"While the latest experiment still required more energy in than it got out, it is the first suspected to reach the crucial stage of ‘ignition’, which allowed considerably more energy to be produced than ever before, and paves the way for ‘break even’, where the energy in is matched by the energy out."
Here [1] is an excellent video by Sabine Hossenfelder about why you should not get too excited about this result.
However, Sabine misconstrues things in the opposite direction and lies through omission to the audience. For example including startup energy and not ammortizing it over runtime, or not assuming that the energy consumption of the experiments is part of the required energy consumption of the fusion reactor, or trying to construe that once you have a fusion power reaction that is burning it is still especially difficult to further create a functioning power reactor out of it.
The true hard part of fusion is the burning plasma aspect. Once you have a burning plasma, it's a heat source like any other (with a few side-effects like neutron output) and everything we know from fission power reactors (but with a much lower radiation) and fossil fuel generators applies.
Where are you getting this impression? Her video pretty clearly focuses on the confusion between the Qs. Where does she get the napkin math wrong? She uses a published figure for total energy required during the operation of ITER when it’s up and running not a one time startup cost figure. Id she misrepresented that number, what would be a more honest total power consumption figure? As far as construing the output, she uses existing loss ratio for heat to electrical energy conversion which really does not seem to work to construe the problem as “especially difficult”, it’s “normally difficult” is how I interpreted. Are there impending advancements in energy conversion that makes 50% too liberal?
Her video multiple times tries to make fake total Q values by looking at the energy consumption of JET and ITER and then trying to say that is Q_total, which is wrong.
She doesn't even show her calculations on how she calculates some of her Q_total examples.
Sabine actually is completely misleading and misconstrues a bunch of facts.
None of these plants are even attempting to have real energy breakeven and spend a ton of energy supplying experiments and unrelated support equipment. They don't even have a method of capturing energy as that's not the point as it would make it harder to test the physics. Additionally these plants have high amounts of "startup energy consumption" that is also factored in to the energy usage but would be amortized out over a long run. Trying to use the absolute power consumption of the experiment as if that's where the state of the art is at for true energy break even is completely wrong.
Plasma breakeven is all anyone is really working on. Once you have plasma breakeven you have a self-sustaining heater basically, which then can be used to create energy. The point of an "ignited plasma" is that it's self-sustaining and just pumps out heat, even if most of the energy is used to keep the reaction going.
I think your statement "Once you have plasma breakeven you have a self-sustaining heater basically" is false. According to Wikipedia [1] - if I interpret it correctly - the fusion energy gain factor from plasma must be 5 (!) to have a self-sustaining heater:
"Most fusion reactions release at least some of their energy in a form that cannot be captured within the plasma, so a system at Q = 1 will cool without external heating. With typical fuels, self-heating in fusion reactors is not expected to match the external sources until at least Q = 5"
I oversimplified in that statement, you need more than a factor of 1 because of heat losses to the environment yes. However 5 is not much different than 1. We've gone from 0.0001 only a few years ago to close to 1 now.
And btw, you really want more than 5, 10 or 20 ideally, but again, that's not too hard as compared to how far we've come and new reactors will be beyond that soon.
Fusion begets fusion. ITER plans to have high-intensity, relatively short Q=10 shots. If the plasma heats itself then it doesn't need much heating. This sudden focus on Q is clearly the result of one vocal non-expert not understanding the field and everyone listening to them like they have something valuable to teach.
I think her meaning is pretty clear and correct. As much as plasma breakeven may be the entire goal of ITER it's absolutely setting them up for a badly missed public expectation. The day they declare net positive output, the world will ask when we can start building infrastructure and the answer will be "30 more years" and then they'll get their funding yanked forever.
>As much as plasma breakeven may be the entire goal of ITER
Who gave you that impression? They were lying. The goal of ITER has always been to study burning plasmas and experiment with solutions to problems that a reactor-grade MCF machine faces.
