For instance, can I build a railgun to shoot things into orbit?
Nah.
https://thebulletin.org/2017/04/fusion-reactors-not-what-the...
This is because a lot of rich countries seem to me to be well placed to benefit partially from global climate change at the moment, at least within the 1-2C range. Changing the climate past that point is likely to be controversial, since the countries who now benefit from the situation will likely not want to give those newfound advantages away.
I would think of it a lot as the end result of a war - the borders are defined by where the armies stopped ie the division of Europe and Asia after ww2. After climate change I expect whoever has benefitted from it to defend their position and reject any further alterations!
But every cent diverted to fusion from solar brings climate disaster closer.
Edit: also, your comments seem to be incredibly negative on fusion, would you mind disclosing if you have any solar or wind connected conflicts of interest?
My beef with fusion is about long-term hucksterism and wholly-legal corruption. STS, SLS, F-35, Big Dig, 2nd Ave, Cal bullet train, fission, fusion.
Dollars are fungible. Would fusion dollars otherwise go to renewables build-out? They might be more likely to go to battery, solar panel, superconducting power transmission, or carbon reclamation research. All of those would be welcome alternatives.
Even FRC fusion would be a better use of funding.
Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experimental evidence to describe the relationships between tokamak parameters and power output. Particularly that the gain is proportional to the radius to the power of 1.3 and the magnetic field cubed. The main caveat to this relationship was that we only had magnets that would go up to 5.5 Tesla, which implied we needed a tokamak radius of 6 meters or so in order to produce net energy.
Well that 6 meter tokamak was designed in the eighties and is currently under construction. ITER, being so large, costs tens of billions of dollars and requires international collaboration; the size of the project has led to huge budget overruns and long delays. Recently however, there have been significant advances in high-temperature super conductors that can produce magnetic fields large enough that we (theoretically) only need a tokamak with a major radius of about 1.5 meters to produce net gain. This is where SPARC (the tokamak being built by the company in the article) comes in. The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly.
Small tokamaks do have downsides, namely that the heat flux through the walls of the device is so large that it will damage the tokamak. There have been breakthroughs with various divertor designs that can mitigate this, but to the best of my knowledge I'm not sure that CFS has specified their divertor configuration.
This was just a short summary of the presentation by Dennis Whyte given here [0]. I do not work in the fusion community.
-Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not).
- Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon? Working fusion enables these to happen woth existing technologies.
I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so.
Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.
Well, at least for a few hundred years but then:
> if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. […] the Earth has only one mechanism for releasing heat to space, and that’s via (infrared) radiation. We understand the phenomenon perfectly well, and can predict the surface temperature of the planet as a function of how much energy the human race produces. The upshot is that at a 2.3% growth rate [in energy consumption] (conveniently chosen to represent a 10× increase every century), we would reach boiling temperature in about 400 years. […] And this statement is independent of technology. Even if we don’t have a name for the energy source yet, as long as it obeys thermodynamics, we cook ourselves with perpetual energy increase.
Source: https://dothemath.ucsd.edu/2012/04/economist-meets-physicist...
How did you arrive at that conclusion?
The biggest problem is the 'in theory' part. With current plausible designs, the vast majority of the fusion reaction's energy is carried away by high-powered neutrons, which are entirely waste products.
I mean if we 10x the waste heat that could be produced by asics solely for the purpose of mining coins, it could be enough to create a mini climate.
> Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.
Citation needed... If the fusion reactors end up needing tape of room temperature superconductors to keep their confinement going, and they degrade rapidly due to neutron radiation, I could easily see solar being cheaper in the long run. I'm not saying this is exactly what will happen, but I have never seen compelling proof that fusion will really be so cheap in terms of capex or opex per Watt.
What does fusion give us that existing nuclear power plant tech doesn't?
I have a couple of physics degrees, hot fusion is the energy of the future and it always will be. This is not a physics problem, this is an engineering problem and we are just not willing to invest enough money to solve the engineering.
It just doesn't strike me as obvious that reducing the major radius by a few meters would have such a huge impact on cost/timelines.
[0] https://library.psfc.mit.edu/catalog/online_pubs/iap/iap2016...
This quote from the presentation summarizes it well:
“The more money that's involved, the less risk people want to take. The less risk people want to take, the more they put into their designs, to make sure their subsystem is super-reliable. The more things they put in, the more expensive the project gets. The more expensive it gets, the more instruments the scientists want to add, because the cost is getting so high that they're afraid there won't be another opportunity later on- they figure this is the last train out of town. So little by little, the spacecraft becomes gilded. And you have these bad dreams about a spacecraft so bulky and so heavy it won't get off the ground- never mind the overblown cost.”
“That boils down to the higher the cost, the more you want to protect your investment, so the more money you put into lowering your risk. It becomes a vicious cycle.” - Rob Manning, Chief spacecraft engineer, JPL
It's all completely bespoke scientific equipment hand made for this project only. The cryostat will be the largest stainless steel vacuum vessel ever made-- all welded by hand.
After welding, a substantial number of in-vessel components have to be installed by threading them through access ports, which is also quite a task: https://www.youtube.com/watch?v=pt70mO2nQac
>It just doesn't strike me as obvious that reducing the major radius by a few meters would have such a huge impact on cost/timelines.
It would, easily. Past a certain size, production costs rise exponentially and require one-off tech.
1. As budget constraints tighten, the number of man-hours spent wrestling with bean counters (and/or waiting around with nothing to do until the bean counter wrestling completes) increases exponentially.
2. "Cheap solutions" often end up being unfit for purpose, and have to be reworked later at great expense.
3. Budget overruns lead to time overruns which lead to more budget overruns, ad infinitum.
We see it lately in the numerous military procurements (particularly the F-35 program), in NASA's SLS rocket, in California's bullet train to nowhere, and urban tunnels such as New York's 2nd Avenue subway extension. It is why nuke plants are invariably so expensive and late.
In a word, corruption.
Lately, this corruption has been arranged to be wholly legal, so there is no possibility of prosecution. The majority of the money spent is funneled into myriad private pockets without moving the project toward completion. Nobody involved, at the monetary level, has any desire for it ever to be completed, because that is when the gravy train stops.
Fusion projects represent the worst case of this phenomenon. Nobody knows what it should cost, and nobody in control of spending wants it over with, ever.
The chance that anything of any practical use could come out at the end was openly foreclosed before it ever started: it was never promised to produce any electrical power, and no turbines, or space for any, appear in any site plan.
Any sort of practically useful Tokamak plant would need to be overwhelmingly bigger and more expensive than ITER, and could never come anywhere near producing commercially competitive power, so the project is a known dead end, to be milked until it is finally cancelled in shame.
What is tragic is that each euro diverted to this boondoggle brings climate disaster terrifyingly closer.
Akin's law of spacecraft #29 "To get an accurate estimate of final program requirements, multiply the initial time estimates by pi, and slide the decimal point on the cost estimates one place to the right."
A 6m device occupies 666 (say) --216 m^3
a 10m device occupies 10 10 6 (say) -- 600 m^3
The scale of volume means that you have to build a much bigger facility to put it in (in order for the electronics to be kept dry and for people to be able to get around it to keep birds off it and things.
But worse - the weight. Concrete is 2400kg m ^3 so the small device might weigh 518 tonnes, but the bigger device is 1440 tonnes, so moving parts of it round becomes 3 * harder, the floors have to be 3* stronger, the supply chain has to be 3* better.
And then time - 3* scale, 3* engineering challenge -> many times more time to deliver, many more $$$ -> risk -> planning -> admin... the less capital at risk the less it's worth spending on avoiding the risk.. the less the overhead of the project is.
FWIW ITER is a science experiment - it's designed to find out more about fusion and that data will be very valuable for future reactor designs.
It's not that simple. The big problem with magnetic confinement fusion is that you need to control turbulence in the plasma so that you can contain the reactions for a reasonable amount of time to extract useful energy. However, turbulence increases with stronger magnetic field gradients, which is exactly what you get when making a smaller reactor chamber with stronger magnets. This wouldn't be the first project claiming to be able to build a small reactor, only to discover that it's virtually impossible without a major theoretical breakthrough. This is usually left out in the venture capital advertisements for these fusion startups. There's a reason why so much money and effort is spent on ITER - it is the only more or less guaranteed path to fusion with the tech and knowledge we have today.
Mmm, this isn't right. The stronger magnetic field reduces turbulence, it's the gradient of the pressure that generates turbulence. As best as anyone can tell, SPARC should be able to get Q~10 without any miracles involved -- the engineering rules of thumb and the advanced simulations all say the same.
https://www.cambridge.org/core/journals/journal-of-plasma-ph...
Maybe your equations and power laws are right, and a "big enough" tokamak would be a competitive source of power. But then there are the details, like "big enough will cost $25 Trillion". Followed by delays, cost overruns, etc.
I'm thinking that a rational, non-expert taxpayer would say, "This fusion thing is a hundred times worse than NASA's Senate Launch System. Stop wasting my money on it NOW, and let gullible investors waste theirs instead."
VIPER: an industrially scalable high-current high-temperature superconductor cable
Most notably, the extreme temperatures, hydrogen pumping, and high-energy neutron bombardment mean that, even with liquid metal blankets, the reactors will very quickly become brittle, probably not lasting more than a year or two. Since neutron bombardment also turns any material radioactive, not only do you need to tear down your fusion plant (or at least the expensive reactor part of it) every few years, but you have to do it with radiation-resistant robots, as human workers can't get close to the reactor after it's been operating for a while.
This talk by the MIT Nuclear Science department head explains the whole rationale behind ARC/SPARC, and this timestamp is where he starts talking about maintenance and the neutron blanket (5 minutes later): https://www.youtube.com/watch?v=KkpqA8yG9T4&t=2400s
I bought a new screen cover yesterday for my phone. It came with a full mounting kit that I discarded after the ten minutes that took me to place the cover. The same kit could have been used to mount at least a hundred covers. The small slice of civilization I'm part of is extremely wasteful!
But, let's analyze that waste. First, energy went into collecting and transporting those materials, plus collateral environmental degradation. Now, energy will be spent collecting and processing my waste, and if it can't be recycled, it will end up also provoking collateral damage.
