Geothermal Energy
As we stray away from fossil fuels and lean toward the use of natural energy production, in an effort to go green, geothermal energy has become a viable industry and is continually growing.
The most common current 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. When heated water is forced to the surface, steam is captured and used to drive electric generators. Geothermal power plants drill their own holes into the rock to more effectively capture the steam.
There are three designs for geothermal power plants. Each design pulls hot water and steam from the ground, uses it, and then returns it as warm water to prolong the life of the heat source. In the simplest design, the steam goes directly through the turbine, then into a condenser where the steam is condensed into water. In a second method, very hot water is depressurized into steam, which can then be used to drive the turbine. The third is called a binary system; the hot water is passed through a heat exchanger, where it heats a second liquid, such as isobutene, in a closed loop. The isobutene boils at a lower temperature than water, so it is more easily converted into steam to run the turbine.
Heat is continually produced under the Earth’s surface. Molten rock is found there and the heat produced within 10,000 meters of Earth's surface contains 50,000 times more energy than all the oil and natural gas resources in the world. Unfortunately, it is difficult to access the energy so far below the earth’s surface. So, we use “hot spots,” which are volcanic areas where the earth’s crust is thin enough to allow heat to pass through. Geothermal has been developed mainly in regions of continental plate boundaries. The western part of the United States is full of “hot spots.” The largest geothermal system in operation right now is a steam plant in California, north of San Francisco.
The most common current 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. When heated water is forced to the surface, steam is captured and used to drive electric generators. Geothermal power plants drill their own holes into the rock to more effectively capture the steam.
There are three designs for geothermal power plants. Each design pulls hot water and steam from the ground, uses it, and then returns it as warm water to prolong the life of the heat source. In the simplest design, the steam goes directly through the turbine, then into a condenser where the steam is condensed into water. In a second method, very hot water is depressurized into steam, which can then be used to drive the turbine. The third is called a binary system; the hot water is passed through a heat exchanger, where it heats a second liquid, such as isobutene, in a closed loop. The isobutene boils at a lower temperature than water, so it is more easily converted into steam to run the turbine.
Heat is continually produced under the Earth’s surface. Molten rock is found there and the heat produced within 10,000 meters of Earth's surface contains 50,000 times more energy than all the oil and natural gas resources in the world. Unfortunately, it is difficult to access the energy so far below the earth’s surface. So, we use “hot spots,” which are volcanic areas where the earth’s crust is thin enough to allow heat to pass through. Geothermal has been developed mainly in regions of continental plate boundaries. The western part of the United States is full of “hot spots.” The largest geothermal system in operation right now is a steam plant in California, north of San Francisco.
Geothermal Heating and Cooling
A much more conventional way to tap geothermal energy is by using geothermal heat pumps to provide heat and cooling to buildings. Also called ground-source heat pumps, they take advantage of the constant year-round temperature of about 50 degrees Fahrenheit that is just a few feet below the ground’s surface. Either air or antifreeze liquid is pumped through pipes that are buried underground, and re-circulated into the building. In the summer, the liquid moves heat from the building into the ground. In the winter, it does the opposite, providing pre-warmed air and water to the heating system of the building. In the simplest use of ground-source heating and cooling, a tube runs from the outside air, under the ground, and into a house's ventilation system.
In regions with temperature extremes, such as the northern United States in the winter and the southern United States in the summer, ground-source heat pumps are the most energy-efficient and environmentally clean heating and cooling system available. Geothermal systems can move three to five times the energy they use in the process compared to electric heating and cooling systems. Residential geothermal systems can save a typical home hundreds of dollars in energy costs each year. The system typically pays for itself in 8 to 12 years. Geothermal energy has the potential to play a significant role in moving the world toward a cleaner, more sustainable energy system. It is one of the few renewable energy technologies that can supply continuous, baseload power. Baseload is the energy used for day-to-day operations, not including energy used in response to outdoor weather conditions. For example, the energy used for all the electronics, appliances, hot water, etc. in a household, not including the energy used for HVAC.
