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Stop Mining for Oil (and Coal), Start Drilling for Heat

The views expressed are those of the author and are not necessarily those of Scientific American.


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The center of the Earth is a roiling ball of heat, roughly 6,000 degrees Celsius as near as we can tell without a sci-fi tunneling effort. The closest humanity has come to that molten core is some 12 kilometers beneath the continental crust in Russia, which isn’t even halfway through said crust and akin to drilling into an apple without piercing the skin. Yet, it’s pretty clear that a lot of that core and mantle heat makes its way to or near the surface—witness: Yellowstone, the big island of Hawaii, all of Iceland—offering a cheap, constant and potentially clean source of energy.

There are already several methods for harvesting the energy in this rock that’s heated by the decay of radioactive elements. It’s also something humans have been doing for a long time—at least since 1911 in Italy to be exact when locals opened the world’s first geothermal power plant in the Valle del Diavolo. We even have an industry devoted to refining and improving the drilling techniques to make such energy available on an even grander scale—you know it as the most profitable enterprise on the planet, yes, the oil and gas industry.

So why in the world don’t we use more geothermal energy? "All the energy we need is right beneath our feet," argues geologist Craig Dunn, chief operating office of Borealis GeoPower, a Canadian geothermal developer, an advisor to the Equinox Summit and its search for alternative energy technologies. The summit paired "future leaders" with old-school scientists to develop a plan to cut greenhouse gas emissions, enhance energy security and extend modern energy to the billions of people who do not presently enjoy it. Geothermal could play a key role. As Dunn says: "the top one percent of the planet has enough energy to power and heat civilization for approximately 6 billion years."

As it stands, geothermal accounts for roughly 0.3 percent of global electricity generation.  A big chunk of that comes from one power plant at The Geysers in Northern California. Other hotbeds of geothermal use range from the Philippines and Indonesia to Germany and Mexico. And there is plenty more to come by, for example in the volcanic seamounts of Hawaii, a state which currently relies on burning imported oil for 90 percent of its electricity, or using the heat in onsen (hot springs) as a replacement for nuclear power in Japan. Even California’s Google has gotten into the act, sinking roughly $11 million into geothermal drilling research.

The volcanoes of Hawaii and hot springs of Japan are just the most obvious places to put a geothermal power plant. "We should hit the easiest stuff first," Dunn says, noting that the geothermal industry is still learning to prospect for "blind resources," or those for which there is very little or nothing evident on the surface in the way of hot springs, geysers or volcanoes. "We’re where the oil and gas industry was in the 1940s and 1950s."

The International Energy Agency suggested in a road map for the technology’s development released this week that geothermal could increase 10-fold by 2050 if the right financial and policy incentives are put in place—along with research funding for more advanced systems, known as enhanced geothermal (or EGS). EGS involves drilling into the Earth, fracturing the hot rock below and then pumping water (or other working fluids) down to capture the heat and return it to the surface—mimicking the kind of heat flow that occurs naturally at a geyser. 

Australia is helping lead the charge to develop such EGS technology, via various drilling programs, the most prominent of which is in the Cooper Basin in the nation’s central desert country. But the companies involved have struggled mightily with drilling risks and financial challenges—a global problem. "Until you get down there, you don’t know the temperature," explains engineer Robin Batterham of the University of Melbourne, former chief scientist of Australia and mining company Rio Tinto. "Until you drill a couple of wells you don’t know how well it will flow."

Drilling a several-kilometer-deep well costs millions of dollars, and one needs at least five such wells (and possibly as many as 50) to prove a given geothermal resource is going to reliably deliver heat with which to make electricity. The "dry hole"—in this case one that doesn’t produce steam—is just as much a challenge for geothermal as it is for oil and gas.

Plus, there’s the fact that drilling for geothermal can set off mini-earthquakes (although this doesn’t seem to bother us as much about drilling for oil or natural gas.) An international, coordinated effort to demonstrate the potential of the technology—as has been done for carbon capture and storage—might help overcome these challenges, and that’s what participants in the recent Equinox Summit called for, along with a billion dollars in funding for such demonstration projects.

