New records on Wendelstein 7-X
iter.org
iter.org
(there is some irony in using the iter.org link for a stellarator announcement)
1.8GJ over 360 seconds, beta of 0.03
Not sure if this is contextually obvious to practitioners, but that figure is the "Energy turnover" / "is calculated as the product of injected heating power and plasma duration".
Especially considering the total budget of it is $340 millions vs ITER's tens of billions.
90% of the basic research Iter does can be switched to 7-X if it turns out to be more successful topology. Among other things, Iter develpes technologies and processes needed for a fusion power station, something 7-X is not even touching.
What's important here is that W 7-X is a stellarator, a different type of fusion reactor from almost all prior reactors (they are tokamaks), with a smaller volume than the co-record holder.
That a stellarator gets these results with a much smaller fusion volume is promising for the performance of future larger stellarators, since fusion reactors typically become more efficient as they get larger.
Tokamak and Stllerator are about equally old, 1953 vs 1954, while both types where for a period developed in secrecy behind either side of the iron curtain till end of the 1960ies where collaboration started.
IPP was founded in 1960 (by, among others, my dad) and focussed on Stllerator since then (while collaborating in JET and ITER around their tokamak projects)
(Heard that on a podcast with two of the lead physicists/engineers working there)
Sorry this is nice for the Wendelstein itself but they are overselling it, albeit in a way that isn't too out of the norm with academic press releases.
There are several interesting net positive tipping points depending on where you draw the boundary that energy in and energy out cross. We're still in the earlier stages of net positive where the boundary is quite small and little consideration is being given to the part of the process where electrons get pushed around in a power grid.
I love vague terms like "long periods". Long compared to the Planck length? Geological time? Is the advertised 43 seconds almost there or "off by 17 orders of magnitude?"
This is shared in the better article here: https://www.ipp.mpg.de/5532945/w7x
> During the record-setting experiment, about 90 frozen hydrogen pellets, each about a millimeter in size, were injected over 43 seconds, while powerful microwaves simultaneously heated the plasma. Precise coordination between heating and pellet injection was crucial to achieve the optimal balance between heating power and fuel supply.
A smooth toroidal magnetic field cannot confine plasma. The field at the outer side (further away from axis) are spread more widely and weaker than in the inner side. In a very short time, this will cause ions to drift out of confinement at the outer side. The solution is to produce a twisted, helical field, where the field lines go in circles in both directions of the toroid simultaneously, like the stripes of a candy cane in the bend.
Different reactor designs have different solutions to this. Tokamaks use a solenoid to drive a strong toroidal current in the plasma. This, in turn, causes a poloidal magnetic field, which provides the second half of the field needed for confinement. But this only works when magnetic field of the solenoid coil is varying smoothly over time in a single direction. Eventually, you hit some limit in your ability to do that, at which point you lose your ability to confine the plasma and the pulse ends.
Stellarators do not have this issue. They get the full field geometry needed from their primary field, by twisting it around the toroid in a very complex path. The downside is that they are much more difficult to design and build.
Anyway, the older generation of devices was pulsed for engineering reasons (like non-superconducting coils getting too hot). The current generation of device is solving most of these and is limited by MHD instabilities alone (neoclassical tearing modes, mostly), if we can get active control mechanism working, then will be finally approach the long-pulse or steady-state regime.
“Off by 17 orders of magnitude” would be off by 136 billion years, so not that much for sure. Assuming you want to be able to test the plant and or maintain it once per year, 43 seconds is less than 6 orders of magnitude off. The jump was more than a full order of magnitude compared to past records, so another handful such developments and we are there.
Nuclear already gets taken offline for several weeks for refueling, but redundancy covers such issues.
This is a much less sexy problem than containment, but it's a showstopper for commercialisation. You can just about imagine an epically huge reactor with unfeasibly powerful containment fields that trap fusion in the centre of a large cloud of hydrogen, which captures neutrons to make tritium to power the reaction. But that's completely unbuildable with current tech.
Aneutronic fusion is possible, but it happens at even more extreme temperatures, which are barely theoretical at the moment.
At this point we've been chasing fusion for more than 70 years, and commercialisation is as far away as ever.
You might as well just build yourself a small star.