But, if we had infinite cheap energy, recycling all of it would be a no-brainier. Even recycling materials contaminated by radiation would be easy; after all, we already do that to refine fission fuel.
Economic incentives? Those are trivial to legislate, absent the environmental cost and with a promise of green-house gases neutrality. Heck, had we infinity cheap energy, we can pack, move out of planet an leave all of Earth as a bio-reserve.
In other words, nuclear fusion holds the promise of being such a civilization game-changer, that the question of "is it better than solar in the next ten to thirty years?" is moot. With that said, the next ten to thirty years will be vital to attenuate climate change, so nuclear fusion should not be used as a deterrent for other climate investments we can do today.
The only useful outcome of any of this work is a generation of plasma-fluid physicists with practical experience. Pray we can find them something useful to do when the whole enterprise finally collapses.
A whole generation heard about it in school decades ago. Multiple generations by now, even. Its right up there with battery/energy-storage technologies. Headline after headline, enrapturing a newer and newer idealist set of people to quickly become disillusioned. People just get tired of it.
But I’m glad to understand whats going on behind the scenes now. I’ll pay attention. Looks like a real sleeper.
So, why is this particular announcement exciting? There are 3 factors:
1. This is a high temperature superconductor. I can't find any references, but as far as I remember the substrate they are using needs to be cooled to (WRONG, it was cooled to 20degK, see reply by MauranKilom) 60-70 degK to achieve super conductivity. Compare to magnets used in ITER which need to be cooled to 4degK. This is the difference between using relatively cheap liquid nitrogen vs liquid helium.
2. Field strength of 20 Tesla is significantly higher than 13 Tesla used in ITER. Given that magnetic confinement fusion scales significantly better with field strength vs reactor size, this will enable much smaller reactor to be power positive. See following links for more details on ITERs magnets: https://www.newscientist.com/article/2280763-worlds-most-pow... https://www.iter.org/newsline/-/2700
3. Finally, the magnet was assembled from 16 identical subassemblies, each of which used mass manufactured magnetic tape. This is significantly cheaper and more scalable than custom magnet design/manufacturing used by ITER.
The kicker is how 3 of the factors above interact with the cost of the project. Stronger magnets allow smaller viable reactors. High temperature superconductors + smaller reactors allow for a much simpler and smaller cooling system. Smaller reactors + scalable magnet design further drives down the cost. Finally, cost of state of art mega projects scales somewhere between 3rd and 4th power with the size of the device. Combining all of the above factors, SPARC should be here significantly sooner than ITER and cost a tiny fraction (I would guesstimate that fraction to be between 1/100 and 1/10,000).
edit: typos + looked at the cost of ITER and refined my cost fraction guesstimate + corrected some stuff based on the reply by MauranKilom.
I feel that fusion is one of humanity's best shots at actively reversing climate change, and it is disheartening to see such widespread pessimism about it. Yeah it's hard. There are huge hurdles in making it economicly viable, but if we can go from first powered flight to the moon in 70 years, and put billions of transistors on a chip in 50, then maybe we can get fusion going. It's clearly possible.
Couldn't the same thing be said about current fission reactors?
I get that fusion doesn't have the downsides of fission... but I'm also worried that people will be "scared" of fusion in the same way they're against GMO vegetables and irradiated fruits, totally irrationally...
Environmentally clean energy source is not enough, it needs to be ideologically pure as well.
I wouldn't call it that, even if there would be a energy gain.
I call it beginning of "fusion age", when we solved fusion ad can build them reliable and reproducible - and if we still need them by that time, for main energy production.
Since any fusion plant would necessarily cost more than 10x fission, and fission is not competitive, that is well out of reach.
[0] https://www.nature.com/articles/s41467-017-02641-7
Just as a note, the max B field here is 600T
https://nationalmaglab.org/news-events/news/lbc-project-worl...
Fusion power density scales like B^4. So if CFS can get 2x the magnetic field, then they can make the plasma volume 16x smaller, which might equate to big savings in cost and construction time. (It doesn't make sense to go much smaller than their ARC reactor design though -- the plasma already takes up only a fraction of the volume of the core at that scale, so compressing the plasma further doesn't improve the power density. If you can increase the field even more, which REBCO seems to allow, then you would rather just pack more power into a device about the size of ARC. So don't expect to put one of these on your DeLorean.)
There are definitely other challenges/limitations. For one, this approach increases the heat flux that the inner wall of the reactor will have to survive. The localized heat flux of the exhaust stream is expected to rival the heat flux of re-entry from orbit (20 MW/m^2) and could be as high as the power flux from the surface of the sun (~60MW/m^2). 20MW/m^2 is on the hairy edge of what's possible with today's technology, and that's without all the complications of neutron damage, plasma bombardment, etc. The current thinking is to spike the outer layer of the plasma with neon or nitrogen, to radiate most of the power as photons, but there are limitations & risks to that idea as well. Commonwealth's plan for SPARC (last I heard) was to oscillate the exhaust stream back & forth across the absorber plate to reduce the average heat flux.
The nuclear engineering side of fusion has been underfunded for a long time, so there's much that needs to be done on that front, in terms of demonstrating that the breeding of tritium from lithium can be done efficiently & without too much losses. Also, we should be developing better structural materials that can withstand neutron damage & not become (as) radioactive.
It's still very much an open question as to whether fusion could be made economical, even though it seems like it should be technically possible.
It doesn't look like they are targeting that here. Does anyone know if that is ARC (not SPARC) specific, or if that has been abandoned?
CFS will be building a lot more magnets, not only for SPARC but for other customers, physics experiments and medical equipment, so I expect they will be working on many additional features including demountable joints for ARC.
One of the early tests they did of the VIPER cable at the SULTAN test facility in Switzerland involved a joint formed by clamping the ends of two cables to a copper bar. It does show that resistive joints are possible with HTS cables, unlike LTS cables, but the actual configuration of a joint for a large magnet is obviously a different matter. Luckily they will have a few years to work on it.
So, sounds like it's for SPARC.
Here's the truth: there's no such thing as free energy. Even if the fuel is so abundant it's actually or effectively free (eg deuterium), the energy isn't. Say it takes $50B to build a plant that produces 1GW of power, which I'll estimate at about 7TWh/year based on [1]. Let's also say it has a lifespan of 40 years and an annual maintenance cost of $1B going to up to $2B in the last 10 years.
So that's 40 years for 280TWh at a cost of $100B, which equates to $0.35/kWh if my math is correct.
I realize ITER isn't a commercial power generation project. My point is that people need to stop getting hung up on the fuel being "free". The lifetime cost of the plant can still make it completely economically unviable.
Second, the big weakness of any fusion design is neutrons. The problem people tend to focus on is that neutrons destroy your (very expensive) containment vessel with (one of my favourite terms) "neutron embrittlement".
As an aside, hydrogen fusion also produces high speed helium nuclei, some of which tend to escape and this is a problem too because Helium nuclei are really small so can get in almost any material, which is a whole separate problem.
But here's another factor with neutrons: energy loss. High speed neutrons represent energy lost by the system.
To combat these problems we've looked for alternatives to hydrogen-hydrogen fusion, the holy grail of which is aneutronic fusion. The best candidate for that thus far seems to be Helium-3 fusion but He-3 is exceedingly rare on Earth.
I really think we get caught up on the fact that this is how stars work but stars have a bunch of properties that power plants don't, namely they're really big and they burn their fuel really slowly (as a factor of their size), which is why they can last billions or even trillions of years. Loose neutrons aren't really an issue in a star and sheer size means gravity keeps the whole system contained in a way that magnets just can't (because neutrons ignore magnetic fields).
So I hope they crack fusion but I remain skeptical. Personally I think the most likely future power source is space-based solar power generation.
[1]: https://en.wikipedia.org/wiki/List_of_largest_power_stations
This is what I remember from memory, I would need to fact check that.
My method uses much lower magnetic fields that could be provided by permanent magnets, but should allow containment times on the order of weeks for small quantities of D-D fuel.
I have more information at http://www.DDproFusion.com
In case others are wondering, looks like this is for SPARC.
FTA: This "MIT-CFS collaboration...on track to build the world’s first fusion device that can create and confine a plasma that produces more energy than it consumes. That demonstration device, called SPARC, is targeted for completion in 2025."
CFS: https://cfs.energy/technology
(edit: clarification)
ITER was designed to use weaker electromagnets and therefore needs a massive building and tons of cranes and a massive budget.
Unfortunately, the ARC design also had 40x worse power density than a PWR primary reactor vessel.
Smaller. Smarter. Sooner. 2018
Currently 2021 where is my fusion energy? But this time must be different, after this advance we are only a few years away from fusion energy?
The video thouches upon magnetic fields and its relevance at this time mark ; https://youtu.be/L0KuAx1COEk?t=2880
Fission has a absurdly high energy density, the step from oil to fission is far more relevant then the step from fission to fusion.
Fusion would mean basically no fuel cost, but thorium is already a waste product and even uranium fuel is a tiny part of any fission plant.
Some people seem to believe the fusion is inherently prove against weapons, but this is equally not really true. If you had a working fission plant there would be ways to use it to get what you want to make a weapon.
There are some places you might want fusion, mainly in space travel but even there we are not anywhere even close to where we could get to with fission. Open gas nuclear thermal rockets anybody?
In sum, I'm not against this reseach but its not a way to solve our problems anytime soon. Fission you could get to run with 60s tech and amazing reactors could be designed within decades and often with comparatively small teams in the 60-80s and somehow we haven't managed to make it competitive.
Fusion looks to be far more complex to build in every possible way. How this will be cheaper is questionable to me.
Haven't Tokamak Energy in the UK done better than this already back in 2019 with their 24T magnet based on similar HTS tape technology?
https://www.tokamakenergy.co.uk/tokamak-energy-exceeds-targe...
In comparison, 20T does not look much, but again it is, I wonder with the Japanese technique what is the highest continuous magnetic field.
[0] https://en.wikipedia.org/wiki/Explosively_pumped_flux_compre...
And I hope the marketers pretending they'll have a commercial plant by 2025 are ashamed.
