| Summary: | Geothermal energy production can be maximized by reaching depths in volcanic areas at which water stays in supercritical conditions. A single well in supercritical conditions of water can produce 50 MWe, which is ten times the production of a conventional geothermal well. Thus, the transition to a carbon-free energy market can be speeded up by exploiting supercritical reservoirs to produce geothermal energy. However, this technology is not exempt of risks, like induced seismicity. We simulate a doublet reproducing the conditions found at the bottom hole of the IDDP-2 project in Iceland. We find that, contrary to most fluid injection projects, seismicity will be mainly induced by cooling rather than by pore pressure buildup. The cooled region around the re-injection well progressively increases, causing cooling-induced stress changes that affect fault stability in the long term. We find that the rate of induced seismicity at the fault increases four orders of magnitude after 7 to 10 years of water circulation. This result suggests that the lifetime of supercritical geothermal projects may be eventually limited by cooling-induced earthquakes. Overall, properly managed volcanic areas have a huge potential to provide low-carbon electricity. Peer reviewed
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