There’s also the simple fact that one can drill to release a transportable commodity worth roughly $100 per barrel (aka oil) or one can drill to produce a commodity that must be instantaneously transported and consumed at a value of roughly 10 cents per kilowatt-hour (aka geothermal electricity). In the absence of a price for using the atmosphere as a dumping ground for the CO2 produced by burning fossil fuels like coal or oil, the dollars and cents of even free hot rocks may not add up. And that’s too bad for the global climate.

Image: Photograph by Julie Donnelly-Nolan, USGS





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  1. 1. JamesDavis 7:09 am 06/20/2011

    Geothermal is still and always has been the cleanest, cheapest, most productive, most environmentally friendly, (at 1% polluting) never ending source of energy on the planet. Once the initial drilling and building is completed; the pay back is almost immediate with the free energy it produces and there is no nuclear or deadly chemical storing. And if there is no H2O on hand, you can use CO2, and with CO2, there is no need to fracture the rocks and there is no cooling down of the shell rock, plus, the CO2 is burnt at a high temperature, which can be used for other useful products.

    America can stop giving incentives to oil, coal, natural gas, and converting food to gas, and put it into geothermal research and production and start mass producing geothermal plants with oil and natural gas drilling rigs – drilling the holes and we can be off fossil fuel in less than ten years and fossil fuel free for the rest of humans’ time on Earth. Drilling for and producing geothermal power plants will create hundreds of thousands of jobs that will last as long as geothermal does.

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  2. 2. eddiequest 8:22 am 06/20/2011

    My thoughts, as well… HOWEVER, as long as we let the current powers of the Earth (coal/oil corps) control things, we will NEVER be free to solve our problems.

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  3. 3. tharriss 8:25 am 06/20/2011

    Maybe I’m missing something but the article says:

    "As it stands, geothermal accounts for roughly 0.3 percent of global electricity generation"

    But says that:

    "The International Energy Agency suggested in a road map for the technology’s development released this week that geothermal could increase 10-fold by 2050 if the right financial and policy incentives are put in place"

    So in 40 years, IF we put incentives in place, geothermal could account for 3% of our energy usage? Hardly sounds like the big solution of the future…

    I’m all for it if it can work without having unintended consequences that screw something up (fracturing lots of rock below the surface just sounds like it might eventually cause some kind of issues), and if it makes sense time&money wise, but if this article is correct, 3% is not going to make much difference in the end.

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  4. 4. lamorpa 9:00 am 06/20/2011

    @JamesDavis: Tell us of this burning (oxidation) of CO2. Are you getting CO3? CO4? How would this help?

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  5. 5. fyngyrz 10:48 am 06/20/2011

    Scientific American is on record as supporting the model output that, if correct, predicts global warming.

    So… as part of the effort to counter the warming of the planet, the plan as laid out here is to pump a lot of heat that was previously retained within the planet’s interior by insulation provided by a great deal of rock and soil, up to the surface.

    My question is, how efficient is the heat-to-mechanical process; more specifically, how much of the pumped interior heat escapes as heat energy added to the biosphere? Is the heat-to-energy conversion 100% efficient, so that no heat is added?

    It seems to me that one should look very carefully at this issue before deciding to label it as zero environmental impact.

    Unless, of course, the global warming models are wrong. Pumping core heat to the biosphere might be just the thing during an ice age.

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  6. 6. tharter 10:56 am 06/20/2011

    This is true, but there are some rather interesting advantages if you can get EGS to work in a wide variety of locations. You can site your baseload power plants rather flexibly. Heck, you can simply provide heat to existing facilities which burn coal etc right now, turbines could care less where the heat comes from. You could simply generate process heat at many convenient locations. Even if it DID amount to 3% it could be a quite useful 3%.

    Frankly this seems moderately conservative anyway. While it may be expensive to do the drilling etc it WILL get cheaper if it is done on a large scale. Not only that but once you’ve got a good facility running you have a big advantage over fossil fuels, no fuel. I mean people are willing to fork over LARGE up front capital costs to build nuclear plants for a similar advantage, and the risks of geothermal rather pale by comparison to those of nukes.

