When they don't mention Q in article, I always assume it is <1. If they do, well, then no need to assume.
When Q>1 times come, we will then have to assume Qtotal < 1 until explicitly mentioned. As there are losses along the way and heat must be converted to electricity.
Tokamaks, while cool (or hot!), are ultimately limited by materials that we know about.
There are IAEA reports for fusion calling for materials that survive >100 displacements-per-atom (DPA) and > 1000deg C[1]. Additionally you might also need highly controllable super-conducting magnets as well as advanced sensing of the instabilities of the fusion plasma to ensure they are well confined (a chief requirement for fusion). There are other problems, but these are typical issues with tokamak-based fusion devices. Chiefly most tokamaks around the world do not operate in "continuous mode", ie they operate on "shot mode" or short duration experiments to attempt to ignite the plasma to fusion conditions. Achieving high-duty cycle operation with a ignited plasma is its own hurdle.
Making hot plasmas is interesting, but if your technology requires the above, you are looking at around 4-5 once-per-decade material science results.
Every national lab in the US is saying we are out of time, we need existing energy solutions to avoid the worst of climate change.
CFS has demonstrated magnets that seem to be up to the job, using REBCO tape. They'll replace the inner wall annually, so it doesn't need to be as durable. MIT already demonstrated practical joints in the tape.
We certainly need to decarbonize as fast as we can without waiting for fusion, but if we're lucky then fusion might make things easier down the road.
The problem is that even 1 DPA is significant for structural materials, and is basically a nightmare for electrically or mechanically sensitive ones. For example light-water fission reactors achieve about 50 DPA to their reactor pressure vessels over their 40-50 year lifetime. Its hard to imagine that anything called a super-conductor could maintain Cooper-pairs after getting the average atom displaced from its original position.
Additionally CFS ran at 20 Kelvin... which again is hard to imagine happening at scales other than CERN-like efforts (ie one-of-a-kind installs):
"In September 2021 Commonwealth Fusion Systems (CFS) created a test magnet with ReBCO wires in which flowed a current of 40,000 amperes, with a magnetic field of 20 tesla at 20 K." [1]
Edit: Also magnets have 1/R^3 field die-away, in direct competition with 1/R^2 particle dispersion die-away.... meaning your magnets control better as you make cavities smaller, however it also means the magnets get much more DPA :(.
Magnets are highly shielded from neutrons in a fusion reactor. The real problem is the first wall, which necessarily is not shielded.
Materials are an ongoing problem, and it's not just dpa. Abdou at UCLA pretty convincingly argues that increasing dpa of wall materials isn't even the most pressing problem; reliability of the wall/blanket is.
I should add that fusion neutrons add a problem beyond that experienced in fission reactors: the neutrons are sufficiently energetic that production of helium by (n,alpha) reactions in materials is a serious issue. The helium migrates to small very high pressure bubbles that break materials from the inside.
Of course. Look, did you really think superconducting magnets would stay superconducting if you hit them with megawatts/m^2 of neutrons? The heating alone would cause them to cease to be superconducting.
If you look at the ARC design, the blanket tank interposes between the coils and the plasma. There's also another neutron shield there (made of titanium dihydride) to further reduce the neutron dose on the magnets. Fun fact: the temperature of the salt in the blanket tank is > the decomposition temperature of TiH2, so in a serious accident large amounts of hydrogen gas could be produced.
There's a reason the ARC reactor is 20 meters tall and weighs as much as several WW2 US destroyers.
In your typical fusion reactor design, the blanket is not just inside the coils, it's inside the vacuum vessel (shielding the vacuum vessel from radiation damage and direct plasma heating too). This means any leak from the blanket is a leak into the fusion chamber itself, a criticality 1 issue for which redundancy is not possible.
Temperature & DPA have to be talked about together. I think Abdou's point is that you can replace the blanket more often and target ~20 DPA to reduce the mean-time-between-failures (MTBF). From the PDF:
"Results show: anticipated MTBF is hours/days (required is years), and MTTR is
3-4 months (required is days), and availability is very low < 5%"
I don't have a problem with talking about MTBF and replacing blankets etc but we are talking about research, not a reactor.
Also of note look at the MTBF of magnets and cryogenics in this system! (1.14years and 0.57 years)
Abdou's point is that the RAMI problem has to be solved to continue to do research, and solving it has a higher priority than getting higher dpa tolerant materials.
What's your view on the Deepmind experiments to use NNs to stabilize the plasma fields, won't better control of the plasma ameliorate some of the material issues? (I think a link to that was posted here some weeks ago)
The Deepmind control of plasmas is interesting, and I think that some of the more recent successes at NIF have been related to more run-of-the-mill deep-learning based control.
The problems above are not just a plasma instability problem, which has impeded progress. The interior walls of the fusion reactors are just pretty extreme environments, and the extremity is made worse by the fact that if you control plasma flow with magnetic fields, you trade the ability to control magnetic fields with dose -to-the-magnets-.
