Hydroelectric power plants capture the kinetic energy of flowing water from a river or reservoir and convert it into electrical energy. These power plants are generally located in hilly areas where a dam can be constructed to form a reservoir. Water from the reservoir flows through penstocks and turbines, using the force of gravity and water pressure to turn the turbine blades. This kinetic energy is then converted into electrical energy by an attached generator. The electricity is stepped up in voltage by transformers and distributed via power lines to customers. Hydroelectric power is a renewable source of energy and provides the additional benefits of flood control, water storage, and irrigation.