[archon1410]

Perhaps a stupid question, but... what are the risks? Wolndn't extracting too much energy from the earth's core cool it down, at least a little bit? Or does it contain so much energy that extracting it to replace all of 'surface generation' won't make even a little difference?

[whatshisface]

We can't drill anywhere near the mantle, geothermal extracts energy from the upper part of the crust.

[archon1410]

Wouldn't drawing energy from the crust cool it down, and wouldn't a cooler crust in turn 'draw' more heat from the lower layers? I guess the earth already radiates out a lot of energy, the process of extracting geothermal energy will presumably lead it to radiate more energy. I don't know by how much though, or if it will make any real difference, or if that's how it even works.

[__turbobrew__]

I guess if you could extract enough energy from the core it would reduce convection which would in turn reduce the strength of the earth’s magnetic field.

[renewiltord]

Look at a cross section of the Earth: https://www.britannica.com/science/oceanic-crust

The deepest bore of all time was 12 km deep. The crust is between 5 km and 100 km and thinnest under the ocean. The numbers involved here are staggering. One might as well hope to stop the Earth's winds with a windmill.

[Paradigma11]

I saw a documentary about some long running geothermal projects and basically the temperature in the well cooled down and made it uneconomical. They said they would have to wait, I think, 30 years for it to heat up again.

[numpad0]

Earthquakes! There are couple comments mentioning "fracking" around, that's destabilizing the land by injecting acid to get energy out. The acid is dangerous, and so are breaking up soil deep down.

[tylerhou]

> Wouldn't extracting too much energy from the earth's core cool it down, at least a little bit?

The earth generates ~50 terawatts of energy through radiation/other processes, while global energy consumption over the last year was 0.003 terawatts. I think we're fine.

[lurk2]

Where are you getting 0.003 terawatts? Another user elsewhere in the thread[0] claimed "Global total energy (not just electricity) consumption is currently 180,000TWh/year, or about 20TW."

Google is showing me other figures like 25,000 terawatt hours of electricity consumption annually.

[0] - https://news.ycombinator.com/item?id=43234856

[boxed]

One might also be careful to count energy properly. The fossil fuel industry has been counting "total energy" including losses to make fossil look bigger and harder to replace. But a gas car throws away like 70% of the energy, so going electric, you don't need the same energy to run the car. Not even close.

[tylerhou]

Oops, I missed the thousands. So 3 TW, which is larger, going by Google stats, and 20 TW by the other users. So that's not negligible.