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plant might not be overwhelmingly better than other modern day methods of electricity, the lack of pollution makes up for the loss in efficiency. Even though The Geysers power plant is relatively efficient, it does not even come close to taking advantage of all the emitted heat. Only 2% of the emitted heat from the source is used to heat water for electricity production. This geothermal resource will not last for ever though. Heat Content of the Entire Geysers Geothermal Site -The Geysers geothermal site covers approximately . -Heat is only recovered from the top 2km of the earth at The Geysers site. -The average temperature in this top 2km of earth is 240 . -The average air temp at The Geysers site is 15 . -The specific heat of the permeable rock that makes up most of geothermal region is . Volume x Specific Heat x Change in Temperature = Heat Content Vol = x = SpHt= = 240 – 18 = 222 Q =( x )( )( )(222 ) Q= Joules of Heat Content in the entire Geysers geothermal region Life of The Geysers Heat Source -Power output of The Geysers plant =2000MW -Fraction of the total heat used in the production of steam = 2% -Power taken from the geothermal resource = 2,000MW/2% = 100,000 MW -Heat content of the entire Geysers geothermal region = Joules -Seconds in one year = -1 Watt = 1 Joule/sec 100000MW = J/year J/ J/year = 24.67years. According to my calculations The Geysers geothermal resource will be depleted in 24.67 years at the current rate of usage. Of course this is not taking into account the rate at which the resource is renewed from heat coming from deeper in the earth. I am assuming that the rate of depletion is so much greater than the rate of renewal that it is not significant in the calculation. The power plant at The Geysers site is run on dry superheated gases. The power plant now has 11 generators and has a rating of over 2000 MWe. The process of electrical power generation used at The Geysers power plant is relatively simple when compared to other modern day power plants. The steam that evolves from the wells flows through pipes that lead to the turbine. The pressure exerted by the superheated steam turns the turbine which produces electricity. The steam then flows into the direct-contact condensers below the turbine. Cooling water from the cooling towers is constantly circulated through the condensers. The condensed steam and cooling water is then pumped back into the cooling towers. Because the evaporation rate from the towers is slower than the rate at which water is pumped into the towers, excess amounts of water accumulate in the cooling tower. This excess water is then pumped to reinjection wells where it flows down through the soil and porous rock and is reheated by the heat source. The cycle begins all over again. See the diagram below. The costs of running this particular geothermal electrical plant are very competitive with the cost of other types of modern day plants. The operation costs for the plant at The Geysers is almost same the as the operation costs of an average fossil fuel powered plant and much less than the operating costs of a hydroelectric or nuclear plant. One of the greatest advantages of this and most geothermal systems is the relative lack of pollution. While most coal plants give off significant amounts of sulfur, somewhere around 93 tons per day for the average coal plant, geothermal plants produce no gas pollution other than the gases that would be naturally emitted from the geysers anyway. Coal plants are by far the worst polluters but other types of plants are not far behind. Average Cost of Geothermal Produced Energy per Kilowatt in the U.S. Total electricity produced in the U.S. during 1985 = 652000MW Percent of Geothermal energy contributed to total U.S. production 3% 3% x 652000MW = 19560MW Methods of geothermal energy production Capital Dollars per Kilowatt Dry Steam Flash 83% $1000/kW Binary 17% $3600kW Dry Steam Flash = 83% x 19560MW x 1000kW/MW x $1000/kW = Binary = 17% x 19560MW x 1000kW/MW x $3600/kW = Total = + total = per 19560MW /1956MW x 1MW/1000kW = $1431.5 per kW The future of geothermal energy looks very promising. There have been many technological breakthroughs that have resulted in increased efficiencies of modern day geothermal electrical plants. I feel that with the current environmental situation that the world now faces a viable method of clean up will include the use of geothermal power plants and resources. In a world that is suffocating from the chemicals, and particulates that are created in the production of electricity and other commercial industries, we have no choice but to change our ways. The earth can not support the current rates of pollution. If we do not change reduce pollution the effects that are beginning to be see now will become irreversible. Using geothermal resources for other purposes such as space heating can only help reduce pollution emission. With in the next century the world will begin to feel the energy crunch. Supplies of other natural resources such as coal, oil and other petroleum products will begin to become scarce. The world today is completely electricity dependent. Without electricity, the world as we know it would cease to exist. In the next century we must learn to be less electricity dependent or find other sources of energy.