Green energy refers to energy that does not emit pollutants and can be directly used for production and life, including nuclear energy and "renewable energy". Renewable energy refers to energy from which raw materials can be regenerated, such as hydroelectric power, wind power, solar energy, biomass (biogas), geothermal energy (including ground and water sources), and ocean tide energy. Renewable energy has no possibility of energy exhaustion. Therefore, the development and utilization of renewable energy has been paid more and more attention by many countries, especially in countries with energy shortage.