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Comment by archon1410 | Hacker News Reader

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?

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

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.

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.

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.

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.

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.

> 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.

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

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.

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.

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