"Once fusion is cracked" is almost on par with "once perpetual motion machines are cracked." It presupposes that fusion being "cracked" is a reasonable thing to expect.
> "Once fusion is cracked" is almost on par with "once perpetual motion machines are cracked." It presupposes that fusion being "cracked" is a reasonable thing to expect.
Oof. One need only to peruse your comment history to see where this sentiment is coming from, but even that is no excuse for that obtuse argument.
"Perpetual motion," on the one hand, is quackery outlawed by straightforward thermodynamics, breaking the rules of which allows assertions like "chair seats and door handles should be spontaneously heating up to incandescence essentially at random." Fusion, on the other hand, is a technical problem.
Fusion researchers at MIT, ITER, and other institutions at the top tiers of academia across the globe are not a cabal of greedy grant-dependent charlatans bamboozling their way through careers in bad faith, deliberately ignoring the lone rational voice of Lidsky and his Johnny-Come-Lately-The-Baptist on HN, u/pfdietz. It's perfectly rational (Sane, even!) to cast aside internet naysayers (no matter how zealous) in favor of deferring to, you know, actual experts.
Fusion researchers are people who have irreversibly (or nearly so) committed their careers to something. They have a very strong incentive to not admit they have wasted their lives. It's touching you think that asking such a person if fusion deserves more funding that you'd get anything but a "yes" answer.
In general, you don't want to ask a person in field X if X needs funding. You might ask them what's the best way of spending money in X, but even then you better phrase the question carefully to avoid conflict of interest.
This is either a bad joke, an incredible misunderstanding of physics. "perpetual motion machine" is not compatible with the laws of physics as we understand them. There's many working fusion reactors, we don't know which, if any, designs will be economical.
A cup of water is enough to power a small city, if the atoms in it were perfectly fused. So for all practical purposes, clean fusion IS pretty close to what we imagine when we think of perpetual motion. The sun would burn out long before we ran out of usable fuel in our solar system.
No, I understand that. What I'm pointing out is that if something has no realistic chance of being economically viable, then from the end user's point of view that's just as bad as if it were physically impossible. The only difference is society is spending billions while pretending an economic miracle will happen, even if that miracle is as implausible as discovery of a violation of the law of conservation of energy.
Fusion indeed has a realistic chance of being economically viable. Your comment assumes that current technologies remain entirely static which is the unrealistic position. Enabling technologies like high temperature superconductors, advanced computation/simulation capabilities, new high current/high voltage electronics, as well as recent advances in alternate (non tokamak) concepts bode well for the field.
Your comment is funny, since "assuming current technologies remain static" is what fusion proponents have done. They have to assume the competition doesn't get better. If solar and wind continue down their experience curves they will be delivering power at a fraction of a cent per kWh, when fusion will be lucky to deliver power at a cost 100x that.
Just look at the multiple engineering miracles that would be needed. I'll mention a couple here.
Note that DT fusion is a thermal power technology. It makes heat that drives a thermal cycle. It turns out that all externally heated thermal cycles have become uncompetitive for power generation, just because of the cost of the non-reactor/non-boiler components. This includes fission, solar thermal, geothermal, and coal. So even if a DT fusion reactor is delivered FOR FREE from the fusion reactor fairy, it will not be competitive. Expecting capital equipment to have zero or negative cost is a good economic analogue for a perpetual motion machine.
So, what's the alternative? It's going to have to be something using advanced fuels and direct conversion. That means all the efforts with tokamaks are ruled out (they cannot work with advanced fuels and have no place for adding putative direct conversion.) And what advanced fuels are we talking about? D-3He would require space mining of the outer planets (the much-discussed lunar resource, even if it could be mined at 10 ppb in the regolith, would only last centuries before being exhausted.) And H-11B is extremely difficult, because the energy out is only about 10x the kinetic energy of the particles, so very little loss can be tolerated. In particular, systems in thermal equilibrium will have a very difficult time reaching breakeven, due to large photon losses.
Another showstopper is the absolutely terrible power density of fusion reactors. This follows from general principles (geometry and the square cube law). If you look at all existing fusion reactor proposals, ask what their thermal power/volume is. You will discover they are terrible compared to fission reactors (ITER 400x worse, ARC 40x worse). So ask yourself: why is this going to be cheaper than fission reactors? The fusion reactors are both larger, more complex, and made of much more sophisticated materials. And fission has already lost the economic race.
The larger more complex reactors are really bad news for reliability and maintainability. Estimates for the fraction of time a fusion reactor will be up, given current estimates of MTBF and MTTR, are just a few percent. This is inadequate even for an experimental reactor. There is not much budget space for operating costs from a fusion reactor before just that becomes prohibitive.
From a hard nosed engineering point of view, fusion is just ridiculous. It piles complexity upon complexity in a large machine that will be too radioactive for hands on maintenance. How could you think this would ever make sense?
Perpetual motion machines are fundamentally impossible by current understandings of physics. Fusion, from my reading, is more like a tremendously difficult modeling problem. Like protein folding. We can't sustain a productive reaction because we can't contain it properly, and we can't contain it properly because we can't yet predict the behavior of the plasma.
Perpetual motion is not hard at all. Satellites are in perpetual motion around globe for decades. It doesn't violate anything. Universe is infinitely old and still moving.
Perpetual motion _engines_ violate law of energy conservation, because perpetual source of energy can create infinite amount of energy, thus they are impossible, like perpetual source of water, or perpetual source of anything.
Oof. One need only to peruse your comment history to see where this sentiment is coming from, but even that is no excuse for that obtuse argument.
"Perpetual motion," on the one hand, is quackery outlawed by straightforward thermodynamics, breaking the rules of which allows assertions like "chair seats and door handles should be spontaneously heating up to incandescence essentially at random." Fusion, on the other hand, is a technical problem.
Fusion researchers at MIT, ITER, and other institutions at the top tiers of academia across the globe are not a cabal of greedy grant-dependent charlatans bamboozling their way through careers in bad faith, deliberately ignoring the lone rational voice of Lidsky and his Johnny-Come-Lately-The-Baptist on HN, u/pfdietz. It's perfectly rational (Sane, even!) to cast aside internet naysayers (no matter how zealous) in favor of deferring to, you know, actual experts.