Biogas is a combustible fuel which is produced through the anaerobic digestion process. Anaerobic means “in the absence of oxygen”. In the right set of circumstances, the organic fraction of liquid or solid biomass is converted into valuable fuel. Biogas consists of roughly 40% – 70% methane, with the rest being CO2 and trace amounts of H2O, H2S, H2 and NH3 produced by the microbiological process. The amount of methane in the biogas is largely a function of the organic input menu.
Liquid and solid manure, vegetable waste, grocery store waste, fats, oils, and greases (FOG), slaughterhouse waste, and selective energy crops, like corn, are ideally suited as inputs to a biogas plant. Biogas, when utilized in a combined heat and power (CHP) unit produces electrical energy for sale and heat energy for use locally. The heat produced by the CHP is used to heat the digestion process to improve biogas yield. Biogas can also be cleaned up for injection into the local natural gas grid or as a vehicle fuel.
The remaining byproduct of the digestion process is digestate which is a fermented organic material which may be used as high quality fertilizer. Biogas has a key role in supporting a diverse energy portfolio as a flexible, dispatchable fuel source.