Achieving high magnetic fields also require high currents -> super conductors -> low temperatures (0.1-20 Kelvin).
I attended a lecture by a bitter ex-LLL scientist who said they had made great progress with the magnet mirror approach but it was scuttled right before it starting it up. This was so they could do the laser project(s) which was really about learning how to build weapons.
Edit: However it is good to note that in comparison with other fusion methods, laser based methods relax materials constraints I listed above simply by spreading the energy/particle fluxes over larger surface areas.
If you built a giant fusion reactor based on NIF you could reduce DPA and temperature requirements, but it would fundamentally be a "shot" based reactor.
To be honest a lot of the fusion news recently has made me skeptical (namely, for CFS guys who kinda smell a little sus to me if I'm being 100% honest), but this on the other hand is fantastic, actual results (although they should publish a paper on it, just my bias as a scientist), meeting good plasma temps with just $70M! Not a gigabuck not even 100 megabucks, that to me is a good sign for actual commercial fusion. Bravo to Tokamak Energy.
> And to think, some people would rather spend $700 million on a boat[1].
This is the weirdest thing to me. How do billionaires think a big boat is cooler than building nuclear fusion? If I was a billionaire, I'd build space ships and underground tunnels and nuclear micro reactors
Large yachts are functional. They’re mobile own territory for people operating on the level of nation states.
Booking out a hotel for hundreds of aides, attachés and visitors is very difficult outside the largest cities. Securing it can be impossible. Particularly on short notice. A yacht solves those problems.
I never thought of it from this perspective. A yacht could serve as a research vessel with slight added protection against political turmoil. One of the problems with setting up organizations inside of a nation-state are the economic and political risks. Without the necessary dive into the ethics of the proposition, it might serve as the Noah's ark for vital research and the associated minds.
Sergey Brin uses his yacht for disaster relief. He has a charity that sends teams around the world to help with disasters.[1]
He also has a startup, LTA (Lighter Than Air), aiming to build blimps for humanitarian purposes.[2] According to this article he also wants to the blimp to be "luxuriously appointed" so it can be used as an air yacht.[3] LTA is based at Moffett Airfield in Mountain View, and I know I've seen blimps take off and land there every once in a while. When I see one I always wonder if it's Sergey's blimp.
Are we sure this isn't one of those tax-haven "foundations" that get you adulation and praise from the march-in-line media and a tax-free yacht and airship to use on the weekends? Maybe a "luxuriously appointed" "humanitarian" "tax haven"? I'm out of quote marks now.
Right? If he wanted to spend 80 million on humanitarian missions he'd be better to have bought the HMS Ocean when it was in sale. As a helicarrier with a proven track record in humanitarian missions, it's vastly better equipped than a party boat stocked up from Home Depot.
> Physicists trapped in indentured servitude aboard Elon Musk's converted droneship research station "Just Fucking Get It Done" as it sails the post-apocalytic seas.
> Just when they thought it couldn't get any worse, they dock at Peter Thiel's island bio-research facility and they have to take matters into their own nitrile-gloved hands before it's too late...
They may have passenger capacity of 12, but they have a larger crew and servant quarters capacity. You can invite 11 more of your billionaire pals, and there'll be plenty of people around to serve their needs.
I've seen stories of megayachts that have their own smaller yacht following them with the water toys, and other humans who help provide entertainment for those owning the larger yacht. The first entry on the link below says that some kind of lab has been fitted into it.
If not for visions of space-faring billionaires, I could easily foresee sea-based billionaires with a small armada of support vessels to provide for them:
Old tankers could potentially be repurposed as massive hydroponic farms, or even fish farms. Why trust the local's mercury-and-parasite ridden fauna, when you can instead pull some fresh Tilapia 2 (genome will be slightly modified to prevent breeding with 'natties', probably will have different-colored skin) out of The Pond's hold?
A cruise ship would probably be the best host vessel for your employees, since it already has a lot of the features you'd need (sleeping, eating, refit some of the entertainment spaces into workspaces), and a smart move would have been to buy one during the Covid crash the operators had early on. Force your employees to register as residents in your port town of choice for optimal tax shelter status, and minimal legislative oversight.
Nuclear submarines could be used as top-secret skunkworks, since they could dive down in order to guarantee some amount of isolation from corporate spies. Once you have your roster for a project, you'd dive down a mile or so, and give the teams metrics to see who earns the most sunlight during the bimonthly surfacings. Lines up nicely with 2 week sprints, right?
But here's something I can't figure out: What would the flagship be? How many people would it need to support? Would it be one of the biggest of the armada (like the capital vessel), or would it be an incredibly-well-appointed cruiser?
Then I discovered that the $700 million superyacht Scheherazade can accommodate "40 guests in 22 cabins". I suppose you could fill the hallways with bunk beds as well for your "hundreds of aids, attaches, and visitors".
I don't think accommodating 40 guests is difficult "outside of the largest cities".
> Booking out a hotel for hundreds of aides, attachés and visitors is very difficult outside the largest cities.
