Hydropower is taking advantage of flowing water, such as a river turning a water wheel to power a turbine or, in the case of ancient times, grind wheat into flour. Blocking the entire flow of water via a dam can effectively make electrical power so long as the water is consistently flowing, but this also creates environmental damages that impact wildlife both up and down stream. It is a cleaner way to produce energy compared to fossil fuels, as hydropower emits very little pollution. China is the largest producer and consumer of hydropower, followed by Brazil, United States, Canada and Russia.