The costs for electricity from geothermal facilities are declining. A considerable portion of potential geothermal resources will be able to produce electricity for as little as 8 cents per kilowatt-hour, a cost level competitive with new conventional fossil fuel-fired power plants. There is also a bright future for the direct use of geothermal resources as a heating source for homes and businesses in any location. However, in order to tap into the full potential of geothermal energy, two emerging technologies require further development. These emerging technologies are Enhanced Geothermal Systems and coproduction of geothermal electricity in oil and gas wells.
Enhanced Geothermal Systems are a type of geothermal power system that would make it possible to harness geothermal energy almost anywhere on earth. A well is drilled several miles into the earth's crust. Water is then injected to fracture the rock, creating thousands of pathways for the water to flow through and be heated. The hot water and steam are piped to the surface to power turbines. The water is then recycled back into the crust in a continuous loop. Enhanced Geothermal Systems provide an endless supply of renewable, clean energy.
Hot water produced from oil and gas wells can be used to generate geothermal power under certain temperature and flow conditions. This is called coproduction. It is simply using what heat is already produced as a byproduct and using it to harness even more energy. It is a very practical approach to energy production.
The Earth is constantly producing energy. It is sensible for us to take advantage of this clean energy source.
The costs for electricity from geothermal facilities are declining. A considerable portion of potential geothermal resources will be able to produce electricity for as little as 8 cents per kilowatt-hour, a cost level competitive with new conventional fossil fuel-fired power plants. There is also a bright future for the direct use of geothermal resources as a heating source for homes and businesses in any location. However, in order to tap into the full potential of geothermal energy, two emerging technologies require further development. These emerging technologies are Enhanced Geothermal Systems and coproduction of geothermal electricity in oil and gas wells.
Enhanced Geothermal Systems are a type of geothermal power system that would make it possible to harness geothermal energy almost anywhere on earth. A well is drilled several miles into the earth's crust. Water is then injected to fracture the rock, creating thousands of pathways for the water to flow through and be heated. The hot water and steam are piped to the surface to power turbines. The water is then recycled back into the crust in a continuous loop. Enhanced Geothermal Systems provide an endless supply of renewable, clean energy.
Hot water produced from oil and gas wells can be used to generate geothermal power under certain temperature and flow conditions. This is called coproduction. It is simply using what heat is already produced as a byproduct and using it to harness even more energy. It is a very practical approach to energy production.
The Earth is constantly producing energy. It is sensible for us to take advantage of this clean energy source.
“Clean Energy: How Geothermal Energy Works.” Union of Concerned Scientists. Union of Concerned Scientists, 16 Dec. 2009. Web. 20 Nov. 2011.
<http://www.ucsusa.org/clean_energy/technology_and_impacts/energy_technologies/how-geothermal-energy-works.html.>
Egg, Jay, and Brian C. Howard. Geothermal HVAC: Green Heating and Cooling. New York, New York: McGraw-Hill, 2011. Print.
“Geothermal Technologies Program: A History of Geothermal Energy in the United States.” EERE: EERE Server Maintenance. U.S. Department of Energy. Web.
20 Nov. 2011. < http://www1.eere.energy.gov/geothermal/history.html>.
Ozenger, Leyla, Arif Hepbasli, and Ibrahim Dincer. “A Key Review of Performance Improvement Aspects of Geothermal District Heating Systems and
Applications.” Renewable and Sustainable Energy Reviews. 11.8 (2007): 1675-697. Print.
<http://www.ucsusa.org/clean_energy/technology_and_impacts/energy_technologies/how-geothermal-energy-works.html.>
Egg, Jay, and Brian C. Howard. Geothermal HVAC: Green Heating and Cooling. New York, New York: McGraw-Hill, 2011. Print.
“Geothermal Technologies Program: A History of Geothermal Energy in the United States.” EERE: EERE Server Maintenance. U.S. Department of Energy. Web.
20 Nov. 2011. < http://www1.eere.energy.gov/geothermal/history.html>.
Ozenger, Leyla, Arif Hepbasli, and Ibrahim Dincer. “A Key Review of Performance Improvement Aspects of Geothermal District Heating Systems and
Applications.” Renewable and Sustainable Energy Reviews. 11.8 (2007): 1675-697. Print.
