We know its possible! Fusion has been achieved on earth many, many times (bombs obviously, but also small scale reactions by all these teams trying to get fusion power going). The thing that hasn’t been done yet is sustained fusion that generates more energy than is required to maintain it or initiate it. That’s when it becomes a power source.
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OK, so they’re “close” to having reactors that are “approaching” net-positive energy (yay), but how are they planning to convert/capture that “extra” energy to produce electricity? Are we back to boilers and turbine generators? Will these “plants” still need to be sucking in massive amounts of water and discharging it at a higher temperature?
All I see on the the linked websites are glorious pictures of tokamaks, but where’s the rest of the infrastructure?
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If only we had a way of harnessing the power of the sun!
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Worst possible thing that could happen. We have already exceeded the carrying capacity of the planet, this just allows things to continue on an already insustainable course. As usual the essential axiom is overlooked: every technological advancement causes unforeseen problems that need even more complex technological interventions to counteract which themselves cause more unforeseen problems. The more complex the technology is, the more serious the side effects.
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This is progress. Back in the 1970s, fusion power was 30 years away. Now it’s only ten. (I had a housemate who was getting his PhD at MIT doing nuclear fusion, and he estimated 30 years.) No one really knows, but there has been a lot of promising work on fusion. If nothing else, what a friend at Los Alamos called “bomb code” has gotten a lot better, and we have much faster computers than we did in the 1970s. One of the first uses of a computer, in the late 1940s, was in designing the hydrogen bomb powered by nuclear fusion.
Apparently, all those tokamaks and other experiments have given scientists a much better sense of how to build a useful fusion reactor. There are a lot of players developing fusion reactors now. Science had a write up of several of them back in 2017. (http://science.sciencemag.org/content/356/6336/360) Of course, the researchers might just be deluding themselves, but some these new ideas might get us down to five years.
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You actually have to create a lot more energy than you put in to be useful. You are putting in a very useful form of energy (electricity) and getting out a not very useful form of energy (heat). You lose a lot of efficiency getting from heat back to electricity.
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Props for referencing Mahavishnu Orchestra. Double props for the first incarnation 
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Flying cars. Jet packs. Paperless offices. Hydrogen fuel vehicles. Safe electronic voting. Anti-hangover pills. Software so intuitive it doesn’t need a help system. Wind and solar power systems with no downside.
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Flying cars – hell to the fuck no. Let’s take traffic on the I-80E and put it in the sky where either idiots or algorithms can rain flaming tonnage down upon us with their mistakes. Let this idea die already.
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Paperless offices – increasingly paperless. This was promoted before stable enterprise IT was even developed. Of course it will take time to filter into all industries.
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Hydrogen fuel vehicles – Toyota Mirai is on the market.
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Safe electronic voting – technologically feasible but not practical while bureaucrats and politicians are illiterate.
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Anti-hangover pills – Pedialyte, citrulline, Gatorade, etc. You have plenty of options already available and you want a frickin pill?
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Software that doesn’t need a help system – what do you think Instagram or Facebook are designed to be to most users?
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Wind and solar without downsides – pay attention to how fast this is moving.
OK cynical grandpa, next.
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I believe fusion power would produce significant amounts of radioactive waste, but the waste it produces is ‘low level’ waste which decays in decades rather than millennia. Basically its irradiated equipment rather than spent fuel. Fission reactors, etc, create low level waste as well. Its fundamentally easier to deal with because of the time scales for which it needs to be contained and the fact that it is mostly solid durable objects.
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Beyond the difficulty of getting a sustained fusion reaction going without using a shit-ton of energy to maintain the conditions necessary, there is the engineering difficulty of getting the energy from a fusion reaction out in a useful form. My understanding is that most of the energy from a fusion reaction is released in the form of neutrons which unlike the gamma radiation of conventional fission reactors is difficult to harness.
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So much pessimism in this thread! Actually, the reason fusion is perpetually in the future also has a lot to do with funding cuts and oil lobbyists.
Yep. You get very penetrating neutrons and gamma rays. These can go though many centimetres of typical structural materials. Your whole plant is not only going to get brittle, it is going to become radioactive. But you can stop the neutrons with a millimetre or so of depleted uranium and make more energy too. But that’s a fast breeder reactor, and we can already make those.
