[GOONIMMUNE]

I love to follow this field because the engineers working on tokamaks/stellarators/other fusion devices are dealing with some truly extreme technical challenges. However, creating devices that economically overcome those challenges at scale seems unlikely when solar panels and batteries are aggressively decreasing in cost. How will these compete if scientists figure out the longevity problem for perovskite solar? Just my opinion as a layman. I still think the research is worthwhile because of possible future applications (space?)

[bombcar]

Even if solar and wind can easily supply all our power needs for the foreseeable future and beyond, it would still be worth experimenting with fusion.

If we can get it to work, we will know much more about the universe than we do now, and if we can get it affordable, we will have nearly unlimited power. muahahahahaHAAHAHAHAHHA

er, oops

[tsimionescu]

Why exactly do you think fusion offers "nearly unlimited" power? In any design conceived today, it is in no way impressive in terms of power/plant, and fusion power plants will be the most expensive power plants ever designed (since they are at the extreme limits of materials science and several other branches of engineering).

[bombcar]

Exactly - IF we can get it to work, we'll know much more.

And IF we can do it affordably (these are both big IFs), the amount of energy available is huge. I see 1 gallon of water to 300 gallons of gas numbers thrown about; that's huge.

https://www.energy.gov/science/doe-explainsdeuterium-tritium...

(Gotta love their optimism - "when").

[ncmncm]

As Hamlet says, "It's as easy as lying."

[TheDudeMan]

Not "unlimited", but "more than anything else".

We know the energy density is there, based on thermonuclear weapons.

Yes, the designs for a power plant that are similarly impressive don't exist today. That's where research and engineering can help.

Yes, any new thing is expensive. These points are not necessarily intrinsic to the process.

[tsimionescu]

> Yes, any new thing is expensive. These points are not necessarily intrinsic to the process.

It's not expensive just because it's new, it's expensive because it's trying to do a very very difficult thing - using magnets to achieve what the entire mass of Jupiter can't achieve, compress hydrogen so much that it starts fusing, and then keeping it compressed while it's essentially violently exploding - and exploding in a rain of extremely fast heavy particles that don't interact with the magnets at all.

[TheDudeMan]

What part of it do you think is intrinsically expensive? The steel? The concrete? The magnets?

[tsimionescu]

Yes, the steel required to withstand the force of the magnets, and to be dense enough to prevent hydrogen from leaking, magnets powerful enough to contain thebl fusion reaction, cooling systems to keep the superconducting magnets in close proximity to the neutron rain at extreme low temperatures.

These are all the parts we know about. Then, there are all the systems that no one has attempted yet that you will need to actually extract some energy from the whole thing, and to inject fuel into the running reactor, and to recycle tritium.

Overall the reactor vessel has to be built similarly to a high-pressure submarine, but it needs to withstand even higher forces. Not exactly something that can be done cheaply, even though we have been building submarines for a good 50 years.

[zardo]

All of that requires a lot of capital, but what makes it expensive is the neutron flux ruining it in just ~5 years.

[russdill]

Fusion is likely to be useful in situations where renewables are just not feasible. For instance, anything large that moves (large boats, spacecraft, or even aircraft) or has no limited to sunlight (bunkers, deep space outposts, etc).

[pfdietz]

Fusion, at least of the most commonly pursued DT variety, is terrible for mobile applications since its power density is so low. The ARC reactor concept (190MW(e)) weighs as much as several WW2 destroyers.

[russdill]

I'm going to go out on a limb and guess they modern fission plants that are not designed with portability in mind also have really low power densities. Just imagine the weight of the cooling towers. And yet, very different designs with different requirements can be made to fit in a submarine.

I'm not saying it's going to be possible to run container ships on fusion, just that using a fixed research reactor as a data point probably isn't very useful.

[pfdietz]

Actually, no, fission reactors have much higher volumetric power density. This is inherent in the technology -- in a fission reactor, coolant flows through the core, with large surface area for heat to transfer from the thin fuel elements. In a DT fusion reactor, the coolant has to flow in a blanket around the core, and all the power has to radiate through the surface of the reactor itself. The square-cube law comes into play.

[john2x]

Doesn't fusion still require vast amounts of water to turn to steam?

[Analog24]

From my understanding this is almost entirely an engineering problem at this point. The physics behind it has been understood for decades so I'm not sure how much more we'll gain in terms of fundamental physics.