ITER isn't even possible to create an economic nuclear reactor out of because it's too big. The sheer size of a ITER-sized reactor doesn't get us to economical reactors. ITER is a science experiment, not a commercial reactor design. High-field strength high temperature superconductor based allows much smaller sizes than ITER, but ITER was designed with the technology that was available in the late 1990s.
> Plasma breakeven is all anyone is really working on. Once you have plasma breakeven you have a self-sustaining heater basically, which then can be used to create energy. The point of an "ignited plasma" is that it's self-sustaining and just pumps out heat, even if most of the energy is used to keep the reaction going.
This is dead wrong. First of all, the experiment described here is ICF, in which you have to constantly re-heat new pellets of fuel. Even for MCF, you have to spend inordinate amounts of energy just containing the million kelvins plasma with few kelvin superconducting magnets, and to constantly deliver new D+T into the plasma.
If containment fails at any time for any amount of time, your reactor is instantly obliterated.
Not to mention, your source of heat only heats up by about half of the energy - the other half is radiated away as hard to capture neutrons, which are almost entirely a waste product.
I have no idea why you think that ignited plasma is enough to maintain an energy-producing reactor.
Edit: million kelvins should have been billion kelvins...
Reading more about this, it seems that one of the ideas is indeed to capture the neutrons in a liquid lithium blanket, that would then produce both heat and tritium, and using that heat, that is outside the magnetic confinement, to connect to a turbine.
Unfortunately, I believe that the area of actually capturing the energy of the fusion reaction is almost entirely unstudied yet in practice.
What's important here is that they may have achieved ignition, that is making the fusion reaction self sustaining[0]. Once it becomes self sustaining one should be able to add more fuel to the pellet to get more energy out for the same input energy.
It's worth noting that NIF was not intended to generate power and is not representative of a potential power plant. The lasers on NIF are old and were chosen to have a lower efficiency for cost reasons. In addition, while NIF could generate much more energy, NIF isn't necessarily going to pursue this because the higher output energy may render the machine inoperable for too long.
Dealing with a high rate of explosions is one thing this class of fusion will need to solve before being able to generate power.
> Once it becomes self sustaining one should be able to add more fuel to the pellet to get more energy out for the same input energy.
That's not how ICF works. Plasma, being a gas-like state, will always expand to fill whatever volume is presented. With ignition, the rate of expansion is essentially lower than the rate of fusion, allowing you to fuse all of the fuel before the plasma dissipates and cools down.
In ICF as studied at NIF, you start with an extremely precisely machined piece of metal called a hohlraum, you put a solid pellet of fuel inside at an extremely precise location, then fire a laser with extremely precise alignment to heat the hohlraum until it generates X-Rays that heat the pellet just right so that its outer layer explodes, creating an equal implosion, generating two shockwaves inside the pellet; if the two shockwaves meet just right, at the center of their meeting place you get a fusion reaction, and you hope that that fusion reaction has enough time to heat up and cause more fusion reactions before the initial implosion loses speed and expansion happens.
That initial shock is the only thing containing the plasma - once it has lost its velocity, the plasma dissipates and cools down. If ignition was reached, the gas that cools down and dissipates should be 100% He, instead of a mix of He, D and T. However, there is no way to stop this dissipation, it is a fundamental part of ICF.
The only way to keep an ICF reactor going is to shoot one laser burst at one pellet, capture the energy of the fusion, and use that to power the next laser burst fired at the next pellet.
Of course, after each burst of laser heating the hohlraum so much that it radiates the heat as X rays, and then briefly containing a 1-10M kelvin burst of hot plasma, plus a neutron bombardment, the hohlraum is destroyed. Since machining the hohlraum to the precise shape required to achieve the shockwaves discussed above is never going to be a cheap process, it is impossible to imagine ICF would ever be even a tiny bit close to economical, even if it could in principle output more energy than it requires as input.
As such, ICF is strictly a scientific pursuit, mostly interesting for nuclear weapons research.
