Explained simply!
What is biogas and how does a biogas plant work?
Biogasis a renewable energy source produced through the anaerobic digestion of organic matter. In abiogas plant, microorganisms break down biomass such as slurry, energy crops or organic waste in the absence of oxygen, producing a methane-rich gas that is used to generate electricity and heat. Biogastechnik Süd, based in Isny, specialises in the key components of these plants: from feed-in technology through mixing and separation technology to the evaporation of digestate.
This process requires the activity of many different microorganisms. Firstly, an airtight fermentation vessel, known as a fermenter, is required. The fermenter is fed with biomass, such as slurry, manure, biowaste or energy crops such as silphium. The mass remains there for several days (in the absence of oxygen) and is continuously stirred by an agitator (e.g.a Varibull paddle agitator). In addition, depending on the substrate and contents, the fermenter is heated to approximately 40 – 55 °C. The bacteria thrive at this temperature; they consume the mass, carry out their work and break down the materials. They constantly ‘fart out’, so to speak, a gas: methane (CH₄). This continuously produces an energy-rich gas mixture: biogas.
This gas is collected in the gas bag, a sealed membrane stretched over the digester. As the gas expands, the dome on top of the digester bulges out. The biogas is channelled via a pipe into a combined heat and power (CHP) plant. There, the gas can be converted into electricity, heat, gas or fuel, as required.
The gas is burnt in an internal combustion engine. The engine drives a generator, which then produces electricity. Part of the electricity is used again by the biogas plant, whilst the rest can be used directly in the house or fed into the grid. The residual or waste heat generated during engine operation can be used for domestic heating, for service buildings and for heating the fermenter. In addition, the waste heat from the CHP unit can be used for Vapogant digestion residue evaporation. The remaining heat can be fed into a local or district heating network, thereby generating additional revenue for the operation.
The fermented biomass is sent to the digestate storage facility. The digestate can be used as a natural fertiliser in agriculture – a truly valuable by-product.
There is also the option of processing the digestate using ourVapogant digestate evaporator. In this process, the digestate from the biogas plant is treated to produce a usable, concentrated fertiliser with a reduced water content. The output from the digestate evaporation process consists of concentrate, ammonium sulphate solution (ASL) and distillate.
The aim is to helptacklethe global challenge of ‘clean energy supply’ by developing sustainable processes for biogas plants and closed-loop systems. Biogas creates renewable energy sources and reduces climate-damaging greenhouse gases.
Biogas Trade Association
The Fachverband Biogas e. V. brings together operators, manufacturers and designers of biogas plants from across Germany, as well as representatives from the worlds of science and research and other interested parties. Through intensive political advocacy at federal and state level, it campaigns for the increased use of biogas technology.
Agency for
Renewable Energy e.V.
The Agency for Renewable Energies e. V. (AEE) works to build support for the energy transition. We highlight the opportunities and benefits of a sustainable energy supply and promote greater acceptance of it within society.
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