A biogas plant can basically be seen as an agricultural integrated system, which produces biogas by decomposing organic matter. The heart of this system is the so called digester or fermenter, where all important biological processes are taking place. This digester has to be continuously supplemented by a feeding system with a feedstock of organic matter like slurry, different types of manure, industrial organic waste or several other organic materials like renewable commodities.
Under certain conditions like a minimum retention time, ph value and temperature the substrate inside the digester has to be mixed and processed continuously. Then, microorganisms have the opportunity to decompose the organic matter or biomass, which results into the byproduct biogas, the source for the energy production. The biogas is after its production pumped into storage facilities and then pumped to the so called block type thermal-power-plant (BHKW), which is used as a combined heat and power plant for the production of heat and electricity. Otherwise biogas can also be upgraded to bio methane.
The generated electricity, heat or bio methane can then be injected into the public grid, which transfers the generated energy to specific end user.
On the other hand, the digestate, the decomposed end product of the biological process, can after the processing be sold or used as a fertilizer on farms and agricultural soil.