[ncmncm]

There is still a great deal to be learned about plasma fluid dynamics. Probably the only good that will come out of all the work is a few generations of plasma fluid dynamicists. Pray they can find something else to do when the whole project finally fizzles out.

[Apocryphon]

Well, it's not as if any of them were going to work on solar or wind power anyway, so what does it matter to you?

[ncmncm]

They are not who is consuming the $billions.

[Apocryphon]

Then why the pearl-clutching over the plasma fluid dynamicists?

[ncmncm]

Perovskite longevity is up to five years, which at the price is already sufficient to be immediately useful in many places.

There will be no fusion.

[px43]

CFS completed the first of 18 coils on their prototype device last October, and it worked better than expected, far more than enough for commercially viable fusion plants. Their prototype is scheduled to be completed and lit up in 2025, and the first commercial plants should be ready in the early 2030s.

The new high temperature superconducting materials that they're using to build the containment coils make them significantly smaller, cheaper, and less complicated. Definitely worth reading up on if you haven't.

https://cfs.energy/news-and-media/commonwealth-fusion-system...

[ncmncm]

That is what they tell their pigeon investors. But they don't say there is not enough tritium to operate commercial reactors, or that no material has been identified that can hold the structure together after bombardment with hot neutrons. They don't say that the reactor would need to be maintained using robots nobody has ever built.

Come 2025, there will not be a useful reactor. They will instead offer an excuse, which is easy to come by.

[wefarrell]

There's only so much surface area on the earth that we can cover with solar panels and global energy consumption is exponential. Abundant energy will enable more possibilities such as removing CO2 from the atmosphere, desalinating water and pumping it into arid regions, and opening up space tourism for the majority of the worlds' population.

[scythe]

>global energy consumption is exponential.

From the link:

https://ourworldindata.org/grapher/global-energy-substitutio...

The trend since 1960 appears instead linear. Also, population growth is slowing. But it's fun to extrapolate "exponential" trends and look at the big numbers.

[jacknews]

If energy consumption continues exponentially we will cook ourselves.

There's plenty of land for solar, and then there are the oceans, and it's here now. In the medium term we should look at modular fission, and deep geothermal, potentially re-deploying fossil extraction technology.

I'm all for fusion as scientific research, but let's drop the pretense that using it to generate power is remotely realistic for many decades, if ever.

[wefarrell]

Once you start covering land that isn't a complete desert with solar panels you start competing with photosynthesizing organisms, even more-so with oceans. I don't think anyone expects fusion to be viable within a decade or two. Beyond that I don't know but I absolutely think it's worth funding.

[Schroedingersat]

Any amount of primary energy consumption that covers more than the already built up areas or the land currently used for fuel ethanol with solar will rapidly cook the planet through nuclear.

Current primary energy is 18TW. Total insolation is 170PW. GHG forcing is about 200TW. We can provide enough solar with smaller than a 1000km square. More than that will kill us no matter the technology used (but solar is better than most as the total heat it produces is a bit more than the work done rather than 3x).

Growth must end or physics will end it for us. Climate change is the warning shot across the bow, not the full volley.

[wefarrell]

"Total insolation is 170PW" - That assumes 100% efficiency, it's from the upper atmosphere, and making full use of it would mean there would be no light left for plants or the ocean. After accounting for solar panel efficiency, battery efficiency, and the amount of surface where it's possible to put panels without displacing nature and agriculture it'll be somewhere in the low hundreds of TWs.

"Current primary energy is 18TW" - That's outdated and only consists of the energy converted from electricity. It doesn't include non-electric heating, driving, maritime transportation, aviation and freight. Taking those int account our total consumption is around 100TW.

[Schroedingersat]

> That's outdated and only consists of the energy converted from electricity. It doesn't include non-electric heating, driving, maritime transportation, aviation and freight. Taking those int account our total consumption is around 100TW.

That's what primary energy means (as well as the heat wasted from allof the above). My best guess as to how you got 100 is you're mixing up 160,000TWh with TW

> That assumes 100% efficiency, it's from the upper atmosphere, and making full use of it would mean there would be no light left for plants or the ocean. After accounting for solar panel efficiency, battery efficiency, and the amount of surface where it's possible to put panels without displacing nature and agriculture it'll be somewhere in the low hundreds of TWs.

