The Potential For The Exploitation Of Geothermal — страница 6
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countries, producing 45 billion kilowatt-hours of electricity per year from geothermal energy.? The growth of geothermal utilisation for power generation has averaged 9% per year over the last 20 years, probably the highest growth rate for a single energy source over so long a period of time.As a result of geothermal production, consumption of exhaustible fossil fuels is offset, along with the release of greenhouse gases and acid rain that are caused by fossil fuel use.? Today?s geothermal energy utilisation worldwide is equivalent to the burning of 150 million barrels of oil per year.? In Europe alone, every year geothermal production displaces emissions to the atmosphere of 5 million tons of carbon dioxide, 46000 tons of sulphur dioxide, 18000 tons of nitrogen oxides and 25000 tons of particulate matter compared to the same production from a typical coal-fired plant (see IGA2 p3).The environmental and political factors suggesting future limitations to the availability of fossil fuels has promoted research into alternative and renewable resources of energy, particularly for electricity generation in the UK.? Aquifers are not able to provide the high entropy energy required for this purpose but interest has been stimulated in the expectation of high temperature heat from Hot Dry Rocks at depths of 6km or more in some areas of the UK. ???The occurrence of high heat flows in the radio-thermal Cornish granites led to a major research programme and much of this research is ahead of comparable work elsewhere in the world.? The prospects for a successful conclusion to this research and development are encouraging.? Economic analysis indicates that both electrical power generation and CHP systems could be deployed economically in the early part of the 21st Century to provide some 2-3% of the UK?s present energy demands for some 200 years, although CHP is seen at the present time as a less likely commercial proposition (see Laughton8 p72).? Economic analysis also suggests that district heating schemes fed from HDR well be economical in given circumstances at the present time and some areas warrant site-specific studies, particularly those where high heat loads are underlain by radio-thermal granites.? The application of low enthalpy geothermal resources to district heating from aquifers has proved commercially advantageous in many parts of the world and is expected to continue supplementing such energy demands well into the future.? In the UK, however, the geographical distribution of the aquifers and the difficulty of forecasting their yields at given sites, coupled with the abundant availability of low-cost fossil fuels and various institutional barriers, have inhibited development of such local energy supplements.? The commercially led applications at Southampton and Penryn may lead to a change in this situation.