Its a common meme here at the Dope when talking about the future:
making fun of the old prediction that we would have unlimited amounts of electricity generated by nuclear fusion within 20 years.
What’s the actual history of this prediction? Was it really repeated over and over again, despite the obvious failure of scientists?
And when was the last time any serious engineer or scientist made such a prediction?
I remember hearing it said circa 1975 but I can’t give you a cite. At the time, I knew some college scientists in the field of nuclear physics but I’m not sure if you’d consider them to be “serious”. I also remember during the 1980s discussions about what to do with nuclear waste from fission plants, it was often brought up that this was just a temporary problem because in 20 years we’d have fusion which doesn’t produce nuclear waste.
Such statements, when made, are also often attached to conditionals, like “If funding for research persists, we’ll be able to develop practical fusion within X years”. But if the funding doesn’t persist (and really, when does funding for anything persist over a span of five presidential terms), one shouldn’t be surprised that the underfunded research hasn’t been fruitful.
I’d always heard 30 years.
Fusion happens in the lab now. There just isn’t more power coming out than going in (although that may have changed) and when it does get past break even, how do you convert that heat energy into electricity?
The sun is a fusion reactor that you can harvest the heat or light from now. It is at a safe distance and has a fuel supply of several billion years. All fossil fuels on earth are stored and concentrated solar energy.
There were still funded research projects for cold fusion in the l;ate4 1990’s, although most of the hype had died by then. Barely 20 years, but it still counts.
Lockheed Skunkworks is claiming 3 years to a compact prototype, 10 to deployment. Sorry about this being a video presentation; you can skip the first 4:30 or so and probably the last 3 minutes to get past the hype. The presenter makes what sounds to me like a major error in stating that the plasma in a tokamak creates the magnetic field, so I have my doubts all around.
From what I have been reading, a tremendous amount of energy has to remain inside the plasma for fusion to be sustained. The heat that can be harvested is drawn from the lithium blanket capturing the neutron flux (where tritium is bred). Thence to steam, to turbines, to generators. I recall many years ago reading of a mirror/bottle design which they said could convert endpoint plasma leakage directly into electrical current, but that was not the primary power output route, it was a pretty small amount.
You can pull that off with the right geometry, but it’s tricky. I don’t know whether that’s the most promising route or not. But a timescale of three years to prototype and ten to implementation sounds ludicrously short to me-- ITAR is looking at more like 25-40 years for those milestones, and they have more resources to throw at the problem.
This guy comes pretty close -