Even the biggest yachts can't host even close to these numbers of people.
E.g. the gigantic Azzam superyacht, at a cost of $600M, and 180m in length, can host only 36 guests according to news reports.
Could be fission powered, if it's an old aircraft carrier.
You'd think a billionaire would have gotten one of those by now. Like China with the Liaoning... though, even the Liaoning isn't nuclear.
Actually, that's pretty amazing. The Americans have several nuclear carriers. The Soviets/Russians had/have several. And the French have one: the Charles de Gaulle. That's it. Nobody else has any. Not even China. Not even Britain (which does have nuclear submarines).
That's pretty amazing.
It really puts into perspective how powerful the United States is.
Granted, there's an argument that these are becoming floating targets, what with ASBMs, and as hypersonics come online. But still. They're pretty impressive things.
And even the Russians seem less capable than expected.
Which leaves basically just the US. Still.
Complacency would be a huge mistake -- and China is projected to start working on nuclear carriers pretty soon -- but, nevertheless, maybe reports of America's dethronement are premature.
Many countries have rules which forbid privately operated ships powered by fission-reactors docking/anchoring. The German-built Otto Hahn wasn't allowed passage through Suez and Panama Channel, the US-built NS-Savannah was excluded from ports in Japan, Australia and New Zealand.
Though that was long ago, I'm unaware of changes regarding that.
So no cruising to your bunker in NZ on your supernukular toy when the SHTF :-)
Aircraft carriers are large targets because they're so valuable. WWII Pacific Theater was centered around taking out enemy aircraft carriers while preserving your own. If you can have one that can operate on its own for months and out-speed any chemically-fuelled vessel: that's a huge advantage. Now imagine having a fleet of them. Nothing short of ready for war.
Many megayachts are chartered when not in use by their owner. So in the end they are investments that produce a return [1]
“ It's worth acknowledging that while owners will ultimately spend a huge amount for the privilege of having their very own superyacht, they're able to recoup some of these costs by chartering them out.
Connor estimates that around 12 weeks of charter represents the annual operating cost of most yachts, which means owners can break even if they hire their boats out for the same length of time they use them during the year.”
I assume people worth several hundred million dollars won't spend 10%-50% of their total wealth on a $100+ million yacht, but will still pay $1mil/week to rent one on occasion.
You might break even on running costs, but when do you break even on the outlay?
I guess you get some back if you sell it, and you probably never actually laid out for it as such rather than though some mad financial chicanery because simply paying for stuff is decidedly plebian.
Here's an example: Moonlight II. It's a 300 foot yacht owned by a sheik [1]. The price is $100 MM. You can rent it for "from $705k per week" [2]. Could be more, I guess. If they manage to charter it for 30 weeks a year, that's a nice $21 MM. That more than covers any conceivable financing and operating costs. In fact, you'd be hard pressed to find an investment with a similar return.
I'm surprised no authority has raided one just after an investment banker party cruise, looked for the forgotten baggies and seized the vessel for "drug smuggling".
Eventually, yeah, I’d think so. I’m not nesting-doll-yacht rich but as I understand it:
1) You don’t buy something for $100+ million out-of-pocket. It’s easy to borrow money when you have money. The purchase would be financed at very close to market interest rates, and the repayments factored into the running costs.
2) The vessel would then be run as a business and chartered out for conventions, luxury cruises etc. Any profits would go to the owner.
3) The owner would then use the vessel as needed, maybe even paying like any other customer (albeit out of the profits generated by the boat itself, I’d imagine.)
4) Any remaining profits could be used to pay off capital, but probably aren’t. Instead, they’d be used to fund new ventures.
Well the yacht is now an 'investment' so you get to claim it on taxes and get an instant 30% refund.
Your buddy sets up a special company just to build it and stiffs all his employees and suppliers. Then the quid pro quo gets you another 30% or so back.
Renting it out for another 12mo/year earns the remainder back in a decade or two.
You can also 'donate' the use of your yacht to have a big party (also known as a charity ball) from time to time if you feel you are paying too much tax. Make sure the 'charity' is one owned by one of your buddies and is primarily used for lobbying or undermining competitors.
Boats are fantastically expensive to maintain. You can surely recover some costs by renting them out, but I’d imagine it’s still mostly a net negative “investment”.
If you're a state level actor, you've got state level security concerns. I doubt, for instance, the American or Russian consulate gets rented out for parties where they turn over the whole kit to some other organization.
Yes, there is "your" staff on-site to protect much of the yacht / facility, but that doesn't stop a determined actor who's got a week of somewhat unsupervised access from infesting the whole ship with bugs bombs and poisons.
Right? Big boats aren't even that big a brag, someone will always have a bigger one, and if yours is longest for now, then theirs has three helipads, and next year some tryhard will build a longer one anyway.
Being first to fusion would mean your name would be above even Einstein in history.
I am reasonably sure trying to commission building one would bring the attention of the United States and ah, the situation would develop not necessarily to your advantage...
