Biogas is produced through the breakdown of organic materials. The origin of the substrates vary, from pig or cattle slurry, energy crops (e.g. grain, grass silage, canteen waste, vegetable oil, municipal solid waste (MSW) from households to organic solid waste from industry (e.g. slaughterhouse, food waste).
Waste products from industry produce biogas and therefore offer interesting opportunities for agriculture/farming. By using organic wastes or residues such as distillers pulp, grease or food wastes, the natural material cycles (carbon and nitrogen) is closed and provides a recirculation of the nutrients into agriculture.
All kinds of chopped biomass can be used for biogas production. Their main components are:
- Cellulose and Hemicelluloses
Materials with a high lignin content, for example any kind of wood, are not suitable for biogas production. The fundamental materials used in agricultural biogas plants are cattle and pig slurry.
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|Energy crop co-substrates like grass-silage, maize-silage or grain (wheat, triticale etc.) can increase biogas yield substantially (see gas yield below). Due to particularly high yields per hectare small amounts of chopped energy crops (grass-silage app. 20 mm, maize-silage 6-8 mm) can be added continuously by a solid feeding system.|
| ||Grass Silage||Maize Silage|
The biogas yield depends essentially on the composition of the used substrates. It is not substrate specific but depends largely on the ambient conditions in the digester (e.g. temperature, inhibitors etc). It is therefore possible that the same input materials/substrates could have different gas yields.
For specific gas yields please download the following table: Gas Yields Table.pdf (size 63.7 KB)