液肥利用を含むバイオガスプラントと液状コンポストプラントの効率性比較

──LCAを用いた温室効果ガス排出及び処理費用の推計──

抄録

　　After the Tohoku Earthquake of 2011, converting biomass resources to electrical energy has becomea major focus in Japan.　The government encourages local governments to use biogas plants to recycleorganic waste.　This study evaluated the biogas and liquid compost plants managed by local governmentsusing life cycle assessment （LCA）, and includes a comparative analysis of greenhouse gas （GHG） emissionswith respect to the economic cost of each plant.　For the LCA, the amount of GHG emissions wascalculated by dividing the whole process implemented by these plants into three stages : carrying andtransporting organic waste, plant operations, and transporting and spraying liquid fertilizer.　The resultsshowed that the plant operations stage accounted for the highest proportion of GHG emissions.　Furthermore,transporting and spraying liquid fertilizer had the lowest percentage of GHG emissions for bothplant types.　In terms of the carbon content of raw materials, the GHG emissions from the biogas plantwere approximately 38% those of the liquid compost plant.　In addition, the economic cost of the biogasplant was superior to the liquid compost plant.

JEL Classifications:Q53, Q54, Q42