In What is Geothermal Energy?, we covered the science of how geothermal energy works. In Part I we looked at direct uses of geothermal energy. In Part II we reviewed how geothermal energy is converted into useable energy through geothermal heat pumps.
In this segment we look at the technologies that convert geothermal energy into electricity known as geothermal power plants. We also briefly look at the pros and cons of geothermal power plants.
Conversion technologies used today are:
- Dry steam power plants
- Flash steam power plants
- Binary cycle power plants
Dry steam power plant
Dry steam technology is also referred to as direct steam geothermal plant. Dry steam plant is the oldest kind of plant and, if possible, the most economical geothermal use of this type. It directly uses geothermal dry steam of 302 degrees Fahrenheit. The process for extracting the heat is direct and straightforward. A pipe system channels dry steam to the surface where it is routed to the turbine that produces electrical power.
This system does not need the boilers used by standard coal and natural gas plants. After passing through the steam turbine, the steam is re-injected into the Earth. To improve performance, the turbines are designed with materials of exceptional quality, such as hardened stainless steel. The direct steam cycle is representative of a geothermal plant at the Geysers, California which is also the world’s greatest pool of geothermal steam.