    Consider a power mix with a decent amount of baseload geothermal, some storage, and widespread use of wind/solar both for demand generation and direct production of liquid fuels. It is not going to happen overnight, but it makes a heck of a lot of sense.

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  7. 7. Lazarus 11:10 am 06/20/2011

    fyngyrz, you seem to misunderstand the causes of global warming. All the direct heat that mankind generates from generating power, cooking, driving vehicles etc., counts for almost nothing as heat in the atmosphere. It is additional heat from the sun being trapped in the atmosphere by our addition of GHGs that contributes to global warming, not heat we produce.

    Heat from released geothermal will add practically nothing to the overall energy in the climate system.

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  8. 8. sault 12:03 pm 06/20/2011

    The efficiency of the "heat to mechanical process" is dependent on the temperature difference between the working fluid coming out of the ground and (effectively) the ambient air outside the plant. You can expect to extract about 30% or so of the potential energy contained in this temperature difference. It’s not that geothermal plants are of a poor design or anything, but this is just how the laws of Thermodynamics and Heat Engines work. ALL Coal and Nuclear plants have about the same efficiency as a geothermal plant with a good temperature reservoir. Coal is a little higher while Nuclear is a little lower. Again this is all based on the temperature of the "heat source" (hot rocks, hot fireball in a coal boiler or hot fuel rods on a reactor) and the "heat sink" or the outside environment.

    To get 100% efficiency, you’d have to design a heat engine that could extract work from a system that exchanges heat from a source at an infinite temperature to a sink at absolute zero. And you’d have to do it with zero friction or any other irreversible processes. That this is impossible just goes to show that a perpetual motion machine would be even MORE impossible.

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  9. 9. HowardB 5:28 pm 06/20/2011

    Sault – this is not my field but I suggest you are incorrect in your assertions.
    You are responding to fyngyrz’s question about the effect of heat liberated, from the core, on the atmosphere. You then suggest that we would have to extract 100% of the heat, when the truth is we would only have to extract enough heat to bring it to equilibrium with that in the atmosphere already ?

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  10. 10. HowardB 5:32 pm 06/20/2011

    I agree – an astonishing claim that geothermal could increase 10-fold by 2050…. what an amazingly modest vista in 40 years ???

    It strikes me that 10 years of research should conquer the drilling problems … and once that is done the door is open to an extensive drilling program all across the world in stable tectonic locations.

    These plants would be extraordinarily efficient and one would ‘imagine’ that a target of 15% would be an achievable one ?

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  11. 11. HowardB 5:35 pm 06/20/2011

    I apologise for my third post in a row…. I didn’t want to bundle everything in one ;)

    Considering the investment in building and then decommissioning a nuclear plant ……. it seems to me that the costs being spoken about for developing high temperature, deep penetration drilling technology MUST be a hell of a lot lower !

    And … once the technology is developed it can be rolled out and duplicated at no major additional cost …. !

    What is the catch ?

    Do we KNOW that this has caused earthquakes ? or could they be coincidences ? Is the risk a one off at the time of the drilling ? of throughout the operational life of of the Plant ?

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  12. 12. Postman1 8:02 pm 06/20/2011

    I find myself in the odd position of having to agree with the post of jamesdavis, nearly 100%. Why aren’t entrepreneurs and small independent power cos. investing in this? If it is as good as the article states, the return on the investment would be enticing, so let’s get drilling.

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  13. 13. Russell 9:08 pm 06/20/2011

    There is a massive problem with goe-thermal, please check out
    http://www.inference.phy.cam.ac.uk/withouthotair/c16/page_96.shtml
    There may be a lot of heat there, but you can’t get it out, the earth around the extraction area cools down.

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  14. 14. sofistek 5:38 am 06/21/2011

    When will Scientific American stop pandering to the seekers of the magic elixir; something that will keep current civilization going for a bit longer. Changing the power source won’t magically make us sustainable. Not that it’s likely that any power source will have the efficacy of fossil fuels, be as scalable as fossil fuels and have no downside at all.

    When will Scientific American get scientific about the real limits we face on a finite planet? Stop running these dream stories (I’ve been reading them for decades) and get real. Please. Let’s think about what sustainable really means and focus on how we can move to a sustainable civilization. No matter what the pain we have to go through to get there, it’s got to be better than collapse (unsustainable societies always collapse).