The big boat is about status, which means attracting mates and increasing the odds of breeding before a lion eats you. Our brain stems don’t know what geological epoch we are in.
Sun is a fusion reactor, and they choose, quite rationally, that getting tanned on a big boat under a big reactor is way better than getting tanned on on a cheap bench with that microscopic reactor.
IMO, spending 15TJ running a research reactor like JET at full whack for 6 hours (which is actually a lot of test fires) is of greater benefit than burning the better part of half a million litres of diesel moving a single billionaire and his lampreys around a bit.
Is it? We’ve been doing this for what, 30 years and all we really have to show for it is 30 years of hoping that the big breakthrough is 5-10 years away.
Integrating the curves is maybe $100 billion. And below a certain level of funding nothing can really be done (you can't build any reactor on $10 and a box of surplus paperclips the IRS donated from pity). The fact we actual got anywhere using the handful of "it's a start" research reactors like JET, which dates to 1984, that could get built is a testament to the scientists and engineers, not a indictment of the field.
Basically, if as much was spent on it as we spent on blowing up poor countries for no real reason (at least $2,000 billion, just for Afghanistan), we'd likely be onto the second or third generation. Or we'd have concluded decades ago that it really can't be done to a five-sigma certainty.
The cynic in me says there's a renewed push for it recently because China has 3 research reactors, the next one (CFETR) is designed to outperform ITER (which China is contributing to) and support research for DEMO (which is to say, it is or is very close to being designed for experimental power generation), and the US feels in danger of being beaten to it.
A lot of billionaires have organized businesses but never tinkered with anything constructive in their lives. They don’t even own a black and decker power tool.
What's sus about CFS? No one else is making 20 T confinement field coils. SPARC's campus is already up and the machine is being built. ARC is expected to have ground broken this year.
ARC is going to begin construction before SPARC is proven? That’s actually great news I just didn’t know about it. I guess they gotta find a way to spend their new $1.8B investment.
For me it’s the “seemingly” crazy unrealistic deadlines, which are achievable if they don’t actually try and hit net energy gain.
Use 20MW of energy to add 10MW into plasma, get 20MW of fusion, convert 30MW of heat into 10MW of electricity and they have reached their stated goal without actually achieving anything useful. And that’s assuming steady state operation rather than a fraction of a second pulse that briefly reaches their goals.
It’s exactly the same thing as a startup selling dollars for pennies and saying yea we’re going to make it up in volume.
ARC will be about the size of JET, and JET was built in four years, with most of that being just for the buildings. The test reactor, SPARC, will be about half that size.
Tokamak scaling is very well established. The output scales with the square of plasma volume, and the fourth power of magnetic field strength. Stronger magnetic fields also make the plasma more stable. JET already demonstrated a five-second plasma, which they only had to shut down because they have copper coils that would melt if operated longer than that.
Because of all this, many independent fusion researchers think SPARC will succeed in getting 10X gain in 2025. After that, the larger ARC should easily reach commercial levels.
Of all the commercial fusion companies, CFS is the most conservative one. Tokamak Energy is a close second, with a very similar approach. The other fusion startups are attempting approaches that have more physics risk, though many of them would have fewer engineering and economic difficulties if the physics does work out.
Simply scaling SPAR or ITER doesn’t result in commercial operation.
First you need fuel, global Tritium supplies are tiny and DD fusion is much harder.
Next stability is an open question, no Tokamak has ever operated near maximum capacity for even 1 hour.
Add to that serious material science questions, etc etc and even Q>100 alone just doesn’t actually mean much.
Now let’s just assume all of that is solved, you still need to actually ensure your design is economically viable. Simply producing energy from fusion alone isn’t enough which means you need to cheaply solve not only all the above but do so cheaply.
These are valid points. I was just responding to your statement that their time frame is "achievable if they don’t actually try and hit net energy gain." They are trying, and are likely to accomplish net gain about as fast as they say they will.
They actually have a fairly practical-looking design though. ARC will use FLiBe for tritium breeding and coolant. That will surround an inner reactor wall that's 3D-printed and replaced annually. MIT already demonstrated joints in the superconducting tape, allowing the reactor to be opened up to replace the core.
Economic viability is an open question for all tokamaks. Some of the other designs would have a better chance of achieving low costs if things work out, but there's a much bigger question mark on the plasma physics.
The other problem is that the thermal power density of ARC is about 1/40th that of a PWR reactor vessel. It's a much larger, much more massive/complex/expensive way to make heat.
Spilling a thousand tons of melted lithium (and beryllium?) would be disruptive enough that containment, safety systems, and armed guards would still be needed. Also, not spending to protect your $100B facility from harm might make your insurance company nervous. (You did find an insurer, didn't you?)
If it actually cost 100B to built then your never going to break even.
As to containment, the lack of high pressure steam makes much thinner walls completely viable. You still need shielding around the vessel, but not a completely redundant system capable of containing highly energetic steam explosions.
