The goal of power plants is to produce electricity that is later dumped into the general supply network. That electricity is produced by an electrical generator driven by a turbine, in all cases. The differences between the several types of power plants come with the way in which that turbine is moved:
- In the hydroelectric power stations, it is the water flow of a river what moves the turbine.
- In an aerogenerator it is the wind what moves the turbine (which consists of a set of three big blades).
- In the rest of the cases it is water vapour at a very high pressure what moves the turbine. That water vapour is produced by heating water, and the heat can come from…
- igniting coal or other fossil fuels or biomass (in thermal power plants);
- breaking nuclei of uranium or plutonium (in nuclear power plants).
This way, the production of heat in a power plant goes through a series of stages in which a transfer and a transformation of energy take place. The following diagram summarizes what happens in a coal-fueled thermal power plant:
- Chemical energy in the coal -> Thermal energy in the water vapour -> Kinetic energy in the turbine -> Electric energy in the generator and to the supply network wires