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Comment by xcskier56 | Hacker News Reader

Iceland has boiling hot water at the surface and so doesn’t need to drill far to reach hot rocks do to all the volcanism there. This does not apply to the vast majority of the world

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Well the question was "Iceland has profitable geothermal, no?" and your answer appears to be yes. Which is important because it means the upshot is that there are viable applications, which contrasts against the argument that lack of generalized solution means we need to reject it wholesale.

The point likely was that even though both are "geothermal" they aren't really in the same category, so facts about one may not apply to the other.

Here's a link to a map of geothermal hotspots comparable to Iceland. There seems to be a lot in the same category.

https://www.edengeothermal.com/about/geothermal-energy/world...

Not quite.

The original comment (by @animats) specified shallow (viable) versus deep (unviable).

> nobody seems to have a profitable deep geothermal power operation.

That nuance got lost.

The original comment stated that shallow geothermal can be useful for heating, but did not say anything about shallow geothermal electricity generation.

No.

See the first paragraph. [0] The reference explicitly gets into "deep geothermal" (i.e., EGS) and talks about power applications that are viable because of limited drilling (i.e., shallow).

> The more than 1 gigawatt of geothermal power currently produced globally — from California to Iceland to the Philippines — relies nearly exclusively on such natural outpourings of the earth’s heat.

The building heat comment is just a reference to another residential/C&I application with ground loops. They're not dismissing or not acknowledging the grid-scale power applications.

[0] https://news.ycombinator.com/item?id=43234465

"Shallow geothermal for building heat works fine, but it takes a lot of drilling just to get some heat."

From my understanding, this is all the original comment says about shallow geothermal. Correct me if I am misunderstanding.

Moreover, I do not see the quote: "The more than 1 gigawatt of geothermal power currently produced globally — from California to Iceland to the Philippines — relies nearly exclusively on such natural outpourings of the earth’s heat" anywhere.

Are we referring to the same comment, or am I misunderstanding something?

You're right that that nuance got lost and I'm sorry I overlooked it.

Insofar as it relates to the commenter I'm replying to, they also seem not to be making a distinction about deep geothermal, but insisting that the difference between Iceland and the rest of the globe is an indictment of geothermal's viability deep or otherwise. Which doesn't follow.

Perhaps, but "we can make a viable geothermal plant, as long as it's in Iceland" doesn't really help with widespread deployment.

Iceland is one of several geothermal "high temperature zones", other zones include effectively the entire West Coast of all of North and South America, including Alaska, as well as a zone stretching from the Mediterranean through the Red Sea that encompasses basically every European country with Mediterranean coastline. There's a major zone stretching from India through Southeast Asia and a separate independent one basically going along the whole western perimeter of the Pacific Ocean.

Geothermal is currently deployed in 32 countries and is regarded as the most abundant source of renewable energy outside of solar, impressively ranking ahead of wind.

So I think the most charitable interpretation of Iceland's example is that it represents one of many regions where geothermal is viable.

Are deepsea power cables from Iceland feasable or they'd have to store it as ie. hydrogen to send over?

Feasable, and the concept has been proposed, but doesn't look likely to be built in the near future. There are still lower hanging (more profitable) fruit when it comes to building undersea HVDC cables.

https://en.wikipedia.org/wiki/Icelink

Seems like one might hold off on underseas power cables until we figure out how to keep Russian and Chinese ships from having so many accidents.

power cables are a lot less vulnerable than fiber since cutting a cable carrying 500kv DC will do nasty things to whatever you're trying to cut with

Estlink 2 (650MW, 450 kV) has been cut twice in a year, with months-long outages in both cases.

Iceland exports carbon free electricity in the form of aluminum.

It's not carbon free. Iceland's geothermal fields have carbon emissions because gasses trapped beneath the surface are released along with the steam when they're extracted. It's still low-carbon compared to a natural gas power plant, of course, but not compared to wind/hydro/nuclear.

And aluminium production is certainly not carbon free: the smelting process reduces aluminium oxide to aluminium metal using carbon electrodes, producing around 14 tonnes of CO2 per tonne of aluminium.

The point is that smelting the aluminium takes tons of electricity, so doing it in Iceland where that's produced via geothermal is effectively exporting that electricity.

And it’s a relatively light material. So if you’ve got some place where the carbon footprint of collecting and transporting bauxite is relatively low, you can use excess power to smelt more aluminum.

The problem with opportunistic loads like wind and solar is whether you can afford to strand expensive factories full of equipment for hours or days at a time while the power availability is compromised. At least with geo this is a smaller problem.

It's actually the reducing of the alumina (aluminum oxide) to metallic aluminum that takes huge amounts of electricity. And as mentioned, that is done with carbon electrodes which are consumed in the process, leading to relatively high CO2 emissions. Though yes, if that electricity would be produced by burning fossil fuels the emissions would be even higher. So it's not like there aren't big benefits to doing aluminum refining in Iceland, or other places with low-emission electricity.

There is some R&D work going on though to do this reduction step without CO2 emissions using other electrode materials, see e.g ELYSIS.

> "It's actually the reducing of the alumina (aluminum oxide) to metallic aluminum that takes huge amounts of electricity."

AKA: "Smelting"

Depends on the source of that carbon

Good point about releasing co2 from the reservoir, thanks for the correction.

I did not maintain that the aluminum was carbon free.

We do have the technology to build HVDC cables from Iceland to Britain / Norway and we can expect the loss of this grid-to-grid interconnect to be < 5%. It's a different question entirely if it is feasible. It would be the longest sub-sea power cable ever, and the projected cost of $4 billion might be much too low.

In the current situation Europe would profit immensely by sending excess renewable energy to Iceland's pumped hydro and Aluminium smelters while using their geothermal baseload capacity. But in 15 years that might no longer be the case and by then the investment would not have paid off and there might be regret that the money wasn't spent on a different HVDC line like another North Africa - Europe link or Bulgaria - Caucasus (which has a lot of undeveloped hydro potential).

US has quite a few hot springs, especially in southwestern states.

SciShow did an interesting video on geothermal potential/drawbacks of Yellowstone. https://youtu.be/rqkJiMDAIpA

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