In the past, the selection of all energy resource for electricity generation was dominated by finding the least expensive power generating plant. Although such all 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 oil cost performance and environmental load reduction. A filial 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.