Types of Geothermal Plants

Dry Steam

In dry steam power plants, the steam (and no water) shoots up the wells and is passed through a rock catcher and then directly into the turbine. Dry stream fields are rare.

Flash

Flash steam power plants use hot water reservoirs. In flash plants, as hot water is released from the pressure of the deep reservoir in a flash tank, some of it flashes to steam.

Binary

In a binary cycle power plant (binary means two different liquids), the heat from geothermal water is used to heat and vaporize a second liquid or “working fluid” in separate adjacent pipes through a heat transfer process.

The water from the well remains in a closed loop and never comes in direct contact with the surface, air or turbines. It is returned to the well unchanged and uncontaminated. Because of this, binary plants operate with little or no emissions of green house gases à Binary is considered the most environmentally friendly method. Most importantly, binary systems allow a working fluid with a much lower "flash" or vaporization point to be used to generate power from lower temperature and shallower sites.