The time has finally come for geothermal energy
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thoughtful
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mixed
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science
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geothermal energy
renewable energy
sustainable power
The article discusses the growing potential of geothermal energy as a reliable source of renewable power, with comments debating its feasibility, scalability, and potential drawbacks.
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11/17/2025, 1:55:53 PM
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> There aren’t gates of Hell just anywhere. A kilometre below ground in Kamchatka is considerably hotter than a kilometre below ground in Kansas. There is also readily accessible geothermal energy in Kenya (where it provides almost fifty per cent of the country’s energy), New Zealand (about twenty per cent), and the Philippines (about fifteen per cent)—all volcanic areas along tectonic rifts. But in less Hadean landscapes the costs and uncertainties of drilling deep in search of sufficient heat have curtailed development.
It's also quite hard to find suitably hot rocks suitably close to the surface.
Focusing on fusion .. I think that's a legacy of 60s SF, when the fission revolution was still promising "energy too cheap to meter".
In a world where anyone could just YOLO any reactor into production with minimal red tape, consequences be damned, fission energy would actually be extremely cheap. Hence the optimism around fusion. The promise of fusion is an actualization of last century's idealistic conception of fission. It can be a silver bullet for all intents and purposes, at least once it's established with a mature supply chain.
At worst, nuclear waste contaminates a discrete section of the Earth. Climate change affects literally everywhere. The correct answer would have been to aggressively roll out fission power 40-50 years ago and then pursue renewables. You can argue that other solutions would make fission power obsolete, but we would have been in a much better spot if it'd at least been a stepping stone off fossil fuels. Instead, we have 40-50 years of shrieking and FUD from environmentalists over an issue that can be kept under control with proper regulation. The US Navy has operated reactors for over 60 years without incident, proving it can be done with proper oversight.
Denser urban living is pretty energy efficient, and forcing lengthy commutes on people because of NIMBYism is a huge waste.
Similarly, better to have people be able to have reasonably energy-efficient houses than demanding they all live in apartments.
(Source needed.)
Plenty of people in dense urban areas are happy with living in an apartment and, where I live, buying a condo in the city is at least as frequent as buying a house 20 km away from it for the same price.
Living in suburbia has its downsides - long commute, very limited entertainment and cultural possibilities, very limited choice in schools. Not everyone loves cutting the lawn etc. either, I surely don't.
Of course, a lot depends on factors such as "is the transport authority willing to make public transport actually safe and nice". That requires keeping raving drugged lunatics out of it, plus paying enough money for it. AFAIK in the US, Republicans have an ideological problem with the "paying money for it" part and the Democrats have an ideological problem with the "suppressing antisocial behavior in it" part.
Reversing the downzoning of the 70s - 00s is about allowing construction in cities again.
The only ones demanding anything are those who show up to try and stop apartments.
Chernobyl took out Welsh farming for years, and in a few places decades, because it spread a thin layer of bioaccumulative poison over the whole of Europe.
Know what else spreads a thin layer of poison over the whole of the world? Coal power.
Democracy just as lazy and apathetic is whatever the USSR counts as; the point of capitalism (which is different to democracy) redirect the laziness into something more productive — this works to an extent, but depends on competition which is greatly reduced in the case of nuclear reactors.
This is also why the not-at-all-democratic military reactors around the world seem to be doing fine.
I wasn't really commenting on the merits of 20th century environmentalist movements, more raising the general point that fission power has inherent costs which aren't immediately obvious from a narrow analysis of how much energy is extractable from U-238. Operation of a fission plant requires much more capex and staffing/opex than it would if we didn't care about cleanliness (waste management), security (fissile material theft prevention), or safety (meltdown prevention).
Fusion power is more complex to invent and practically depends on modern technologies that didn't exist 50 years ago, but once the first demonstration plants are operational, marginal costs to deploy and operate more should be much lower and become very low at scale.
That's basically it. Most geothermal plants today are in locations where there are hot rocks, maybe geysers, close to the surface. "Deep geothermal" gets talked about, because temperatures high enough for steam are available almost everywhere if you can drill 3,000 meters down. There are very few wells in the world that deep, not counting horizontal drilling runs.
The economics are iffy. You drill one of the most expensive wells ever drilled, and you get a medium-pressure steam line. Average output is tens of megawatts.[1]
[1] https://pangea.stanford.edu/ERE/db/GeoConf/papers/SGW/2020/A...
I went to high school with two guys who are working on geothermal as a means to remediate orphan wells. I’m biased in their favour, but the numbers make a lot of sense.
The worst earthquake that was induced that way was 3.5, but given that one of the quakes happened in an area that had a catastrophic earthquake in the Middle Ages, some caution might be warranted: https://en.wikipedia.org/wiki/1356_Basel_earthquake
Ground-source heat pumps extract about 1000 times more power from ground loops, where does the difference come from?
https://www.withouthotair.com/c16/page_96.shtml
The problems are that rock isn't a good conductor of heat, so once you've cooled a bit down, you have to wait for it to warm up. Warming only happens very slowly at the rate of < 50mW / m² which limits the amount of power you can get out.
If economically viable fusion was "cracked" what would the nature of it's unreliability even be?
The reactor breaks because it's a large device operated at high stresses (power/area, neutron loading). There are many components and joints that can fail.
BTW, this means fusion will be expensive, because getting all those components to be reliable right off the bat becomes expensive. No tiny cracks in the welds means expensive quality control.
Since you're comparing it to nuclear, I'm assuming you mean electricity production here, not energy production?
It's always worth remembering that electricity only accounts for ~20% of global energy consumption (in the US it's closer to 33%).
I suspect people confuse these two because in a residential context electricity plays a huge part of our energy usage, but as a whole it's a smaller part of total energy usage than most people imagine.
But any serious discussion of renewable energy should be careful not to make this very significant error.
The Lawrence Livermore National Laboratory publishes a great diagram of US energy use: https://flowcharts.llnl.gov/sites/flowcharts/files/2024-12/e...
Great chart, by the way.
When I drive my daughter to school when it’s -40 fucking degrees, a lot of the energy I use goes into heating my vehicle, swearing, moving and swearing. But this energy also leaks through my windshield, through my exhaust system and through my engine. This energy (heat) doesn’t provide any benefit to anyone and just leaks out into the atmosphere (which we’ve already established is trying to kill me).
That’s rejected energy. Or when it’s below -40, rejected motherfucking energy. :)
I managed to get to a gas station with some stop leak in stock... If they didn't, I was ready to crack an egg in it.
Sounds like a very unique experience :)
The 1 megajoule of useful electricity is also ultimately dissipated as low grade heat, but it can do work first (like generating light, or pumping water uphill).
Which (not sure if you did this intentionally or accidentally) brings up an interesting point on the parent comment and the LLNL sankey:
> It's always worth remembering that electricity only accounts for ~20% of global energy consumption (in the US it's closer to 33%).
That "global energy consumption" figure includes a lot of Rejected Energy going out tailpipes and smoke stacks turning burnables into electricity. A secret bonus of wind and solar is if you produce electricity without burning things, you actually decrease the energy demand! If you're not losing 70% of your energy consumption to the Rejected category, you suddenly need a lot less total energy.
So even in a residential context, electricity is only about 1/4 of the demand. Across the whole country it's less than 300TWh out of 1500TWh, under 20%.
That excludes "imported energy" though, as in goods which used energy to make but were then imported.
Driving can push up the low points (charge cars overnight), but heating would put a lot of demand in winter months, meaning a day time cold day in January with no wind will require a lot of dispatchable electricity, at night time in September with a gale blowing wind will be providing almost all the demand.
Nuclear doesn't really help as it's more expensive than the wind when it's windy and demand is low, and its impossible to build enough to cover the peak January demand unless you spread the fixed cost over the entire year, which means getting rid of every other form of electric production, and you'd still end up paying more per kWh than you would with other forms of storage.
Nuclear can't survive in a free market. It can't scale up to provide for areas of high demand, low supply, and it can't scale down to be affordable when there's high supply and low demand.
I like how David Hamel put it: We live in this thin sliver on the surface of the planet where it is reasonably peaceful. This is the tranquility! It's a good thing! If you go up or down by a mere few miles there is so much energy it kills you.
citation needed
> “West Virginia has numerous coal plants that have powered this country for decades. We need these plants to remain operational,” [WV Governor] Morrisey said. “… We will never turn our backs on our existing coal plants and we will work with the federal government to pursue new coal-fired generation.”
https://westvirginiawatch.com/2025/09/11/morrisey-shares-new...
https://wvpublic.org/story/energy-environment/data-center-bi...
https://www.wvlegislature.gov/Bill_Status/bills_text.cfm?bil...
Also, due to solar not panning out at scale.[1]
More seriously, coal is just cheaper and, with incentives being removed for green energy, it's the cheapest and fastest option to deploy. It's dead simple and well understood reliable power.
[1]https://apnews.com/article/california-solar-energy-ivanpah-b...
Direct solar continues to be installed at greater amounts every year and coal is economically uncompetitive with basic anything (which is why it is collapsing), and especially against natural gas.
On twitter I saw someone claim PV is useless for heat because non-PV solar water heating is just so much more efficient. Not even true (I think it's a approximately a wash, different advantages in different applications), but very strangely in the weeds on a specific topic. Much too narrow a factual context to substantiate general level claims about solar as an energy writ large.
I think for whatever reason the missing the forest for the trees trap is really potent in energy discussions.
They either have only read propaganda pieces from fossil fuel producers or are trying to create some of those.
I would expect the number of people that honestly don't know anything but propaganda to be way higher than the number of people creating propaganda. But there's probably a selection bias due to HN being a somewhat large site with some influence on SEO and AI training.
Solar+storage is not a solved problem. The storage problem gets continually hand waived away in the conversations about how cheap solar is.
As I said in a sibling comment, I don't think the people running energy companies are stupid. If solar really was cheaper as a baseline power supply, what it needs to be to replace fossil fuels, they'd be doing it.
So, you haven't looked at what energy companies are doing for the last 3 years...
With the way power demand is growing, new fossil plants aren't being built really because renewables can pick up a lot of the new demand but solar is at the point in some places where utilities don't want your excess power.
Renewables are great in the places they fit but they don't fit everywhere.
Methane, yes. The coal plants are being slowly shut down, as they are too expensive to run even after they were paid for.
You also seem to ignore the huge amount of utility-level PV farms and generation-side storage built recently. You are technically correct in that renewables don't fit everywhere, but that's again a common propaganda phrase because they fit the places where almost everybody lives, and long distance transmission already solves the problem for most people outside of that area.
So why focus on the unrepresentative cases, unless the intent is to be misleading? There'd better be a very good reason for being willing to court such misunderstanding that's more substantive than a random aside to tee effect of "gosh renewables, gee, I don't know. Denmark sure has a lot of renewables already, don't forget about that." It's the "You Forgot Poland" of the 2020s.
At lower capacity because their generation is being actively offset by renewables.
Your framework is bizarre in the extreme. Despite the fact that no one thinks of mirror plants as having anything to do with the future of PV generation, you treat the future of all solar as if it hinges on that consideration. Meanwhile, back in reality, solar power could realistically occupy up to 30% of the grid's energy generation capacity without intermittency becoming a deal breaker. Combine that with the fact that the grid itself is going to continue to grow, and so 30% of whatever that future amount of total generation capacity is going to be a rather extraordinarily high number, solar is going to be an exceptionally important part of the energy generation picture in the future even if we never made an inch of progress on solving the intermittency problem.
So again, it's bizarre in the extreme to take that picture, which is about billions of dollars of grid capacity, and swap that out for a hypothetical relating to mirror plants, which is never going to happen in which no one is seriously entertaining, and to treat that question like it's decisive about the fate of solar power in the future.
This is what I mean about people coming out of the woodwork and treating big picture energy questions like they hinge on these bizarre idiosyncratic hypotheticals that have nothing to do with anything.
That solar plant you linked is an obsolete experimental technology. Obsolete because regular PV became so much cheaper.
I see yow it can read that way but it isn't what I said. Coal plants exist, either shuttered or running low loads due to financial incentives (not favoring them).
Studies show solar is cheaper but businesses continue to choose coal. I think the entity who's entire existence depends on them making the correct financial choice is a much better indicator of economic reality than a study made by people who have zero stake (at best) in the game.
I'm all for green energy but I also don't think people are stupid.
What businesses are choosing coal?
The LED bulbs I have access to (whatever's in the aisles at Home Depot, Costco, etc.) fail much more frequently than the incandescent bulbs I used to buy, and produce an uglier light that is less warm even on the softest/warmest color settings.
My suspicion is that incandescents were at the "end" of their product lifecycle (high quality available for cheap) and LEDs are nearing the middle (medium quality available for cheap), and that I should buy more expensive LED bulbs, but I still think that there are valid "complaints" against the state of widespread LED lighting. I hope these complaints become invalid within a decade, but for now I still miss the experience of buildings lit by incandescent light.
The other thing with AI--the LED revolution was led on this idea that we all need to work as hard as we can to save energy, but now apparently with AI that's no longer the case, and while I understand that this is just due to which political cabals have control of the regulatory machinery at any given time, it's still frustrating.
Do they fail more than incandescents? idk maybe not, but they fail much more often than their advertising would suggest.
LED lamps work just fine, you just need to pay more attention when you’re buying them. Philips makes decent LED lamps.
Make sure you’re buying lamps with 90+ CRI, that will help with the quality of light. 2700K is a good color temp for indoor living room/dining room/bedroom lighting, 3500-4000K for kitchen/garage/task lighting.
You also need to buy special lamps if you put them in an enclosed fixture, look for ‘enclosed fixture’ rated lamps. Regular LED lamps will overheat in an enclosed fixture.
Look for ‘enclosed fixture rated’ LED lamps for enclosed fixtures.
I figured out why this happens.
The light color they call "daytime" is around 5000K, so I expected it to look like being outside in the sun; but instead I got a cold blueish vibe. The problem? Not enough power! I got the equivalent of a moonlit room.
So I got this 180W LED lamp (that's actual 180W, not 180W equivalent) [1]. It's so bright I couldn't see for 5 minutes. I put two in my office on desk lamps. The room now looks like being outside, without the "ugly blue" tint, even though the product says it's 6000K. The days of my SAD suffering are over!
None of this will change the CRI.
Assuming zero growth in energy consumption (hello AI), extracting even half of that seems like it would be consequential.
Looks like it's more like 200,000Twh / Yr
"Geothermal energy" involves drilling down to hot rock to tap intense heat to run a turbine that produces electricity.
Geothermal is a great fit for dispatchable power to replace coal and fossil gas today (where able); batteries are almost cheaper than the cost to ship them, but geothermal would also help solve for seasonal deltas in demand vs supply ("diurnal storage").
https://reneweconomy.com.au/it-took-68-years-for-the-world-t...
https://ember-energy.org/data/2030-global-renewable-target-t...
I also love geothermal for district heating in latitudes that call for it; flooded legacy mines appear to be a potential solution for that use case.
Flooded UK coalmines could provide low-carbon cheap heat 'for generations' - https://news.ycombinator.com/item?id=45860049 - November 2025
We deploy solar PV capacity, this doesn't mean we actually get that much power from the deployments. Nuclear fission provides reliable, baseload power, and doesn't require huge battery arrays to compensate for the sun setting or winds calming.
Unsophisticated investors like the Chinese government? 'Nearly every Chinese nuclear project that has entered service since 2010 has achieved construction in 7 years or less.'
https://thebreakthrough.org/issues/energy/chinas-impressive-...
China is installing the wind and solar equivalent of five large nuclear power stations per week - https://www.abc.net.au/news/science/2024-07-16/chinas-renewa... - July 15th, 2024
Nuclear Continues To Lag Far Behind Renewables In China Deployments - https://cleantechnica.com/2024/01/12/nuclear-continues-to-la... - January 12th, 2024
China built more solar power in the last 8 months than all the nuclear power built in the entire world in the entire history of human civilisation. And even if you adjust for utilisation rate to compare against nuclear utilisation China built more solar power generated per hour than all the nuclear power currently in operation generate in an hour - and did so in 12-18 months - https://bsky.app/profile/climatenews.bsky.social/post/3lggqu... - January 23, 2025
Even if the Western world lags behind due to labour regulations, the cost still pays off in the long run due to overall less complex infrastructure and stable, AC baseload power. You are thinking only about the cost of building. What about the cost of maintaining all that infrastructure? Huge solar and wind farms spread out over vast areas, essentially destroying the local ecology? NPPs have a relatively tiny footprint.
Every cited source has a bias. You think 'Clean Technica' is unbiased? Come on.
Plus, Germany invested 500 billion Euros in its energy transition and is STILL heavily dependent on coal.
This is basically nonsense to the extent that it is becoming difficult to extend the presumption of good faith to you. In the 70s solar panels cost US$25+ per peak watt, in 02021-adjusted dollars: https://en.wikipedia.org/wiki/Solar_energy#/media/File:Solar...
Now they cost 5.9¢ per peak watt: https://www.solarserver.de/photovoltaik-preis-pv-modul-preis...
Installing a gigawatt of solar power generation capacity for US$25 billion is in no way comparable to installing a gigawatt of solar power generation capacity for US$59 million.
Wind power has experienced a similar but less extreme cost decline.
https://ourworldindata.org/grapher/solar-pv-prices
Wind has gone down significantly too.
https://docs.nrel.gov/docs/fy12osti/54526.pdf
It seems like you're going out of your way to be misleading.
https://www.reuters.com/business/energy/edf-fleet-upkeep-wil...
Go and throw all your money into renewables stocks and ETFs if you’re so convinced.
I bet you’re not doing that because you realize that the industry isn’t doing well and it’s nuclear power nowadays where all the money goes.
https://about.bnef.com/insights/clean-energy/global-renewabl...
https://www.bloomberg.com/opinion/articles/2025-10-28/white-...
Wind and solar do not replace conventional power plants and never will.
Heck, Germany tried that on the small island of Pellworm and failed and yet some people think this will work out for the whole country.
It does not work.
Nuclear is actually the leader in waste management. No other energy source has as complete a story. Eg what happens to solar panels when they EOL in 25 years? They go into landfills and leach toxic chemicals into the ground. These chemicals, like lead and cadmium are toxic forever. They have no 'half-life' in which their toxicity reduces.
https://www.epa.gov/hw/solar-panel-recycling
https://www.energy.gov/eere/solar/articles/beyond-recycling-...
https://e360.yale.edu/features/solar-energy-panels-recycling
That's very clever wording. If someone glances at this sentence they might interpret it to mean that almost all solar panels are recycled. But your own citation tells a different story: https://e360.yale.edu/features/solar-energy-panels-recycling
> Today, roughly 90 percent of panels in the U.S. that have lost their efficiency due to age, or that are defective, end up in landfills because that option costs a fraction of recycling them.
Let's compare to spent nuclear fuel, which we know for sure does not end up in landfills. I am talking about today, not some hypothetical utopian future. Today, NPP spent fuel is safely sequestered while solar panels are dumped into landfills.
> nuclear waste in the US does not have permanent storage or recycling solutions
It does, it's just not built yet because it doesn't make sense to do it now. In a few decades, maybe a century we will have commercialized fusion reactors. Once we do, we switch to fusion completely and build the deep geological repositories or whatever other solution makes sense then. Or we can even recycle the spent fuel–the only thing stopping us from doing that now is misguided US politics (as usual).
> we keep spending more the more we attempt to build it.
It's capex. We are investing in nuclear technology. If you have a proven design and build the reactors at scale, the costs will flatten or decline, which is obvious to anyone who knows about economies of scale.
https://www.epa.gov/hw/end-life-solar-panels-regulations-and...
'Today, roughly 90 percent of panels in the U.S. that have lost their efficiency due to age, or that are defective, end up in landfills because that option costs a fraction of recycling them.'
https://e360.yale.edu/features/solar-energy-panels-recycling
And for good measure: 'Recycling Lead for U.S. Car Batteries is Poisoning People'
https://www.nytimes.com/interactive/2025/11/18/world/africa/...
https://particulier.edf.fr/content/dam/2-Actifs/Documents/Of...
Geothermal is not nuclear fission. The heat comes from a combination of primordial heat (from the gravitational energy turned to heat as the Earth formed) and radioactive decay (which is some combination of alpha and beta decays; spontaneous fission is extremely rare.)
Having smaller scale local power generation, whether it’s SMRs, solar, wind or geothermal, there’s a huge advantage in terms of economy, investment, and politics.
Maybe SMR's, thorium, 4th gen, etc will work out, but maybe not.
Or you could assume that the complete inability to build a merchant marine fleet was also a strategic advantage!
That's pretty niche, though. Think about trucks, tanks, aircraft, generators for outposts, etc. It might be cool if you could safely package a zillion nuclear reactors for those use cases, Terminator style, but I'd guess that reactors are a better fit for centralized, permanent power generation.
The smallest nuclear submarine was NR-1, which had a total displacement of 400 "tons": https://en.wikipedia.org/wiki/American_submarine_NR-1 so the reactor must have weighed less than that.
The 10MW version of SSTAR was supposed to weigh 200 tonnes: https://en.wikipedia.org/wiki/Small,_sealed,_transportable,_...
A 4.95-kg americium thermal reactor design outline has been published: https://www.researchgate.net/publication/239521070_The_Small...
Arleigh Burke class destroyers displace 8300 to 9700 tons, so weight isn't an issue for ships.
Probably you are right that many small reactors would be more dangerous, but warships exist so that they can go into dangerous situations. You have to weigh the risk of a reactor problem against the risk of being unable to fight because you have no fuel.
The EU also forgot how to build airports and train stations on budget and on time.
Should we stop building airports and train stations?
As for nuclear power plants: Germany and France built most of their reactors on budget and on time.
The renewables are so cheap and quick to provision it's hard to see how fission can compete.
installs: https://www.pv-magazine.com/2025/01/13/the-fastest-energy-ch...
costs: https://www.reddit.com/r/energy/comments/11q58pe/price_trend...
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