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From the article you linked to... "Still, if we don’t care about sustainable use of geothermal, we can just keep drilling new holes to deplete one region after

From the article you linked to... "Still, if we don’t care about sustainable use of geothermal, we can just keep drilling new holes to deplete one region after the other. In this sense, we could evaluate the thermal endowment in the upper 5 km of crust under land. The average temperature in this layer is about 60°C above the surface value, so that each cubic meter (3300 kg) contains 180 MJ of thermal energy. Summed over 1.4×1014 m², we get about 1026 J. This is 250,000 years of our global appetite. A quarter-million years might seem close enough to indefinite that we’re willing to call it sustainable. Truly it is a substantial endowment. It’s the practical considerations that hold us off from rushing into this resource." There are some practical issues to overcome before geothermal could take a bigger share of the energy mix, but they're being worked on. Whilst I don't believe we should ever rely on one energy source, not even when we have nuclear fusion, I still think that geothermal has enough potential benefits to make it unwise to rule out whilst we still need to move away from polluting sources of energy. Here's one idea for improving the practicalities of geothermal: "Bhargava’s other hobby is tackling the world’s dependence on polluting fossil fuels with geothermal energy. His twist? Use a grapheme cord, which is stronger than steel and an impressive conductor of heat, in lieu of the usual steam-and-chemicals to gather and distribute underground heat. By his estimate, geothermal energy like this could replace 85 percent of fossil fuels." http://energyefficiencymarkets.com/quick-energy-efficiency-news-a-billionaires-clean-energy-bike-and-a-twist-on-geothermal/ http://energyefficiencymarkets.com/quick-energy-efficiency-n...

dredmorbius 11y ago
I'm a big fan of turning to empirical data where it's available. One case in point is the "Habanero" well dug in Australia as a pilot for an enhanced goethermal field. This is a nonsustainable proposition, with individual wells having a fixed life I don't recall offhand, though it's < 40 years. The project's been plagued by multiple setbacks, for which some of the most candid accounts come from the company's own investor filings with the Australian government, though the upshot is: * The whole durned thing done blowed up. There was a steam explosion which, putting things mildly, proved a substantial setback. Fortunately no one was killed. * Power output of the pilot project has been scaled back tremendously. Again it's been a few years since I looked at this, but actual achieved output was 1/50th initial estimates. * Costs were tremendously higher than initially anticipated. For achieved output, $30,000/kW, vs. about $4,000 kW for solar (less today). * Schedule overruns, even accounting for accidents, were on the order of years. Ah, turned up my earlier article, you can see that here: https://reddit.com/r/dredmorbius/comments/1wpa90/how_not_to_write_about_renewable_energy_the/ https://reddit.com/r/dredmorbius/comments/1wpa90/how_not_to_...

dredmorbius 11y ago

I'm a big fan of turning to empirical data where it's available. One case in point is the "Habanero" well dug in Australia as a pilot for an enhanced goethermal field. This is a nonsustainable proposition, with individual wells having a fixed life I don't recall offhand, though it's < 40 years. The project's been plagued by multiple setbacks, for which some of the most candid accounts come from the company's own investor filings with the Australian government, though the upshot is: * The whole durned thing done blowed up. There was a steam explosion which, putting things mildly, proved a substantial setback. Fortunately no one was killed. * Power output of the pilot project has been scaled back tremendously. Again it's been a few years since I looked at this, but actual achieved output was 1/50th initial estimates. * Costs were tremendously higher than initially anticipated. For achieved output, $30,000/kW, vs. about $4,000 kW for solar (less today). * Schedule overruns, even accounting for accidents, were on the order of years. Ah, turned up my earlier article, you can see that here: https://reddit.com/r/dredmorbius/comments/1wpa90/how_not_to_write_about_renewable_energy_the/ https://reddit.com/r/dredmorbius/comments/1wpa90/how_not_to_...