In the story "The Last Human Light," the geothermal plants would eventually shut down due to corrosion, as stated in the following passage:
"The geothermal plants, built beneath the surface of the earth, had been the primary source of energy for the remaining human settlements. However, with each passing year, the corrosive properties of the underground environment took their toll on the plants' infrastructure. The pipes that carried the hot fluid from the depths of the earth to the surface started deteriorating, leading to leaks and system failures. Despite constant efforts to repair and maintain the plants, the corrosion became too extensive, rendering them inoperable."
(Textual evidence supports that corrosion is the reason for the eventual shutdown of geothermal plants due to the deteriorating pipes and limited repair efforts.)