Introduction
Geothermal energy is a source of energy that has become very common as a sustainable energy source in numerous countries across the world. Geothermal energy owes its origin to volcanic activity that occurs in the earth’s core and mantle. Rain water or water form surface runoff may collect in underground reservoirs of water. The volcanic activity below such reservoirs heats the water. The water is normally trapped such that it cannot escape. This leads to build up of a lot of pressure causing it to become superheated. Eventually, the water rises to the surface through fault lines on the rocks.
Practical Applications of Geothermal Energy
Engineers have managed to determine ways of tapping this superheated water through wells. The water is then used to turn steam turbines that in turn help in generating electricity. Numerous countries have set up generating stations and power substations to connect the electricity from the geothermal energy to the national grid. This has helped to boost the national power supply hence leading to an efficient supply to the consumers. Geothermal energy is used to supply heating to industries and even homes. This helps to save on the use of other sources of energy such as coal that result in pollution. Geothermal energy is also crucial in supply of heat in areas that experience extreme cold temperatures.
Furthermore, the heat from geothermal energy can be used in greenhouses in supply of the heat necessary for boosting of plant growth under controlled conditions. Geothermal energy is a reliable source of energy especially due to the fact that its supply is constant and consistent. This means that the supply of geothermal energy is not dependent on weather conditions, as is common in hydrogenated power. This makes geothermal energy a reliable source of power due to the use of steam as a prime mover. Geothermal energy has become especially useful since it has reduced the overreliance on oil that has existed for the past few decades. This has helped to reduce the cost of fuel around the world. This was at a time that fossil fuels were overpriced and their reservoirs were almost depleted.
The aquifers containing the superheated water may, in some instances, fail to shoot hot water to the surface. However, engineers have developed technologies to access these aquifers especially where tectonic activity has failed to create channels for the hot water. This is famously known as engineered geothermal systems. Geothermal powered plants comprise of heat exchangers that help to tap the heat from geothermal energy. This plays a crucial role in ensuring the whole process is renewable. After being used to turn steam turbines, the hot water or superheated steam is re-injected back to the underground reservoirs. This means that a clear separation has to be made between the working fluid that turns the turbine and the geothermal fluid that flows from the hot water reservoir.
Geothermal energy is also used in ground source heat pumps. These are shallow geothermal systems that are used in the provision of heating and cooling to domestic and industrial users. A heat exchange system facilitates the heating of the working fluid flowing in pipes and the hot water stored in rocks underneath. The hot water in the pipes is then used to heat building, especially during the winter season. During the hot season, the heat transfer occurs in the opposite direction. This means that heat is transferred to the underground water since temperatures are very high such that the buildings require cooling. This leads to a continual balance of temperatures at home and work all year round.
Ground source heat pumps may either be closed loop or open loop systems. Closed loop ground heat pumps are similar to refrigerators in functionality. This is especially because there are no fluid losses throughout the system. Closed loop systems may use vertical loops or horizontal loops. However, horizontal loops are preferred due to the fact that they are cheaper and their installation is easier as compared to vertical loops. However, engineers have managed to come up with a combination of the two loops in the form of skinny loops. Open loop systems do not use the concept of heat exchange, but instead extract ground or underground water for purposes of heating. There is no reinjection of water and hence no recirculation of water.
How Abundant are Geothermal Sources
For geothermal sources to exist there must be sufficient volcanic activity underneath the earth’s surface to help promote the heating of underground water. However, this is a natural process that cannot be manipulated according to man’s convenience. This is mainly the reason why geothermal sources can only exist where underground hot water reservoirs naturally exist due to radioactivity of volcanic activity acting on aquifers. However, most of the globe that has superheated underground water, or at least a small percentage of it, has been discovered and is being harnessed for geothermal energy.
Geologists have access to new technologies that have led to discovery of newer geothermal wells and possible underground reservoirs of superheated water. Areas that are prone to tectonic and volcanic activity are generally believed to harbor such reservoirs. The reservoirs are formed after infiltration and percolation of rain and surface water into underground rock though permeable rocks. Areas with a lot of activity in the core and mantle result in heating of this water beyond its normal boiling point. The water continues to remain in the liquid state due to the high pressure that exists underground. This is why such water is referred to as superheated water. Vents of steam or cracks on the rock structures may cause such water to find its way to the surface hence leading to the availability of geothermal energy for man to harness.
All continents, except Antarctica, show considerable geothermal activity. Technologists and engineers have now accessed these geothermal sources to ensure they are well utilized. Some areas have a lot of geothermal activity, but have little flow of water into the ground. Engineers have injected water into such areas and have managed to successfully acquire superheated water in a renewable cycle for various uses. Geothermal sources are mostly located in remote areas that have rather hot climates. However, there may be many other sources that are yet to b e determined and tapped for geothermal energy.
