[epistasis]

There's currently no technological path for fusion to be cheaper than fission. It would require a technological breakthrough that we have not yet imagined.

And already, solar plus storage is cheaper than new nuclear. And solar and storage are getting cheaper at a tremendous rate.

It's hard to imagine a scenario where fusion could ever catch up to solar and storage technology. It may be useful in places with poor solar resources, like fission is now, but that's a very very long time from now.

[noosphr]

The low energy future that was envisioned is not happening.

The AI arms race, which has become an actual arms race in the war in Ukraine, needs endless energy all times a day.

China is already winning the AI cold war because it adds more capacity to its grid a year than Germany has in a century.

If we keep going with agrarian methods of energy production don't be surprised that we suffer the same fate as the agrarian societies of the 19th century. Any country that doesn't have the capability to train and build drones on mass won't be a country for long.

[epistasis]

You have that exactly backwards: solar + storage is what will give us energy abundance at less money than we could ever imagine from nuclear fission or fusion.

China is winning the AI Cold war because it's adding solar, storage, and wind at orders of magnitude more than nuclear.

I'm not sure who's doing your supposed "envisioning" but there is no vision for cheap abundant energy from fusion. Solar and storage deliver it today, fusion only delivers it in sci fi books.

Nuclear is 20th century technology that does not fit with a highly automated future. With high levels of automation, construction is super expensive. You want to spend your expensive construction labor on building factories, not individual power generation sites.

Building factories for solar and storage lets them scale to a degree that nuclear could never scale. Nuclear has basically no way of catching up.

[noosphr]

China has been building out nuclear capacity at 5% a year for 25 years.

Solar and wind capacity had shot through the roof in the last five years because they can't sell hardware to the west any more.

The other big item is hydro power, which China has a ton of untapped potential for. Unfortunately for the West every good river has already been damed so we can't follow them there.

[epistasis]

> Solar and wind capacity had shot through the roof in the last five years because they can't sell hardware to the west any more.

"can't sell hardware??" hah! I've never heard that weird made-up justification, where did you pick it up from?

China installed 277GW of solar in 2024, capacity factor corrected that's 55.4 GW of solar power. That's equivalent to the entire amount of nuclear that China has ever built. One year versus all time. And then in the first half of 2025, China installed another 212GW of solar. In six months.

Nuclear is a footnote compared to the planned deployment of solar and wind and storage in China.

Anybody who's serious about energy is deploying massive amounts of solar, storage, and some wind. Some people that are slow to adapt are still building gas or coal, but these will be stranded assets far before their end of life. Nuclear fusion and fission are meme technologies, unable to compete with the scale and scope that batteries and solar deliver every day. This mismatch grows by the month.

[cyberax]

> China installed 277GW of solar in 2024, capacity factor corrected that's 55.4 GW of solar power.

The problem is not just the mean capacity factor, but the capacity factor in _winter_. It's terrible for China, less than 15%. And more importantly, you can have _weeks_ with essentially zero solar power when you need it most.

[noosphr]

This is not an issue in China as they overprovision demand by 50 percent. Their grid can run off baseload generation alone in their 2060 plan.

Trying to explain that a grid build by electrical engineers, rather than financial engineers, has resilience build in to people whose whole idea about electricity generation is greenwashed bullshit from McKinsey and Co is at best a waste of time and at worst an excellent way to raise one's blood pressure.

[ben_w]

> It's terrible for China, less than 15%.

55.4 GW per 277 GW is an (annual) capacity factor of 20%, so the response here is "yes, and?"

> And more importantly, you can have _weeks_ with essentially zero solar power when you need it most.

Half the country is a mid-latitude desert. What makes you think the whole country has "weeks" with zero solar? And it does have to be the whole country in this case, because one thing a centrally planned economy can do well is joining up the infrastructure, which in this case means "actually make the power grid the USA and the EU keep wringing their hands over".

[ben_w]

> Solar and wind capacity had shot through the roof in the last five years because they can't sell hardware to the west any more.

They can't sell as much as they would like, specifically to the USA, due to tariffs/trade war, but there's a much bigger world out there than just the US, and the overall exports are up over the last five years: https://www.canarymedia.com/articles/solar/chart-chinas-sola...

There's a Chinese-made Balkonkraftwerk sitting a few meters away from me on my patio, it cost €350, of which €50 was delivery and another €50 was the mounting posts, the remaining €250 got me 800 W of both panel and inverter.

> Unfortunately for the West every good river has already been damed so we can't follow them there.

For generation, yes. For storage, no.

[bryanlarsen]

> Unfortunately for the West every good river has already been damed so we can't follow them there.

You don't need a river for hydro power storage. All you need are two reservoirs with a height difference between them. Typically one of the two reservoirs is preexisting and the second is constructed. ANU identified ~1 million potential sites.

https://re100.eng.anu.edu.au/global/

[pfdietz]

> sci fi books

I blame these for the unquestioned belief that fusion is desirable. It's a trope because it enables stories to be told, and because readers became used to seeing, not because science fiction has a good track record on such things.

The fact that the volumetric power density of ARC is 40x worse than a PWR (and ITER, 400x worse!) should tell one that DT fusion at least is unlikely to be cheap.

With continued progress down the experience curve, PV will reach the point where resistive heat is cheaper than burning natural gas at the Henry Hub price (which doesn't include the cost of getting gas through pipelines and distribution to customers.) And remember cheap natural gas was what destroyed the last nuclear renaissance in the US.

[formerly_proven]

It's hard to imagine a form of energy production less desirable than fusion.

Okay, sure, burning lignite and using the exhaust as air heating in the children's hospital. You got me.

[apendleton]

> It would require a technological breakthrough that we have not yet imagined.

Maybe, but not necessarily. The necessary breakthrough might have been high-temperature superconducting magnets, in which case not only has it been imagined, but it has already occurred, and we're just waiting for the engineering atop that breakthrough to progress enough to demonstrate a working prototype (the magnets have been demonstrated but a complete reactor using them hasn't yet).

Or it might be that the attempts at building such a prototype don't pan out, and some other breakthrough is indeed needed. It'll probably be a couple of years until we know for sure, but at this point I don't think there's enough data to say one way or the other.

> And already, solar plus storage is cheaper than new nuclear.

It depends how much storage you mean. If you're only worried about sub-24h load-shifting (like, enough to handle a day/night cycle on a sunny day), this is certainly true. If you care about having enough to cover for extended bad weather, or worse yet, for seasonal load-shifting (banking power in the summer to cover the winter), the economics of solar plus storage remain abysmal: the additional batteries you need cost just as much as the ones you needed for daily coverage, but get cycled way less and so are much harder to pay for. If the plan is to use solar and storage for _all generation_, though, that's the number that matters. Comparing LCoE of solar plus daily storage with the LCoE of fixed-firm or on-demand generation is apples-and-oranges.

I think solar plus storage absolutely has the potential to get there, but that too will likely require fundamental breakthroughs (probably in the form of much cheaper storage: perhaps something like Form Energy's iron-air batteries).

[bruce511]

One can discuss base load and season shifting all day long. But ultimately fusion will fail for two simple reasons; time and money.

If we started building a fusion commercial scale plant today (ie started by planning, permits, environmental assessments, public consultation, inevitable lawsuits, never mind actual construction and provisioning) it'd come online in what? 10 years? 15 years? 20 years?

Want to deploy more batteries? It can be online in months. And needs no more construction than a warehouse.

Financially fusion requires hundreds of billions, committed now, with revenue (not returns) projected at 10 years away (which will slide.) Whereas solar + storage (lots and lots of storage) requires anything from thousands to billions depending on how much you want to spend. We can start tomorrow, it'll be online in less than 2 years (probably a lot less) and since running costs are basically 0, immediate revenue means immediate returns.

Of course I'm not even allowing for fusion being "10 years" from "ready". It's been 10 years from ready for 50 years. By the time it is ready, much less the time before it comes online, it'll be redundant. And no one will be putting up the cash to build one.

[pfdietz]

High temperature superconducting magnets are not a panacea for the problems with DT fusion. Those issues follow from limits on power/area at the first wall, and the needed thickness of the first wall; these ensure DT reactors will have low volumetric power density, regardless of the confinement scheme used.

With HTSC magnets, a tokamak much smaller than ITER could be built, but ITER is so horrifically bad that one can be much better than it and still be impractical.

[epistasis]

And these are not new issues, they've been known for more than 40 years, but never addressed. From the 1983 Led

> But even though radiation damage rates and heat transfer requirements are much more severe in a fusion reactor, the power density is only one-tenth as large. This is a strong indication that fusion would be substantially more expensive than fission because, to put it simply, greater effort would be required to produce less power.

https://orcutt.net/weblog/wp-content/uploads/2015/08/The-Tro...

[apendleton]

In terms of cost of materials to build a reactor, sure, that seems right. But most of the cost of fission is dealing with its regulatory burden, and fusion seems on track to largely avoid the worst of that. It seems conceivable that it ends up being cheaper for entirely political/bureaucratic reasons.

[pfdietz]

Relaxed regulatory burden doesn't seem to be making fission competitive in China; renewables are greatly overwhelming it now, particularly solar.

We might ask why regulations are so putatively damaging to nuclear, when they aren't to civil aviation. One possibility is that aircraft are simply easier to retrofit when design flaws are found. If there's a problem with welding in a nuclear plant (for example) it's extremely difficult to repair. Witness the fiasco of Flamanville 3 in France, the EPR plant that went many times over budget.

