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Notes: Japan imports almost all of the energy resources with 40% of them used for electricity generation. Electricity is generated mainly by five types of power plants (LNG-fired, LNG-CC, oil-fired, coal-fired, and nuclear), which have various environmental impacts, for example, fossil fuel depletion, global warming, acid rain, etc. The purpose of this paper is to make a life cycle assessment (LCA) of the electricity generating processes of power plants in Japan and to suggest some concrete measures to reduce the environmental impacts.Our study proceeds as follows. We focus on the fuel procuring process reflecting Japan's import of fuel resources and then the whole electricity generating process of the different types of power plants. Firstly, we quantify the environmental loads resulting from each type of plant by Life Cycle Inventory (LCI) analysis. Secondly, Life Cycle Impact Assessment (LCIA) method is applied to evaluate the total impacts of each type of plant. Thirdly, we make some concluding remarks on reduction of the environmental impacts. LCI analysis and LCIA evaluation are done with use of the 'LCA-NETS' scheme we have developed. Our LCIA evaluation shows that in the fuel procuring process nuclear plants rank top, coal-fired plants second, oil-fired plants third, and LNG-fired plants bottom in the ascending (better) order of the `NETS/MJ' values, and that in the whole electricity generating process LNG-CC plants rank top, LNG-fired and coal-fired plants second, oil-fired plants third and nuclear plants last in the ascending (better) order of the `NETS/kWh' values.Our findings about the fuel procuring process imply that if LNG-fired plants can find an effective usage of their byproduct of cold energy or import natural gas without liquefaction directly from nearby countries, they will rank up next to nuclear plants and that if any legal regulations of desulfurization are imposed on sea transportation the impacts of crude oil and coal will be reduced a great deal.It follows from the total evaluation of the whole electricity generating process that if coal-fired plants can reduce the total impacts by 20% by introducing a technology of coal gasification they will be superior to LNG-CC plants and that if nuclear plants can adopt a technology of recycling uranium to reduce the total impacts by 50% they will be as good as LNG-CC plants.