Hydroelectric power stations generate electricity by using the energy of flowing water. They typically consist of a dam that creates a reservoir, where water is stored. When water is released from the reservoir, it flows through turbines, causing them to spin. This spinning motion drives generators that convert mechanical energy into electrical energy. These power stations are a renewable energy source, as they rely on the natural water cycle. They produce little to no greenhouse gas emissions during operation, making them an environmentally friendly option for electricity generation. However, they can impact local ecosystems and communities when constructed.