Abstract
This paper reports the actual operation data of Yagi Bio Ecology Center which is received manure, tofu residue and so on and these waster are digested by methane fermentation. Based on the results of operation of the Center, we evaluate the biogas plant as the energy supply plant in Japan. The performance of the co-generation system is that the electrical efficiency of gas engine generators is 28.1%, the heat recovery efficiency is 43.2%, and total efficiency is 71.3%, the heat utilization efficiency is 18.8% and the total utilization efficiency is 46.9%. 95.6% of the generated electricity is used in the biogas plant. If the quantity of tofu residue would increase more 5t/d, the ratio of supplying electricity to outside among the generated electricity in the plant will increase to 24.9%. Further if the digested liquid would be used as liquid fertilizer, the ratio of them will increase to 76.4%. We calculated excess electricity and heat based on the Center's actual data, that if the biogas plants are received 40% of manure, food processing waste and kitchen garbage which are produced in all Japan, these plants will supply electricity about 110,000kW to out side of plants. If these plants would use digested liquid as liquid fertilizer directly, these plants will supply about 300,000kW to out side of plants.
