Life Cycle Inventory for 1 kWh of Electricity Distributed by 10 Electric Company in Japan

Abstract

Since most industrial products consume electricity during their life cycle, the results of inventory analyses are usually sensitive to the data of electricity. In Japan, electricity is supplied by 10 electric companies that have their own regions to supply electricity. Constitution of power stations differs with each electric company. Thus, resources consumption and emissions per kWh of electricity are different with each electric company. It is, therefore, necessary to develop the inventories for electricity grid mix of each electric company for LCA practitioners in Japan. In this work, life cycle inventories for electricity gird mix of 10 electric companies in Japan have been developed.
It was found that average CO₂ emissions related to 1 kWh of electricity distributed by electric companies were 0.45 kg-CO₂/kWh, whereas average SO₂ and NOx emissions were 0.51 g/kWh and 0.47 g/kWh, respectively. Relative contribution of fuel production and fuel transport to CO₂ emissions was 4-12 % of total emissions. On the other hand, relative contribution of fuel production and fuel transport to SO₂ and NOx emissions was around 50 %. Average values of CO, CH₄, NMHC and dust emissions were 1.3×10^-4 kg/kWh, 1.3×10^-3 kg/kWh, 3.3×10^-4 kg/kWh and 2.4×10^-5 kg/kWh, respectively. Heavy metal emissions into air were also investigated.