can produce very large amounts of energy.
  • Digestate by-product can be used as fertiliser.
  • Power output not limited by variable conditions, such as wind and sunlight.


  • AD plants are expensive to build
  • They require a high degree of technical management to ensure consistent power output.
  • Can be unpopular with local households if smell is not carefully controlled.