As of November 2008, a new market, the CO2 free electricity market, started pilot trading within the Japan Electric Power Exchange (JEPX). The electricity in this market comes from renewable resources, nuclear or fossil thermal power with CDM credits. The demanders of the CO2 free electricity are supposed to be the power companies with high emission rates. In this paper, we analyzed the effects of the new market by using a multi-agent based model to simulate the markets. From our simulation results, we found that the demander, under strict CO2 emission regulations, tends to buy more electricity from the new CO2 free market even though the price of this market is higher than that of the normal power exchange market. Suppliers with hydro or nuclear power plants only sell their electricity to the CO2 free market, and suppliers with coal power plants also enter this market (with CDM credits). The media and peak demands in the normal market are met mainly by electricity from LNG power plants. We also compared the results from the multi-agent approach with those from the least-cost planning approach and found that the results of the two methods were similar. (C) 2010 Elsevier Ltd. All rights reserved.