In terms of risks, sabotage at a nuclear reactor can be vastly more expensive than just the cost of equipment. Modern reactors are reasonably safe, but not if people where actually trying to break them. Especially when you consider what someone could do with access to the fuel. It’s not weapons grade, but dirty bombs are horrific.
You do still need a very strong structure to resist outward pressure. It's isn't steam pressure, it's magnetic pressure, from JxB forces in the magnets. For ARC, the stainless steel supports for the magnets weigh 5300 tonnes, and comprise 3/4 of the mass of the entire reactor. The energy stored in that magnetic field is (I think) larger than would be stored in the steam of a PWR of the same thermal power output.
The building housing an ARC will be very large. The reactor itself is 20 meters tall, and the entire top half of it has to be lifted off and moved aside when changing out the vacuum vessel. All that lifting and moving will have to be done remotely because of radiation from the activated vacuum vessel, which then will need yet another shielded area where it can be broken down for disposal and the debris from that cleaned up or at least contained.
> would be stored in the steam of a PWR of the same thermal power output.
Safety system don’t just need to handle normal operations. The energy in a fusion reactors magnetic fields is very well known, a fission reactor steam explosion or potentially hydrogen explosions can bet vastly more violent.
Using Fukushima as a baseline. ~1,000 kg of hydrogen * 142 MJ/kg is a lot of energy and that was vented outside the primary containment vessel before detonating.
Granted this is not an inherent requirement for fission, but good luck convincing regulators it’s unnecessary.
The ARC reactor uses 380 tonnes of TiH2 as a neutron shield for the magnets. This fully decomposes at the temperature of the molten salt, which could yield up to 15 tonnes of hydrogen.
> If it actually cost $100B to build then you're never going to break even.
IOW, we're never going to break even. You and I are paying now, and would in any case never get any of the revenue, if in fact any could be had.
But we are supporting the careers and research of plasma fluid dynamics physicists and their students, and a few of them might do other, actually useful, and anyway wholly unpredictable things, later. With a good measure of luck, none of those things will build up to any world-spanning catastrophes the way the steam engine did.
I give it 10% chance of being better than nuclear power in 30 years. That’s worth the investment even if the odds of a solid payoff are low, the upside is significant.
Lower risks should mean fewer NIMBY issues, which means wider adoption. Nuclear advocates miss that if fission played a larger role in energy generation it would also see more major incidents. Which then risks a backlash etc.
It sounds like you might know the answer to this: I vaguely recall hearing them say the tritium is created in the reactor from duterium? Is that a thing?
It is, deuterium fusion's final product is half tritium (and half He3).
But D-T reactors would mainly breed tritium from lithium. The CFS reactor, for example, will immerse the reactor in a pool of FLiBe salt, which also functions as coolant. Each beryllium atom hit with a neutron emits two neutrons, and when neutrons hit lithium atoms they breed tritium. General Fusion does something similar with lead in place of beryllium.
Thank you. So do they need to source tritium externally at all? I’ve seen people claim CFS will have to source tritium, making it expensive to operate. Can they breed all they need?
In practice it means the mix of Li-6 and Li-7 in your coolant pipes has to capture more than half of the neutrons emitted, and not too many of the slow neutrons released in intermediate reactions get stolen.
Yeah. Someone the other day said in a comment that commercial fusion will never be viable because tritium is so expensive. But it does sound like breeding is the plan at least with ARC so I don't know what that commenter was thinking.
3He on the moon occurs in regolith at a concentration of maybe 10 ppb. At that concentration, simply heating the regolith to drive out the 3He uses more energy than the 3He would produce in fusion, unless extreme heat recycling can be achieved (and good luck transferring heat into/out of powders in vacuum.)
Even if it could be recovered, all the 3He on the entire moon might power the world for maybe 100 years.
Thanks, didn't realize the energy balance was so bad.
That strengthens the point I was trying to get at, which was that there's no reason to go to the moon for He3 when, if we can get net power from He3, we can just make it in a D-D reactor and gain energy in the process.
My favorite 3He source would be "Planet X", if it exists and is an Earth (or perhaps even Mars) size planet out far enough that the temperature at the exobase is low enough to retain 3He in its atmosphere. Sure, getting there would be difficult, but this scenario assumes we have D3He fusion, which we can handwave would get the miners out there in a reasonable amount of time.
It will take fundamental advances to get to p-11B fusion. A startup working today is anyway in no position to achieve such fundamental advances; that is more in the line of national laboratories, or would be if they were not fooling with ITER instead. Maybe some of the ITER work will be useful for other things.
For D-3He fusion to be useful, we have to hope that it will be economically viable to synthesize 3He, in the meantime. Arguably, we ought to be making and stockpiling tritium now so there will be enough 3He when we need it; but that might be too optimistic.
I don't think they'll have SPARC by 2025 but the physics work out. It's basically a bog-standard tokamak with superconducting magnets but with much more current capacity and therefore magnetic field strength from newer HTS. It's the fabrication of the magnets at scale that's totally new engineering and manufacturing; as we saw with Tesla that's quite hard. Plus the supply chains of HTS tapes aren't exactly mature.