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  15. 15. ssm1959 5:55 pm 06/21/2011

    I hope the previous commenter is not carefully couching the sentiments of certain previous individuals with totalitarian leanings as the mainstay of his premise. The problem with taking the Malthusian position is that it is second to millenarian claims in its perpetual wrongness.

    The issue is not replacing fossil fuels in as much as it is moving away from a monoculture of energy generation. The energy density and portability of fossil fuels is undeniable and insures their continued use at some level. The fact that we have other need for energy generation where where portability is not the issue. In those instances we can develop more local alternatives be they geothermal, Thorium base nuclear, solar, wind etc.

    The one thing that will not happen is a turning the clock back to some presumed idealized magical sustainable point in time. Of course this presumed nirvana could be brought about should a new black death emerge. However recent history shows that well intentioned elitists have the ability to "reduce the excess population" far more efficiently than than any other force on the planet. Auschwitz anyone?

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  16. 16. Dr. Strangelove 11:27 pm 06/21/2011

    You should compare geothermal energy vs. burning fossil fuels. The thermal efficiency of the best combined cycle power plants is around 60%. So 40% is heat loss that ends up in the atmosphere. This is true for both geothermal and fossil fuels. But geothermal does not emit CO2 so the heat (infrared radiation) can escape into space and not trapped in the atmosphere by CO2.

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  17. 17. Dr. Strangelove 11:42 pm 06/21/2011

    Btw, the heat loss in heat engines is miniscule compared to the sun’s radiant energy that’s warming earth. I think the heat from heat engines cannot cause global warming but the greenhouse gases they emit can by trapping solar energy in the atmosphere.

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  18. 18. Dr. Strangelove 12:25 am 06/22/2011

    It’s incredible that Hawaii uses 90% imported oil when it could tap geothermal energy like Iceland which uses 100% geothermal energy. The whole island of Hawaii is sitting on a giant volcano. And Yellowstone is on top of an ancient supervolcano. It has enormous geothermal energy if only the federal government would allow drilling in a national park.

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  19. 19. sofistek 4:09 am 06/22/2011

    ssm1959, there isn’t some past idealised age. I’m concerned that we start to tell ourselves factual stories about our place on this planet and the impact of our behaviour. I’ve yet to see any sustainable energy replacement for fossil fuels and our civilisation requires a continual increase in energy. But energy isn’t the only problem even though many people here and, perhaps the magazine itself, likes to compartmentalise. We have an energy problem so let’s fix that (and each month seems to bring out news on the latest favourite). If we suppose that eventually we’ll hit on some magical mix of energies that has a good enough EROEI and affordability to allow civilisation to go on as what has become "normal", that will not help us at all, since just about everything else we do is unsustainable (i.e. must end, just in case you weren’t aware of the consequences of unsustainable behaviours).

    That we live on a finite planet isn’t malthusian, it is just stating a fact.

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  20. 20. Dr. Strangelove 5:01 am 06/22/2011

    Yellowstone is a catastrophe waiting to happen. When that supervolcano erupts, it would be the largest eruption in history 1,000x more powerful than Mt. Helens. Geothermal drilling may prevent extremely violent eruption by letting underground gas pressure out preventing too much pressure buildup. The energy of potential huge volcanic explosion can be turned into electricity.

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  21. 21. marticollin 6:10 am 06/22/2011

    Please check out Iceland, a nation whose population is currently amongst the most advanced in the world, which has quietly utilized its geothermal energy resource to a point where nearly all home heating and lighting is geothermally-based. Were the rest of the world to deign to take their example and learn from their insight, initiative, and experience, humanity could finally free itself from the inertia of its current slavery to the global curse of the fossil-fuel malaise currently threatening climate change, sea level rise, and a serious future of significant human suffering, degradation of our planet’s environment, and the mass-extinction of much of its fauna & flora.

