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Re:Geothermal May Beat Batteries for Energy Storage by VilleOr on Tuesday October 11, 2022 @06:24AM (#33161543)
Majority of geothermal enery comes from the decay of radioactive isotopes. It's not renewable, but there will be enough heat for millions of years.
Re:Geothermal May Beat Batteries for Energy Storage by CorrectHorseBat on Tuesday October 11, 2022 @07:03AM (#33161814)
Surprisingly it's about 50/50 radioactive decay and heat left over from the forming of the solar system: https://en.m.wikipedia.org/wiki/Earth%27s_energy_budget#Eart...
Re:Geothermal May Beat Batteries for Energy Storage by HPsquared on Tuesday October 11, 2022 @07:10AM (#33161877)
It's not renewable, but exploiting it doesn't reduce the overall output. It's "not depletable", you could say.
Re:Geothermal May Beat Batteries for Energy Storage by Schroedingersat on Tuesday October 11, 2022 @07:36AM (#33162086)
At some point you're increasing the conductivity of the crust and mantle.

You have a bunch of bigger problems that come to roost much sooner than this if you're using that much geothermal though,

Re:Geothermal May Beat Batteries for Energy Storage by CorrectHorseBat on Tuesday October 11, 2022 @08:49AM (#33162711)
How is that different from renewables?
Re:Geothermal May Beat Batteries for Energy Storage by marcosdumay on Tuesday October 11, 2022 @01:31PM (#33166195)
It's not. Renewable on energy discussions basically means "not depletable".
Re:Geothermal May Beat Batteries for Energy Storage by dredmorbius on Wednesday October 12, 2022 @03:43PM (#33182011)
At the macro scale, correct. Humans might cool the outer crust somewhat in localised regions. Odds we'll be able to significantly change overall core and mantle thermodynamics are exceedingly slight.

At the micro scale, that is, for an individual geothermal well or source, not so much. Single wells or geothermal fields may be depleted or degraded.

Because heat conductivity of rock is very limited, extraction of that heat by some mechanism will eventually cool that rock below viable levels for power generation. For enhanced intensive geothermal energy --- drilling holes in rock to depths of multiple kilometers and circulating a working fluid (typically water) through the substrate --- that is thought to be on the order of 1--3 decades. After which the borehole is no longer viable and must be left to recover for some period of time, perhaps centuries.

For conventional (geyser / steam vent) geothermal, the limiting factor tends to be groundwater. The instance I'm most familiar with is The Geysers powerplant in northern California, which saw a roughly 40% reduction in capacity over several decades as the groundwater feeding the geyser system was depleted. That would have to be restored by some means.

Note too that there may be contamination issues in repeatedly cycling deep-layer water to the surface, particularly of heavy metals or radioactive isotopes. These include "sulfur, vanadium, silica compounds, chlorides, arsenic, mercury, nickel, and other heavy metals".

<https://www.ucsusa.org/resources/environmental-impacts-geoth...>