I think both Tokamak and CFS have roughly the same strategy of using bigger magnetic fields. Given the scalings here https://royalsocietypublishing.org/doi/10.1098/rsta.2017.043... + JET working well it's a lot less risk than whatever most others are doing. Make a JET sized tokamak but have 5x the magnetic field strength gives a 625x gain in power, ideally.
I agree with what your saying, but that’s doesn’t mean the end result is even close to an economically viable fusion reactor. Look back in 1990 people could have spend a lot of money building a truly monumental reactor and hitting Q>100 briefly. Nobody suggested that was a good idea because all the other unsolved problems which is why ITER was being built in the first place. The point wasn’t simply to scale it was to test blanket materials etc in an environment very close to a working reactor.
SPARK is undoubtedly a more efficient design but it’s not a solution for any of the major outstanding problems.
By those kinds of metrics, Tokamak Energy haven't "achiev[ed] anything useful" either.
Note that both companies are aiming to build a tokamak using high-temperature superconducting coils, which will facilitate energy gain in a small, high-field tokamak. CFS has built the coils, but no tokamak yet. Tokamak Energy has built a tokamak, but it doesn't use HTS coils yet, it uses standard/super-inefficient copper ones (they're developing the HTS coils as a separate project and expect to marry them in a future prototype). This prototype has the same "make it up on volume" problem, it's just lossy in a different way.
Both have made important advances that demonstrate critical components that will be necessary to do the full thing, but different ones, and neither of them has demonstrated everything. If anything, CFS's piece is arguably more important, because other copper-magnet high-field tokamaks have been built before (e.g., Alcator C-Mod at MIT, essentially the predecessor to CFS's prototype), but nobody has built a full-sized HTS coil before.
I am all for fusion research, in the context of research. But CFS’s short term goals comes off as a publicity stunt which rubs me the wrong way. Like IBM’s Watson playing Jeopardy etc, where what’s achieved seems like a breakthrough for non exports.
It’s possible they could succeed long term, but I don’t think it’s particularly likely.
Sure, I think that's valid. I just don't think Tokamak Energy's announcement is less of a stunt. They've both made progress on a well-defined but ultimately not-that-big piece of a big pie. Just different pieces. If the act of making big press pronouncements around incremental progress is a stunt, they all do it.
I hardly view "build a machine to understanding burning plasmas and steady-state tokamak operation" as a publicity stunt. These are hard machines to build in the best of conditions. The design of any power plant must be informed of results from machines like SPARC.
Speaking of, do you know any good channel/educational video that goes deep into nuclear fusion and the challenges we're facing for a layman such as myself?
Not in classical thermodynamics, but temperatures above the Planck temperature aren't understood with current quantum models. It would probably require a theory of quantum gravity to shed further light on this.
No, it does not. In a closed system if you add enough energy the temperature will eventually become negative (after ‘passing through’ +inf).
As you reach a state where almost all particles are in their maximum energy states (this is assuming there is one) you will slowly approach negative zero (which again you can never quite attain).
In particular even with a quantum non-interacting gas with particle-in-a-box modes, the Hamiltonian is not bounded from above and there is no reason to expect a negative temperature, no?
There exist systems, like spin systems, where energy is bounded from above and so entropy decreases as you add energy, which is the definition of negative temperature... But I find it dubious that every system is such, unless I am missing something nonintuitive about say relativistic effects or so
No you're quite right, that's why I said "...maximum energy states (this is assuming there is one)". Of course with no upper bound on energy this isn't possible, that's the definition straight up, just like you say.
> This is only possible if the number of high energy states is limited. For a system of ordinary (quantum or classical) particles such as atoms or dust, the number of high energy states is unlimited (particle momenta can in principle be increased indefinitely). Some systems, however [...], have a maximum amount of energy that they can hold, and as they approach that maximum energy their entropy actually begins to decrease.
In my (limited) understanding, it's somewhat like the phenomenon that a communication channel bit error rate over 0.5 actually results in less information loss (imagine a BER of 1: that's just a NOT gate).
If your energy states are limited, adding energy actual brings you closer to an ordered state (that of everything being in the highest state).
But, this is not a situation you get by simply heating something up with a blowtorch, no matter how hot it is.
interestingly, no. Temperature can become infinitely high, and you can still add heat, at which point it becomes infinitely low. You can carry on adding heat, and the temperature will get back to absolute 0. https://chemistry.stackexchange.com/questions/36885/how-is-n...
You can't heat something to negative temperature, although negative temperature things will transfer energy to positive temperature things. Negative temperature can be achieved through lining up many small magnets against a larger magnetic field. Disordering the magnets will reduce the potential energy, running opposite to the usual trend where increasing disorder involves the occupation of higher-energy states.
> Temperature can become infinitely high, and you can still add heat, at which point it becomes infinitely low. You can carry on adding heat, and the temperature will get back to absolute 0.