I wasn't implying all of that was available, merely that around 0.1% of that in thermal forcing is enough to be a problem on the same scale as GHG emissions. Wind is the technology which produces the least new heat (none, although if you exceed around 1W/m^2 for too large an area you change the climate in other ways), followed by solar on existing asphalt, grass, or water (up to ~1W of new heat per watt).

Any thermal fuel that didn't recently come from sunlight is in the 1.4 to 3 range (excluding extraction and processing).

This caps primary energy around 400TW for renewables or 200TW for nuclear (with only around 70W as work if you are using a steam engine).

Nuclear provides less end-state access to abundant energy on earth than renewables at higher cost. There is no reason to pursue it.

[IshKebab]

We are many orders of magnitude away from needing to worry about solar using up precious land.

[ncmncm]

False.

There is exactly zero need to devote any land surface at all exclusively to the solar panels that will provide for all our needs. Solar coexists nicely with numerous other uses. Similarly, for wind turbines.

Storage may consume some area, but nowhere near what existing fossil fuel extraction activities do.

There will be no fusion.

[the_third_wave]

Either you have not seen solar parks taking up arable land or you do not understand how this type of land use makes the land unavailable to agriculture. This may not be an issue when those solar parks are built in a desert but it does when they're displacing good farm land like they're doing in e.g. the Netherlands. There are experiments with less dense solar parks and those with vertically placed bifacial panels which should allow combined land use but this has not gotten beyond the experimental stage yet.

Of course it is possible to forego on using arable land for solar parks, only using rooftops and similar constructions for this purpose. Roofs - especially large flat ones like used in industry - are natural locations for PV panels and it is hard to see why one would not install them on new constructions, either on top of traditional roof cladding or in place of it. The same goes for large south-facing walls.

Wind turbines can be placed on farm land without unduly reducing land availability to farming, here the problem comes from nearby population complaining about noise pollution (infrasound, [1]) coming from those turbines as well as 'horizon pollution' [2].

[1] https://www.nature.com/articles/s41598-021-97107-8

[2] https://worldcrunch.com/culture-society/skyscrapers-turbines...

[ncmncm]

I have seen plenty of land foolishly wasted on single-use solar farms. That does not make it smart. In the future those will find themselves undercut by dual-use farms that continue doing what they did before solar was added.

Rooftops will not be much that.

Deserts are a particularly dumb place for solar farms, but ignorant investors love the idea, so lots of money is wasted on them.

[lovemenot]

You could be right, and I hope you are. But, given the current state of development in agrivoltaics and such, your prediction has too much certainty.

All power to those projects, but they are really just experimental at this point. Not inevitable.

[mmazing]

> There will be no fusion.

Scream it into the ether with veins popping out of your head all you want, it doesn't make you correct.

Additionally, there's literally no reason to not pursue both avenues.

[ncmncm]

Nobody is screaming.

Even presuming usable structural materials can be discovered (not worked on in 3 decades) and tritium at PPB concentration can be extracted from thousands of tons of blanket material every day (never worked on at all), a working plant would cost more than an order of magnitude more on every axis than fission.

But fission is already not competitive. Fission falls farther behind better methods each day.

So, no one will build a fusion power plant, and there will be no fusion power. "Pursuing avenues" with no possibility of desirable results is wasted effort and wasted money. We have valid reasons to avoid waste.

[mmazing]

I wonder how many people said the same thing about airplanes, or electricity, or any of the countless other amazing things we have accomplished as a species.

Maybe the current trajectory of fusion is unlikely to bear fruit, but we'll learn from it. We may learn something that makes it far easier to implement. A discovery here or there and you change trajectory to something that IS worthwhile.

If you never try, you never get there, you can't see that?

[ncmncm]

If you do try, you never get there. But you also never get to the other thing that actually has some prospect of working.

Look up "opportunity cost", "sunk cost fallacy", and "good money after bad".

Victorians believed in fairies, very strongly. Their heirs believe as strongly in fusion energy.

[Apocryphon]

If no one is building fusion power plant, what money or effort is being wasted? Also, do you think all of these nuclear physicists are able to pivot to working on renewable energy, as if they are Silicon Valley tech startups? From what point of view of action are you even operating from?

[Schroedingersat]

Doing science is fine.

It's the thousands of scam artists that will divert resources from actual solutions as soon as their lies are plausible to rubes that are not.

If we're busy paying for 100s of victoria county stations that will never open, the coal plants will remain on.