Hydroelectric power is the energy derived from flowing water. This can be from rivers or man-made installations, where water flows from a high-level reservoir down through a tunnel and away from a dam.Turbines placed within the flow of water extract its kinetic energy and convert it to mechanical energy. This causes the turbines to rotate at high speed, driving a generator that converts the mechanical energy into electrical energy.The amount of hydroelectric power generated depends on the water flow and the vertical distance (known as ‘head’) the water falls through.
Types of hydroelectric schemes
There are 3 main types of hydroelectric schemes in use:
Storage schemes: In storage schemes, a dam impounds water in a reservoir that feeds the turbine and generator that are usually located within the dam itself.
Run-of-river schemes use the natural flow of a river, where a weir can enhance the continuity of the flow. Both storage and run-of-river schemes can be diversion schemes, where water is channeled from a river, lake or dammed reservoir to a remote powerhouse containing the turbine and generator.
Pumped storage incorporates two reservoirs. At times of low demand, generally at night, electricity is used to pump water from the lower to the upper basin. This water is then released to create power at a time when demand, and therefore price, is high. Although not considered a renewable energy (because of its reliance on electricity), pumped storage is very good for improving overall energy efficiency.