"Cons Of Geothermal Energy"
Eric Wang Cosmos Cluster 2 8/1/08 Geothermal Energy: A Solution to the Energy Crisis Abstract So far, scientists have not found a successful substitute for fossil fuels that can handle both the large demand for energy and solve the global warming problem. I propose that geothermal energy is a clean, widely available, and renewable alternative to the usage of fossil fuels. In this paper, I will explain how use of geothermal resources can be energy-efficient, environmentally clean, and cost-effective. I believe that the US government should increase funding for geothermal energy research. This may be the solution to our present energy crisis and global warming. Introduction There is a call of action to solve today’s energy crisis. What we need urgently is a clean, abundant, and reliable source of energy. Geothermal energy may be the solution. Geothermal energy does not produce CO2 and is inexpensive compared to the unbelievably high gas prices. This type of energy is also renewable so it can continue to feed the growing population of the world. “New [geothermal] facilities can produce electricity for being between 4.5 and 7.3 cents per kilowatt-hour, making it competitive with new conventional fossil fuel-fired power plants.” (Union of Concerned Scientists, 2) This shows that if there is more research focused onto this topic, geothermal energy may become the solution to our energy crisis. Current Energy Consumption Currently, the energy consumption has been increasing exponentially. Energy consumption increases by 2% each year causing a doubling in only 35 years. As of 2003, the energy consumptions in quadrillion BTU (British Thermal Unit= 1055.06 Joules) are: North America- 118.3, Europe- 127.4, Asia- 120.2, Middle East- 19.6, Central/South America- 21.9, Total world- 420.7. (International Energy Association, 3) The ranking from most used to least is: oil, coal, gas, hydro, nuclear, and renewable. Fossil fuels (oil, coal, natural gas) take up about 80 % of total energy consumed. Fossil fuels cause pollution and global warming yet we continue to use them. Our demand for fossil fuels has become so great that according to current projections, Earth’s reserves will be depleted within the next 200 years. But we do not actually have 200 years to wait. Our run-away consumption of fossil fuel not only endangers our ability to meet our future energy needs but also the environment. Fossil fuels cause significant pollution and global warming. This in turn compromises wildlife habitats and can even lead to extinction of animal and plant species. By looking at new sources such as geothermal energy, we can move towards a source that is not extremely harmful and yet still effective. Geothermal Energy Geothermal energy is heat energy that is stored underneath Earth’s surface. It is mainly found at volcanoes, hot springs, or geysers. Heat stored in the hot water and steam found at these locations is captured and can be used to heat buildings or generate electricity. This energy source is renewable because heat from the earth is continuously produced. To obtain energy, you must either use hot water or steam from the source. The most common way of capturing the energy from geothermal sources is to tap into naturally occurring “hydrothermal convection” systems where cooler water seeps into Earth’s crust, is heated up, and then rises to the surface. (Union of Concerned Scientists, 6) The steam is then captured and used to power electric generators. There are three types of geothermal power plants: dry steam, flash steam, and binary cycle. In the first, steam is directly brought through the turbine. After the turbine has been powered, the steam is condensed back into water to be reused. For the second design, hot water is converted to steam by depressurization. The steam then follows the same steps as the first and powers the turbine. In the last design, the hot water is used to heat another liquid. This liquid will boil at a lower temperature than water so it will require less heat to convert it to steam. This steam is then used to power the turbine again. Different types of plants are built depending on the resource found at the site. The first design, for example, can be used for a steam producing area while the second and third can be used for hot springs. Pros and Cons of Geothermal Energy Geothermal energy is efficient and abundant. The Geysers in California, for example, produces energy that comes from steam and has a maximum capacity of 850 MW. Most fossil fuel plants produce about 1000 MW. While geothermal energy rivals fossil fuel in terms of power production, they produce no CO2 emissions. Geothermal energy is generated with indigenous resources and is found in most countries. “[Geothermal power plants] are also more reliable, as there are fewer parts to break down…. [and] are also more compact than most regular heating and cooling systems. The piping is buried underground or in some cases, looped through a pond or well.” (Solar4Scholars, 5) Also, unlike solar and wind energy, geothermal energy is not disrupted by weather or time of day. But geothermal energy sources also have its disadvantages. Geothermal energy requires large water sources in arid conditions and at steam plants, there is a higher seismic risk because the easiest places to access the hot rocks are near fault lines. (World Changing Team, 4) In some systems, this type of production of energy creates hazardous waste water that cannot be reused. This water may have hydrogen sulfide, arsenic, or other harmful particles, and therefore must be stored in dig sites. Also, geothermal energy is not available everywhere, and the energy source must be close by if used directly to generate electricity. Efficiency and Costs of Geothermal Energy Geothermal Energy offers high efficiency with low costs. “New [geothermal] facilities can produce electricity for