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Finnish City Inaugurates 1 MW/100 MWh Sand Battery

(cleantechnica.com)
190 points erwinmatijsen | 2 comments | 03 Sep 25 06:00 UTC | HN request time: 0.001s | source
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arowthway ◴[03 Sep 25 09:02 UTC] No.45113659[source]▶
This is super cool but the ending is bizarre.

> A comment on the YouTube video below complained, “Not a word about return on investment in the presentation. That means it’ll never pay off” MAGAlomaniacs are everywhere these days.

Given the supposed 50+ year lifespan of such a battery, I find it hard to believe it doesn't turn a profit at some point. And I understand that debunking low-effort accusations is asymmetric warfare. But why cite a random YouTube comment if you have no intention of addressing its claims? A more charitable interpretation is that it's meant to ragebait the readers. But to me, it seems like trying to make people feel ashamed for having doubts, by making a public example of a skeptic.

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kragen ◴[03 Sep 25 11:18 UTC] No.45114440[source]▶
If, say, further insulating your house or building a sand battery will pay for itself in 50 years, it's a bad investment, financially speaking, and probably environmentally speaking as well. You can deploy "the same amount" of resources in something else with a higher ROI, like maybe solar panels with a one-year payback, and get a much bigger benefit. This is an important consideration as long as you are constrained by some kind of resource limitation.

So I think ROI is a first-order consideration.

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bryanlarsen ◴[03 Sep 25 11:56 UTC] No.45114692[source]▶
Finland is the only country in the world where solar isn't the cheapest form of electricity because they get so little sun and they have good alternatives.
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hulium ◴[03 Sep 25 12:39 UTC] No.45115007[source]▶
Certainly not the only country. Iceland is even more extreme in this regard and unlike Finland it is powered by 100% renewables, hydro and geothermal energy. In Finland the only good renewable alternative is wood/biomass.
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1. CRConrad ◴[05 Sep 25 13:08 UTC] No.45138113[source]▶
Actually, calling geothermal energy "renewable" is a bit of a misnomer, isn't it? At least if the heat energy in the Earth's crust, which is what "geothermal energy" harvests, comes from the inside. The Earth's core may not be cooling down very fast, but we know for sure it's not getting any warmer (not before the Sun in its death throes swells up into a red giant and swallows the inner planets, anyway).

Yeah, I know, super-nitpicky — but, hey, it's the Best Kind Of Correct™. (Unless the crust is actually heated more by the Sun than from below, but I doubt that.)

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2. kragen ◴[05 Sep 25 13:18 UTC] No.45138216[source]▶
Most geothermal energy comes from the decay of radioactive elements in the Earth's crust, although heat from Earth's formation is a non-negligible fraction of it. If you check out the web site of Iceland's geothermal energy agency, I believe they do have a calculation there of the sustainable power level that could be extracted (without cooling down the crust), but I don't remember if they're currently above or below it.

If I recall correctly, however, the fossil heat trapped in the crust under Iceland is several billion years of the sustainable extraction rate.

And, on the third hand, even if you only extract energy at the rate that radioactive decay produces it, in only a few tens of billions of years, most of the radioisotopes will have decayed away if you don't replenish them.

You are correct that the crust is heated more from below than by the Sun. That's why the bottom of the crust, where it contacts the mantle, is hotter than the surface.