Euh ? In a few paragraph you basically say that even if fusion works, getting energy out of it will be almost impossible in a meaningful way (you're showing order of magnitudes of difference). But, don't the engineers at ITER and other facilities have already though about that ? It'd be very irresponsible to start such a project knowing in the beginning that, at the end, there's a high chance of failure...
That's a good question. Why do fusion people not pay attention to this issue?
The answer is some do. And those people tend to get frustrated and quit the field (or, if they are lucky, notice the problem early and never go into fusion at all.) Lidsky is a famous example; Pfirsch and Schmitter in Europe are others. Others bottle up their objections and only let them out as they retire.
The more common coping mechanism is just to assume someone else is going to solve it and not pay too much attention while working on other issues. It helps to focus on physics issues -- which are very interesting, after all -- and tell yourself that this problem is "just engineering" and can't be too hard to solve, in comparison, and that anyway telling yourself it's bad to think about it before the physics is nailed down (which is wrong, but lets you stop worrying that you've wasted your career.)
As for ITER specifically: ITER is costing > $20B for something that could produce maybe 400 MW gross fusion power (and isn't engineered to produce tritium, electrical power, or to survive more that a few weeks at full power). Industrial levels of denial are needed to tell oneself something like that is on a trajectory to relevance.
Perhaps an even better question is: why are people funding DT fusion? For governments, I think it's because in many cases the purpose of government research funding isn't to solve problems, it's to be seen working toward solutions in the distant future (and that perception can be achieved even if there is no actual chance of success, if the public is sufficiently unaware, which it is.) For venture capital I'm not clear what the explanation is. Spinoff technologies like high Tc superconducting magnets, maybe?
And yet history has usually proven them right to have this kind of attitude. The first instance of everything is ludicrously expensive and commercially non-viable as it is. Then it gets cheaper and easier and eventually commonplace and boring.
It's often the case that the commercial applications for a technology are not apparent to the researchers doing the research. They're focusing on the science/engineering challenges. Later, sometimes much later, it becomes part of an economically-viable product or service.
Sure, for successful technologies, naysayers were wrong. But almost all technologies (sufficiently finely defined) fail. The naysayers are usually right.
compare it to the space program. that didn't really have any directly useable goal. but the technology produced in the process is used everywhere.
DT fusion may or may not work. maybe the problems may get solved some day, maybe not. we'll never know if we don't try. and the technology we get in the process is valueable regardless.
Spinoff technologies from space are another "sell the perception" thing. There's a lot of BS there. But as long as the public swallows it, it works to justify the program.
Even if you choose to ignore all that has come from it.. Space is quite possibly the most important thing we can be investing time, money and research into in terms of future advancement and sustainability of the human race.
Tell me: what exactly would have been worse if the US had never had a manned space program? The whole thing feels like a vanity project, not something that delivered value. It could all have been delayed while launchers got cheaper without loss, as far as I can tell.
Kapton is a great example of the spinoff racket. You take something that was USED in the space program (but not invented by NASA; Kapton came from Dupont), you carefully blur the story, and now you claim it was the RESULT of the space program. It doesn't help that the marketing of these things often used the space program, calling them "Space Age", trying to mooch off the glamour Apollo had at the time. Integrated circuits, teflon, velcro, glass ceramics are other examples.
Moonshot programs are what create demand for the sort of R&D that Dupont did to bring kapton to market.
Polyimides date back to 1902, but you couldn't buy anything like kapton tape before the space programs created a need for such materials and capital to build out plant for them.
I promise you there was enormous demand for products to stimulate R&D outside of NASA. Orders of magnitude more. That's why technology was leaping ahead even before NASA existed, and even after NASA's budget shrank. It's also why all that new technology came out of countries without manned space programs.
To make a valid spinoff argument, you have to show that the particular technology would not have come about without NASA. That sort of contrafactual, alt-history argument is really hard to do. It's why alt history has such a bad name in history circles -- you can't really show anything. This means all spinoff claims are dubious. Not only are they presented without the necessary evidence, it's difficult to see how the evidence ever could be acquired.
No, it's just saying they we haven't really done the serious work and engineering yet required to have an answer for this yet. Remember, we still aren't even sure which type of reactor design will work/be used. These are the type of problems that we can't seriously deal with until we have at least the basics down.
This is the "ignore the engineering until we get the physics to work" mantra. There are generic problems that can kill DT fusion independent of the physics, and these need to be investigated to see if a solution is even plausible. If one is not, then continuing to invest in the physics for DT fusion reactors is a complete waste of resources.
ITER is a technology demonstrator intended to show sustainable fusion. The amount of power it generates is lesser than it will require to operate. The physicist Sabine Hossenfelder has a great video on her YouTube channel that I highly recommend watching.
It’s also a large international collaboration, a study on the engineering challenge involved with building a fusion reactor and a way to improve the technological know how of some participants.
The truth of ITER is that the way the work is shared slow down the project considerably. It would have been much faster as a collaboration between the three or four countries in the world with actual hands on experience on large scale reactor building but ITER is first and foremost a political thing.
