Today's power system can accommodate thermal power, hydropower, wind power, solar power, nuclear power, biomass power, geothermal power, waste-generated power, etc. It converts natural energy sources (e.g. coal, oil, light, heat, water and wind) into electric energy in the power generation device. Then the electric energy is supplied to the user through the power transmission & transformation system and the power distribution system. With zero or close to zero carbon dioxide emission in the process, green power has lower impact on the environment compared with electricity produced by other means (e.g. thermal power generation). Green power is green electricity generated by renewable energy sources, including solar energy, wind energy, nuclear energy, hydro energy and biomass. Bioenergy power generation is a kind of renewable energy power generation, including power generation by direct combustion of agricultural & forestry wastes, power generation by gasification of agricultural & forestry wastes, power generation by waste incineration, power generation with landfill gas and power generation with biogas.