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If we extract enough heat from the earth using geothermal energy, could we offset global warming? -- Linda P., Portland Oregon
Great question. You apparently know the basics of geothermal electricity production, but let me recap for those not as familiar. To oversimplify, geothermal electricity consists of:
Locating a suitable geothermal reservoir (underground collection of hot water or steam).
Drilling a well to penetrate the hot underground water or vapor (geothermal fluid).
Extracting the hot fluid.
Using a power plant and related infrastructure to produce electricity, cool the geothermal fluid, and inject some of it back into the system for reuse.
Since we are using the heat of the earth to run the power plant, some of this energy is transformed into electricity. This means there will be a net heat loss from the reservoir, and the earth temperature must decrease (blame the laws of thermodynamics). Your question is, could we do enough of this to actually measurably cool the earth. The simple answer is no-geothermal does result in cooling, but the impact is insignificant.
Some 42 million megawatts of energy reach the surface continually and are radiated into space as the earth cools from its initial molten state more than 4 billion years ago. No feasible amount of geothermal development could make even a small dent in this process. Furthermore, the earth's heat budget is continually replenished by the radioactive decay of naturally occurring elements, and almost all of the energy associated with each decay event is converted to heat. Plus, the heat content of the geothermal reservoir rocks is continually replenished by conduction of heat from the earth's deeper interior.
But, if you're thinking about global warming, using all of that heat to provide clean energy is obviously a way to go. Like the sunlight hitting the earth every day, the energy available from the heat of the earth is enormous and largely unused as a source of energy. If we could tap just a fraction of the heat reaching the surface of the earth every year, we could provide all of the heat and power needed to run our society, and avoid the potentially tragic consequences of overusing fossil fuels.
The information and views expressed in this article are those of the author and not necessarily those of RenewableEnergyWorld.com or the companies that advertise on its Web site and other publications.
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10 Reader Comments
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2 of 10 |
January 23, 2008
Can anyone help me out with tje public and private companies with exposure to Geothermal Heat Pumps? |
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3 of 10 |
January 23, 2008
The areas on the Earth's surface which need high amount f Energy inputs for heating as well as Mechanical action are the coldest ones. Actual input of such high doses of Energy is actually one of the main reasons behind the Polar and other high Altitude melting of the ICE CAPS.This is not to ignore the impact of the CFC et al, but to keep in fcus one aspect rarely discussed.
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4 of 10 |
January 23, 2008
Relevant question and its nicely answered
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5 of 10 |
January 23, 2008
Karl, while geothermal electricity holds great potential, we seldom see any focus on geothermal heat pumps for both industrial and home use. The technology is mature and its application almost universally available. It would seem to me to be a no-brainer, and i don't understand why it is not well promoted and utilized.
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6 of 10 |
January 24, 2008
M. Rokes, regarding emissions of CO2 at geothermal sites; yes, but the CO2 at these sites is released whether or not the geothermal energy is tapped for human use. Thus, would it not be fair to say that the net CO2 emissions would be less, because carbon based fuels would not be transformed into gas and heat?
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7 of 10 |
January 25, 2008
M. Rokes, I would like to echo Glenn's comment on CO2 emissions from geothermal energy. In the case of NZ, the geothermal energy is coming from the subduction of the Pacific plate which transports substantial amounts of calcium carbonate down in the heated interior of the crust and upper mantle. As in a cement kilm, this calcium carbonate is transformed into CO2 and calcium oxide. Regards, this CO2 will be released back to the ocean or atmosphere via hot vents and volcanic action. However because the high CO2 emissions are primarily associated with the geothermal hotspots associated with such subduction zones, the NZ CO2 figures are not as applicable to geothermal applications in mainland areas (e.g., Nevada) nor in areas where the geothermal hotspots are the result of plate spreading (e.g., Iceland) versus plate subduction. |
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8 of 10 |
January 26, 2008
THis article on possibility of cooling the earth by extensive use of geothermal energy for electricity, puts me in mind of the simple facts that the earth goes thru essentially endless cycles on cooling and heating mostly due to solar cycles. About a thousand years ago the earth went thru quite a significant warming cycle that lasted several centuries and rivaled todays warming trend to the extent that the Vikings of the time actually colonized Greenland and were able to farm lands where several centuries later ice sheet reigned. Earth peoples might be glad to have C02 levels lots higher someday several centuries from now. |
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9 of 10 |
January 28, 2008
Good Article on Basic's of the "Hot Rocks" geothermal stuff, but an even more affordable,decentralized, useable and widely accessible version of geothemal energy use can be provided to the public with the use of "ground source heat pump" technology. It is a mature marketplace item that has been proven in every continent. Substaintial fossil fuel energy conservation and dollars can easily be acquired by everyone. To lean more, visit a few of these web sites: www.climatemaster.com, www.geoexchange.org, www.igshpa@okstate.edu
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10 of 10 |
January 28, 2008
Can carbon reduction thru geothermal use be traded? Philippines is compose of small island states. Can a particular island gets carbon credit for exploration or futher expansion and development of geothermal energy found in the locality? The island of Leyte is one producer of geothermal enery for the country. It has served many developed islands and provide electricity to big cities. But there are still some islands in the Province of Leyte that are still using diesel for electricity. Hope carbon credits, if there is any for geothermal energy is decentralized. Thank you.
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