Westewitz, Germany — The small village of Westewitz in Saxony is home to the Krawczyk family and their farm. It is where the head of the family, Volkmar, and his two sons, Thorsten and Sven, cultivate 700 hectares of land and keep 300 head of cattle. The Krawczyks first started to think about biogas several years ago as a way of putting the farm’s organic waste to efficient use.
After thinking long and hard about the best approach to adopt and after weighing up the finan- cial risks, the Krawczyks made their decision: they invited the environmental technology company U.T.S. (Umwelt-Technik-Süd GmbH) to set up a “showcase” biogas plant in Westewitz and at the end of 2004, the plant went into operation.
It consists of a preliminary tank for liquid manure and sewage, two fermenters each holding 1,350 m3 and a secondary fermentation tank (2,000 m3) which also functions as a gas storage unit. 60 m3 of liquid manure and 25 metric tons of solid waste are fed into the fermenters every day.
Under the German Renewable Energy Act (EEG), that means that the plant operators not only earn basic rate payment for their electricity, they also receive an additional bonus for using exclusively liquid manure and renewables. Since the end of 2005, the plant’s powerhouse has been occupied by two biogas combined heat and power modules supplied by mtu which were installed to replace original plant manufactured by a different company.
Each of the Type GC 350 B5 CHP modules is powered by a 12-cylinder gas engine and each produces 350 kilowatts of electrical power as well as 475 kilowatts of thermal energy. Both modules are monitored by the mtu Module Control (MMC), which incorporates vital plant control elements and serves the CHP plants’ auxiliary drives.