Geothermal Energy - Research Paper Example

Geothermal Energy Introduction The heat from the Earth is called geothermal energy. The advantages are many as it is renewable and does not spoil the environment. It is renewable because the heat emanating from the earths interiors is virtually limitless. There are many countries worldwide including U.S that produce geothermal energy in a considerable amount. This paper will focus on the origin of the geothermal energy, scientific principles on which it is based and how it is being harnessed safeguarding our environment. The paper will also look into the cost of production of geothermal energy and other cost economics when compared with the energy produced from fossil fuels. Formation of a Geothermal Reservoir The heat from the earths core keeps on flowing outward. That heats up the water underground and usually it is trapped in permeable and porous rocks beneath impermeable rock forming a geothermal Reservoir. The reservoir appears on the surface as hot springs. Thus, geothermal reservoir is nothing but a natural collection of hot water beneath the surface of the earth. Suitability of Geothermal Energy Heat in a geothermal reservoir can be in the solid rock as well as in the fluids that fill the spaces within the rock. Geothermal resource estimations are done on the basis of geophysical and geological data such as depth of aquifers, salinity and geochemistry of fluids in the aquifers, properties of rock formations such as temperature, permeability and its porosity. The detailed reservoir datasets will decide about the true reserves that can be extracted economically. The important factor in estimating reserves is the cost of drilling. Radioactive decay of isotopes such as uranium, thorium, and plutonium generates heat within the earth. The temperature gradient found between the Earths surface and a few kilometers deep is only in the order of 100 degree C and power plants at such small temperature gradient will have very low efficiency. Due to new technological advances in binary-cycle geothermal plant, it has been possible to harness such moderate temperature gradients at low depths for the generation of power. Drilling technology has also improved over the years and it is possible to go deeper more than 5 km so as to reach higher temperature gradient of 200-300 degree C. Further, rocks need to have enough pore space and fissures for the fluids to permeate and circulate. As depth increases, the weight of the rocks closes the pores and fissures thus reducing the permeability to a large extent. Due to unsuitable geological conditions it becomes difficult to extract geothermal energy at many places. Sometimes, under some geological conditions heat may be transferred by magma or molten rocks through convection as found at Hawaii Island. The magma has temperatures of 1000 degree C and due to suitable geological conditions, the heat manifests in form of hot springs, and geysers. The advantage in such areas is that it needs to drill only a few hundred meters to get the temperature in the range of 200-300 degree C and the region is found to be most potential area for harnessing the geo thermal energy. (Gupta 2010, p 49-50) Why is Geothermal Energy a Renewable Source? According to the Pacific Northwest Electric Power Planning and Conservation Act of 1980 and the National Energy Policy Act of 1992, geothermal energy is a renewable resource. The reason being rainwater continue to feed the underground aquifers. The Earths heat is an inexhaustible and continuous source of energy. At the Earths core, temperature is said to be 5000 degree centigrade. Heat radiates from the core to the surface heating water trapped underground. (Geothermal Basics – Environment, 2010) Geothermal Technologies Program in U.S Geothermal Technologies Program (GTP) comes under the Department of Energy of U.S government. The objective of the program is to develop innovative geothermal technologies to harness the United States geothermal resources so that nation is provided with clean, renewable energy source. GTP is assisted by academia, industry and DOEs national laboratories in its efforts to establish geothermal energy as a major contributor in nations economy. Currently, it is a $1.5 billion industry providing heat for various uses and generating electricity. GTPs five major thrust areas are Hydrothermal Power, Enhanced Geothermal Systems Technology, System Analysis, Low-Temperature Resources and Technology Validation. (Geothermal Technology Program 2011) Geothermal Energy in the Past The Romans used to make the good use of geothermal water to treat skin diseases. Even Native Americans used the energy for cooking purposes. Since 1960, France has been using geothermal energy to heat 200,000 homes. A way back in 1904, the Italy was the first country to make use of geothermal energy to produce electricity and since then the worldwide capacity of geothermal electricity plants has reached to 7,000 megawatts. The U.S alone produces 2700 megawatts of electricity using geothermal energy. (Geothermal Energy Facts 2000) Harnessing Geothermal Energy Today Geothermal reservoirs