A hydro-electric power station. Image credit MediaWiki

ZIMSEC O Level Geography Notes: Natural Resources: Energy:Hydro-electric power

  • At a hydro-electric power plant, water leaves the lake or reservoir at high pressure (speed) and goes through pen stocks (concrete or steel pipes) to the turbines in a power house underground.
  • The force of the water is determined by the head of the water which is the depth of the water from the surface of the lake to the entry into the pen stocks.

The internal structure of a hydro-electric power station. Image credit populationeducation.org

  • The larger the depth, the more the pressure and the more the electricity generated.
  • As the high speed water hits the cups of the turbines, the turbines will start spinning and rotating.
  • These in turn, turn the generators to which they are attached to with pistons.
  • As the generators turn, they in turn produce electricity in the process.
  • The water passes from turbines to surge chambers which suck the water from the power house to discharge it back to the river through tailrace pipes.
  • The electricity from the generators meanwhile is transmitted to a huge stepdown transformer at the switchyard and switching station.
  • The step down transformer is regulatory mechanism to reduce the power entering the high-tension cables, otherwise these will burn and melt from so much energy being produced.
  • From the switch yard, pylons carrying high tension cables are erected to transmit the electricity to consumers.
  • Along the transmission line, step-up transformers are installed here and there to govern the amount of power needed by consumers.

To access more topics go to the O Level Geography Notes page