being between 4.5 and 7.3 cents per kilowatt-hour, making it competitive with new conventional fossil fuel-fired power plants.” (Union of Concerned Scientists, 2) “The average retail price of electricity [from fossil fuels] for February 2008 was 8.96 cents per kilowatt-hour.” (Energy Information Association, 15) This shows that geothermal energy can be produced with lower cost than the more commonly used fossil fuels. Also, it has no resources are consumed except water that evaporates. Considering this, geothermal energy is one of the most efficient energy sources for its low cost. Research on Geothermal Energy Geothermal energy could be widely available in the next 50 years and additional research can make it more efficient and accessible. Los Alamos National Lab has, in the past, attempted to develop and demonstrate a technology to use the heat from a hot dry rock (HDR) to the surface for practical use. (David V. Duchane, 1) This project took place at Fenton Hill in New Mexico. In HDR, very hot rocks underneath the earth are used to heat pressurized water. The heat from the water is then converted into electricity, and the cooled water is returned underground to be reheated, so the system works as a closed loop. The only drawback in this cycle was that 7 % of the water used was lost. They also tested if the HDR could handle generating more power by creating faster loops and the test produced successful. These tests continued from 1978 to 1995 and showed that HDR testing was a reliable source of energy. “HDR technology has a number of unique characteristics that make it particularly suited to the developing energy needs of the world. These include operational flexibility that can provide energy as needed to rapidly meet peaking or unanticipated power demands and the potential for cogeneration of both energy and clean water.” (David V. Duchane, 24) Although there is no research currently being performed, geothermal has been tested as a viable energy source that can become a major source in the future. Massachusetts Institute of Technology has also done research on geothermal energy. “The goal of the study was to assess the feasibility, potential, environment impacts, and economic viability of using enhanced geothermal system technology to greatly increase the fraction of the US geothermal resource that could be recovered commercially.” (MIT, 3) They recommended that geothermal energy become the major electricity supplier for the US. Fossil fuels are becoming increasingly expensive and our supply is mainly from foreign sources. This may cause problems in our long-term energy supply. Also, geothermal energy has the potential to be able to supply the entire nation without CO2 emissions. Through testing, they discovered that geothermal power plants will not need any fuel and has no time limits like other non CO2 emitting power sources (solar and wind). MIT panel member Brian Anderson said that geothermal research must be more enthusiastically like the 1970-80’s before the oil surplus. Applications of Geothermal Energy Usage Over 2800 megawatts of electricity from geothermal power plants are supplying about 4 million people in the US and 8200 megawatts are supplying 21 counties. (Geothermal Education Office, 1-2) Iceland has many volcanoes, hot springs, and terrain suitable for many sites of geothermal energy. As a result, it has the largest percentage of energy that comes from geothermal energy in the world. About 25% of total energy and almost 85 % of heating in homes come from geothermal energy. There are five geothermal plants in Iceland. These plants work by having water saturated with dissolved oxygen boil and then absorb the heat. However, the water released becomes toxic and cannot be used. The waste geothermal water must be disposed of and cannot be filtered to become usable again. The geothermal plants in Iceland are highly effective although there is a downside. Because Iceland runs on mainly renewable energy such as geothermal and hydroelectric, they produce comparably little greenhouse gas. The Geysers in California is the largest geothermal plant in the world. This plant went into operation in 1921 but has not been used extensively. It uses steam to generate enough energy to power 725,000 homes. (The Geysers, 2) The steam acquired is found from holes more than two miles deep and is then used to power their turbines to generate electricity. The steam found in the holes are at 350o Fahrenheit. About two million pounds of steam per hour are used to operate a 110 megawatt-generating unit. (The Geysers, 4) However, this plant is not as efficient as some others because only 25% of the water is recycled back into steam reservoir and the rest is lost to evaporation. Summary After looking at the pros and cons of geothermal energy, I believe that this is an excellent alternate energy source in the future. It has all the desired properties of an energy source: sustainability, low cost, efficiency, cleanliness, and abundance. As fossil fuel reserves diminish and prices escalate, geothermal energy will become more appealing. With additional research and development, perhaps geothermal energy will surpass fossil fuels in terms of cost and accessibility. We already know that it is vastly superior in terms of sustainability and cleanliness. Hopefully in the future, we can convince lawmakers and leaders to reduce our dependence on fossil fuels and to invest more in geothermal energy. Works Cited About Geothermal Energy. 27 July 2008 <http://www.geysers.com/geothermal.htm>. Duchane, David V. 27 July 2008 <http://ieeexplore.ieee.org/iel3/4058/11981/00553344.pdf?tp=&isnumber=&arnumber =553344>. Energy Information Assosciation. Electric Power Monthly. 10 July 2008. 27 July 2008 <http://www.eia.doe.gov/cneaf/electricity/epm/epm_sum.html>. Energy Information Assosciation. Geothermal Energy. 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