Law for renewable energies, regulates the preferred feed-in of electricity produced by renewable energies into the network and guarantees the producers fixed feed-in payments. Into effect sind April 2000.
Renewable raw materials (corn, whole plant silage, gras, …) are harvested off the field (mowing, chopping, …), carted away, backfilled and compressed (= rolled) at the intended area near the biogas plant. Afterwards one or more foils (clinging foil + main foil) is spreaded above and weighted with silo bags, silo belts or something like that. An additional net makes it more difficult for birds and rodents to harm the foil. There the substrate is stored until it is feeded into the fermenter. This technique is used because the plant’s own enzymes as well as aerobic and optional anaerobic microorganisms (bacteria, yeasts, mould) are suppressed. The lactic bacteria transform the glucose into acid (mostly lactic acid) and the pH typically falls to 4,0-4,5. As a result further bacteria which are harmful for the fermenting process are prevented in their growth: coli-aerogene-group, listerias, clostridias, Thereby the substrate is more durable and longer rich on energy.