Or perhaps even spend all that research money on making better use of the star we already have.
https://en.wikipedia.org/wiki/CIRUS_reactor
> "Canada stipulated, and the U.S. supply contract for the heavy water explicitly specified, that it only be used for peaceful purposes. Nonetheless, CIRUS produced some of India's initial weapons-grade plutonium stockpile,[6] as well as the plutonium for India's 1974 Pokhran-I (Codename Smiling Buddha) nuclear test, the country's first nuclear test.[7]"
Fusion is incredibly difficult just to start, let alone keep burning - unlike fission, which is only too happy to enter runaway conditions if not very carefully regulated. Fusion is like a little ember in your fireplace you have to carefully blow on to keep alight; fission is like keeping a fireplace lit by pouring gasoline into it.
https://library.sciencemadness.org/library/books/ignition.pd...
Indeed there's no such thing as a free launch, and that is rocket science.
Building bridges (and large structures in general) has always been about the tension between over-engineering (for safety) and under-engineering (for cost/aesthetics).
The Brooklyn Bridge is massive; they'd never built a bridge like that so they over-engineered it. But once they saw that it was more than strong enough to stand up, the next bridge was lighter. And the next one after that was even lighter. And so on, until a bridge collapses because some new factor came into play (e.g., harmonic resonance).
Source: To Engineer Is Human by Henry Petroski--one of my favorite engineering books.
disclaimer: I don't follow this stuff at all. It just looks like a b.s. photo deliberately exaggerating how simplified #3 is vs. the others to this grease monkey.
https://x.com/gwynne_shotwell/status/1821674726885924923?s=4...
I don't think that applies to Stellarators, so there may not be an incentive to simplify it. [But what do I know; I'm just a simple programmer.]
It's fuel burning, not glow. Speed is too low for glowing; glow would start at the edge, not from deep inside the skirt etc.
Yeah, a single welded tube of the right diameter that necks down just so in that one spot to prevent cavitation, which has that sweeping multi-planar bend to just barely sneak through that obstruction, will look neat and tidy to a casual observer. Conversely, a stack of triclamp flanges, a straight length of pipe that shoots way out away from the guts of the equipment before it jogs sideways and down and back in with 90 degree couplings and gaskets and a manual shut-off valve and a pressure transmitter/flow meter and a "T" with a cap (just in case) and a sight glass looks like an awful mess.
But I can build the latter in half an hour with parts we have on hand. And I'm not even a fitter, I'm an engineer! And when you do want to add something to it, I can do that in 5 minutes. After observing it function through the full regime of pressure and flow and viscosity parameters the equipment might have to deal with, I can maybe generate a print for the real plumbers to build the former dedicated-purpose component that sets all the constraints in stone (or rather, in welded stainless). That part will be unique and inflexible, embedding all the restrictions and history and test results and design decisions into a component that looks deceptively smooth to a layman's eyes.
Is that simpler? I suppose it depends on your perspective.
Yes and no. I think you are right that the plasma shape is going to remain very complex.
But that's not the only reason why W7-X looks complicated. It has a ton of diagnostics ports on the plasma vessel just for research. Most of those we can probably design out for a production version.
So I would expect a production version of a stelarator to be simpler than W7-X, but still remain very complex.
Economically all the cost of building a "boil some water and turn some turbines" plant is _already_ in the "boiling some water and turning some turbines" part of the generation, and even if the heat part of it was _free_, the rest of it would be too expensive to bother building a plant for it, compared to just building solar and wind generation and some better batteries.
And there are efforts to make building out transmission and interconnecting with the grid more streamlined, so maybe some of those problems will be gone by the time fusion’s ready.
Someone said recently that it’s nicer to have bad laws and good tech than a bad tech and good laws, solar+storage seems like it’s in the former now, and if we can clear the bureaucratic hurdles, we’ll see it boom here like we’ve seen elsewhere.
This is difficult to say when comparing an emerging technology with an established technology in an emerging economy.
Based on every historical prior, it would be surprising if there weren't diminishing returns to solar and wind. And I wouldn't underestimate the degree to which power is, in part, fashion. Today we value emissions. Tomorrow it may be preserving and expanding wild spaces.
On a practical level, fusion research doesn't compete with solar and wind deployment. Pursuing both is optimal.
I'd be shocked if we max out on insolation before area we're willing to cover with solar panels and windmills.
For every other way of producing energy you need separate land for PV you don't. You can put them on rooftops, over parking lots or even vertical in a field. The last one increases the crop yield. Crops get less harsh sun, lose less water and the evaporation cools down the panels, which increases their production.
