DT fusion would be just ridiculous for space flight. Anything a DT reactor could do a fission reactor could do much better -- much smaller, much higher power density, much less complexity. And similarly for use in ships down here on Earth.
In practice, synfuels would be better than either for ships on Earth.
Isn't the main reason for us not having fission rockets the fact that we don't want to have radioactive material explode a few kms above our head aka a dirty bomb?
A DT fusion reactor would have a thrust/weight ratio much less than 1, so it could not be used in a launch vehicle. It would be purely for use up in space. So, none of this "a few kms above our heads" nonsense.
I don't understand this; if fission reactors were "better", we wouldn't be pouring so much into fusion?
Also, if it makes a difference, I didn't mean we'd be bolting a first gen tokamak to a container ship; I meant, much later down the line, if we were able to miniaturise (similar to how we have nuclear powered subs and ice breakers).
Much more money is "poured into" fission than fusion, likely by a few orders of magnitude. There's one mega project around fusion (ITER) that has a price tag of about 1-2 billion dollars a year if you average it out over the many-decade life of the project, while any given fission plant built also costs billions of dollars.
Like, whether or not fusion itself is a "meme," the idea that we spend obscene amounts of money on it is absolutely a meme with no real backing in reality.
The appeal of fusion is really more about getting out of worrying so much about meltdowns and weapon proliferation, and that there is potential for much higher overall energy output if we can figure it out.
That last bit is why, imo, we should be investing in it now even though it won't really help us reach net zero carbon "in time". If we want to reverse our carbon impact, if and when we get to net zero, we're going to need immense amounts of energy to do it.
Some people quite reasonably object to spending billions of dollars every year on a project with a vanishingly small prospect of success, and of exactly zero practical value if it ever did succeed. There will never be so much as a single kWh of commercial power from these turkeys.
We can all think of numerous projects going unfunded that would have much higher chances of success, and much greater positive impact. But we have a research institution whose only possible recommendation is to continue giving it money, indefinitely.
We see the same dynamic in Alzheimer Syndrome research, where almost all the research money goes to people still fooling with amyloids and tau tangles. The people who control publication, funding, and hiring are people who would have nothing to do if funding for amyloid work stopped. So, they continue funding amyloid work long after it was recognized as a dead end. They have bred up mice that get dementia, and literally everything they do is about the mice.
This is somewhat different from the current crewed spaceflight program in the US, where the absurdly expensive SLS rocket is mandated to be used because senators have constituents in their districts depending on income from building them, useless as they are. In this case NASA would dearly love to abandon SLS, but is required by law to try to launch them. The best they can do is delay launches. Anytime the shoot one, they have to spend $billions building another one.
> We can all think of numerous projects going unfunded that would have much higher chances of success
I can think of far more things getting funded that are either even less likely to succeed or likely to succeed and, in so doing, will cause harm and death to many people. There are so many things we're spending so much money on that do nothing but harm it's absurd to laser focus on something you consider merely pointless as a Boogeyman.
Who said it was "obscene"? You seem to be putting words in mouths.
I will say I do think money has been spent unwisely on fusion, particularly on approaches that have very little chance of success, with programmatic dysfunction that even fusion advocates have noted with anger. Chance of success does have to enter into the evaluation of whether funding is wise, or else one could argue for spending on perpetual motion machines.
I.. wasn't replying to you? And I wasn't referring to you or the person I was replying to specifically anyways, but the common sentiment whenever this comes up.
But it is absolutely a common misconception that fusion is very well funded when, given the challenges involved, it is funded quite poorly. If it was well funded, ITER might have been finished 20 years ago.
That said I think the results would have been disappointing, it doesn't really seem like material science was there yet and it's not clear more money thrown at it then would have gotten us there.
Imo I think even if you think it's a boondoggle it'd be better to fund it well (much better than we are) now and find out than drag this slow march of wasted money on old designs and ideas out forever. The ITER funding should have probably gone to something more like milestone awards and letting a bunch of paths proliferate.
You seem to think that government decisions are rational.
Fusion is a meme technology. People just have this assumption that's it's valuable, without having rationally arrived at that conclusion (which, when you examine it in detail, is very difficult to justify.) I suspect this was because it started back in the 1950s when consent was easier to manufacture and nuclear was being pushed. Fission lost that glamour with most people, but fusion somehow has retained it.
It's not only governments pouring cash in, but private equity too.
With all due respect, it seems ridiculous to me that fusion is a "meme technology" - aside from money, are all those many thousands of scientists really working on a technology they know can't work?
Some of that private investment has been sadly lacking in critical due diligence.
Look at Tri-Alpha. The people involved with that (Rostoker, Binderbauer and Monkhorst) were told 23 years ago that their colliding beam H-11B concept didn't work, for multiple reasons. Yet look at how much money they raised.
Let us just observe that securities fraud is very unevenly enforced.
None of these startup companies will ever produce a lone kWh of commercial power. But they will very diligently spend every dollar they are handed by VCs. The VC brokers know the score, but the money spent goes for equipment from quite profitable companies. It is not their money, and there seems to be plenty of it.
In practice, synfuels would be better than either for ships on Earth.