> I guess large-scale geothermal power plants are an unproven concept
Depends on the definition of large-scale, the biggest plant in the world is the 300MWe Hellisheiði power station in Iceland, and the largest geothermal field (a single "location" hosting multiple plants) is The Geysers in California, with 1500MWe over 22 plants.
Depends on the definition of large-scale, the biggest plant in the world is the 300MWe Hellisheiði power station in Iceland, and the largest geothermal field (a single "location" hosting multiple plants) is The Geysers in California, with 1500MWe over 22 plants.