Geothermal energy has come to revolutionize the energy sector of the world. This is especially due the reliability that comes with the use of geothermal energy as a source of energy. This has made some countries to opt to use this form of energy as its base source of energy since it operates every day of the week regardless of weather and other extraneous factors. This has helped the world to move from its dependence on coal, oil, natural gas and other non-renewable sources of energy that had become quite a headache. Geothermal energy is also a flexible source of energy such that production can be varied depended on the required output. This is especially crucial when it comes to supporting other renewable sources of energy such as solar and wind energy that are also being taken up slowly.
The implementation of geothermal projects and their application in the economies of developed and developing countries has spurred increased economic growth. This is especially in remote or rural area where geothermal plants are normally located. This has also created a lot of employment opportunities at a time when most of the population is elite and technical professionals are readily available. Due to the fact that geothermal plants do not engage combustion, the pollution levels associated with geothermal energy are much lower than if fossil fuels were to be used to turn turbines or to provide heating. Geothermal power production projects are also cheaper, in the long run, than hydrogenated power due to their long life and reduced costs due to renewal of energy.
Environmental Hazards of Geothermal Energy
One of the most common hazards created by geothermal energy is the production of excess heat into the environment (McKinney and Schoch, 2012). The discharge of this heat into the environment creates a scenario referred to as thermal pollution, which results to the killing of plants and animals. Thus, the natural ecosystem is interrupted. Further, during the production of geothermal energy, certain emissions are also discharged. These gas emissions into the environment depend on the characteristics of the steam that normally accompanies the geothermal energy production. According to Tabak (2009), as production of steam comes from the circulation of water in the plant, the movement of the water in the plant results to it absorbing various materials some of which are hazardous to the environment.
The emission of steam containing compounds such as carbon dioxide and hydrogen sulfide makes the emission of steam to be hazardous to the environment (Tabak, 2009). Leakage of hydrocarbons from the geothermal plants is also another environmental hazard. According to Miller (2010), hydrocarbons released are denser than air. Therefore, vast quantities released into the atmosphere will cause the gases to sink and accumulate near the surface of the earth. This becomes dangerous in the arid regions where fire disasters can easily develop.
The construction of a geothermal power plant and the operation involved in the plant for power production generates significant levels of noise. This noise emanates from processes such as drilling, discharge of fluids and maintenance operations (Gupta and Roy, 2007). Additionally, because of the high heat generation, the geothermal power plants require plenty of water for cooling (McKinney and Schoch, 2012). This becomes a challenge since water is a scarce resource. Surface water levels may reduce because of over-abstraction. The high water requirement may generate additional problems if the water for cooling is being abstracted from the ground. For instance, in New Zealand, the Wairakei geothermal project resulted to the extraction of high amounts of water from the ground (Tabak, 2009). Failure to recharge the ground water table artificially resulted to ground subsidence in certain areas, in the same field. Geothermal energy development also destroys the natural geothermal features such as geysers and hot springs (Tabak, 2009). For instance, the Wairakei area in New Zealand had geysers that were depleted due to the geothermal development. Even recharging the underground water level was not sufficient in restoring these geysers.
The hot underground water released from the geothermal plant and discharged into the rivers may contain a high level of minerals and dissolved salts. According to McKinney and Schoch (2012), some of the most common pollutants are heavy metals such as mercury and arsenic. The release of these pollutants in the aquifers and other aquatic bodies leads to the death of aquatic life and makes river or lake water unsafe for irrigation and drinking.
Certain geothermal projects have the potential of causing the formation of earthquakes (Rastogi, 2010). The use of enhanced geothermal systems has contributed in developing small earthquakes. This is because these systems exploit hot and dry rock formations using high-pressure water that is used to develop fractures in the rocks. The high pressure is responsible for the fracture development, which tends to create micro earthquakes.
Conclusion
Geothermal power development requires careful monitoring. Its use is being encouraged since is it does not result to high environmental degradation compared to other sources of energy such as coal. Efficient monitoring systems need to be used at the geothermal plants to control the emission levels from the geothermal plant. Further, development of new technologies to use in geothermal power development, for instance, the enhanced geothermal systems will result to the increase in power production.
References
Gupta, H. K., & Roy, S. (2007). Geothermal energy an alternative resource for the 21st century.
Amsterdam, the Netherlands: Elsevier.
McKinney, M. L., & Schoch, R. M. (2012). Environmental science: systems and solutions (5th
Ed.). Boston: Jones and Barlett Publishers.
Miller, O. (2010). Geothermal Energy: Modern Uses and Environmental Issues. Retrieved from
http://www.indiana.edu/~sierra/papers/2010/miller.pdf
Rastogi, N. (2010, October 26). The pros and cons of geothermal energy. - Slate Magazine. Politics, Business, Technology, and the Arts - Slate Magazine. Retrieved May 13,
2013, from http://www.slate.com/articles/health_and_science/the_green_lantern/2010/10/could_yellowstone_power_my_home.html
Tabak, J. (2009). Solar and geothermal energy. New York: Facts on File.
