8.4.16
Describe the main energy transformations that take place in hydroelectric schemes.

Hydropower plants are actually quite simple. The core process involves converting the mechanical energy stored in falling water into electrical energy that is used to power our homes.

external image clip_image003.pngHere is a typical hydroelectric power plant:


  • Dam – The dam is an essential part of the plant, since it holds back the water, resulting in a reservoir.
  • Control Gate – This controls the flow of water into the plant, depending on whether it is opened or closed.
  • Intake – The intake is the mouth of the plant. This is where the water flows through.
  • Penstock – When the gate is opened, the water falls down into the penstock, a pressurized pipeline that leads water to the turbine.
  • Turbine – The turbine is typically a large disc with curved blades. When the water hits the blades, it causes them to turn. The turbine is attached to the generator by a shaft.
  • Generator – The turbine are connected to a series of magnets inside the generator. The turning blades of the turbine cause the magnets inside the generator to also turn. When these magnets turn past copper coils, electricity is produced.
  • Transformer – The transformer is a voltage booster. It takes the current flowing into it and increases its voltage.
  • Power Lines – The electrical energy that has been produced is now transmitted to our households for usage.
  • Outflow – The water that was used in the process flows back out into the river further downstream.

Main Energy Transformations:
1. When the water from the reservoir falls into the intake, the gravitational potential energy stored in the water is converted into kinetic energy.
2. When the pressurized water in the penstock pushes the blades of the turbine, the kinetic energy of the water is transferred onto the blades.
3. When the turning blades of the turbine turn the magnets inside the generator, the kinetic energy of the blades is transferred onto the magnets.
4. Inside the generator, the kinetic energy of the magnets is transformed into electrical energy, which is then distributed to the households.

Bibliography:

"HowStuffWorks "Hydropower Plant Parts"" Howstuffworks "Science Channel" 29 Mar. 2009 <http://science.howstuffworks.com/hydropower-plant1.htm>.

"Hydro power." ESRU Home Page. 29 Mar. 2009 <http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/Hydro%20Power.htm>.