Geothermal Flash Steam Power Plants

Flash steam power plants force water down into an injection well by a groundwater pump. The well must be sunk deep enough to reach subterranean rocks at a temperature higher than the boiling point of water. The water filters through the rocks where it becomes heated and rises back up through the nearby production well. The hot water from the production well enters a flash tank where the reduced pressure causes the water to boil rapidly or "flash" into vapor.

flash power plant animation

Water that remains liquid in the flash tank is returned to the groundwater pump to be forced down into the earth again. The vapor from the flash tank drives a steam turbine, which turns the shaft of an electric generator. After passing through the turbine, the steam is cooled in a condenser. This returns the water vapor to the liquid state, and this liquid is forced by the groundwater pump back down into the earth along with the diverted water from the flash tank. Some of the condensed vapor can be used for drinking and irrigation because it is, in effect, distilled. The flash tank must be periodically flushed and cleaned to get rid of mineral buildup. If the water from the production well has high mineral content, the flushing must be done more freqently.