What would this imply for fusion? Nothing good. A fusion reactor is very complex, and any design flaw in the hot part will be extremely difficult to fix, as no hands on access will be allowed after the thing has started operation, due to induced radioactivity. This includes design or manufacturing flaws that cause mere operations problems, like leaks in cooling channels, not just flaws that might present public safety risks (if any could exist.) The operator will view a smaller problem that renders their plant unusable nearly as bad as a larger problem that also threatens the public.

I was struck by a recent analysis of deterioration of the tritium breeding blanket that just went ahead and assumed there were no initial cracks in the welded structure more than a certain very small size. Guaranteeing quality of all the welds in a very large complex fusion reactor, an order of magnitude or more larger than a fission reactor of the same power output, sounds like a recipe for extreme cost.

[cyberax]

Regulation is not a problem, and even the construction costs are not terrible. We can take the Rooppur NPP as a base, it produces reliable energy at 6-7 cents per kWh. The reason for cost overruns is simply because NPPs are one-off products, the Western countries don't have a pipeline for NPP production.

For comparison, utility-scale solar with 16 hours of storage is 21 cents: https://www.utilitydive.com/news/higher-renewable-energy-cos...

Just raw solar without storage can be as low as 2-3 cents per kWh.

[epistasis]

Regulatory costs and waste disposal are not significance cost centers for nuclear, at least as far as I can tell from any cost breakdowns.

One doesn't need super high quality welding and concrete pours becuase of regulations as much as the basic desire to have a properly engineered solution that lasts long enough to avoid costly repairs.

Take for example this recent analysis on how to make the AP1000 competitive:

https://gain.inl.gov/content/uploads/4/2024/11/DOE-Advanced-...

There are no regulatory changes proposed because nobody has thought of a way that regulations are the cost drivers. Yet there's still a path to competitive energy costs by focusing hard on construction costs.

Similarly, reactors under completely different regimes such as the EPR are still facing exactly the same construction cost overruns as in the rest of the developed world.

If regulations are a cost driver, let's hear how to change them in a way that drives down build cost, and by how much. Let's say we get rid of ALARA and jack up acceptable radiation levels to the earliest ones established. What would that do the cost? I have a feeling not much at all, but would like to see a serious proposal.

[pfdietz]

> let's hear how to change

One approach would be to reduce the size of the containment building by greatly reducing the volume of steam it must hold. This would be done by attaching Filtered Containment Venting Systems (FCVS) that strip most of the radioactive elements from the vented steam in case of a large accident.

The containment building is a significant cost driver, costing about as much as the nuclear island inside of it.

If such a system had been attached to the reactors that melted down at Fukushima exposure could have been reduced by maybe two orders of magnitude. And if the worst case exposure is that low, perhaps much more frequent meltdowns could be tolerated, allowing relaxation of paperwork requirements elsewhere.

[apendleton]

Oh for sure, I'm not claiming that CFS (or Tokamak Energy or Type One or whoever else) will for sure succeed, or if they do, that they've already solved all the problems that will need solving to do so. My only assertion/prediction is that I think if they end up succeeding, when future historians look back and write the history of this energy revolution or whatnot, HTSC magnets will turn out to have been the key breakthrough that made it possible.

[nandomrumber]

Fusion reactors are self destroying, just ask any star.

More seriously: what to do about the neutron flux destroying the first wall inside the reactor vessel?

[pfdietz]

> needed thickness of the first wall

I meant, needed thickness of the tritium breeding blanket.

[cesarb]

> If the plan is to use solar and storage for _all generation_, though, that's the number that matters.

And that's the problem with these Internet discussions: that's almost never the plan, but commenters trying to make solar look bad assume it is (to your credit, you made it explicit; many commenters treat it as an unspoken assumption).

In real life, solar and batteries is almost always combined with other forms of generation (and other forms of storage like pumped hydro), in large part due to being added to an already existing large-scale grid. The numbers that matter are for a combination of existing generation (thermal power plants, large-scale hydro, etc) with solar plus storage. Adding batteries for just a few hours of solar power is enough to mitigate the most negative consequences of adding solar to the mix (non-peaking thermal power plants do not like being cycled too fast, but solar has a fast reduction of generation when the sun goes down; batteries can smooth that curve by releasing power they stored during the mid-day peak).

[adrianN]

In the end we're still making steam and running a turbine. Just the steam turbine part of the power plant has a hard time competing with solar in sunny locations.

[Dylan16807]

Fission is expensive for regulation reasons more than technological reasons, so if fusion doesn't face the same barriers then it could be cheaper than fission.

But I agree that it doesn't look like fusion is going to be cheap any time soon.

[bryanlarsen]

Fission is also expensive for several mundane reasons, like the fact that massive steam turbines are expensive, and because any large construction project in the West is expensive. Neither fusion nor regulatory reform are going to solve those.

[BurningFrog]

The regulatory hurdles are probably bigger than the difficult enough technological ones you mention.