Evaluation of Technology of Generating Electricity with Woody Biomass—Estimate of Reduction in CO2 Emission

Publisher Summary Biomass, which is renewable and fixes atmospheric carbon dioxide (CO2), has attracted attention as an environmentally compatible energy resource that is effective in mitigating global warming. Its extensive use has been advocated by IPCC reports and at COP3. This chapter discusses the processes for converting woody biomass-to-energy and estimates the gross reduction in CO2 emissions (Rg), which was made possible by the use of these processes compared with coal or diesel fuel burning. The chapter assesses 4 processes: combustion for steam turbine power generation, gasification for gas turbine power generation, pyrolysis for diesel engine-driven power generation, and ethanol fermentation for diesel-engine-driven power generation. The net reduction in CO2 emissions (Rn) can be estimated by considering five CO2 release processes: biomass production, from field preparation to harvest, collection of biomass, biomass transportation to power generating plant, pretreatment of biomass for power generation, and conversion of biomass to fuel, which is only in the cases of pyrolysis and fermentation. The chapter considers two transport scenarios: the use of biomass generated in Japan and the use of biomass imported from abroad. The process that reduced CO2 emission most effectively in both the scenarios was gasification for power generation.