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This only happens if you're pulling more energy than the long-term capacity (i.e. heat flow from the interior of the Earth) of the site. If you end up doing thi
by azernik 9y ago
This only happens if you're pulling more energy than the long-term capacity (i.e. heat flow from the interior of the Earth) of the site. If you end up doing this, you can just draw less power until the temperature rises back up.
- WalterBright 9y ago> This only happens if you're pulling more energy than the long-term capacity Well, of course that's true. The problem was the capacity was too low to be cost effective.
- azernik 9y agoIt turns out that this is not true. In many cases the issue is just depletion of water, in which case re-injecting water restores power output - the long-run sustainable power is quite economical to harvest.
- WalterBright 9y agoThen the obvious question is why don't we see a lot more of these plants?
- jgamman 9y agodrilling the well is about $1 million per km. only a few spots around the world make 1-2 km wells cost effective for extracting energy for electricity. this is even worse with the costs of PV installed now 100 fold less than the marginal cost of geothermal. having said that, a resilient system would have a baseload of electricity from geothermal, some peaking from hydro and plenty of PV/wind. mind you, i'm biased since i live in NZ and we're well on the way to 95+% electricity renewables...
- azernik 9y agoTwo things: 1. Capital expenses are quite high, even though running expenses are low. 2. It's only viable in specific geographic places, where heat is brought up close to the surface by magma and water flows. Otherwise you just need to drill too deep to get useful heat. So the big sites are at places like The Geysers in California, the hot springs of Iceland, and the places the site mentions in Kenya.