Today we value costs of energy production and tomorrow we will to. Especially if it results in energy independence. You don't need to buy fuel for PV and wind. As with nuclear fuel only a few countries are probably going to manufacturing the fuel needed for fusion reactors. Producing enough of it and in a sufficient purity needs specialized facilities and they will only be profitable if they produce a lot of it.
Turbines are also mass manufactured. (Albeit less than PVs.)
> You can put them on rooftops, over parking lots or even vertical in a field
The first power plant burned coal in Manhattan [1]. You can put turbines on top of buildings. We don’t because we don’t want to.
I think wind turbines are pretty. But lots of people don’t, and many wouldn’t want their rooftops to be shaded by panels, or wide open fields and natural expanses turned into something that looks more industrial. (I personally think looking down on rooftop gardens is far prettier than panels.)
Maybe there is a perfect power source out there, one which justifies a monoculture. I haven't seen it. I don't believe it's solar or wind.
Currently the cheapest non-intermittent energy source is gas; solar costs about half as much, and nuclear costs 50% more than gas [0]. Battery storage is currently competitive with gas for storing around 4 hours of electricity [1].
If we would want to replace the baseload with solar + batteries we would need to store 12 hours instead, during the dark half of the day, so it would cost 3x as much, 200% more than gas.
Maybe we can hope for battery prices to drop, but extrapolating from a Wright's law curve, for them to become cheaper by a factor of 3 we need to produce 32 times as many of them [1, again], it won't happen in the near future.
[0] https://www.eia.gov/outlooks/aeo/electricity_generation/pdf/... [1] https://www.lesswrong.com/posts/mnaEgW9JgiochnES2/2024-was-t...
- Those designs have been in parallel R&D for decades
- Tokamaks are conceptually simpler, thus might be easier/faster/cheaper to make into viable installations
- Stellarators are WAAAAAY more complex to design and build but AFAIU they would have the huge benefit of being able to sustain the plasma for way longer for the same "startup cost" of a cycle since the particles of the plasma are routed somewhat like they're on a mobius strip instead of a simple torus (which should make it easier to confine more particles for a longer time).
I recall having read (several years ago) that the simulation technology of the 90's wasn't really up to the task of aiding in the design of those weird wavy magnets for Wendelstein 7-X, an unfortunate reality which delayed the project a lot.
So it might end up being cheaper to construct a larger tokamak.
There are 2 podcast episodes with the guys who run Wendelstein here: http://www.alternativlos.org/51/ (it's German tho)
The bigger question is if magnetic confinement fusion will lead to the best energy producing devices. Competitors include inertial confinement, pinches, or some other exotic method. If a magnetic confinement fusion device produces net power, it's going to be a stellarator.
Sources:
I would also be super careful about celebrating new designs as the way forward that will replace everything. When you look at the history of combustion engines we had a ton of new approaches (for example rotary engines) but after looking at all factors it turned that evolutionary changes to existing designs was the way forward.
-Homer Simpson
Gotta think big!
God, this contraption appears to be the kind of thing I wouldn’t trust my life with. Every time I look at a fusion reactor, it seems far more dangerous than my hobby lab, failing to inspire any confidence. The numerous moving parts create an equal number of potential points of failure. In contrast, a nuclear reactor doesn’t have to contend with plasma gases hotter than the Sun, contained within an artificial bubble solely through the assistance of electromagnetic radiation.
I’ve often tried to imagine the worst case scenario, but I am limited by my knowledge on the subject. What kind of damage can hot plasma at a few million degree C do?
On one hand, the plasma is hotter than anything on earth created by mankind. Then I believe there’s also a significant number of wild neutrons shooting around which can cause havoc in their own right, if not contained. But on the other hand, unlike an uncontrolled chain reaction, without a source of heat, the whole operation shuts off by itself. I’m probably wrong about a few assumptions here but this is what I often find myself wondering.
Once they get everything dialed in, they can make a static purpose built machine with dramatically less complexity. Generally with research machines they are very unwieldy while still being dialed in.
This is unlike fission reactors, where a failure causes reactivity to increase. That causes meltdown and the possibility of explosion and all the nasty radioactive contamination.
You still have a very hot very radioactive lump of death in the middle of your busted reactor when it's all done though, and that's definitely not fun. Fusion failure modes - in current designs anyway - are far more appealing to anybody who happens to be in the area at the time.