Water turbines are used in hydroelectric power plants to convert the kinetic energy in flowing water to the mechanical energy of a rotating shaft, which is then converted to electricity in a generator. In a hydro plant, water is directed through an intake into a large pipe called a penstock. At the end of the penstock is a turbine, which spins from the force of the moving water. A series of wicket gates surround the turbine and are used to control the flow of water through the turbine. By controlling the water flow the plant operator can choose when and how much force to apply to the turbine thus controlling unit power output.
Various types of water turbine designs are commonly used in hydropower plants: