The time has finally come for geothermal energy

It's nuclear fission. It's always been nuclear fission (well, at least since the '50s) and it will continue to be until we commercialize fusion reactors. Everything else is nice to have but it's like NIH syndrome.

Geothermal is fission, and wind, solar, and batteries are fusion at a distance. In both cases, the failure scenarios are benign vs traditional fission generation. It's fine to keep striving for fusion humans control, but the problem (global electrification and transition to low carbon generation) is already solved with the tech we have today. It took the world 68 years to achieve the first 1TW of solar PV. The next 1TW took 2 years. Globally, ~760GW of solar PV is deployed per year (as of this comment), and will at some point hit ~1TW/year of deployment between now and 2030.

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

Failure scenario in modern fission reactors is also benign. Reactors are designed to lock down to prevent any leaks.

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.

Ive been very pro nuclear my whole life, but a part of me is disheartened by the mega projects that commercial fission deployments have become (even if the reasons are bad) that’s a problem that nerfs traditional fission. If nuclear remains both political, extremely bureaucratic and requires public investment, it just won’t be the solution, and not because the tech or physics is bad, but the decision makers & investors can no longer organize large infrastructure projects effectively (except maybe China). This is not unique to nuclear.

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.

Enough renewables are deployed annually to replace the global nuclear fission fleet, year after year, even when accounting for capacity factor derating (to make a like for like comparison). The race is over, and renewables (with batteries) won. If you can find someone unsophisticated to invest in a fission reactor that takes billions of dollars and 10-15 years to build, more power to you. There will be no need for it by 2035-2040 when it prepares to send its first kwh to the grid.

(and to stay on topic for this thread, geothermal is a component of this when geothermal potential exists, cost is competitive, and dispatachability is a requirement to push out fossil generation in concert with renewables, hydro, legacy nuclear, battery storage discharge, and demand response)

https://www.google.com/search?q=baseload+is+a+myth

https://cleantechnica.com/2025/11/15/coal-killing-sodium-ion...

https://ember-energy.org/latest-insights/q3-global-power-rep...

https://ember-energy.org/latest-insights/solar-electricity-e...

https://ember-energy.org/latest-insights/solar-electricity-e...

https://world-nuclear.org/information-library/economic-aspec...

https://www.lazard.com/research-insights/levelized-cost-of-e...

https://ourworldindata.org/grapher/solar-pv-prices

https://ourworldindata.org/battery-price-decline

https://ourworldindata.org/data-insights/solar-panel-prices-...

https://news.ycombinator.com/item?id=44513185 (lfp battery storage cost citation in 2025)

Nuclear is great, but it does require wheelbarrows of cash, and we don’t have a solution for waste products.

Things are more expensive when we keep reinventing the wheel and trying to do new things instead of just reusing proven designs. Remember that solar power also used to cost wheelbarrows of cash back in the day. When you do something repeatedly, it becomes less expensive over time.

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.

Solar panels are recycled at almost 100% of total materials. Redwood Materials (founded by Tesla's former CTO) has already established a supply chain to ingest and recycle EV and stationary storage batteries at scale. The problem is that the hardware is lasting longer than expected, and meaningful recycling volume does not yet exist.

Conversely, ~95,000 metric tons of nuclear waste in the US does not have permanent storage or recycling solutions, as of this comment, and there is no plan for long term storage or recycling. Nuclear generation is experiencing a negative learning curve; we keep spending more the more we attempt to build it.

(solar PV panels have a 25-30 year service life, at which point they will still produce power at ~80-85% initial rating, batteries have a 15-20 year service life, with sodium ion chemistries estimated to have up to 50 year service life assuming once daily cycling)

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

https://www.cnbc.com/2025/11/09/nuclear-power-energy-radioac...

https://www.gao.gov/nuclear-waste-disposal

https://decarbonization.visualcapitalist.com/visualizing-all...

(nuclear power accounts for about 10% of electricity generation globally, as of this comment)

> If you can find someone unsophisticated to invest in a fission reactor that takes billions of dollars and 10-15 years to build

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-...

Nuclear has broad bipartisan support, and the Trump administration is heavily into it, so I wouldn't count it out just yet. If the various Green parties of the Western world ever come into power though, we are cooked.

They dabble in nuclear, but it is not their focus. China can do what the developed world cannot because they are a command economy with less expensive labor, which will only last for a bit longer due to their structural demographics. Unless the developed world no longer has labor regulations, developed world wages, and capital based allocation systems, my statement stands with regards to investment. If capital and labor does not matter, certainly, anything is possible (Paraoh demanding pyramids, for example).

Your citation comes from an organization with pro nuclear bias.

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

Can China Break Nuclear Power’s Cost Curse—and What Can the US Learn? - https://rooseveltinstitute.org/blog/can-china-break-nuclear-... - September 17th, 2025

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

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

Nuclear Energy & Free Market Capitalism Aren’t Compatible - https://cleantechnica.com/2023/11/06/nuclear-energy-free-mar... - November 6th, 2023

https://x.com/MoreBirths/status/1910780131318374524 | https://archive.today/iu9jx (China demographics citation)

It could be but the US and EU have so far been unable to build commercial fission reactors without going 2x+ over budget in time and money. China is having success but even they are not projected to have nuclear account for more than single digit percentages of their generation.

Maybe SMR's, thorium, 4th gen, etc will work out, but maybe not.

If France–a country known for its strong labour laws and unions–could transition to nuclear in the '70s, any Western country can do it.

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.

> Solar panels are recycled at almost 100% of total materials.

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.

> If France–a country known for its strong labour laws and unions–could transition to nuclear in the '70s, any Western country can do it.

France had to nationalize EDF because they could not afford the costs associated with their nuclear fleet. The 70s are 50 years in the past, and are not what the future will look like.

This is also why Spain plans to retire its remaining nuclear generators, and go all in on renewables.

EDF fleet upkeep will cost over 100 billion euros by 2035, court of auditors says - https://www.reuters.com/business/energy/edf-fleet-upkeep-wil... - November 17th, 2025

French utility EDF lifts cost estimate for new reactors to 67 billion euros - Les Echos - https://www.reuters.com/business/energy/french-utility-edf-l... - March 4th, 2024

Explainer-Why a French plan to take full control of EDF is no cure-all - https://www.euronews.com/next/2022/07/07/edf-nationalistion - July 7th, 2022

Spain’s Nuclear Shutdown Set to Test Renewables Success Story - https://www.bloomberg.com/news/articles/2025-04-11/spain-s-n... | https://archive.today/4fB7K - April 11th, 2025 (“Spain is a postcard, a glimpse into the future where you’re not going to need baseload generators from 8am to 5pm” with solar and wind providing all of the grid’s needs during that time, said Kesavarthiniy Savarimuthu, a European power markets analyst with BloombergNEF. Still, she said, there is a reasonable chance this goal may take longer than expected and “extending the life of the nuclear fleet can prove as an insurance for these delays.”) (My note: As of this comment, Spain has 7.12GW of nuclear generation capacity per ree.es, and assuming ~1GW/month deployment rate seen in Germany, could replace this capacity with solar and batteries in ~28-36 months; per Electricity Maps, only 17.25% of Spain's electrical generation over the last twelve months has been sourced from this nuclear)

Tangentially, Europe has enough wind potential to power the world, for scale.

The options in the '70s were much different from those of today. And for France specifically what they have underground (lots of uranium, no oil, no gas & no coal) strongly suggested exactly one way forward.

The US Navy consistently builds reactors on-time and in-budget

Look at Electricity Maps and realize that France is the only large industrial country where electricity generation is permanently carbon-free and cheap.

https://particulier.edf.fr/content/dam/2-Actifs/Documents/Of...

»Enough renewables are deployed annually to replace the global nuclear fission fleet, year after year, even when accounting for capacity factor derating (to make a like for like comparison).«

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.

Yes, but unfortunately that is because it is coasting on decades old labor and capital investment that will not be made again. It is not permanent, as it will cost tens of billions of euros to continue to operate those generators reaching the end of their service life.

»Your citation comes from an organization with pro nuclear bias.«

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.

Wind and solar existed in the 70s as well.

Plus, Germany invested 500 billion Euros in its energy transition and is STILL heavily dependent on coal.

Personally, I've invested ~500k EUR in a Portuguese Golden Visa fund invested in renewables (IRR is ~7-13%). Macro speaking, renewables investments keep hitting new records. I am convinced, and if you are not, I would strongly suggest consuming more data, because you appear to have a potential blind spot in your mental model on this topic.

https://about.bnef.com/insights/clean-energy/global-renewabl...

https://www.bloomberg.com/opinion/articles/2025-10-28/white-...

»It could be but the US and EU have so far been unable to build commercial fission reactors without going 2x+ over budget in time and money.«

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.

Norway, Iceland and British Columbia are other examples and are more carbon-free than France is. The latter isn't a country and the former don't count as "large industrial"?

There’s something to be said for a standardised design with replaceable parts.

But that illustrates the point. Most investors don’t want to put money towards something that may be put on indefinite hold depending on political winds. These projects are often much longer than presidential terms.

> Wind and solar existed in the 70s as well.

Not really. Solar has gone down in price almost 500X since 1975.

https://ourworldindata.org/grapher/solar-pv-prices

Wind has gone down significantly too.

https://docs.nrel.gov/docs/fy12osti/54526.pdf

Meanwhile, the graph for nuclear waste disposal is going rapidly in the opposite direction.

https://www.ans.org/news/article-6587/us-spent-fuel-liabilit...

http://large.stanford.edu/courses/2024/ph240/kendall1/

A nuclear plant about 50 miles from my house was closed 15 years ago. The spent fuel rods will be stored there indefinitely until a federal facility is built.

They’re at ~60% total power from renewables in 2025, and increasing every quarter. I’d say they’re doing pretty well! The coal is unfortunate, but was due to the Ukraine war and gas situation.

50+ years ago, not relevant.

Solar + wind is being installed at about 100x the rate of fission because it's so expensive. And the differential is only increasing.

installs: https://www.pv-magazine.com/2025/01/13/the-fastest-energy-ch...

costs: https://www.reddit.com/r/energy/comments/11q58pe/price_trend...

> Wind and solar existed in the 70s as well.

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.

Solar panels do not become useless in 25 years and need to be discarded, do not leach toxic chemicals, and do not contain cadmium. They do contain small amounts of lead, but leaching metallic lead out of landfills is very difficult and probably does not ever happen unintentionally.

The US and Russian Navies deciding to remain mostly petroleum-fueled is one of the strongest arguments against nuclear becoming very cheap: surely they would do it if it wasn't ruinously expensive, because it eliminates the national security risk of a petroleum blockade and simplifies at-sea logistics immediately.

Don't presume too much about the US Navy's fleet decisions. Using that same logic you could presume that smaller, aged and poorly maintained fleets are advantageous for naval supremacy since that appears to be the choice of the US Navy for a couple generations now.

Or you could presume that the complete inability to build a merchant marine fleet was also a strategic advantage!

68 years ago we already had fission plants. the engineering side of energy production has been solved since then, it's all political now

that seems fine

I don't know much about militaries or nuclear reactors, but I know that reactors are used in some submarines and in some aircraft carriers -- situations where you want a vessel to to remain at sea for long periods of time without refueling, and weight is not a primary concern.

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.

> Geothermal is fission

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.)

It's not just the US Navy. It's also the Russian Navy, the French Navy, the Chinese navy of the PLA, the British Navy, the Indian Navy. If nuclear power were cheaper than oil, or anything other than much more expensive, at least one of those would have gone all-nuclear.

Pellworm is something like 95% renewable without storage. That really doesn’t sound like failure to me.

That could possibly be true, if fission is cheaper than solar, wind, and batteries.

The renewables are so cheap and quick to provision it's hard to see how fission can compete.

I dunno. Even China, which has built a lot of nuclear, is building way more renewables. Do you think they have it wrong somehow?

'The most common reason that solar panels would be determined to be hazardous waste would be by meeting the characteristic of toxicity. Heavy metals like lead and cadmium may be leachable at such concentrations that waste panels would fail the toxicity characteristic leaching procedure (TCLP)'

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/...

No, it makes sense because it's cheaper. At least, it is if we ignore the negative externalities and the future costs of maintenance of the infrastructure. Time will tell.

Yes, all of that is correct as far as it goes, and isn't in contradiction with what I said. You'll notice that the EPA page you linked https://www.epa.gov/hw/end-life-solar-panels-regulations-and... is mostly about an effort to reclassify solar panels as non-hazardous waste, which is specifically because of what I said. See for example https://www.sciencedirect.com/science/article/pii/S030147972... "About 8% of traditional PV samples exceed the 5 mg/L limit for Pb in TCLP tests. No modern PV samples exceed the 5 mg/L limit for Pb in TCLP tests."

But TCLP is already an extremely rigorous test, far worse than nearly all actual landfills, intentionally. It uses acetic acid, one of the very few acids that forms a soluble salt of lead, and none of the anions present in normal soils that normally immobilize lead, such as carbonate, phosphate, sulfate (!), and chloride.

And air pollution from pyrometallurgical recycling of the kilogram quantities of lead from car batteries is totally irrelevant to the safe containment of the milligram quantities of lead from (probably hydrometallurgical) recycling of solar panels. I am really struggling to imagine how your understanding of the issue could be so shallow that you thought it might be relevant.

Scrap lead is like US$1/kg. Nobody is going to recycle solar panels for that.

The Aircraft Reactor Experiment https://en.wikipedia.org/wiki/Aircraft_Reactor_Experiment, yielding 2.5 megawatts, was about two meters tall and one meter in diameter; the fuel was 15kg of U-235, but I think the reactor as a whole may have weighed several hundred kg. (It couldn't have been more than about 40 tonnes, just because no material would be dense enough, but I think it was much lighter than that.

Oh, here it is: https://media.githubusercontent.com/media/openmsr/msr-archiv... page 24/139 budgets 48400 "pounds" for "reactor and reactor shield", which is 22 tonnes, about 110kW/tonne.

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, 50kW/tonne, while the 100MW version was 500 tonnes, thud 200kW/tonne: 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 have 80MW of propulsion and displace 8300 to 9700 tons, compared to which the SSTAR's 500 tonnes is almost insignificant. So weight isn't an issue for ships, and weight doesn't get ridiculously high until you're down below the megawatt scale.

So, you may be right that existing proven reactors won't scale down to a single truck or tank. There isn't a known physical reason it's impossible, or even impossible to do safely, but it hasn't been achieved.

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. And we've certainly seen that many militaries have little concern for sailor safety.

Despite all this, no navy has switched all their ships to nuclear fuel. The only explanation I can come up with is that it's unsustainably expensive.

Forever is a long time.

The US Navy doesn't build them, private companies do. None of the SMR companies that I am aware of have attempted to use designs from naval reactors. Perhaps it has something to do with the fact that they use highly enriched fuel which is a no-no for civilian reactors.

In any event, if your more general point is that naval reactors indicate its possible that SMRs can be built on time and budget, I don't disagree. It certainly is possible. NuScale was the furthest along of the SMR companies and had their project implode before it got off the ground. So, its also possible for them to crash and burn.

So, I'll stick with my classification of SMRs as "maybe it will work out, maybe not".

they're in big concrete containers rated to withstand everything its fine