are identified with the help of geologists, and engineers. Drilling operations are done to bring those geothermal waters up above the ground and used either to generate electricity or for the heating purposes. Hot water or steam from geothermal reservoirs is used to rotate the turbines to produce the electricity. The used or condensed water then is injected back to the reservoir for reheating and maintaining the sustainability of the reservoir. (Geothermal Energy Facts 2000) Binary Power Plant It has been possible now to produce electricity from geothermal resource with temperature of 150 degree C or lower by using the technology called binary geothermal plants. This makes possible already low emission rate to near zero. Organic Rankine Cycle System is in the root of Binary Plants. The geothermal water is used to heat another liquid, usually isobutane or some other organic fluid that boils at a lower temperature. The liquids are separated through heat exchangers so as to transfer the heat from geothermal fluid to the liquid. The liquid converts into gaseous vapor and its force runs the turbine. The important aspect is that all geothermal water is sent back into the reservoir. A typical schematic of the system can be presented as per the following. Source: www.geo-energy.org Advantages of Using Geothermal Energy Geothermal Energy does not pollute our environment and therefore it is a good replacement to fossil fuels which spoil our environment enormously. The energy is absolutely clean and renewable in the sense that it can provide an uninterrupted supply of energy all through 24 hours and 365 days in a year. It does not generate any emissions and that is why the energy is as clean as wind and solar energy. Lake County California is known to have five geothermal electrical power plants operating for last two decades and has successfully met with most stringent government air quality norms in the U.S. It requires small land area per unit of megawatt when compared with any other type of power plant. The plants are free of some usual nuisance factors such as oil spills, waste heaps, spoiling of rivers, open pits, landfill, or harvesting of forests. They work on modular designs so easy to install, expand and create new capacities as and when needed for growing need of electricity. They are free from any fuel price fluctuations as found in case of fossil fuels. (Geothermal Power Plants - USA 2011) Currently, the U.S is a leading producer of geothermal energy in the world with installed capacity of almost 3,100 MW. Currently, nine U.S states produce geothermal energy as per the following graphic. California is a largest producer of geothermal energy in U.S. April 2011 Geothermal Power Capacity Online Source: http://www.geo-energy.org/plants.aspx In 2007, Geothermal energy contributed almost 4.5 percent of total electricity needs of the State of California. Geothermal Plants in Comparison to Fossil Fuel-Fired Plants Geothermal plants emit only steam from the plant side. Emissions such as particulate matter, sulfur dioxide, nitrous oxide, carbon dioxide are quite low particularly when compared with fossil fuel emission. Lake County California plants have met all environment norms for last 25 years. In all there are 21 operating plants at The Geysers and quality of air is found to be excellent. (Geothermal Basics – Environment, 2010) Puna Geothermal Plant at Hawaii Island The Puna Geothermal Plant located at Hawaii Island generates power tapping Kilaueas volcanic heat. It is the only commercial plant in Hawaii producing 30 MW of electricity. The plant is located in the area of 30 acres along the East Rift Zone of the Kilauea Volcano. Kilauea Volcano has been spewing lava since last three decades. Magma usually remains below earths crust that heat up rain and sea water and nearby rock. Due to pressure some of the hot water reaches Earths surface in the form of hot springs. Geothermal Exploration in Hawaii started in the 60s. The operations began with 3 megawatt power plant in July 1981; however production ceased in 1989 for it failed to meet regulatory standards. In the 1990s, Puna Geothermal Venture again received permission to produce geothermal energy in the East Rift Zone at Puna. Since then it is producing almost 30 megawatts of electricity which is sold to Hawaii Electric Light Company. Hawaii Island is situated above the most active volcanic region and has capacity to produce much more geothermal energy; however, its potentials are not fully tapped. The Puna plant wishes to double the capacity in near future. (Puna Geothermal Venture… 2010) Ormat Technologies took over Puna Geothermal Venture in 2004. The facility was then modified to produce 30 megawatts of electricity which is now further getting enhanced. The Geothermal energy at Puna currently saves fossil fuel to the tune of almost 144,000 barrels of oil per year. More than 30,000 Island residents are served geothermal energy. Geothermal in this region has potential to cater to the 100 percent needs of the people; it has been estimated that Punas geothermal resource can produce 200 MW of electricity. Source: http://www.punageothermalventure.com/PGV/17/power-generation Noise and H2S Concentration in Puna Plant Noise levels are found to be in the region of 52-54 decibels and H2S Concentration has been found less than one micrograms per cubic meter which is very much within the norms. New Projects under Geothermal Technology Program Several new projects have been undertaken in the field of geothermal energy. The details for some of the project are as per the following. Cald-Well Ranch Exploration and Confirmation Project The project is located at Caldwell Ranch Area for hydrothermal and Resource confirmation. Geysers Power Company, LLC is in charge of this project. The project has commenced on August 2010 and likely to end on August 2012. It is spread in the area of 870 acres. The project may generate 22-45 MW of power. If drilling results confirm the presence of a viable resource, further eight additional wells will be drilled for further exploration. The total funding outlay is estimated at $12,130,647. (Geothermal Technology Program 2011) Intra-Basin Geothermal Exploration Project The project is to locate geothermal resources in Gabbs Valley, NV by integrating several established rock technologies from mining, and geotechnical. The project aims at reducing exploration risks. The project outlay is estimated at $5696835, which started in October 2011 and likely to end March, 2013. (Geothermal Technology Program 2011) Hurdles in Tapping the Geothermal Energy Bronicki (2009) describes exploration of the resource as the crucial aspect on the tapping of geothermal energy. It is crucial and complex in the same way as found during oil and gas exploration. It is time consuming too. Heat, water and the rocks are the three elements that are needed in tapping geothermal energy. Permeability or fractures in rocks is crucial for the water to flow inside and outside. Exploration activity takes nearly three years after getting site permission. On technical aspects availability of drilling rigs is crucial. There is a real dearth of good geologists as younger generation does not prefer to go in this field. There are only few institutions such as MIT and University of Nevada which run the program on geology and hydrology. For geothermal to grow, it is needed that more students go in this field so that manpower needs can be met with. Geothermal plants have now good working efficiencies but it is a capital intensive industry and major challenge comes in the form of exploration techniques that needs to be improved so as to reduce the time taken on exploration. Bronicki (2009) argues that better exploration accuracy can reduce the cost by one third. He also talks about the engineered geothermal as per the study done in M.I.T. He states that hot dry rock is much more in the world than the areas that have both hot rocks and water. In hot rocks, it is required to drill at least two wells so that cold water is pumped from one side that comes out from the other well gaining heat that is sufficient to generate the power. According to him, the estimate for power generation through EGS is 100,000 MW which cannot be overlooked. Geothermal Costs Comparison with Other Renewable Sources Geothermal is low on operating costs but high on capacity costs and that is why it offers most attractive propositions among all renewable source of energies. Taking into account the tax incentives, geothermal levelized cost of energy (LOCE) is found to be between $0.042 and $0.069 per kWh depending upon the use of technology. California Energy Commission calculated geothermal LCOE in the range of $0.04 to $0.09 per kWh. Geothermal costs are found to be lesser than solar, nuclear and certain biomass technologies. (Geothermal Technologies 2008) Without taking into account tax concessions, the costs for various technologies are tabulated as per the following. Costs are in $/kWh of power produced. Technology Without Tax Concessions Binary Geothermal $0.049 to $0.1021 Dual flash steam Geothermal $0.0563 to $0.0979 Dry steam Geothermal $0.0781 Solar PV - Crystalline $0.339-$0.405 Fuel cell $0.151-$0.161 Solar PV-Thin Film $0.244-$0.318 Solar Thermal $0.220-$0.349 Biomass Direct $0.075-$0.150 Wind $0.089-$0.15 Source: http://www.nrel.gov/analysis/pdfs/46022.pdf p.28-29, Table-6, Figure-21 Impact of Current Financial crisis on Geothermal Projects The current financial crisis has impacted the new installations of geothermal projects too. Even companies like GE Financial Services find difficult to provide funds for new projects. Those who are on initial stages of implementation such as exploration or drilling stages will have much bigger impact for they are likely to be starved of the funds. Due to fewer number of financing companies that are active in the markets, new geothermal plants will have limited options to finance their projects until the world and U.S in particular is out of the recession and financial crisis. (Geothermal Technologies 2008) Worldwide Geothermal Uses Direct-use of geothermal energy is quite common in other countries. Turkey and Iceland make a good use of geothermal energy for their heating requirements. Almost 89 