Geothermal Power

        Most power plants need steam to generate electricity. So, the steam rotates a turbine that activates a generator which then produces electricity. Many of the power plants still use fossil fuels to boil water for steam. But, geothermal power plants use steam produced from reservoirs of hot water that are found a couple of miles or more below the Earth's surface. There are three types of geothermal power plants and they are dry steam, flash steam, and binary cycle.

      Dry steam power plants draw from underground resources of steam. The steam is piped directly from underground wells to the power plant. Where it is directed into a turbine/generator unit. There are only two known underground resources of steam in the United States. Those two known are The Geysers in northern California and Yellowstone National Park in Wyoming. 

     Flash steam power plants are the most common. They use geothermal lakes of water with temperatures greater than 360°F. This very hot water that flows up through wells in the ground under its own pressure. As it flows upward, the pressure goes down and some of the hot water boils into steam. The steam is then separated from the water and used to power a turbine/generator. Any leftover water and condensed steam are injected back into the big lake.

    Small geothermal power plants that are under 5 megawatts have the ability for widespread application in country areas even as energy resources. Energy resources refer too many of small modular power-generating technologies that can be put together to improve the operation of the electricity delivery system. In the United States most of the geothermal are located in the western states, Alaska, and Hawaii.

Sources

·       http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-geothermal-energy-works.html#.VGTFNfnF-So