未利用農産物からのバイオ燃料製造に関する可能性評価―山梨県中央市を対象にしたケーススタディ―

抄録

This study analyzes the energy balance of bio-ethanol production from agricultural residue biomass in Chuo City. A specially valued local product of this area, located in central southern Yamanashi Prefecture, is sweet corn. Sweet corn production can be useful for solving both food scarcity and energy-resource depletion problems. The second crop in idle fields, sorghum, is examined based on its climatic properties. Herein, we propose a simple format to produce ethanol from juice liquid sugars of both crops. Calculation of the energy balance is classified in terms of cultivation, collection, transport, and production. Results show that the potential ethanol production of Chuo City is 667 kiloliters. Bio-ethanol can be a renewable fuel for transportation that is sufficient to replace the use of gasoline in Chuo City's Office functions. Calculation results suggest that the energy balance is from 0.643 to 0.717. Reduction of fossil fuel consumption during production processes is important. In this study, five cases are investigated to calculate a unit price. The production unit price is 350 yen per liter in this city, which can be decreased to 208 yen per liter with increased plant operation days from 100 to 300 days annually. It would thereby be necessary to collect other agricultural residue biomass and to expand the collection area to achieve unit price reduction. Methane emissions from rice fields could be reduced by half by switching fuels to those produced from sweet corn residues. Results of these studies underscore the useful role of bio-ethanol production for communities of the future.