> This is because energy gain and power density scale exponentially with magnetic field strength but only linearly with reactor size
Nit: It scales polynomially, not exponentially. Specifically (according to those formulas) energy gain scales with the cube of field strength and power density with the fourth power. Still massive scaling indeed, but exponentially would be something else.
> as far as I remember the substrate they are using needs to be cooled to 60-70 degK to achieve super conductivity
The video in the article shows 20 K. Could of course be that higher temperature is feasible and they just played it safe (or the video is wrong).
But they don't need to, do they? If their claim is sound, they could as well just optimize the magnets and wait for ITER to complete to offer an ITERation (pun very much intended) on the design. The fact that they focus on this weird race against an international research project makes me wonder if SPARC is mostly a vehicle to attract investors.
ITERs plasma density will be comparatively low, and that is where SPARC with stronger magnets comes in. SPARC will produce data on lower volume and limited burn time, but significantly higher plasma density.
The new superconductors that allow these larger magnets are also very recent, not in discovery but in actual mass production. So they don't have as much experience with using these as with the classical superconductors. So I hope there is still quite some quick improvement there on the table.
If I remember right from one of the videos from the SPARC reactor folks, they were experimenting with not bothering with insulation between the magnet windings. The ReBCO film is bonded to a layer of stainless steel, and they figured the conductivity of the film is so much better than stainless steel that they wouldn't actually get much loss from current leaking through. That seems kind of crazy, but I guess there's a lot of things about superconducting materials that don't behave intuitively.
Maybe manufacturers can make film that's bonded to a thinner layer of stainless steel or whatever, and thus allow for more windings in the same space?
This is D-T fusion. Which means you have to have T. Which currently comes from fission reactor and has a half life of 15 years.
So the plan is to use a molten salt blanket with Be to breed T. But Be isn’t scalable for consumption, so maybe lead eventually. That’s probably do-able, it just slows down the rate new reactors can come online since Pb is not as good a neutron multiplier.
Once they breed extra T, they have to capture and refine it. Hydrogen is very corrosive and hard to work with… and T is radioactive hydrogen. Again, probably doable. But guess what? Refining spent nuclear waste in fission reactors is also do-able. It’s also super expensive.
And they still need a containment vessel that will withstand the wear and tear from sitting next to a mini hydrogen bomb all day.
These challenges are likely all surmountable. But are they surmountable AND cheaper than existing nuclear or other energy sources? Meh?
Though most of the reactors do not harvest the tritium, a small number do.
CANDU operators have long been ready to make the capital investments in tritium harvesting, once demand materializes. ITER has long been seen as a potential major source of tritium demand.
DT fusion solves the two biggest arguments that are always raised by nuclear energy opponents: storage of nuclear waste (it doesn't produce high-level waste) and safety (it's not perfect but it can't explode). I wouldn't call it a "meh", even if it comes off as much more expensive than fission.
"T is radioactive hydrogen": True, it emits low energy beta radiation, which is an electron, and is stopped by a sheet of paper. I used to have a wrist watch with a tritium dial; I haven't died of cancer yet.
For the other uninitiated, (or far enough out of secondary school and didn't take it further!) this seems to refer to Deuterium-Tritium fusion, D & T being the isotopes of hydrogen with an atomic mass of 2 (1 neutron, 'heavy' but stable) and 3 (2 neutrons, radioactive) respectively.
Very little is invested into fusion power as a project, overall. So advancements seem to come when outside influences cause breakthroughs.
I wonder how different the world would have been if it had for whatever reason been easier to produce fusion power than a fusion bomb. Military investment into the bomb would have probably pushed things forward a lot quicker. As is, the US military built thermonuclear bombs very quickly and then the appetite for advancement just dried up.
I really wish that press release would put the link to the paper at the top -- I found it very hard to work out what was actually new!
https://english.cas.cn/newsroom/research_news/tech/201912/t2...
Googling "30T magnetic field" shows some papers that have apparently "pulsed" 30T.
Q (the ratio of energy out to energy in) has improved by about four orders of magnitude since controlled fusion was first achieved, and it's been a slow, at least reasonably steady march since the middle of the 20th century to achieve that progress. The current record-holding Q for magnetic confinement is around 0.67, so we need well under one more order of magnitude to get to the point of "theoretical break-even" (Q>1) -- we're most of the way there. A plant just barely better than break-even probably wouldn't be commercially viable, though, and while estimates vary, that point is probably somewhere in the 10-30 range, so we have maybe another order of magnitude to go after break-even. I don't think there's anything to suggest that after decades of progress we'll suddenly stop being able to make more.
It's true that things have slowed down somewhat in the last 10-15 years, but most of the blame there goes to the need, in order to continue moving forward, to build bigger and bigger reactors, and the need to divert resources to that goal (mostly ITER). To the extent that promises of going faster have turned out to be hot air, it seems like they've mostly been in the form of novel approaches that do fusion in some fundamental new way that avoids the need to build an ITER-like thing. These approaches seem to often involve lots of unknowns, and end up getting bogged down in practical issues once they're actually tried (surprise plasma instabilities and so on).
Recent advances in materials science (mostly REBCO magnets) and computing, though, offer a path to progress on the regular, bog-standard flavor of magnetic confinement fusion (tokamaks) on a smaller scale -- that's what this is. The nice thing about that is that the plasma physics here are very well understood, and have been heavily researched using conventional/not-super-conducting magnets that won't ever achieve break-even, but create identical plasma conditions inside the reactor (MIT Alcator C-Mod is effectively the conventional-magnet predecessor to this project). Up until now, the only real question was whether or not they could build strong-enough REBCO magnets, and now they have, so this is all good news and reason for optimism.
Of course, commercial viability is a whole other question involving lots of questions besides physics. But the physics here seem to not be in serious doubt, unlike some of the proposals from other startups that are more exotic.
What sort of computing advances? Modeling? Real time controls? I'm guessing modeling, but would like to know more details.
There are a bunch of issues still to be resolved. Higher magnet strength is/was just one of many.
That it would cost overwhelmingly more than solar+storage is what will ultimately kill it. Someday. Many more $B will be spent first.
No commercial reactor will ever be built, so this is just for showing off.
The only real good to come from these efforts is employment of plasma fluid physicists. I just hope non-military work can be found for them when this stuff fizzles. Solar Physics is fascinating and important, but has limited budget.
Space-based solar power generation (itself "fusion power" in the loosest sense) would be great in the inner planets.
Though to open up the outer planets, Kuiper belt, Oort Cloud, and any other stars, we'll need non-solar* power: hopefully fusion, at least fission.
*Unless we want to go the stellaser route, but I'd bet we'll crack fusion before getting near K2.
H-3 is not nearly so scarce as cletus suggests. It is uncommon, but you don't need much.
However, those maintenance costs (your estimates) would be the first thing to drop. Any company producing/operating these will be competing with wind and solar, and thus highly incentivized to improve. There should be plenty of low hanging fruit, since it hasn't happened once yet.
I think the hope is that with economies of scale, we could build really huge fusion plants one day, and drive down the cost of energy to less than a cent per KWh, and of course completely eliminate our dependency on fossil fuels. If energy becomes that cheap, we could use electricity to produce hydrocarbons from CO2 and water to power airplanes and such. Currently, we can imagine short-distance flights being electrically powered, but transatlantic flights are going to be difficult to achieve with batteries.
Space based power generation to me is incredibly dumb. It would be far easier to build solar on earth and transport it around with high efficiency DC lines.
And if you are really looking into the cheapest possible energy a thorium breeder reactor could run for ever with no fuel cost and could be built with 70s technology. These reactor be produced in a factory at a manufacturing line and then dropped into a containment facility.
How this should be more expensive then space based solar makes no sense to me.
They are now claiming to have done the latter. Are you skeptical of the new design? Or do you think it does not represent as significant a departure from earlier designs as they claim?
I really want this to work. I am a bit concerned, with how “the old guard” will react, once we have successful, productive, fusion.
I foresee an astroturf NIMBY campaign against construction of fusion plants.
They forgot to say that it is not the H2O that comes out of your tap. The earth is especially not full of tritium.
https://www.reddit.com/r/Futurology/comments/5gi9yh/fusion_i...
Nuclear ruined it's own reputation for generations though hopeful not as long as they'll have to care for the waste we already have.
The only real open question is how long the gravy train will run before the plug is pulled. F-35 and SLS have demonstrated that with careful management, that can be longer than anyone could have believed.
The goal is to get fusion power om the grid in the 2030's and scale up in the 2040's. Stop moving the goalposts.
Paper studies of fusion reactor designs given an availability figure, but this is mere aspiration, chosen because that number is necessary, not because it known to be achievable. The few actual studies of how available a fusion power plant would be (using MTBF and MTTR figures from related technologies) have come to very troubling conclusions: the plant may be operating just a few percent of the time. Getting fusion technology to the point where working reactors aren't perpetually down for repair is even more important than developing materials tolerating higher neutron displacements-per-atom (because it's hard to do the latter without the former). This requires building an experience base with all the kinds of things that will go into a fusion reactor. It also argues for making fusion reactors as small as possible (so there are fewer things to break); this is probably the best argument for these small high field devices (but an even better argument for high-beta plasma configurations).
There is nothing about fusion that makes it essential for putting carbon back into the ground.
That's why I specifically said field gradients - i.e. the thing that gets larger when you have a stronger field in a smaller volume.
>it's the gradient of the pressure that generates turbulence
How exactly do you think that pressure is created?
Also, that link you provided is an editorial from one of the directors behind SPARC. If you want an objective analysis that is not geered towards possible investors, you need to look elsewhere. FYI, anyone selling you Q~10 designs without a considerable theoretical breakthrough is almost certainly conning you. If you don't believe me just look at how Lockheed's compact fusion reactor panned out. Stronger magnets are not some kind of miracle solution that will enable fusion tomorrow.
One purpose of the support material that isn't super-conducting is thermal protection. If your superconducter quenches, you have to dissipate the energy contained in it without destroying the magnet. In classical ones they use copper wire around them as far as I remember, and the high-temperature ones are a very thin film of ReBCO deposited on metal tape, so the actual superconductor is always a small part of the material.
