How does a hydroelectric plant work?

Answer 1

Hydroelectric power, or hydroelectricity, is generated by the force of falling water. (Hydro comes from the Greek word for water.) It’s one of the cleanest sources of energy, and it’s also the most reliable and costs the least. Water is needed to run a hydroelectric power-generating unit. The water is held behind a dam, forming an artificial lake, or reservoir. The force of the water being released from the reservoir through the dam spins the blades of a giant turbine. The turbine is connected to the generator that makes electricity as it spins. After passing through the turbine, the water flows back into the river on the other side of the dam.

Electricity is produced by spinning electromagnets within a generator’s wire coil that creates a flow of electrons. To keep the electromagnets spinning, hydroelectric stations use falling water. Hydroelectric power plants convert the kinetic energy contained in falling water into electricity. The energy in flowing water is ultimately derived from the sun, and is therefore constantly being renewed. Energy contained in sunlight evaporates water from the oceans and deposits it on land in the form of rain. Differences in land elevation result in rainfall runoff, allowing some of the original solar energy to be captured as hydroelectric power. Most hydroelectric stations use either the natural drop of the river or build a dam across the river to raise the water level and provide the drop needed to create a driving force. Water at the higher level (the forebay,) goes through the intake into a pipe, called a penstock, which carries it down to the turbine. The turbine is a type of water wheel that converts the water's energy into mechanical power. The turbine is connected to a generator, and (4) when the turbine is set in motion it causes the generator to rotate, producing electricity. The falling water, having served its purpose, exits the generating station through the draft tube and the tailrace where it rejoins the river.

At Ontario Power Generation (OPG), hydroelectric generation is their lowest-cost power source, producing approximately 34 terawatt-hours in 2002. OPG operates 36 hydroelectric stations, as well as 29 small hydroelectric plants and 240 dams on 26 river systems. The smallest station has a generating capacity of just 1 megawatt; the largest more than 1,300 megawatts.