KRAFT Biogas Plant Description
	Location:	Germany
	Time of erection:	1994/1995
	Input:	Manure, other organic waste
	Fermenter:	2-stage-concrete tanks, 800m³ and 1.000m³
	Co-generator:	2 gas engines, 90 kW, 200 kW
	Specials:	Gas holder above 1. Fermenter
	Responsibility: conception, permission plannings, detailed and final plannings, supervision of erection, start-up (for TBW GmbH)
	Description
	Mr. Kraft has a large farm with about 800 cattle. Additionally, he has got extensive areas of field and a distillery. A lot of fat and the distillery residues are digested together with the manure from his animals in his biogas plant. There are several companies that deliver these fats to the biogas plant. Fats deliver much biogas with high methane concentrations. Therefore, all owners of biogas plants appreciate digesting fats within their plants. This is called cofermentation.
	Mr. Kraft's biogas plant has a digester with a volume of 800 m³. In the foundation there is a heating unit that keeps the temperature inside the digester at approximately 35° C. Around the digester there is another concrete ring. The space between digester and ring is used as a storage tank for digested manure, volume 1,000 m³. In this manner, the digester has perfect insulation. Only the parts of the digester above the outside ring had to be insulated. Beneath the roof of the digester there is a gas storage membrane.
	Directly nearby the digester there are two further tanks for manure storage. They also have gas storage possibilities beneath their roofs.
	There are two gas engines of different sizes and an overall electrical power output of 290 kW. The smaller engine is located in a standard 20-foot-container close to the digester. It produces the heat to warm up the digester's contents. The larger engine is located inside the distillery building and connected with the biogas plant via a biogas tube. It produces electricity and heat for the distillery. Similar to Mr. Schloetterer, Mr. Kraft sells his surplus electricity according to the Renewable Energy law ("Erneuerbare Energien Gesetz") and improves the economy of his biogas plant.
	In the near future Mr. Kraft plans to enlarge his biogas plant. In addition to fats he wants to digest kitchen wastes. By expanding in this manner he is going to earn money in two ways: first, for taking the kitchen wastes he will get a commission for each ton from his clients and second, through higher amounts of biogas production. Mr. Kraft plans to erect a second digester for this reason. When he has done this he will be the owner of one of the largest agricultural biogas plants in Germany.
	The engineering for Mr. Kraft's biogas plant was done by an expert engineering consulting company. Especially experience with digestion of fats (biogas production, minimum hydraulic retention time, mixing of fats and manure, etc.) was very much appreciated by Mr. Kraft. Together with the engineering consulting company Mr. Kraft developed his biogas plant and could save a large amount of money by doing much of the work himself.
	Description of a Cofermentation Biogas Plant [plant types] [project overview] [worldwide]

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