The real dream are fusion reactions which don't produce neutrons, such as H1+H1 or much more realistically, H2+B11 (though still many times harder than H2+H3).
Not much more nor less, since the amount of Bitcoin generated every 10 minutes is controlled by an algorithm independent on how many machines are mining.
Feeding 100% of Europe electricity use with solar panels in North Africa would required many years (!) of the world’s current aluminium production, just to build the transmission cables.
Do the calculation, you’ll see.
Long distance power lines do not work to transmit massive amount if electricity on a global scale.
That said building the first is a lot harder than scaling it up.
(That's right. ITER, which will cost more than $65 billion and take decades to build, can't run continuously!)
Chiefly, how does that further the conversation? More pointedly, why should we listen to you?
Credentialism in this arena is valid, and what I currently see are multiple subject matter experts, albeit with a bias/incentive towards believing in themselves, versus you. Please substantiate your claims, or word them more carefully as to reflect them being conjecture.
FRC, though, maybe. But you would have to have people actually working on that.
You're spot on. Which makes no sense at all. Given the potential of commercial fusion, we should be (globally) spending at least several tens of billions per year on R&D.
Assuming the engineering issues are solved, those hundreds of billions would be chump change compared to the economic benefits of volume of cheap, clean power.
Or is it massive like the tokamak is a 6 meter engine to a 100 km collider? Like there's a ton of other stuff being built in a massive structure?
I've never heard of hydrogen-filled balloons (at least not the kind of balloon you can hand to a kid) - we're you thinking of helium?
[0] unless Mark Rober is involved in some way.
SpaceX's advancement is impressive, but if NASA had never happened, I doubt SpaceX would even exist today.
>In 1992, Dan Goldin became the NASA Administrator. Goldin believed in a philosophy of Faster… better… cheaper—i.e., he thought NASA could do more with less. Hence, Goldin did not support the idea of having large EOS platforms in space and in fact once referred to them as “Battlestar Galactica.” He believed smaller, less expensive missions that could be built more quickly were the way to go and supported development of new programs that actually diverted funds from EOS.
[1] https://eospso.nasa.gov/sites/default/files/eo_pdfs/Perspect...
Viewed another way: if you could make a fission reactor with a power density as low as ARC, it would have so much thermal inertia that meltdowns would be essentially impossible. You should then ask why such fission reactors are not built.
As to why massive fission reactors aren't built: there are plenty of already-available passively-safe/meltdown-proof fission designs (many gen-IV designs qualify), and from what I can tell, the reasons they're not built are as much political as anything -- people don't like them, and the consequent regulatory regime has made any fission projects prohibitively expensive regardless of their size. None of this need be the case with fusion.
As to tritium: I think you're overstating the tritium risk. They're only dealing with grams at a time, and even if it all leaked out, it would rapidly diffuse such that risk to the public would be infinitesimal as compared to normal background radiation (plus its half-life is only something like 12 years). ITER has a safety page: https://www.iter.org/mach/safety that essentially says as much.
https://en.wikipedia.org/wiki/World_energy_supply_and_consum...
Extrapolating exponential growth over long timescales leads to silly results.
Being delayed imposes costs on downstream work, which must now be ready but in some kind of holding pattern, which imposes costs on work downstream of that work.
So a large part of throwing "Manhattan project" / excess funding (and the potential savings by just funding it that way from the start) is avoiding these delays, to the extent possible.
It costs +$200,000 to tackle some challenge in a critical piece? Sometimes it's cheaper just to pay.
So there’s very little incentive to constrain costs.
ITER is likely bigger in terms of volume of concrete or actual footprint.
1) HVDC designs I’ve seen are copper (towers use aluminium because it’s light, IIRC)
2) http://www.necplink.com/docs/Champlain_VT_electronic/04%20L....
Gives 2500mm^2 cross section for a 1 GW cable
3) WolframAlpha says Europe’s electricity production is 410 GW: https://www.wolframalpha.com/input/?i=total+Europe+electrici...
Which means the total conductor cross section needed is ~1 million mm^2 = 1m^2. Ok, this sounds like it’s going to be a lot.
4) Lets put a line across the Sahara to connect all the panels plus connections to the existing EU grid in Gibraltar, Athens, and Milan.
It’s about 3700km from Casablanca to the middle of Egypt: https://www.wolframalpha.com/input/?i=casablanca+to+egypt
Likewise 350km for Gibraltar, 1000 km Awjilah to Athens: https://www.wolframalpha.com/input/?i=Awjilah+to+athens
This gives a total length of about 5000km, if I spec the cable for 100% of EU power going through each cable, which is excessive as I was trying to suggest this as an adjunct to batteries and local PV rather than a total replacement for either: any combination (including none) of transmission and storage only has to cover lower nighttime/seasonal averages).
This gives me a total volume of 5000km * 1m^2 = 5e6 m^3.
5) This is copper, worldwide production of copper is 14.6e6 tons/year, given the density this is indeed 1.4e6 m^3/year and therefore multiple years at current mining.
6) Global aluminium production is 82.6 million tons/year: https://www.wolframalpha.com/input/?i=worldwide+aluminium+pr...
Aluminium is 60% the conductivity of copper; I assume that means I need the conductor to be 1/0.6 times the cross section? Not my field. Assuming that, I want 8.3e6 m^3 aluminium, given the density that’s 22 million tons, so 3 months.
Edit: I forgot Milan!
7) Tataouine to Milan is about 1500 km: https://www.wolframalpha.com/input/?i=Tataouine+to+Milan+
Therefore multiply my mass estimates by 1.3
Edit 2:
410 GW is also 2-2.5 times current global PV installation: https://en.wikipedia.org/wiki/Growth_of_photovoltaics
If you did put enough PV for all of Europe on top of/along side the Casablanca-Egypt line, the PV would need to be about 550m wide: http://www.wolframalpha.com/input/?i=%28410GW%2F%281kW%2Fm%5...
(I only need to care about peak power in this case, not average, hence only the 20% efficiency factor and not including the additional 25% duty factor).
Couple examples: You put a line to cities in the south of Europe. But existing lines from there are nowhere large enough to take all that power, you will have to build lines from Milan and others all the way inside Europe. You can’t build a line to Gibraltar and call it a day, it has to go all the way up to Norway (albeit with tapering)
You also overestimate the efficiency of aluminium power lines, don’t take into account the amount of towers and/or plastic material that would be needed to wrap the lines if you make them underground.
We are talking about years of production, and that’s just for Europe, if you want to replicate this to other continents you quickly get a supply challenge, even if you spread this over 30years, at which point it will be too late, regarding global warming. Not to mention that m the CO2 emissions associated with building such massive lines would take decades (if ever) to be offset with the gains from the use of Solar, which was the point of the thing in the first place...
But in the end my point was not that this is impossible, but that efficiency is not the largest limiting factor here. Material supply is the largest problem. It is not insurmountable but it is a real challenge.
> But existing lines from there are nowhere large enough to take all that power, you will have to build lines from Milan and others all the way inside Europe.
Really? Okay. All I can do is look at maps like this one:
https://www.researchgate.net/figure/7-Modelled-AC-transmissi...
Which look, to my completely non-expert eye, like a decent size grid already exists.
I know that picture doesn’t contain enough info even though this isn’t my domain, but it represents the limited level I’m coming from.
[1] https://books.google.com/books?id=KSA_AAAAQBAJ&lpg=PA234&ots...
Also, not sure why imgur has that image marked as adult content.
People are terrified of radiation, even if the danger is very low. This means it becomes prohibitively difficult and hence expensive to build and run a fission plant because safety has to be prioritized so heavily. That is even if permission is granted to build in the first place.
I think it is unlikely for irrational fear of fusion to become mainstream like it has with fission.
Because of this I think the barriers to fusion power are at this point lower than the barriers to scaling up fission power.
We can just rename fission to #goodenergy or something, that would be cheaper then developing fusion.
People don't even know that nuclear reactors use fission, so the idea that this would change anything is crazy. People opposed will call fusion reactors 'nuclear' just like they do fission.
If a Fusion reactor blows up, the radiation risk is basically 0, aside from the lack of potential melt downs.
Fusion does indeed come with radiological hazards: a fire could release radioactive gas and dust. If designed right, the worst-case scenario would still be way less severe than for a fission plant -- and the worst-case scenario is really what stokes all the popular fears about 'nuclear'. OTOH, tritium leakage could mean that routine emissions are larger.
The day-to-day danger perhaps, but it's kind of hilarious in a sad way to read this right after fukushima spent god knows how long leaking radioactive shit into the ocean.
Tritium will be handled in such large quantities in a fusion reactor that even small leaks will be problematic. As I like to point out, the tritium made and burned in a 1 GW(e) DT fusion reactor in one year would contaminate 2 months of the entire flow of the Mississippi River above legal limits for drinking. Even small leaks could cause serious harm to property values (sorry, your ground water can't be drunk for the next 50 years.)
Gen-IV reactors aren't built not for political reasons, but because nuclear has become such an economic orphan that there aren't stakeholders to drive the construction of these things. The money isn't there because the ROI isn't there.
There are all sorts of approaches to fusion, and things such as type 2 superconductors were undiscovered 30 ago and uneconomic/unpractical 10 years ago. Timing control systems for magnetised target fusion were impossible but now are doable. Our understanding of plasma has been advancing a lot, simulations are good now, we can control plasmas much better. Chirped pulsed laser amplification is a thing now and really good at making high amplitude pulsed lasers for inertial approaches...
I could go on and on. This isn't the 90s anymore, and our technology is still rapidly advancing. What happens if we find more efficient/cheap/high power density thermocouples, or find a direct energy electrostatic power capture method?
Fusion's economic realities today may be overcome soon, we really do not know what we can do in even 20 years from now. The fundamental truth is that there is vast amounts of energy available in hydrogen, and all it takes is 100MK to ignite it.
And then you have the problem of having to stick sophisticated stuff in the hot zone where hands-on maintenance is impossible (compared to a fission reactor, where just the fuel and relatively simple hardware is in that zone.)
The engineering undesirability of DT fusion has been known for decades. All the recent excitement doesn't address any of the known showstoppers.
