Anaerobic digestion (AD) can use a wide range of feedstocks – types of biomass – in its biogas-producing process.
These feedstocks can range from purpose-grown energy crops such as rapeseed, which can be turned into meal. Like all oily biomass, rapeseed delivers a high yield of biogas.
The yield of a feedstock is measured by cubic metres (m3) of biogas capable of being produced per tonne of feedstock.
Animal waste – or slurry – has a much lower yield, but it is often a cost-free feedstock in ample supply on farms. Slurry also has the advantage of being naturally high in the bacteria needed to make the AD process work.
Food waste and sewage can also be used, but these feedstocks are subject to tighter regulations around their handling.
One of the advantages of AD is that it can use a combination of feedtsocks and wastes at the same time, although the biogas yield will vary.
Dry matter and water content and can affect the yield of biogas from feedstocks considerably. The table below gives approximate yields possible for a selection of feedstocks.
|Feedstock||Biogas Yield (m3 per tonne)|
|Cattle & Pig Slurry||15-25|
|Food & Drink Waste||30-145|
|Fats||Up to 1200|
Page Last Updated: 15 December 2020