Perhaps the correct measure is not temperature, but inverse temperature (i.e. 1/T)?
Temperature has to do with how the entropy changes with the addition of energy. It helps to use the “coldness” or “thermodynamic beta” scale, β = ΔS/ΔΕ is the coldness of a system, the thermodynamic temperature is defined as 1/(k β) where k is a conversion factor, the Boltzmann constant, to convert between units of energy and kelvins.
For most normal systems, entropy increases with an addition of energy, and they have a positive coldness. Confusingly, the lower the entropy change, the less cold or hotter we would regard it: if you bring two systems into contact, they share energy to maximize their total entropy, so something which has low coldness = low entropy change will donate a lot of energy to something with a higher coldness = higher entropy change, the smaller negative will be balanced out by a larger positive.
You can extrapolate this to an infinite temperature, this would be an object with β = 0 or zero coldness, it can take or lose energy without changing its entropy at all. An example is an assembly of electron spins in a magnetic field, when 50% of them are aligned with and 50% are aligned against the magnetic field: this is the most entropic that the spin system could possibly be, so there is no way to increase it and to first order changes in energy do not decrease it. It has zero coldness or infinite temperature.
Add a little bit of energy and it is in the state where it actively wants to lose energy, putting more energy into the system requires aligning more of the spins along the magnetic field. This is a negative coldness, which is also regarded as a negative temperature by this T =1/(k β) formula.
Not a physicist, if temperature of particles is movement (I think chemical bonds will break long before the following limit), then the upper limit is just below the speed of light. To make it even hotter would require infinite amount of energy. Now what that temperature is in kelvin, I don't know.
Temperature is more about the kinetic (and other) energy of the particles than the velocity — you can keep adding energy indefinitely, or at least until you hit some kind of planck-scale weirdness point, even though the velocity is only asymptotically approaching c.
For each specific fusion reaction there is an optimal temperature (for maximum reactivity). Usually around a billion kelvin or so, plus or minus a few orders of magnitude.
Children's TV level astrophysics (it's not astrophysics, but that's the context where stuff like that is presented?) suggests that if Brownian motion approached 1c, mass would grow towards the infinite. So you could always add even more energy?
(There is another constant in the formula that depends on what definition of mean you use, but it's safe to ignore it for this discussion.)
So if T is big enough, the result of this formula is faster than light.
But this formula is useful only for a not relativistic gas. Once the temperature is so big that relativistic effects are important, you must use another formula. (The other formula is more difficult to calculate, but when the temperature is low the result is almost identical to the formula I wrote.)
More children's TV level of astrophysics: so you keep adding energy to your particles, they approach 1c, they gain and gain mass... until they collapse into nanoscopic black holes and immediately evaporate into hawkins radiation, right?
I mean that's the general upper limit on stuff in the universe: it eventually collapses into a black hole.
Yes it does - the plank temperature, where the wavelength of light emitted is the plank length. Current theories predict that this would be the maximum possible temperature. Of course, this is so hot as to be totally irrelevant to anything practical.
I mean the obvious upper limit is the particles moving at C, but I suspect quantum physics means that the limit is actually below that (my uneducated low level undergrad physics courses make me assume some relationship to the plank constant)
For those who know more, how meaningful is this achievement"
"We are proud to have achieved this breakthrough which puts us one step closer to providing the world with a new, secure and carbon-free energy source."
Seems like every fusion energy announcement, always one step closer but never quite arrived.
This is how R&D projects work. It’s extremely difficult to estimate timelines. Someone might have said the same thing of, for instance, image recognition - we kept getting “one step closer” for years and years. You could look at Fei-Fei Li making ImageNet in 2006 and go, “she didn’t really solve anything - they keep saying we’re one step closer to image recognition but this is just some new dataset.” Of course that actually was a very significant step, it was crucial groundwork for AlexNet.
There is absolutely no way to know whether getting to 100M in a spherical tokamak is really significant. Maybe this design is a dead end that will never see actual use. Maybe you will have a tiny one in your tea kettle by 2050.
What’s clear, though is that the pace of fusion research is really much faster than it was. That should be exciting to everyone except oil barons.
If it was anywhere close to being commercially feasible, you'd first see it in oil/gas futures. Money will know long before you or I or any news outlets will know.
This doesn't sound right to me. How many years out do oil/gas futures project? Even if someone from the future arrived today with blueprints of a perfect fusion power plant design, it would take many years to build up enough fusion power plants to make a dent in the world's oil/gas consumption. You'd not only need to switch over power plants, but replace every car, truck, house, ship, smelter, xxxx to use electricity.
The poster is saying the stakes in oil/gas are high enough that someone IS already paying millions of dollars to have dedicated staff follow projects and give people a heads up if anyone seems actually close (or it seems remotely feasible) - and you'd see it reflected in various market moves, either by hedge funds or by the companies themselves in how they invest on projects.
Which is probably true.
I've heard from friends of some of the typical shenanigans played among state actors involving oil and gas, and that would be the least underhanded thing going on.