percent needs of the heating and cooling in Iceland is satisfied by geothermal. Japan has installed more than 2,000 hot spring resorts and 5,000 public bath houses using geothermal. More than 15,000 hotels in Japan use natural hot springs for their customers. Switzerland too makes tremendous use of geothermal energy including heating homes and melting roadway snow and ice. (Geothermal Technologies 2008) Worldwide Geothermal Capacity Worldwide Installed capacity of geothermal energy (up to 2007) can be seen in the following table. Country Name Installed Capacity (MW) USA 2,687 Philippines 1,970 Indonesia 992 Mexico 953 Italy 811 Japan 535 New Zealand 472 Iceland 421 El Salvador 204 Source: http://www.nrel.gov/analysis/pdfs/46022.pdf p.36 Cost of Development The cost of development of geothermal energy depends upon several factors such as geology, geography, reservoir size, plant type and geothermal temperature. Breakdown of the total cost in $/kW installed has been published by New Energy Finance in 2008 and the same can be seen in the following table. The construction constitutes major cost in the installation of the plant followed by drilling costs. Type of Cost Cost ($/kW ) Plant & Construction 1,700 Production Drilling 1,367 Steam Gathering 250 Exploratory Drilling 169 Transmission 100 Permit 50 Exploration 14 Total 3,650 Source: http://www.nrel.gov/analysis/pdfs/46022.pdf p,23 Geothermal power plant is capital-intensive project but the advantage lies in very low operating costs. The kind of plant or technology that is employed also has an impact on the cost. Binary power plants are used for low-temperature reservoirs while reservoirs with moderate-to high temperatures use either dry steam or flash steam plants depending upon the availability of water or steam from the wells. Thus, current market scenario prevents any geothermal project to have liberal finances either from venture capital equity partners or availability of easy credits from any lenders. Prominent Steps in Development of Geothermal Power and Risk Profile Development uncertainty is one of marking feature of this technology. Considerable up-front capital requirements coupled with longer project lead times forces developer to have some risk-related mark-up over other traditional and renewable energy options and at times that goes against this geothermal source of energy. Any geothermal power project passes through the stages of exploration, resource identification, drilling, the development of reservoir, plant construction, and then power production. Each of these steps constitutes a level of risk. The major risk is associated with initial development such as drilling work, which may not give desired results even if geological data are positive. Moreover, risk increases as per the depth of drilling desired or necessary. Once the project comes at the production stage, overall risk goes down and then financers are more readily available to finance the project on easy terms. (Geothermal Technologies 2008, p 24-25) Geothermal Energy and Tax Incentives United States geothermal energy industry passed through a tumultuous phase during 2008. US energy policy makers have given all around importance to the renewable energy development. The Obama Government has earmarked over $42 billion for energy programs and $21 billion in tax incentives for renewable source of energy. The recovery Act has tax provisions that provide support to the geothermal energy developers. The Renewable Energy PTCs for geothermal projects are now applicable until January 1, 2013. The revisions now provide necessary flexibility to geothermal developers as current economic scenario has eliminated tax equity financing to them. (Geothermal Technologies 2008 p.39) Conclusion It is an established fact that geothermal energy has a promising future due to its environmentally friendly nature and being a renewable type. The cost economics tilt hugely in favor of this renewable source of energy and recent advances in drilling and exploration technology will make it more lucrative in coming years. Global warming and ecological disturbances throughout the world necessitates the use of natural and clean energy resource replacing the fossil fuel based energy as much as possible. Reference 1. Gupta H.; Roy, S. (2007); Geothermal energy: an alternative resource for the 21st century, Elseviers Science & Technology, Oxford, UK. 2. Geothermal Energy Facts (2000), online from November 24 2011, http://geothermal.marin.org/pwrheat.html 3. Geothermal Power Plants - USA (2011), http://www.geo-energy.org/plants.aspx 4. Geothermal Basics – Environment (2010) , online from November 24 2011, http://www.geo-energy.org/geo_basics_environment.aspx 5. Puna Geothermal Venture (2009), online from November 24 2011, http://www.punageothermalventure.com/PGV/17/power-generation 6. Geothermal Technologies (2008), online from November 24 2011, http://www.nrel.gov/analysis/pdfs/46022.pdf 7. Bronicki (2009), Beyond Fossil Fuels: Lucien Bronicki on Geothermal Energy, online from November 24 2011, http://www.scientificamerican.com/article.cfm?id=energy-bronicki-ormat-technologies Read More