Abstract
Recently, biogas plants (BGPs) receiving cow manure as a main source have been constructed in dairy region, Hokkaido. A BGP plays a role in material cycle and economy within a region, such as mitigation of nitrogen groundwater pollution and GHG emissions and saving money for inorganic fertilizer and energy from outside, through proper management of manure, energy recovery from biogas and application of fermentation residue as fertilizer. This study analyzed effectiveness in material cycle and economy in two regions, which introduce BGP, as a case study, using statistical data including inter-industry relations table and a model which presents behavior of carbon and nitrogen in cultivated field. As a result, introduction of BGPs promoted fermentation residue utilization, raising the cyclic usage rate. Economic effect by BGP introduction was estimated to 3.6~6.8% in the agricultural production value.
