Energy Crops Biogas Plant
The cultivated renewable raw materials are ensiled in a substrate storage and there stored until they are used in the plant. The most commonly used are corn silage, grass silage, manure, slurry and other renewable resources. All organic substances are introduced through the substrate entry. This mixing tank is connected with screw conveyors to the fermenter. These screws then dose very precisely the desired amount into the system.
The substrate stays for several days in the lying hydrolysis step. To avoid sinking or floating layers, the substrate must be constantly stirred. The first two process steps occur in this hydrolysis step at about 40 ° C.
Subsequently, the digested material enters the developed by Archea ThermDes® process. In this treatment, the substrate which has been previously digested in the hydrolysis stage is heated up to 70°C for about an hour. This not only kills the pathogens and parasites, but also the anaerobic biological communities from the hydrolysis, which makes the anaerobic degradation faster and does not affect the following steps.
By separating the first two stages of the process of biogas production from the actual formation of methane, up to 15% higher gas yields are obtained.
The 70 ° C heated substrate, is fed after the ThermDes® to a methane stage. In this stage, the substrate is totally digested through thermophilic methanogens and converted into biogas. This stage is operated between 50 ° and 55 ° C. In these temperature ranges, the conversion rate and the bacterial duplication time is significantly higher than for mesophilic bacteria. In between 20 and 35 days, the substrate will be almost completely degraded.
The product formed in the two-stage system biogas is stored in a gas storage after the methane step. It is desulphurised and cleaned with the addition of a defined air supply
This clean biogas is now driven into the cogeneration system (CHP) which works with pilot injection or gas engines. In this CHP, the extracted gas is converted into electrical and thermal energy.
These two forms of energy can then be, according to the Renewable Energies Act (EEG), fed into the grid. The thermal energy could be used as useful or district heat, or also sold to third parties
The biogas manure is then stored in a fermentation residue storage, and in autumn as a high quality fertilizer spread on the field. Due to the fermentation process in the biogas plant, the manure develops several advantages. The manure contains significantly less odor-forming substances, and significantly better flow characteristics.