Water stored in dams falls freely with the force to make a turbine move. the turbine moves and produces electricity. this electric energy is supplied to homes. at home, we use electricity for heating, cooling, and lighting.

The water in a reservoir behind a dam is an example of potential energy. The stored energy in the reservoir is converted into kinetic  energy (motion) as the water flows down a large pipe and spins a turbine. Both use a power source to turn the propellers of a machine called a turbine. As the turbine spins, it turns a metal shaft connected an electric generator, which is basically a motor that produces electricity. In the case of a hydroelectric dam, it's flowing water that's used as the power source to turn the turbine.