    Geothermal energy is no silver bullet, and there’ll be a price-tag; but it appears to be a great deal more attractive as an projected basis for global power than any currently competitive sources. It appears that oil-gas-coal corporate interests are succeeding in leading humanity via a Luddite solution, which shackles our near future by means of an inertia that roots our economies and technologies in the fossil-fueled culture of the past 100 years. Might it not be time for humanity’s entrepreneurial spirit to break free of fossil-fuels, embrace its heritage of Earth’s inner resources, in order to power an economically-efficient, Earth-embracing, environmentally-effective age of human development? Could this usher in that ‘Age of Aquarius’ we’d so fondly envisioned in the 1960s?

    As a geologist and land-use planner, i haven’t much expertise to offer as regards the mechanics of harnessing geothermal energy, but the logic of its inevitability as an ultimate source of power for human culture and technology appears unavoidable. I say we give it a serious try!

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  22. 22. marticollin 6:11 am 06/22/2011

    Please check out Iceland, a nation whose population is currently amongst the most advanced in the world, which has quietly utilized its geothermal energy resource to a point where nearly all home heating and lighting is geothermally-based. Were the rest of the world to deign to take their example and learn from their insight, initiative, and experience, humanity could finally free itself from the inertia of its current slavery to the global curse of the fossil-fuel malaise currently threatening climate change, sea level rise, and a serious future of significant human suffering, degradation of our planet’s environment, and the mass-extinction of much of its fauna & flora.

    Geothermal energy is no silver bullet, and there’ll be a price-tag; but it appears to be a great deal more attractive as an projected basis for global power than any currently competitive sources. It appears that oil-gas-coal corporate interests are succeeding in leading humanity via a Luddite solution, which shackles our near future by means of an inertia that roots our economies and technologies in the fossil-fueled culture of the past 100 years. Might it not be time for humanity’s entrepreneurial spirit to break free of fossil-fuels, embrace its heritage of Earth’s inner resources, in order to power an economically-efficient, Earth-embracing, environmentally-effective age of human development? Could this usher in that ‘Age of Aquarius’ we’d so fondly envisioned in the 1960s?

    As a geologist and land-use planner, i haven’t much expertise to offer as regards the mechanics of harnessing geothermal energy, but the logic of its inevitability as an ultimate source of power for human culture and technology appears unavoidable. I say we give it a serious try!

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  23. 23. ennui 6:56 pm 06/22/2011

    Cheap?I think it will take a heck of a lot of money to drill a two inch hole. Has anyone tapped Old Faithfull?
    When it is close to the surface like in Iceland, it can be used. The only other system that would be cheap is the generation of power by using Gravity Control.

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  24. 24. Dr. Strangelove 8:55 pm 06/22/2011

    The president of a geothermal energy company told me that their operations cause frequent seismic activity – small earthquakes that are hardly perceptible. But this gradual release of energy prevents the sudden big earthquake. They never had a big earthquake in any of their sites despite being in earthquake prone area.

    Japan has geothermal resources. They should develop it and that would mitigate the risk of big devastating earthquakes.

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  25. 25. mallen10 10:58 am 06/23/2011

    Not my field but aren’t the location of most possible geothermal sites basically unstable?

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  26. 26. Dr. Strangelove 11:17 pm 06/23/2011

    It’s unstable in the sense that geothermal resources are usually found near volcanoes and active tectonic plates. By that definition, the whole of Japan, Hawaii and Iceland are "unstable."

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  27. 27. gmperkins 4:52 am 06/24/2011

    I’ll make another article just like this titled "Why on Earth are we not using Fusion????"

    State alot of pie in the sky stuff about Fusion and then just stop.

    Where are the facts? Where are drilling costs? Maintenance costs? Overview of sites and drill depths? Conversion ratios? All the engineering stuff?

    Anyone with a highs school understanding of pyhsics can understand that heat can be converted to energy. Getting to that heat is a very tough engineering problem. Plus sites close to the surface are usually unstable, an earthquake later and there goes your billion dollar drill hole.

    I would love to see Geothermal in more use but these fluffy "articles" are really starting to annoy me. I don’t subscibe to SciAm or these email articles to get so much junk.

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  28. 28. iWind 10:31 am 06/25/2011

    No, that’s not how it works. Not that I’m an expert, because I’m not, but I’m quite sure what the president you talked to was implying, is that their activities did not appear to *trigger* big earthquakes.

