6.3.1 CO2 Emission of biomass

On energy evaluation of biomass in the preceding paragraph, light oil, natural gas and electricity are consumed for planting stage; electricity for crushing stage; heavy oil for drying stage. And light oil, gasoline (light oil equivalency), electricity are consumed for coal mining. Evaluating CO2 emission to consume energy such as light oil, heavy oil, gasoline and natural gas, it is necessary to consider CO2 emission from combustion and production processes of
them. The power resources composition should be considered to evaluate CO2 emission of electricity consumption. It was assumed that CO2 emission according to production process of these energy was equal to those of Japan, and the emission factors were obtained from LCA results (Table 6.3.1) (Tahara 1997, Tahara 1998).

CO2 emissions of biomass and coal are obtained by multiplying CO2 emission factor, to energy consumption about biomass production (Fig. 6.2.1). The CO2 emission of biomass production is 0.0130 kg-CO2/MJ-biomass. The CO2 emissions of open-pit and underground coal mining are 0.00053 kg-CO2/MJ — coal, 0.00039 kg-CO2/MJ — coal respectively and both of them become 0.091 kg-CO2/MJ-coal with consideration burning(combustion) stage. It was assumed that the forest would absorb the CO2 emission (CO2 @) from biomass combustion as shown in Fig. 6.2.2.