水电, or hydropower, is a renewable energy source that generates electricity by harnessing the energy of flowing or falling water. It typically involves the construction of dams on rivers, where water is stored in reservoirs. When released, the water flows through turbines, converting kinetic energy into electrical energy. This form of energy is considered environmentally friendly because it produces little to no greenhouse gas emissions during operation. Countries like 中国 and 巴西 have invested heavily in hydropower projects, making it a significant part of their energy mix. Hydropower can also help with flood control and irrigation.