[0]https://ieeexplore.ieee.org/document/1018583 [1]https://www.iter.org/mach/Magnets
Also thinking, we target deuterium + tritium fusion because it's the least energy intensive. However, once we have working proof of concept reactors, could we just make them slightly bigger and fuse more abundant molecules/isotopes instead?
I'll have to find the citation, but IIRC the answer is "theoretically, yes" - the concept is that molten lithium could be used in a tokamak to absorb neutrons and produce tritium at the same time.
EDIT: Here are two citations I was able to find quickly - it looks like one of the ITER experiments will be to validate the concept [1] and that this could also be the way that heat is removed from the reactor. [2]
[1] iter.org/mach/TritiumBreeding
[2] https://www.euro-fusion.org/faq/top-twenty-faq/what-is-a-lit...
Their plan is to use FLiBe (Google it) blanket to breed tritium. The Be acts as a neutron multiplier.
As for non D-T fusion, the next best candidate is D-He3. Unfortunately, the only large scale source of He3 is on the surface of the moon and it would have to be mined, on the moon, and sent back to Earth.
Not as bad as I expected but not yet feasible economic wise. Assuming the fusion part exists.
"Fusing two deuterium nuclei is the second easiest fusion reaction."
"The optimum energy to initiate this reaction is 15 keV, only slightly higher than that for the D-T reaction."
If we have to scale up fission reactors to produce enough tritium to scale fusion reactors, then don't need the fusion reactors.
When you have no turbine or any other means to extract power from a heat source, none gets extracted. Do you need a source for that?
Deuterium is plentiful in tap water.
We are purely lucky that, for structural reasons, corruption is minimal on solar and wind projects. Probably this is because what it ought to cost is readily visible from the outset. There just isn't enough fat to attract graft.
"criticizing [The Death of Environmentalism: Global Warming in a Post-Environmental World] for demanding increased technological innovation rather than addressing the systemic concerns of people of color."
The sole fact that such a scientific undertaking can be done internationally, over decades, is a great thing considering the global problems we face.
Yes, ITER doesn't follow the USA economic ideology of "much", "cheap", and "now", but the world doesn't consist only of the USA and not everything works well with that ideology.
ITER is not a PV or battery factory. It is more like the ISS.
I have no doubt that plasma fluid physicists will learn a great deal from trying to get ITER lit up. Just handed the money, they could have learned a thousand times more, and maybe even achieved practical D/H-3 fusion propulsion for spacecraft. But that will not happen at ITER.
And for comparison, look what the ISS has brought us commercially: We have a fully commercial manned spaceflight planned for next week. That is a massive achievement without even considering all the scientific work on the station.
In any case, this exact question was asked here, and the top-rated response indicates that it's unlikely that the design requirement was ever meant to refer to grabbing an uncooperative payload:
https://space.stackexchange.com/questions/41741/was-the-spac...
I won't even go into this baseless bashing of "environmentalists". It's cheap and disgusting. Some of them have dedicated their whole life to the cause while a shitty anthropologist bashes them while being paid by the same companies which pollute the planet.
The 1976 projection was that, assuming funding was kept at the level of 1976 (~1 billion a year), fusion would not be achieved in the foreseeable future. It further shows that actual funding has been below that level.
In short: Yes, getting fusion off the ground sooner would have required more money. Not "always more", but more than "we project no success" levels.
The alternative would be that management cannot be judged on its results.
Some bridges, invariably urban, go massively over budget and schedule. Urban tunnels, routinely. Military procurement, routinely. Are people who manage those systematically dumber than the rest? Or do they have different measures of success?
What is common to those apparent failures is that they serve as a reliable, legal, long-term conduit from public funds to a multitude of private pockets. F-35 can never be cancelled, no matter what, because it has subcontractors in 48 states. The F-35 is a massive success to its backers: it secured monumental patronage. That it can actually take off and land, too, is a miracle.
This is already demonstrated by your own examples provided, just at a smaller scale.
If there were ever such a project to push against the capacity of our ability to do truly enormous, complex engineering, I’d say a massive, cutting-edge fusion reactor is as good a candidate as one could propose.
Moreover, the economic and educational stimulus these projects provide cannot be ignored when accounting for the indirect, long-tail returns this project, and those similar, provide.
Put another way: ostensibly, achieving net energy gain from fusion is the end of our near-term (energy) needs, conveniently breezing over the evolution and refinements of any system, as well as delivery and storage, but these are paths that are comparatively well mapped out. It then follows that, short of catastrophic losses prior to succeeding (which while not a given per se, seems more a function of time than of ability outright), any reasonable cost is worthwhile. Reasonable, in this context, meaning one that doesn’t bankrupt, or otherwise severely impact the participants in a negative fashion. Given the scale of these budgets vs. that of social welfare programs, military spending, etc. I don’t see that as an issue worth being concerned over. One can know the budget has been exceeded, without that also bringing down the house.
Ultimately, to an extent you’re asserting a false dichotomy. It can be true that there’s continued, substantial progress towards the stated goals of these projects, even if the budgets, horizons, and timelines aren’t to your taste. It can also be true that there’s waste, inefficiencies, and even (both legalised and otherwise) corruption. One does not preclude the other.
The energy generated per unit mass in a fusion reaction is ~9 times that generated in a fission reaction[0]:
Considering the mass of the four protons/hydrogen
nuclei (4.029106u) and the mass of the Helium
produced (4.002603u) we get a mass difference of
0.026503u or 24.69MeV. So it is easy to see that
fusion reactions give out more energy per
reaction. However, the energy per unit mass is
more relevant. This is 0.7MeV for fission and
6.2MeV for fusion so it is obvious that fusion is
the more effective nuclear reaction.
The phrase "electricity too cheap to meter" is likely somewhat hyperbolic, but in comparison to pretty much any other mechanism fusion is enormously more productive and efficient.
If we found a way to extract 10x as much energy from coal as we currently do, electricity from coal wouldn't become 10x cheaper, nor would we build power plants 10x as big.
Sure. Specific energy (or energy per unit mass) between different types of materials makes a huge difference. For example (Source here[0]):
Material Type of generation Specific energy (MJ/Kg)
Hydrogen Fusion 639,780,320
Coal Oxidation 24.0-35.0
You're right. Cost and availability play into this as well. There are estimated to be ~1.06 trillion tons of coal on earth[1], hydrogen is the most abundant element in the universe and even makes up a significant amount of the mass of coal.
Burning hydrogen/hydrocarbons is, compared to fusing hydrogen, an incredibly inefficient process.
I'd say that being able to generate 200,000 times the energy per unit mass is an important consideration.
As for availability, hydrogen is more abundant and cheaper to produce (unless you have petatons of plant matter, the right conditions and a few tens of millions of years at no cost to you) than any fossil fuels. Or just about anything else.
[0] https://en.wikipedia.org/wiki/Energy_density#List_of_materia...
[1] https://www.worldcoal.org/coal-facts/what-is-coal-where-is-i...
Edit: Clarified availability.
[1] https://en.wikipedia.org/wiki/Fusion_power#Radioactive_waste
Water is more abundant than Uranium?
The statement is that a blue-sky project such as a fusion system is easily recognized by people on the lookout for sources of unlimited money with no strings attached. When they get control of the project, the bulk of the money will not end up spent on the extremely difficult problems entailed. If the problems are as difficult as expected, handing the money over to people who benefit by not solving them will reliably fail to solve them.
We know with absolute certainty, already, that there is no "holy grail of energy production" at the end of it. The most favorable imaginable result is a system much more expensive to operate than a fission plant that produces no more power.
We know already that if the project achieves all of its projected goals, the result will be much more expensive than fission. We know already that if any power is ever generated, at any price, it can come no sooner than decades in the future.
It's not clear why one should expect fusion to have good experience effects. Fission didn't, and the non-nuclear parts of fusion power plants will be mature technologies.
All of the "scientific work on" ISS is done with crew literally pushing an "on" button on each bit of automated equipment running it. Experiments are forbidden to involve more interaction, and also forbidden to operate without that "on" button, so the crew has something, anything to do.
Commercial manned spaceflight could better have been worked without ISS. ISS's role was nothing more than a place to take them. Plus, a huge money sink on its own. It will soon fall out of the sky, and with any luck not hurt anybody where it crashes down.
Why is this relevant?
Fusion power plants still need land, buildings, generators, switchyards, wire, own power consumption, environmental impact reports, planning permits, regulations, inspections, and all the rest. And they need exotic materials and weird engineering in their construction.
Really: how does fusion get us to ~1% (correction: ~5%) of current power prices?
I've never seen a convincing explanation. Usually it's bare assertion. Infrequently it's handwavium/unobtanium.
If you could hypothetically build a fusion plant that would generate several times more power than existing fission reactors at a similar construction cost, you would have so much power you wouldn't have to worry much about transmission losses. At which point you could put it in the middle of nowhere without those constraints and make it actually less expensive for several times more power.
Then for cities power gets cheaper, but for anything that can be built out in the middle of nowhere near the reactor, power gets a lot cheaper.
Unless fusion power is dramatically more efficient than other thermal plants, like 99.9%, your bigger plant will still need massive heat removal structures and systems, which means siting them near water. All the good spots are already taken.
Alternatively you can use truly massive air heat transfer structures, driving up your construction costs again.
I neglected to mention finance costs also. With an untried technology the rate of return demanded is going to be very high, further driving up project costs.
I don't know how it works in the US, but this is notably not true in the UK and Europe. Gas plants are comparatively small and nestled in, but big coal (to a limited degree) and particularly fission plants are frequently in the middle of nowhere. They're somewhere near a village that can supply a workforce, but siting concerns for nukes were more based on making sure any criticality excitement could be shared with neighbours across whatever nearby border was handy than putting them anywhere near cities.
I don’t know how it costs in US, but in France, fully charging a Model 3 costs about ~5€ at night. That’s not 10x cheaper than gas but that’s a lot cheaper.
https://www.statista.com/statistics/418087/electricity-price...
