Then, the results indicate that the effectiveness of power generation in ASEAN and OECD countries as well as development of alternative energy play an important role to reduce CO2 emission, especially in Thailand and Vietnam for ASEAN countries and United States, Italy and Germany for OECD countries. Therefore, the government should be implemented in earnest policy on the production of electricity from alternative energy, creating awareness on energy conservation and improving the efficiency of electricity generation, which are the policies that can reduce the CO2 emission from power generation sector.