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Comment by Tuna-Fish | Hacker News Reader

There's not much geothermal available when you are standing atop the baltic shield.

Either fusion or drill baby drill is necessary. Watt’s steam engine was absolutely horrible, but it was the worst steam engine ever built. If Finland builds the worst deep geothermal ever that still works, we can hope for better ones.

Yeah I know drilling through ~8-10 kilometers of rock is kinda hard… they know, they tried, maybe it now is a good political climate to try again?

Or just fission, we know how to do that.

8-10km is not anywhere enough, the Baltic Shield is ~50km thick.

You don’t need to drill to magma, just deep enough to get to 120-130C rock. (‘Just’)

> Yeah I know drilling through ~8-10 kilometers of rock is kinda hard… they know, they tried, maybe it now is a good political climate to try again?

The Finnish 7 kilometer geothermal drilling failed commercially, I guess that's what you're referring to. Is there any reason to assume drilling deeper would work?

Ref. https://fi.wikipedia.org/wiki/Otaniemen_syv%C3%A4rei%C3%A4t

Yeah, that’s the one. Economics of this are hard - but money is numbers in computers, it’s just a question of how serious the government is with getting it done - physics-wise it gets like 10-15C warmer with every km, which is important for the delta T obviously. I know nothing about drilling the extra couple km, though, only assuming it can be done with enough engineering.

I understood that temperature wasn't the problem. How it works is that you pump water into one well, and get it out from an adjacent one. The main problem was permeability, they couldn't get the necessary flow rate between the wells.

Ah good to know, I for some reason thought it wasn't hot enough. Sounds like they need to figure out horizontal drilling 8km deep in volcanic rock.

They tried in southern Finland not long ago. At great expense and spending a lot of time they managed to drill down 6-7 km until they figured out that the porosity of the rock down there was so poor that it was impossible to make the project economical, so it was cancelled. The idea was to pump this heat directly into the district heating grid.

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