Environmental and economic evaluations of centralized biogas plants running on cow manure in Hokkaido, Japan

Abstract

The introduction of biogas plants (BGPs) is a promising measure to reduce greenhouse gas (GHG) emissions in Hokkaido, Japan. This study estimated the price of renewable electricity and cost of GHG emissions reduction by introducing centralized BGPs in 139 municipalities in Hokkaido. The locations of centralized BGPs were analyzed by using a Geographical Information System (GIS), and the initial and annual costs, amount of power generated, and GHG emissions reduction were calculated. The estimated initial and annual costs were 8162 and 1089 M$ (1 USD = 80 JPY), respectively, for 330 centralized BGPs. These BGPs were estimated to generate between 150 and 390 GWh of surplus power, and between 490 and 730 GWh of total generated power. The surplus power was equal to the energy needed to power approximately 34,000 to 86,000 households (around 1.3%–3.3% of total Hokkaido households in 2007). The GHG emissions reduction was estimated to range from 1.07 to 1.2 Mt of carbon dioxide (CO2) equivalent per year (about 1.5%–1.7% of total GHG emissions in Hokkaido). A reduction of 1 tonne of CO2 equivalent costs at least 245 $ when considering revenue from selling tradable green certificates for surplus power. The price of renewable electricity must be at least 1900 $ MW h−1 for centralized BGPs to be feasible in more than half the municipalities. The current purchase price of renewable electricity is too low to operate centralized BGPs in Hokkaido.