Power plants

Both pictures sourced from Google, Inc. (www.google.com)

The word Geothermal from the Greeks directly translates to geo meaning Earth and therme meaning Heat. In order for us to use this heat from the earth for power, we need to be able to convert it into usable power. This can be done by taking the hot water and running it through a heat exchanger to heat another fluid to the point of vaporization (usually a refrigerant). Next, the refrigerant is sent as a vapor into a turbine nozzle where it is expanded supersonically causing the turbine to spin at very high velocities around 10-20 thousand revolutions per minute (RPM). The turbine is connected to a generator and threw induction created usable electric power. This process continues by taking cold water to cool the warm refrigerant back to liquid in another heat exchanger and the whole process repeats. This is just a small scale power plant example and a very basic one. As you can imagine, this can be much more complicated on a larger scale. The largest group of power plants in the world is located at the Geysers in California. The amount of power produced with geothermal means as of 2007, is around 1 percent of the worlds power. The set backs mainly include location, environmental concerns, and the fact that these locations can cool over time the more we use them.