This doesn't matter, though, because France doesn't need many nukes anymore, therefore doesn't subsidizes new plants anymore. One new plant is built in France, and it already is hellishly expensive: "As of 2020 the project is more than five times over budget and years behind schedule. Various safety problems have been raised, including weakness in the steel used in the reactor." https://en.wikipedia.org/wiki/Flamanville_Nuclear_Power_Plan...
Fission is not cheap if you build a new nuclear plant, not in the Western world. That's why almost no nuclear plants are being build. Making a safe plant is just really, really complicated.
Second, this specific argument can be used to see why fusion is a pipe dream. The primary competitor to fusion is fission. And the fuel costs of fission are pretty low, as you just said. So fusion will not be competitive unless you can built them around the same price as fission plants.
Someone else in this thread talked about S curves. Well, those kind of S curves happen for tech that gets produced in larger quantities, where it is economical to spend engineering resources making the production of the tech cheaper.
But the majority of the reaction energy is carried away by high-speed neutrons, which are pure waste - they can't be captured by magnetic fields, they are heavy and penetrate almost any material, leaving holes behind that make the structure brittle, and when they do get absorbed, they make the atom that absorbed them unstable, turning the material radioactive.
So, at least as long as we use neutri-producing fusion (and any realistic fusion reactor has to) the actually usable energy is not that impressive compared to fission.
Direct conversion is theoretically about 60% thermally efficient, on par with combined cycle gas generators.
But with fusion the endless claims of "too cheap to meter" are because how much energy there is in a fusion reaction. [0] We know that fission produces a lot of energy (but is expensive) but fusion produces significantly more. It also doesn't have the radiation drawbacks and so it is expected to follow the S curve (fission did initially but things changed. This is part of why France has so much nuclear).
So if (big if) fusion does follow this S curve (which there are good reasons to expect it to) then it could provide a very cheap and sustainable energy source. Yes, it is a bet, but every technology is. We won't know until we spend significant time and money into researching it. But honestly, a few billion dollars isn't that crazy for the potential upsides. We've spent that money on far greater risks with lower payout. Despite what the OP said, the money for ITER does not require international collaboration. Any rich country could do it themselves.
[0] (Fission and fusion can yield energy graph) http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin.htm...
> I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so.
> Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.
If the 10x is from avoiding fossil fuels, why does fusion get that credit, but the other non-fossil sources don't?
Because while renewable energy production is increasing rapidly, it is nowhere where we need it to cancel fossil fuels.
Nothing will be soon enough. That would have been now or ten years ago.
But anything that gets us there sooner will reduce the damage we have done, and fingers crossed, allow us to start undoing it.
You do see the irony of embedding this statement in a comment full of generalization and hyperbole, and lacking any evidence or credible sources, right? I genuinely laughed until I realized it may not have been intended as a joke.
You might try to argue high fuel energy density implies low cost, but this is clearly not the case in general.
Though it's also true that the infrastructure to process, deliver and store large amounts of fossil fuel comes at a higher cost than is usually considered (as some of it is subsidised and socialised), plus there's the pollution.
... But if "cost wasn't a factor" then we could just simply dedicate the electrical output of fusion plants to brute-force CO2 out of the air.
But there are other environmental impacts. Fusion, even compared to fission, has an extremely small footprint (per megawatt). Its fuel is easily available (isotopes of hydrogen). It does require some pretty advanced magnets though, so it will contribute to the strip mining that we do for rare earth materials (though this applies to all energy forms, including solar and wind). I don't have numbers to say if a fusion reactor would use less total rare earth metals per megawatt compared to something like solar or wind.
One thing to note though. Once we get sustainable fusion reactors, it will still take a bit for that cost to come down significantly. That usually takes 10-20 years. This is a pretty common pattern. We've seen it from the price of laptops and cellphones to the price of solar panels.
I live close to a wind turbine factory. They could easily have scaled production multiple times over the past five years. The only reason they didn't is funding, in fact during that period they at some point cut production when subsidies were cut.
I think it's getting to a point now where subsidies are not needed. But still, if you're talking about speeding up the process, you can just provide a little extra funding and get big results.
This is the non-theoretical part
> that cheaply.
This is the theoretical part. I think a lot of people are misinterpreting my comment. I have absolutely no idea if it can be done that cheaply. But I can say for a fact that the yield of energy is massive. The question is if it can be done cheaply. That's the bet. The question is if you want to take that bet. You have to make similar bets on tons of technologies. It usually takes 10-20 years after something is made till it starts to follow the S curve and become cheap. Even solar and wind followed this.
If reactors were ten times cheaper but no safer, we'd be building them like hotcakes.
The western world has made development of new fission plants practically impossible. Requiring 100s of millions in development before you might get a hint if the government would actually allow you to build a plant.
Thankfully this has finally started to change. Mostly in Canada and that's where we will likely see next generation fission first.
What has also prevented changes from happening is that nuclear scales down poorly, so the cost of iterating designs is so large. Making a new kind of PV cell or module, or wind turbine, is comparatively much cheaper, because these are individually much smaller and cheaper. The replicated nature of these sources is an advantage in so many ways.
But maybe I’m too optimistic :)
No it isn't. If you have a regulatory structure that makes progress so expensive and counter to the government plan then progress is very hard to make.
Even the regulatory agency themselves have realized this and are changing their structures.
> What has also prevented changes from happening is that nuclear scales down poorly, so the cost of iterating designs is so large.
US regulation allows nothing between fully commercial and university research making any time of prototyping impossible.
Its in fact very possible to make smaller reactors that can teach you a lot and are not absurdly expensive and still useful. That data then could be used for to further inform regulatory agencies.
> The replicated nature of these sources is an advantage in so many ways.
Yes but even if it doesn't scale down well in terms of engineering you can still do factory construction of reactors. If we can mass produce plans, rocket engines, rockets and cars then the same could be done with reactors.
The reality is the government selected one winner and made deploying anything else practically impossible. The change in regulatory agencies has basically made progress impossible beyond marginal improvements.
A major cost of the most utilized existing power plants (coal and natural gas) is fuel. If you build a natural gas plant which is twice as big so that you can put it out where the land is cheaper and eat the transmission losses, now you need twice as much natural gas.
Renewables don't need fuel but their construction cost is fully linear, you get no economies of scale. If you want twice as many solar panels then you need twice as much land. If you want to double the size of your fusion reactor, you build an eight story building instead of a four story building on the same piece of land.
> Unless fusion power is dramatically more efficient than other thermal plants, like 99.9%, your bigger plant will still need massive heat removal structures and systems, which means siting them near water. All the good spots are already taken.
An obvious solution is to build them out in the ocean. Then you have plenty of water and you're still not near anything.
And the good spots near population centers are already taken. Some lake a hundred miles from any city won't be.
> I neglected to mention finance costs also. With an untried technology the rate of return demanded is going to be very high, further driving up project costs.
That's only true for the first one. If it's hypothetically ten times more power for the same money, that'll get one built even at a high interest rate. Then once you have it running it's proven technology.
Coal is dead. The competition is PV, and to a lesser extent wind.
> Renewables don't need fuel but their construction cost is fully linear, you get no economies of scale. If you want twice as many solar panels then you need twice as much land.
Yes, and you use odd bits of land close to consumption sites, many of which will have simultaneous use for other purposes. Edit: the linearity is an advantage in that it enables mass production, and gets the benefit of the manufacturing learning curve. So your suggestion of overbuilding on cheap land a long way away from cities applies even more to PV.
> If you want to double the size of your fusion reactor, you build an eight story building instead of a four story building on the same piece of land.
Quadrupling your construction costs. Edit: mainly in the finance cost of the time taken.
Also, making your generators much bigger than current practise increases project risk and therfore cost.
> An obvious solution is to build them out in the ocean.
Quadrupling your construction costs again, and decreasing reliability, capacity factor and productive lifetime. Seawater is nasty stuff.
> And the good spots near population centers are already taken. Some big lake a hundred miles from any city won't be.
It will be used for productive farmland, though. Again, why aren't fission or CCGT plants being built in those places? How is fusion different?
> [High finance cost is] only true for the first one. If it's hypothetically ten times more power for the same money, that'll get one built even at a high interest rate. Then once you have it running it's proven technology.
It's about time to cashflow for utility finance types, and they also tend to want a longer track record than "it worked once". The linearity/modularity of wind and PV is an advantage in the time to cashflow aspect.
Edit: I haven't so far seen anything significant in your replies that doesn't also apply to fission. Utilty project financiers are hard-headed; they'll finance fission if it makes them enough money soon enough.
You are fiddling around the edges rather than demonstrating an order of magnitude cost reduction from PV.
Coal is dying but it's still ~20% of US generation. The natural gas share of US generation has gone up.
> Yes, and you use odd bits of land close to consumption sites, many of which will have simultaneous use for other purposes.
Until you run out of those and then your costs increase worse than linearly because you have to start using more expensive land.
> the linearity is an advantage in that it enables mass production, and gets the benefit of the manufacturing learning curve.
Anything you're going to use for a large fraction of the power grid is going to be mass produced.
> Quadrupling your construction costs.
This is the opposite of how economies of scale work. If you make something bigger, the variable costs scale linearly and the fixed costs stay the same but are amortized over more units.
> Also, making your generators much bigger than current practise increases project risk and therfore cost.
This is no different than needing twice as many turbines to generate twice as much power. It's a variable cost, offset by you getting twice as much power without increasing your fixed costs.
> Quadrupling your construction costs again, and decreasing reliability, capacity factor and productive lifetime.
You keep saying "quadrupling your construction costs" without evidence. We build oil platforms in the ocean on a regular basis. They cost some tens of millions of dollars. Existing fission reactors cost some billions of dollars. The difference from being on the ocean is evidently not the dominant cost. And then you don't have to pay for land.
> Seawater is nasty stuff.
Many existing reactors are situated on coastlines and cooled by seawater. It's not some kind of insurmountable problem.
> It will be used for productive farmland, though.
The price of "productive farmland" compared to the price of land near a city is multiple orders of magnitude less, and high density power generation doesn't need that much land.
> Again, why aren't fission or CCGT plants being built in those places? How is fusion different?
New fission reactors largely aren't being built at all because of regulatory suppression. CCGT plants can't afford to spend fuel generating power which is then lost to long distance transmission.