This report found that ICF could reach LCOE as low as $25/MWh "with optimistic but not obviously unrealistic inputs."[0] This does require hohlraums cost about $2 each and are fired every 20 seconds. With mass production and process optimization it may not be ridiculous to reduce hohlaum cost to this amount. However, the yield is about 5 gigajoules which is equivalent to about 1 ton of TNT.
Making equipment that can handle 1 ton of TNT exploding every 20 seconds is an interesting engineering challenge.
"Optimistic but not obviously unrealistic inputs" include reducing the cost of hohlraums from the million dollar range to 10$ (not even sure if that accounts for the price of the gold itself), a reactor capable of resisting 50 million pulses before needing replacement, and a few others.
It also considers the price of a fusion power plant to be less than that of a fission power plant, based entirely on the observation that it would have less stringent safety requirements.
Overall this article may be right in principle if taken to refer to an arbitrarily far away future (hundreds of years away at least, if ITER and DEMO are to be taken as realistic examples of the pace of improvement of fusion power in general, even if they are MCF instead of ICF).
Don’t you still need to spend energy on confinement? You don’t need to “reignite” the plasma but w/e confinement solution you chosen still has a cost and a non marginal one when it comes to magnetic confinement.
What is the goal of NIF? I've read repeatedly that fusion power isn't their end goal but rather to study inertial confinement. That's fine but why study inertial confinement if not to generate power? I've always been very confused about their goal. I'm a total layman when it comes to this stuff so there's some nuance I'm not understanding. Appreciate any clarification anyone can give.
Nuclear weapons, more specifically stockpile stewardship (what happens as weapons age) and verification of weapons codes/simulation software (can we make new weapons without full-scale testing).
Everything else is gravy. There's a reason it's at one of the weapons labs (vs. the unclassified work done at most other national laboratories).
The thing you are missing is that in addition to fusion power research (which is valuable and NIF has made major contributions to) there is also fusion weapons research. Inertal confinement is (kinda) close to the conditions inside a fusion bomb, and NIF also has a mandate to research those conditions. For that kind of research, a single pulse of fusion ignition is exactly the kind of data they need. Since we have a nuclear weapon test ban, and computer simulations need some kind of ground truth to be calibrated against, achieving fusion ignition in a lab is valuable to NIF for that reason alone.
In terms of the NIF's broader goal, as opposed to the specific goals for their ICF work, the NIF is meant to keep nuclear physicists fresh on research relevant to nuclear weapons design in the aftermath of the end of the Cold War and Comprehensive Nuclear Test Ban Treaty. [1]
The NIF is a facility for conducting experiments. The goal for the field is fusion power, and these experiments may wind up contributing toward it, but it will never be anything more than a stepping stone. The primary purpose of the NIF is validating computer models for simulating nuclear reactions. These models are used both for the design of nuclear weapons and nuclear reactors. They also develop technologies to support their activities, such as new sensors and laser control methods. Compare this program to say a mars rover where we don't expect the rover itself to do anything of great practical utility, but the lessons learned along the way have many potential applications both directly for future missions, and indirectly for spinoff technologies.
"The pace of improvement in energy output has been rapid, suggesting we may soon reach more energy milestones, such as exceeding the energy input from the lasers used to kick-start the process."
I think it is neither. Most nuclear fusion news is focused on magnetic confinement. This article is about reaching ignition on an inertial confinement system.
Neither, it's inertial confinement fusion, which isn't really seen as a way to a successful commercial reactor (at least not that I've heard of) and is more a tool to study the physics of D-T fusion reaction in a controlled way that's not inside a nuclear bomb. It's a tool for experiments.
You may be surprised to know that there are loads of people working in ICF who think they're working on a plan to supply the world with energy, and have detailed and elaborate designs for commercial ICF reactors, including pellet factories, tritium extraction, and everything. With calculations of the final cost per delivered kW-hour. It’s all a fantasy, but it’s a real research activity, funded by the US DOE (mainly through the NNSA).
