This study suggests the effectiveness of an "extended" power system evaluation methodology based on LCA and energy input-output analysis techniques. This "extended" evaluation methodology is designed to incorporate total energy system costs through fuel cycle and external costs, including CO$_2$abatement cost. As an empirical test, we applied the methodology to orimulsion-fired power generation technology and found that orimulsion could be considered as in attractive base-load power generation fuel in terms of economic and environmental aspects, compared to conventional coal-fired power plant.