> It's about time to cashflow for utility finance types, and they also tend to want a longer track record than "it worked once".
If it worked once but is now generating ten times more power per unit of investment capital than any of the alternatives then investors would be lining up, and may not even be needed because the plant operator could use revenues from selling such a large amount of electricity to build more plants with.
It's not competing with fission, though. It's competing with renewables + storage + load shifting + efficiency. Compared to those, it might indeed be "meh".
Until prices do start to bottom out, investment in storage is wasteful, so dollars go to generating capacity of known utility.
Each square meter of panel that goes online delays climate disaster by a precisely understood amount. Each panel made can go into service almost instantly. No matter how big the project, it can start delivering power anytime. There is no smallest-useful facility, right down to the residential rooftop.
Every dollar diverted to Tokamak instead brings climate disaster nearer.
This is not intended as a rant against solar (again, I'm an enthusiastic supporter), but I'd guess a landscape of fusion generators would take fewer square meters of land than the equivalent using solar. And that is nothing to scoff at.
It is incredibly unlikely to offset the carbon related gains of solar, because the carbon sequestration efficiency of plants and trees is very low to begin with, far lower than solar's capacity to displace carbon emitted from coal when area is held constant.
Sure, it's better to put the solar where there is no existing tree cover, but it seems like most of Appalachia is covered in trees.
Renewables are key to having a sustainable energy economy. Fusion power is what will let us do the drastic things to recover from climate disaster that is already here.
Tritium is not pleasant though, but veeeeeeeeery far from anything that could do real harm: https://en.wikipedia.org/wiki/Tritium#Health_risks (you'd need to leak a lot of it continuously)
In the same way, a fusion plasma doesn't hold that much energy because of the extremely low density (4×10^-6 that of air). An explosion (a runaway/chain reaction) is also not possible: the reactor must continuously supplied with fuel or the fusion reactions will stop in a matter of seconds.
There are situations which could result in significant damage to the reactor components, but still not a public safety concern. Distruptions are events in which the plasma confinement is lost and a large amount of heat is released that could damage all components that face the plasma, but reactors are designed to withstand this.
Another drawback, if you like, are runaway electrons, which are populations of relativistic particles that become unbound and penetrare the vacuum vessel for several mm. Again, this is not a particular issue from a safety point of view, but they can do a lot of damage: if they hit a magnetic coil and cause a loss of the superconductivity state, the coil can heat very rapidily (due to the huge current that goes through it) and potentially melt. Replacing such a coil could cost years of maintenance, for this reason reactors are build with many fallback systems.
Costing hundreds or thousands of times as much as solar + storage is a more serious problem. Since it won't be built, that is a theoretical problem. But the project can absorb an unlimited amount of money first.
And you can burn up the waste majority of that waste, the leftover waste after that would not really a huge issue.
Both of these are far more political problems then actual real problems a society based on modern fission would have.
There are known well understood engineering solution that have been known since the 70s and that work fine.
The real danger is the high pressure that PWR are under and the chemical instability of the elements that were put together in those designs.
Reactors that are not under pressure and do not have chemical instability that lead to explosive cases have a very contained area of effect even in a worst case.
It does. You cannnot fuse just D+T, other trace gasses, and lighter isotopes will be present as well.
The radiative losses do exist, but are caused by detached atoms from the plasma facing components. Everything close to the plasma is made of light elements and specifically chosen to not produce dangerous radioisotopes when neutron activated: no high-level waste materials, meaning the half-life is lower that 10 years and they can be recycled in around 100 years.
[1]: http://www.iter.org/faq#Can_you_declare_fusion_is_really_saf...
It is: it's definitely the biggest challenge after plasma confinement.
> Molten isotopes salt and lead?
There are two main blanket technology in development: ceramic and liquid breeders. They're called breeders but are very different from the kind of breeders you have in a fission reactor. Both are based on converting lithium to tritium by capturing fusion neutrons, but in one case the lithium is in the form of solid pebbles, while in the other, in a molten mixture of lithium-lead (there are no salts AFAIK).
To produce more tritium than you start with you also need a neutron multiplier: beryllium in ceramic breeders and lead in liquid breeders. The problem is beryllium is rare (and also toxic): a 500MW reactor needs ~200 kg/year, which is not a lot, but there's very very little beryllium on earth. If you factor in the initial reactor inventory (170 t/reactor) it turns out ubiquitous fusion energy it's not sustainable if we choose beryllium. If you go with lithium-lead you need more material: 3 t/year (but remember lead is a lot heavier and more common too). If you plan to cover the world energy base load with fusion, you would need a lot of lead (~10% world annual production) but it's doable.
For me, the biggest problem right now is lithium: DT fusion needs lots of pure ⁶Li, which is extracted by enriching even more natural lithium. If we're not careful enough with recycling it from old batteries, we are likely to exhaust the world resources in a few decades.
> What do you do with when it goes bad? It may not go boom Chernobyl-style, but it's still far from the birds-in-the-sky deuterium-from-the-sea fusion dream.
The worst case scenario is still the loss of coolant accident (LoCA). The blanket is exposed to a ~2MW/m² heat load from the plasma (in addition to all kind of radiation), so failing to cool adequately a module means it will very rapidly turns into a (radioactive) molten mess that's not easy to handle. Yeah, it's bad but not nearly as bad as the same accident in a fission reactor.
https://en.wikipedia.org/wiki/FLiBe
> FLiBe is a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2).
If we are lucky enough, none will be built.
The population will most definitely not continue to grow (in fact it will start to decrease slightly the more countries reach "developed" status), and the energy consumption per-capita will also stagnate. After all, there is a huge difference between going from living in a log house to a modern apartment with utilities and AC, and not much of a difference between one laptop and a slightly better one some years down the line. Also, attitudes towards environmental protection are changing with the generations so we are likely making different decisions 50 years from now.
If you increase the amount of energy flowing into the human body, the metabolism increases as well (although almost never proportionally - there are many variables) to compensate.
Similarly, it's rather unlikely that humans will continue to use exponentially increasing amounts of energy, unless we intentionally do something to effect that. Human population growth, which is partially driving energy consumption, is not exponential (it would be exponential absent of resource constraints or cultural factors, but guess what - both of those are in effect rather strongly in the real world) - and neither is energy consumption per capita. For instance, from 2005 to 2020, the US gained 30M people[1] while keeping energy consumption roughly constant[2].
[1] https://datacommons.org/place/country/USA [2] https://www.statista.com/statistics/201794/us-electricity-co...
In a way, the US (and Western countries) are outsourcing their energy consumption.
Exactly, the original link I posted is more or less an argument against infinite economic growth.
The same goes for infinite growth. In the close future it sure looks infinite, but I'd say it's infinitely hard too to predict what will happen in say a 100 years (a fourth of the time before we hit the heat death wall predicted here).
That text is exactly an argument against infinite economic growth – and it carries out said argument by looking at energy consumption (which necessarily grows with economic activity).
We would have the same (if not higher) energy consumption per capita on any other planet. And unless that planet is humongously large (which would also increase its surface-level gravity, thus rendering it uninhabitable), the relation between surface temperature and energy consumption will be similar[0]. Now there's only a finite number of planets in our solar system and leaving our solar system, say in the direction of Proxima Centauri (the star nearest to the Sun), amounts to traveling ~4.2 light-years. At a velocity of 0.1c (which is a lot – especially if you're trying to move an entire species[1]) that means a travel time of 42 years (as seen from our current frame of reference). Any velocity lower than that and we're getting into hundreds-of-years territory, so we'll be needing space ships across we can live for generations.
Also, a space ship is not that different from a planet, in that it also has to obey thermodynamics. So the surface temperature issue there is just the same. (In fact it's worse, since our space ship will likely be smaller and we also need to factor in additional waste energy of the space ship's propulsion engine or whatever we're using.)
[0]: https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
[1]: Or, say, half the species (or whatever amount necessary to make the total energy consumption on the planets we already inhabit drop to levels such that the planets' surfaces don't start to boil).
We can barely speculate about such a world, but interstellar travel would not be much of a challenge with that sort of energy abundance. We'll find a way.
On an interstellar ship far from a star, I think you're more likely to freeze to death, because temperature in space is near zero Kelvin.
Inside the solar system however, you could reflect away the received radiation (and heat) using mirrors.
I wonder, in a strictly thermodynamic way (ignoring CO2 etc), how big of an impact it would have to remove all internal combustion engines in land-based transportation and power generation (coal plants).
ICE's have like a 30-40% efficiency? Compared to electric engines 80-90%. But on the other hand, you probably consume quite a bit of energy producing the batteries...
Per unit of storage, Wikipedia says the lifetime storage capacity of batteries etc. relative to energy needed to construct them is:
Lead acid: 5 times construction energy; Vanadium redox: 10; LiIon: 32; Pumped hydro: 704; Compressed air: 792.
I can’t remember where I’ve seen this, but I think a unit of PV produces all the energy it took to manufacture after a month or two.
If you mean overall? As a rough guide we emit about 35GT CO2/year which is about 9.5e12 kg carbon; burning carbon releases about 32MJ/kg; so about 3e20 J/year, or 9 TW, or 19 mW/m^2.
There’s more energy in the hydrogen in gases and oils, this is just a ballpark estimate of the thermodynamic output of burning that much does to directly heat the planet.
Global energy use is around 170,000 TWh/year (1). This includes electricity generation, as well as fuel for transport, burning wood for heat, etc.
Heat flow from mantle is 403,000 TWh/year (2)
Solar irradiance is ~1200W/m2, which adds up to massive 5B TWh/year.
Extra radiative forcing from greenhouse gases in IPCC scenarios is ~3W/m2, or around 12.5M TWh/year.
The radiative forcing is two orders of magnitude larger than our energy use.
(1) https://en.wikipedia.org/wiki/World_energy_supply_and_consum...
The 1200-ish W/m/m figure is hitting a flat plate circle, not hitting the whole spherical surface.
Taking 173,000TW of continuous solar energy* times 24h/d times 365.25 d/yr yields a little over 1.5B TWhr/yr
Hand-warmers can keep part of the body warm for a few hours. Coats can keep the whole body warm for years.
