Abstract A new system combining fossil fuel and renewable energy to produce methanol (environmentally benign) with a zero CO2 emission process was studied. The objectives of this paper are to propose a practical process for the new system, to prove the zero CO2 emission process for this new system using a system evaluation simulator, and to provide an economical evaluation. The system combining the electrolysis of water (producing both O2 and H2) using solar energy with the partial oxidation of coal and natural gas (Case 1) gives the best evaluation for CO2 reduction and for energy conversion efficiency to upgrade the fossil fuel energy using solar energy. An economical evaluation shows that the product (methanol) cost is nearly the same as that for the conventional (commercial) methanol production process (29.5 yen/kg methanol) when the CO2 recovery and disposal process is taken into account.