Dry steam geothermal plants are the most simplistic of all geothermal technologies as these plants take advantage of naturally occurring steam reservoirs and pump this steam directly into the turbine for the production of electricity. There is no water that is pumped in the process, however the steam condenses after passing through the turbine and is returned into the ground. Natural steam can be seen by the nearby proximity of geysers or hot springs, with the actual reservoirs trapped at depths between 3,500 – 13,000 feet.
The largest dry steam field in the world is The Geysers, an 850MW power plant located 72 miles north of San Francisco. The only other location in the U.S. capable of generating dry steam geothermal is at Yellowstone National Park (Old Faithful), which is protected and cannot be used for power generation.