Kinetic energy will end up getting converted to waste heat nonetheless.
> or bound carbon
This seems hard to imagine. We're dealing with waste energy here, so a very high-entropy type of energy. Bound carbon is low-entropy, so the conversion is impossible[0] unless we put that entropy elsewhere.
As an analogy, consider a fridge: It brings your food from a high-entropy (high-temperature) to a low-entropy (low-temperature) state but in order to do that it also has to produce waste heat (entropy) on the outside.
[0]: https://en.wikipedia.org/wiki/Second_law_of_thermodynamics
Eventually it all decays to heat, as per the 2nd law of thermodynamics
If you were to use 100% of solar panel energy to heat up something else the overall balance would be 0.
Contrarily, nuclear fission/fusion that releases energy from its fuel, ultimately heating up the planet.
I honestly can't tell if you are joking. The energy expenditure to get anything into orbit would produce more heat than you are offsetting.
He's basically describing a giant air conditioner... it's definitely theoretically possible.
How to tell an undereducated journo.
We're talking about a civilization on board an interstellar ship that had to leave their home planet because they were consuming so much energy that the resulting waste heat ended up making the oceans boil. So the assumption that they'll keep on consuming lots of energy (and producing lots of waste heat) on board such a ship sounds rather reasonable to me.
> Inside the solar system however, you could reflect away the received radiation (and heat) using mirrors.
The discussion is about getting rid of heat produced on board the space ship, not heat that's received from elsewhere.
In theory yes, but in practice: Not so much.
Even if we put aside GP's concerns, shooting big blobs of lava into space would require heating up the lava/rock in the first place. But this process doesn't happen on its own (through thermalization) given the average temperatures on Earth, meaning that the process of moving waste heat (from the environment, i.e. air/ocean) to the lava will once again decrease entropy (of the combined lava + air/ocean system) and you thus need to move the missing entropy elsewhere. (Meaning that you have to do work to accomplish this heat transfer / dethermalization and you will once again incur waste heat.)
Sure, we could also try to tap the heat bath of the Earth's core but then we would build a deep-Earth elevator to transport lava and solid rock (or, say, water) back and forth and GP's concerns apply once more.
There's another option, though: Don't build an air conditioning system/fridge – use thermalization with another (lower-temperature) system. That is, don't take lava (or anything that needs to be heated beyond ambient temperature) – "just" take rock at (Earth's) ambient temperature, move it to a lower-temperature $PLANET and then move cool rock from $PLANET back to Earth. I doubt this would be very efficient/fast, though.
In any case, the difference between the two approaches is that an air conditioner (or a fridge) cools things below ambient temperature and requires additional energy for that (which it will expel as waste heat), while the second approach "simply" moves energy from the heat bath that is Earth to some lower-temperature reservoire (i.e. $PLANET). If $PLANET and Earth were thermodynamically connected not just through the exchange of infrared radiation, this would happen by itself over time through thermalization.
Short of shooting hot lava into space[0] we pretty much are because, once again, thermalization through radiation is governed by Stefan-Boltzmann's law and there's no way around that.
The same problem crops up when you're talking about moon bases and so on - you've got the same problem of venting heat from an ecosystem into a vacuum. For that situation, one of the solutions that got designed out was to basically spray an oil mist across a gap, catch it, and recycle it into the cooling system. As a fine mist, the oil has a colossal surface area compared to its mass, and all that surface area can radiate heat off into the vacuum.
So... scale that up? I realise it's a hell of a leap, to go from human-scale to humanity-scale, and I don't know exactly what it would need to look like, but limitless energy is a hell of a springboard.
Also note the construction timetables: 72 months vs 18 months for PV.
1. EIA 2020, Capital Cost and Performance Estimates for Utility Scale Power Generating Technologies: https://www.eia.gov/analysis/studies/powerplants/capitalcost...
That's not how construction works. Past some small scale, construction cost scales quadratically or worse with size. Building a 100m tall sky scraper is not 10 times as expensive as building a 10m tall 3-story house - it is at least a hundred times more. The only reason why it's sometimes worth it is in ultra-high land-cost areas, such as Manhattan. But you'll never see sky scrapers outside city centers, because construction costs scale horribly with size, even for simple structures. Building a fusion chamber twice the size of ITER would likely be a new 50 to 100 year research project.
> You keep saying "quadrupling your construction costs" without evidence. We build oil platforms in the ocean on a regular basis. They cost some tens of millions of dollars. Existing fission reactors cost some billions of dollars. The difference from being on the ocean is evidently not the dominant cost. And then you don't have to pay for land.
Is anyone building fission reactors, or any kind of huge concrete building out in the ocean at all? Extracting oil from the ocean is many times more expensive than extracting oil on land. I have no idea why you even imagine that it's possible at all to construct a nuclear power plant out in the ocean. There is certainly no precedent for anything even close to that.
First, the power output of a fusion reactor is limited by what the first wall can withstand. Therefore, the power goes as radius^2, where as the cost goes (at least) as radius^3.
Second, the larger a fusion reactor becomes, the more parts it has, and the more reliable each individual part has to be (since there will be no redundancy in many; an leak into the vacuum chamber shuts down the reactor, for example). Reliability is expensive, so each part becomes more expensive as it is required to be more reliable.
Renewables sources are extremely redundant, so they'd scale just fine even with unexceptional per-unit reliability.
Most of your cost difference is that a commercial building isn't just taller than a house, it's also wider. Instead of taking up a third of the lot, it uses the whole thing, and then has 30 times more interior space despite being only 10 times taller. They're also built to commercial building standards which are more expensive to meet.
The costs start getting non-linear when you get into extremely tall buildings that pose special engineering challenges, but nobody is talking about building a fusion reactor into a skyscraper.
> I have no idea why you even imagine that it's possible at all to construct a nuclear power plant out in the ocean. There is certainly no precedent for anything even close to that.
Nuclear submarines survive the ocean just fine.
Yes, they are and it is a huge political issue in nearby countries.
https://en.wikipedia.org/wiki/Russian_floating_nuclear_power...
Solar power will never need to remove more than a tiny fraction of tree cover from Appalachia. What's a far bigger threat to the ecosystem, including animal migration, is mountaintop removal for coal mining:
https://law.lclark.edu/live/blogs/134-de-regulation-of-mount...
The argument in the UCSD blog post linked above will apply to any finite system if you assume exponential growth in power use, and exponential beats cubic for expansion to other worlds (I’m assuming no FTL for a cubic limit to expansion).
Abundant power — be it from fusion or solar or quantum magic — does not actually need to guarantee eternal exponential growth of power use, but the absence of such growth would necessarily lead eventually to the absence of economic growth.
We can still have a SciFi future without that, it will just look different in a way our current society can’t properly envision (which I think is an unsurprising a claim to make even in the absence of the rest of this argument).
I don't think I agree.
1) The extremely high (but still finite) amount of energy required to evaporate the Pacific Ocean is still much less than the infinite energy you need to accelerate even one single space traveler to the speed of light. Infinity is weird.
Of course we won't be trying to reach the speed of light but the energy (and fuel) required to move half the species (so that the other half can stay on Earth/Mars/…) will still be significant.
2) My second argument was that the Stefan-Boltzmann law is just the same on board the space ship. And if we live there for generations, chances are our energy consumption per capita will be similar as on the planet we left, and so we will be running into similar issues with Stefan-Boltzmann's law. Sure, we can split up the passengers across multiple space ships and make each ship much bigger (to increase surface size) but not only will this increase the total mass and thus fuel required for the trip but we would probably still not achieve the (rather high) surface area per capita ratio that we have on Earth.
Thinking a bit further, just because we can produce a high amount of energy that doesn't necessarily mean we can automatically convert it into kinetic energy for a space ship very well. Most propulsion systems in space still require expelling a propellant and conservation of momentum means this is unlikely to change. (Sure, one could imagine solar sails but the little momentum exchanged there won't get half of humanity to Proxima Centauri very fast.) So while we might have unlimited energy we might still be constrained by momentum requirements.
The only way I can see to solve this conundrum would be producing enough propellant on board the space ship, e.g. (lots of) photons, using a laser. Definitely not impossible (especially not at these energy levels) but it'll be interesting to see what these propulsion systems will look like exactly. :)
Ideally, we would of course try to use the propellant to also get rid of the waste heat mentioned earlier but I'm not sure whether this would work entropy-wise.
True, but how many tons of space junk can you accellerate to 95% of light speed for the same amount of energy?
Approx. mass of Pacific Ocean[0]: m_ocean = 7.1×10²⁰kg
Specific heat of water: c = 4.2kJ/(kg · K)
Temperature of Pacific Ocean: T_1 ~ 293K
Temperature at which water starts boiling: T_2 ~373K
E_heat = c m_ocean ΔT = c m_ocean (T_2 - T_1) ~ 3×10²⁶ J
E_kin = (γ-1) m c²,
Setting E_kin = E_heat therefore yields:
=> m = E_heat / [(γ-1)c²) = 3×10²⁶ J / (2.2×10¹⁶ m²/s²)] = 10¹⁰ kg
- We haven't taken into account the space ships required to transport everyone
- E_heat was waste heat but since practically all energy will become waste heat at the end of the day, E_heat gives us a pretty good estimate of the total energy we will have (had) access to.
All in all 0.95·c doesn't seem feasible for moving humanity to Proxima Centauri, given E_heat. For moving 10¹⁰ kg of space junk, sure, though I'm not sure what you were planning to do with all that space junk in the first place?
> We super-heat some dense materials
This won't work as you would need to put in additional work (leading to additional waste heat) in order for this process to lower ambient temperature. The only thing you could do is shoot stuff out that's precisely at ambient temperature, compare https://news.ycombinator.com/item?id=28471620 .
If such land were available at an equivalent price to the hillside in question, why would anyone clear a hillside to install solar? All else equal, it's strictly more work/expense to build a solar farm on an incline. The price for the "other land" must not be right, or must have some other serious disadvantage.
Now .. putting solar farms on top of already strip mined mountains makes sense to me. You've already flattened them, and farming is of the question. And it ... looks like that is happening. Tjough I don't know how the Surface Mining Control and Reclamation Act plays into that.