<a href="https://www.youtube.com/watch?v=KkpqA8yG9T4" rel="nofollow">https://www.youtube.com/watch?v=KkpqA8yG9T4</a><p>Here's a video lecture from the MIT Professor (Dennis Whyte) who was leading the research group that provided some of the key designs for the SPARC reactor. As the NYT article explains, that research has been spun out into a startup that raised $200M.<p>The key breakthrough is the advancement of REBCO tape superconductors which allow you to (1) generate record breaking magnetic field strengths (2) easily disassemble the super conducting loop for fast repairs / refuels / more modular design.<p>It's a long talk, but it's extremely fascinating. Basically everything becomes much easier once you can increase the magnetic field strength. This talk is fairly accessible to even relative laypeople who have a vague understanding of E&M physics.
I wish these people the best, and I really hope they get a working fusion plant soon. That said, I can't resist sharing Admiral Rickover on academic reactors vs practical reactors:<p><i>Important decisions about the future development of atomic power must frequently be made by people who do not necessarily have an intimate knowledge of the technical aspects of reactors. These people are, nonetheless, interested in what a reactor plant will do, how much it will cost, how long it will take to build and how long and how well it will operate. When they attempt to learn these things, they become aware of confusion existing in the reactor business. There appears to be unresolved conflict on almost every issue that arises.</i><p><i>I believe that this confusion stems from a failure to distinguish between the academic and the practical. These apparent conflicts can usually be explained only when the various aspects of the issue are resolved into their academic and practical components. To aid in this resolution, it is possible to define in a general way those characteristics which distinguish the one from the other.</i><p><i>An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose ("omnibus reactor"). (7) Very little development is required. It will use mostly “off-the-shelf” components. (8) The reactor is in the study phase. It is not being built now.</i><p><i>On the other hand, a practical reactor plant can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. Corrosion, in particular, is a problem. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.</i><p><i>The tools of the academic-reactor designer are a piece of paper and a pencil with an eraser. If a mistake is made, it can always be erased and changed. If the practical-reactor designer errs, he wears the mistake around his neck; it cannot be erased. Everyone can see it.</i>
Here's the actual summary:<p>"Although many significant challenges remain, the company said construction would be followed by testing and, if successful, building of a power plant that could use fusion energy to generate electricity, beginning in the next decade."<p>In other words, "very likely" in this case means "if several roadblocks are overcome, it might be a net-positive power generator in a decade". Even so, this is still exciting given how anemic advancement in the fusion space has been for 50+ years.
So, I'm a physicist, and I went to a number of talks from people involved with the JET fusion reactor over the years, though fusion is not my area. And my understanding is not that it's difficult to make plasma, or even build a reactor in particular that is the main problem (though instabilities can be problematic), but it's that the internal structure degrades very rapidly and becomes highly radioactive, because you get helium bubbles forming inside the steel which causes fractures and the heavy metals that are often put into steel to increase strength are highly fissionable. So you need to use special types of steel to actually construct the reactor, and these need to have a lifetime that's ~5 years+ and it needs to not have very very radioactive steel at the end of it's usable life. And this is basically an unsolved materials science problem at the moment. So while you might even be able to build a fusion reactor, it's not going to last long enough to make it commercially viable using current technology.
My current favorite future fusion reactor project (I'm a layperson) is the Wendelstein 7-X: <a href="https://en.wikipedia.org/wiki/Wendelstein_7-X" rel="nofollow">https://en.wikipedia.org/wiki/Wendelstein_7-X</a><p>Seems like they're meeting all their planned milestones and it's going well!<p>Excited for their next updates...<p>More from their project page: <a href="https://www.ipp.mpg.de/w7x" rel="nofollow">https://www.ipp.mpg.de/w7x</a><p>"Wendelstein 7-X is the world’s largest fusion device of the stellarator type."
Having read about tokamaks for thirty years, I'd be curious what specific breakthroughs and innovations have occurred since the 1980s, which lead to the optimism described in the article (which is otherwise frustratingly devoid of detail).<p>It's great there are seven-peer reviewed articles about SPARC, but plasma was not my specialty in physics -- would any specialists care to comment on whether there is anything particularly exciting here?
I never quite understood the math behind power densities in a fusion reactor.<p>In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW?<p>Is the density of the plasma so much higher in a fusion reactor?<p>Also, something else I never grokked, how do you get the power out? The plasma heats up, but how do you turn that into useful electrical energy?<p>Nevertheless of course I hope it does work as advertised... someday.<p>Edit: thanks everyone for the thoughtful, insightful replies!
<i>“Sparc takes advantage of a newer electromagnet technology that uses so-called high temperature superconductors that can produce a much higher magnetic field, Dr. Greenwald said. As a result, the plasma is much smaller.”</i><p>So, is this ‘just’ a matter of ITER being obsoleted by improvements in magnet tech before it is completed, or is there more in this design than scaling down ITER?
