Abstract
In this paper, we have developed a unit commitment model of Japanese electricity market from 2005 through 2007 and
checked its validity comparing electricity generation with actual data by each fuel type. Using this model, we estimated
marginal costs of electric supply by each of 9 electric companies and identified “sell or buy position” of each company on
hourly basis. Then we compared JEPX prices with marginal costs estimated above and examined the reasonableness of JEPX
prices. Finally, we simulated hypothetical market within which electric companies are economically rational players, and
estimated the potential of electricity trading among market players.
