Following on to this, enough sunlight hits the Earth in 30 minutes to power humanity for a year. So geothermal wouldn’t need to provide all of today’s human energy consumption, just that last bit that renewables, existing nuclear, transmission, storage, and demand response can’t provide for today.
(1GW of solar PV is deployed every 15 hours globally as of this comment)
I wonder how much ΔT you need at the crust to meaningfully change Earth's magnetic field by altering convection patterns in the outer core. I don't know enough physics to attempt an answer.
The outer core is 2,890 KM (~ 1800 miles) below the earths crust, and has the mantle in the way. The crust itself is only 30KM thick. [https://phys.org/news/2017-02-journey-center-earth.html] The crust is basically a thin layer of slag on top of a giant ball of molten everything.
Even at million+ year timescales, I can’t see any way the temperature of the upper crust could matter to the core at all - even if the crust was at absolute zero.
Dirt insulates relatively well, and the amount of thermal mass present is mindboggling.
> would be a rounding error above absolute zero anyway
Kind of joking: unless there are nonlinear effects near 300K? Fig 4 [1] seems to suggest that the thermal diffusivity of the mantle grows very fast as temperature declines past 300K... but the data stop at 200K.
Reason for initial comment: we could probably set up a spherical heat equation to guess how crust cooling would change heat conduction at the outer core. But I have absolutely no idea how to reason about changes in heat conduction affecting the convection dynamics that generate the field. I was silently hoping for one of the domain experts lurking this forum to see it and share wisdom. (But overall it was a silly question, I know).
Calculating or simulating how earths magnetic field behaves or is generated is quite a complex task. So im doubtful we can usefully estimate it to such precision. It would be interesting though.
We know that if the convection in the outer core stops, the Earth's magnetic field stops, and removing enough heat from the core will stop the convection.
My conclusion: Geothermal makes research into plate tectonics and earthquake mitigation considerably more valuable, so we can figure out how to do it in a way that reduces earthquakes rather than creating them.
I wonder, if we draw enough heat out... would the core cool enough to shrink? And if so, would the crust collapse to the new size?
Pure speculation of course, but did the first guy burning coal know the outcome?
Anyhow, I love geothermal, think you're right, but just got tweaked on the word "infinite".