Electricity or fuel from renewable energies is not always available exactly when it is needed. Wind turbines only produce electricity when the wind blows and solar plants only when the sun shines.

A biogas plant generates energy by fermenting plant material, manure or residuals. The best part is that this biomass is available all over the world and is always being created! But how does it actually work?

It requires the work of many different microorganisms. The first thing needed is an airtight fermentation container called a digester. The digester is fed with the biomass, such as liquid manure, dung, biowaste or energy plants such as silphia. The mass remains there for several days (without oxygen) and is constantly stirred with an agitator (e.g. paddle
agitator Varibull
. In addition, the fermenter is heated to approx. 40 – 55 °C, depending on the substrate and contents. The bacteria feel very comfortable at this heat, eat the mass, do their work and decompose the substances. They constantly “fart out” a gas: methane (CH4). This continuously produces an energy-rich gas mixture: biogas.




This gas is collected in the gas bag, a tight film, stretched over the digester. The spread of the gas causes the hood on the digester to bulge. With the help of a pipeline, the eco-gas (biogas) reaches a combined heat and power plant (CHP). There, the gas can be converted into electricity, heat, gas or fuel as desired.







In an internal combustion engine, the gas is burned. The engine drives a generator, which then produces electrical power. Part of the electricity is used again for the biogas plant and the other part can be used directly in the house or fed into the grid. The residual or waste heat that is generated when the engine is running can be used as thermal heat in the home, for operational buildings, and for heating the digester. In addition, the waste heat from the CHP unit can be used for the digestate evaporation Vapogant. The rest of the heat can be fed into a local or district heating network, thus generating additional income for the operation.






The fermented biomass goes into the digestate storage. The digestate can be used as a natural fertilizer in agriculture – a truly valuable by-product.



It is also possible to refine the digestate using our digestate evaporation Vapogant. In this process, digestate from the biogas plant is processed to such an extent that a usable, concentrated fertilizer with reduced water content is produced. The output from digestate evaporation is concentrate, ammonium sulfate solution (ASL) and distillate.

The aim is to contribute to solving the global problem of “clean energy supply” by developing sustainable processes for biogas plants and closed cycles. Biogas creates renewable energy sources and reduces climate-damaging greenhouse gases.


The German Biogas Association (Fachverband Biogas e. V.) brings together operators, manufacturers and planners of biogas plants, representatives from science and research institutions and stakeholders in Germany. It advocates the use of biogas technology through intensive political lobbying at the federal and federal state level.



The Renewable Energies Agency (Agentur für Erneuerbare Energien e. V. – AEE) works to convince people of the benefits of the energy transition. We present the opportunities and advantages of a sustainable energy supply and promote greater acceptance within society.


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