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In the past, the selection of an energy resource for electricity generation was dominated by finding the least expensive power generating plant. Although such an approach is essential, there is growing concern about other aspects of power generation such as social, environmental and technological benefits and consequences of the energy source selection. The aims of this paper are first to introduce a life cycle assessment (LCA) scheme with the aid of the NETS (Numerical Eco-load Total Standardization) method that we have newly proposed. This method provides a numerical measure for evaluating the quantitative load of any industrial activity on the environment, and has been used to analyze the energy flow and the environmental loads of various power generation systems. A second goal is to develop a computer program to examine the applicability of technology options based on cost performance and environmental load reduction. A final goal of this work is to select the power system using life cycle assessment (LCA) and life cycle costing (LCC). As a result, environmental load and economical cost for various power generation systems are discussed from the LCA point of view for further ecological improvement.

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This paper describes the LCA environmental impacts resulting from fuel fired co-generation systems using our NETS (Numerical Eco-load Total Standard, [1]) scheme having GUI (Graphic User Interface). Following a brief introduction of the NETS evaluation method, firstly the total eco-load from commercial electricity power plants in Japan is numerically calculated in the NETS unit. We take here almost all factors into account including fuel mining, transportation and processing, plant manufacturing, assembling and its building construction, fuel consumption and maintenance during twenty durable years, plant dismantling and waste processing, thermal efficiency and delivery loss, etc. This evaluation greatly helps in the eco-load estimation of co-generation plants when electricity purchase is needed during the plant operation with a minimum eco-load. Next, co-generation systems are paid attention to their ecological effectiveness. Here, we select different fuel fired co-generation plants of natural gas, heavy oil, and coal. Environmental impacts resulting from the respective plants include fossil fuel depletion and natural resources depletion, global warming due to green house gases, ozone layer depletion due to CFC type gas emission, various water and air pollution, rain acidification due to NOx and SOx, waste processing, recycling etc. Each item can be successfully calculated from the inventory database accumulated by authors. Hourly energy demands of electricity and heat (steam, hot water and cold water) are set to a typical model for eight office buildings and two hotels. The NETS method is applied to the co-generation model, resulting in the best cost-operating scheme of co-generation plants with a minimum environmental impact.