Rocking on with hot rocks geothermal energy
Box 2 | Electricity generation
Most electricity today is generated using heat. In a coal-fired power station, for example, coal is burnt to heat water, which turns to steam, which is used to spin turbines, which generates electricity. A geothermal power plant operates in a similar way to power plants that use uranium, coal, natural gas or oil. These systems all rely on the use of steam or another gas to turn the blades of a turbine (wind and hydro power also work by turning turbines). As the steam or other gas hits the blades of the turbine, it causes a central shaft on the turbine to rotate.
The shaft of the turbine is attached to a device for producing electricity called a generator; it consists of large magnets attached to the shaft inside a coil of copper wire. The rotating turbine turns the generator shaft and its attached magnets; as they rotate the magnets cause a flow of electrons – an electrical current – in the wire coil by a process known as electromagnetic induction. Electrical current can also be produced if, instead of moving the magnets in the coil, the coil is rotated inside large magnets.
The coil is connected at both ends to an electrical circuit; the electrical current flows from the generator coil through the electricity grid to light and heat our houses, work our appliances and run factories.
Boxes
1. Layers of the Earth
2. Electricity generation
3. Geothermal electricity generation systems
Related sites
Generating electricity: Using high temperature geothermal and other resources (Geothermal Education Office, USA)
How generators work (Wisconsin Valley Improvement Company, USA)
External sites are not endorsed by the Australian Academy of Science.
Posted September 2009