I am saying that the timeframe between a breakthrough in fusion, and it having a measurable effect on energy usage is so large that "money" will not reflect it with immediate and large moves in the market.
‘Breakthroughs’ like fusion typically does are useless. Something viable is not.
When something viable happens, you’ll see markets move, because market pricing is based on expectations of future performance, not current performance.
The comment I was responding to was specifically talking about oil and gas futures. Not general stock prices, or which projects are started.
My non-expert understanding is that Futures are a specific financial instrument with set expiry dates, and are about locking in prices for these commodities at a certain date. The vast majority of these would be expiring in under low digit years. I am arguing that the ramp up time for fusion to go from "feasible design" to "having a significant impact on the the amount of oil/gas consumed" is much longer than most futures expiry dates, and would therefore have little impact.
That said, I guess people can (and do) buy futures with expiry dates for more than 10 years out, presumably they just have to find a counter party. Is this a significant amount invested? Bringing me back around to my original (and honestly asked) question: How many years out do oil/gas futures project?
For me, I'd take 'viable' to mean something like a demonstration plant actually working somewhere, a team with the ability (somewhat proven) to reproduce it at scale, and after that exists the math pencils out it's profitable even on a risk adjusted basis.
At which point, it's a real thing that will happen, and prices will start to adjust based on the likely adoption curve (with various speculative values of the curve of course too).
Which yes, may or may not change future values for delivery depending on the timeline.
Just for example, I have seen strong market movements days before Ukraine war, clearly indicating that war will happen. Even some buying mar and April put in December. Money is where the news reach first.
Clearly the market disagrees with you. I’ve never heard of neo or xpeng and GM has a long history of manufacturing vehicles to North American safety standards. Whatever neo or xpeng do is GM incapable of hiring some engineers (they might already have some) to copy it and then build it in their existing factories?
No, GM are incapable of doing it. For a whole bunch of reasons:
- ICE factories can't just be switched to be EV factories, so having an existing ICE factory is a burden not a benefit.
- They don't have capacity to build batteries
- Even if they did, they don't have the raw materials
- Even if they did, they don't have the raw materials processing capacity
- Even if they did start securing the capacity now i.e. Building Lithium mines, battery factories, EV car factories etc. By the time they come online... GM will have run out of money, because no one will be buying their cars anymore, but they'll still be paying for ICE factories/workforce/etc.
Xpeng and Neo are kind of Tesla clones, but they have home ground advantage in that they are Chinese based which is where the majority of the EV market is right now, it's also where all the battery supply is. You haven't heard of them, because they haven't entered the US market yet.
So GE is doomed because their strategy is to buy battery cells instead of manufacturing them themselves? There are a lot more parts in a vehicle than the cells.
There aren’t any cells to buy. And no, there is no way to make an EV without a battery.
GM don’t have a strategy, it’s clear they are just hoping for a miracle. Hence: Penny stock.
The market agrees with me (look at the growth rate of EV sales globally). The stock market disagrees with me… but it’s clearly irrational… again look at the growth rate of EVs.
Oil and gas are investing in fusion startups, so maybe it already does. Equinor and Eni have both invested in CFS, Chevron has invested in Zap, and Cenovus has invested in General Fusion.
The context here is that this is a private company who have hit an important milestone. They have managed to raise capital, hire people and build a plausible foundation for a viable reactor without billions in government subsidies and done it in a little over ten years. They are claiming grid-connected reactors will be online by 2030.
Depends on the meaning of "sustained," but not all fusion startup concepts are aiming for steady-state operation; some are planned to be pulsed (Helion, Zap, probably others). The important thing is that they get more energy out than in, and enough more to justify the capex. (This is probably Q_scientific of somewhere between 10 and 30, depending on the specific concept and who you ask.)
commercial fusion as in the sense of the title is probably meant to mean "making profit", so significantly harder than just sustained fution, which will likely be obtained much earlier.
But it doesn't really matter, for now that's just an aspirational goal, not an imminent reality.
It marginally reduces the size of a fission plant, a non-problem.
It presents klingon level engineering problems.
The feedstock and its subsequent volatility are civilization grade problems.
In the designs I've seen thrown around, you end up generating tritium and helium inside the lithium reactor cover/blanket.
I'm not saying we shouldn't pursue it for research purposes, but the desire to research is politically/emotionally driven and not based on the discovery of any recent phenomena.
Parent comment has a point: given a power plant and a hostile attacker/incompetent crew, it's preferable it becoming a blackout and 1 square km of rubble over a blackout, 1 square kilometer of radioactive rubble and 2600 square kilometers of radioactive exclusion zone.
> While several government laboratories have reported plasma temperatures above 100M degrees in conventional tokamaks, this milestone has been achieved in just five years, for a cost of less than £50m ($70m), in a much more compact fusion device.
Governments should only fund things. They should not actually run them.
This private company was only able to move so quickly and cheaply because government labs had already shown how to do it. If anything, this case is evidence against your view.
