Japan's Ministry of International Trade and Industry (MITI) is considering the gradual introduction of an obligation on electric power companies to meet a percentage of their annual electricity retail sales with renewable energy. The aim is to increase renewable energy's share of Japan's electricity portfolio to about 2%, up from today's level of 0.6%, thereby reducing CO2 emissions and making up for the delayed installation of new nuclear capacity. An advisory body to MITI, the New Energy Department of General Energy Research Society, has begun discussing the shape of such a Renewables Portfolio Standard (RPS) with the aim of introducing it within two to three years. Under the RPS, the government would issue green certificates corresponding to the amount of green energy sold by electric power companies. If an electric power company exceeds its obligatory minimum standard for purchase of renewables, it may sell its surplus green certificates to another utility company, which might not have ready access to a renewable energy resource.