    It would take on the order of billions of microearthquakes to release the same total energy as just a single big one, and even the hundreds occurring naturally each day in Japan clearly have no such effect.

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  29. 29. iWind 11:05 am 06/25/2011

    I would say the difference between geothermal and fusion power lies in all the geothermal power plants already in operation? And for the remaining questions, apart from being well outside the scope of a blog post, I get the feeling you didn’t actually read the article, because those questions are pretty much what was called for to be answered, as I read it…

    Just one correction though, a high school understanding of physics should tell you that heat can NOT be converted into "energy," (any high school student who didn’t sleep during physics classes, should be able to spot at least one of the two errors in the original statement) but a DIFFERENCE in heat can be converted into mechanical or electrical power.

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  30. 30. jsobry 12:12 pm 06/27/2011

    Sorry iWind, I think you made a minor mistake. It is not a difference in heat but a difference in temperature that allows heat to be converted into another form of energy.
    To wit, the ocean contains an enormous amount of heat but you can not use it unless you have a sink that is at a much lower temperature than the ocean. Otherwise all motorized ships could navigate the ocean without any requirement for fuel of any kind. In other words all the heat in the ocean is useless for our purposes.
    Similarly there is an enormous amount of criticism on the internet of other people’s statements but it is not the amount of criticism that matters but the veracity of the underlying assertions of that criticism.
    In other words the veracity is like the temperature and the many unwarranted criticisms are so much useless heat.

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  31. 31. jsobry 12:30 pm 06/27/2011

    "Japan has geothermal resources. They should develop it and that would mitigate the risk of big devastating earthquakes."

    It is highly unlikely that the exploitation of geothermal heat in Japan will mitigate the risk of big devastating earthquakes. The most recent earthquake in Japan was caused by the breaking of the upper tectonic asian plate under which the lower tectonic pacific plate is being pushed. The energy for that tectonic process comes from many hundreds of kilometers away at a spreading centre of the tectonic plate system.
    No conceivable amount of local geothermal energy exploitation in Japan could have stopped this tectonic process and it’s ensuing earthquake.

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  32. 32. Dr. Strangelove 8:48 pm 06/27/2011

    iwind, jsobry,

    The analogy used in triggering an earthquake is that of a stretched rubber band. The stored energy accumulates as tension in the rubber band. When the breaking point is reached, the rubber band snaps and all the stored energy accumulated over time is suddenly released.

    You don’t have to use up all the stored energy to prevent the rubber band from snapping. You just have to use up a small amount of energy to prevent reaching the breaking point. Yes, of course if the epicenter of the earthquake is far from the geothermal drilling, it will have negligible effect.

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  33. 33. KiwiBuzz 2:08 am 07/26/2011

    There are 2 sorts of geothermal power. One is developed by tapping into underground hot water and steam. This has been done for years and was pioneered in Italy followed by New Zealand. The Geysers in California was also a world leading plant. But there is a limit to the amount of power available from this source. There are only so many geothermal areas in the world.

    The other sort of geothermal power is so-called “hot rock". The idea is that you drill two or more very large holes deep into the ground and fracture the rock between them. You pump water down one hole and hope it emerges as very hot water or steam out of the other. The cost is enormous and the yield is low. Geodynamics in Australia has been working on it for 10 years and, as a result their share price has steadily declined. They still seem to be far away from producing any electricity-let alone economic electricity.

    If you want clean power, the answer is obvious. Nuclear power. If, like me, you do not believe man-made global warming, then coal and gas are perfectly satisfactory. They’re all cheaper then hot rock geothermal could ever be.

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  34. 34. adrixmerkado 9:20 pm 01/16/2012

    Yes, Indeed Geothermal is still one of the best solution for power or energy out source though the issue is how clean does that power be in effect with the environment. I’ve seen how they do from drilling core bit drills http://www.gilatools.com/diamond-core-bits.html to the target area up until setting up the plant – it’s quite a workload. Though in the other side, Nuclear power plant is something a no-no for me since like what happen to FUKUSHMA’S plant failure from the quakes in Japan – very devastated effect.

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