Im just going to keep plugging my reactor effort every time fusion is mentioned here...<p><a href="http://www.DDPROfusion.com" rel="nofollow">http://www.DDPROfusion.com</a>
After watching the video posted in the top comment, I have to wonder why we would keep dumping money and time into ITER. I know, don't put all your eggs in one basket, but if the ITER design is so out-of-date, why wouldn't we just scrap it in favor of something that we could build 10 years faster and for much less money?<p>It seems that if we can't make fusion work for SPARC it won't likely work in ITER either since they're both based on the same understanding of the physics. Am I wrong on that point? Is there some reason to think that ITER will succeed even if SPARC does not?
The papers on the SPARC reactor seem to be here:<p><a href="https://www.cambridge.org/core/journals/journal-of-plasma-physics/collections/status-of-the-sparc-physics-basis" rel="nofollow">https://www.cambridge.org/core/journals/journal-of-plasma-ph...</a>
A couple of reflections. The first one being that fusion might very well be the remedy to get rid of carbon emissions once and for all, however it won't affect global warming. In fact, it might make it even worse.<p>The simple line of reasoning being that if energy becomes 100 times cheaper, humanity will fast find ways to consume 100 times the amount of energy. A high amount of that energy will end up as heat.<p>The second reason... and you'll find it apparent I'm not a physicist, but reading about fusion research always has me worried. We're basically talking about starting a "controlled" chain reaction at millions of degrees, "like the one on the sun". The sun isn't a nice place, and the sun's fusion happens to be controlled just because it's surrounded by lightyears of vacuum.<p>-Yeah but we'll have magnetic fields and super coils and stuff. It's totally safe.
-Totally safe?
-Yes, our calculations say its totally safe.
-Your calculations based on current theory? Guess what, theory is a moving target. Just a few years ago you didn't even know if the Higgs particle exists?
Related:<p>Cities Snub Plan to Save Nuclear Power With Mini Reactors:<p><a href="https://www.bloomberg.com/news/articles/2020-09-28/cities-snub-plan-to-save-nuclear-power-with-mini-reactors" rel="nofollow">https://www.bloomberg.com/news/articles/2020-09-28/cities-sn...</a><p>Kaysville withdraws from nuclear power project:<p><a href="https://outline.com/LAfTYG" rel="nofollow">https://outline.com/LAfTYG</a><p>Small Modular Reactor Decision Made With Inadequate Information:<p><a href="https://losalamosreporter.com/2020/09/14/small-modular-reactor-decision-made-with-inadequate-information/" rel="nofollow">https://losalamosreporter.com/2020/09/14/small-modular-react...</a>
I'm rooting for LPP Fusion <a href="https://lppfusion.com/" rel="nofollow">https://lppfusion.com/</a> it is a "garage" startup but their approach of using plama instability instead of trying to stabilize it (and the fact they're very close already to net gain <a href="https://lppfusion.com/investing-in-lppfusion/our-plan-to-net-energy/" rel="nofollow">https://lppfusion.com/investing-in-lppfusion/our-plan-to-net...</a>) sure sounds great. Garage sized 5MW aneutronic pb11 fusion reactor with direct-to-electricity conversion sure sounds like something we all can use :)
Likely to work, but unlikely to lead to something economical. The volumetric power density (including the volume of everything inboard of the biological radiation shield) will still be grossly inferior to a fission reactor.
About time to consider alternative paths to fusion.<p>ITER and similar projects are abject failures from non-scientific perspectives, they fail to improve on the economic weaknesses of fusion (radiological waste, massive capital costs, scarcity of fuel, proliferation risk), and only deliver on issues that have become irelevant for modern fision, like the risk of a meltdown.<p>There is zero economic potential for any ITER direct descendant.
Basic thermodynamics. Particle energy grows as T (because energy = 3/2 kT). Thermal radiation energy grows as T^4. At fusion temperature up to 80% of energy is in radiation. Energy density of radiation in this case is close to energy density of metals. It's impossible to contain such radiation.
a lot of people commenting who actually didn’t watch the presentations and making sweeping bad takes nuclear power in general which are really just criticisms of PWRs (pressurized water reactors)
Fusion has always been "just around the corner." These stories aren't helpful until there is demonstrable evidence it delivers on the so-far vaporware promises of many other projects before it.
> <i>Sparc would be far smaller than ITER — about the size of a tennis court, compared with a soccer field</i><p>If we could make efficient fusion reactors the size of a truck, the solar system will become our backyard.
What are the decommissioning costs?<p>Who will pay for the cost overruns?<p>Just one of the big problems with nuclear is that it is very centralized and takes individual control away from the consumers, who foot the bill through increased taxes and fees, and who could otherwise be using their money to finance options that give them individual control over their energy costs.