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The basic research into doing it cross-pollinates with the sort of basic research that nuclear weapons states are interested in because it might enable them to make better bombs. I think that was the initial impetus
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Fission reactors were originally researched for their military uses, in airplanes (never got off the ground) and in naval ships, especially submarines. Fusion reactors are more appealing than fission reactors for these purposes because they never need refueling and never need to have ash removed - just add heavy hydrogen, which you get from water, and the only ash is helium. So, again, military uses during the cold war propelled a lot of research.
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Then with spikes in oil prices and the OPEC crisis in the 70’s, plus the rise in environmentalism at the same time, there was a strong desire to look for energy sources that were non-polluting and that did not rely on expensive imported fuels. That’s been the appeal for the past 50-ish years and it’s enough of a promise to keep the research dollars flowing.
The energy released is the same as in a fission reactor - gobs and gobs of heat from the conversion of tiny amounts of matter into energy. So you hook it up to a steam turbine, same as in every other electrical power plant the world over, and generate electricity the old fashioned way. (The neutrons emitted by a Deuterium-Tritium fusion reactor are actually a very minor component of the energy released. You’re correct that high energy neutrons are the primary form of energy released, but those neutrons eventually collide with something and when they do, they release heat. As with fission, if you do the math you have the same number of neutrons and protons before as after - the mass converted to energy is from the sub-elementary particles that help hold the nucleus together).
eta: I was wrong about the high energy neutrons.
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We’re nowhere near the carrying capacity of the planet, even at our current technology levels in the western world, or even the average technology level of the planet, it’s just that we’re not using things economically because politicians find it more beneficial to pay farmers to grow crops that aren’t needed rather than crops that would be more efficient for the planet. While the 2001 UN estimate ranged from 4 billion to 16 billion, with a median of 10 billion, that’s at the unequal spread of technology of the time (and today). With proper stewardship the Earth likely has a carrying capacity in the tens if not hundreds of billions.
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I think this is analogous to speculating whether one automobile would have a chain reaction and blow up all the gasoline in the world.
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I don’t know about “back to” – steam turbines have always been how you convert heat into electricity at scale – but yes, that is how fusion power plants would work. The energy comes out as neutrons, which are absorbed by shielding material to produce heat, which is carried away by steam, which drives a turbine.
But there’s nothing inherently dirty about steam turbines, and to the extent that waste heat is a concern, fusion power plants would have the same options that are available for existing plants – secondary thermoelectric generation, Stirling-cycle turbines, combined-heat-and-power installations, and things of that ilk.
Some fusion reactions (D–3He and 1H–11B) produce energy almost entirely in the form of charged particles rather than neutrons, and it is often claimed that this energy could therefore be captured directly as electrical current without the need for turbines. But that claim is highly debatable, and also those reactions are even further from being achievable than D–T fusion.
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Exist: Flying car - Wikipedia
Exist: Jet pack - Wikipedia
Exist, but not as ubiquitous as we’d like perhaps.
Not just exist, but in production: Hydrogen vehicle - Wikipedia
Held up not by technology but by social and political factors.
Seriously? That’s been around for decades, if not centuries. The problem is that people don’t actually know to take them (with enough water to be effective).
Limited by the user, not the OS 
Also not a technology problem, but a cost problem.
Everything’s always 10-15 years out, until it’s not.
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I think I was a third grader (which would be around 1958) when I read in one of my textbooks that fusion power would be available by the 1980s. Living halfway between Harvard and MIT, I try to pay attention to these things and even know some people who worked on fusion (that student working on magnetic containment in the actual 1980s told me “it will never work”) and do theoretical physics.
Experience has shown me that an announcement of a scientific breakthrough takes at least five years to a decade to make it to market even if you have a working bench model. Fusion isn’t even close to that yet. Yes, please, do all the basic research necessary but don’t hold your breath for another techno deus ex machina.
Incidentally, utilities even in the USA are now contracting for wind and renewables at prices of about 2¢ per kWh which is cheaper than the operating costs of existing coal plants (up to 20¢ per kWh) and coal gasification and new renewables also beat the prices for natural gas peaking plants now too.
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I think you’re thinking of D–3He fusion; D–D fusion produces neutrons aplenty.
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Having worked a bit on this sort of thing…
You need a combination of temperature, confinement time, and confinement volume. Irritatingly, any press release will only quote one of these. ‘Hotter than the Sun!!’ doesn’t do you much if it is one or two atoms in a vacuum that never meet, but it makes a good headline.
- Magnetic confinement
I have heard this likened to trying to build an internal combustion engine when the most rigid material you have is paper bags. In theory, you can make something work; but in practice nothing you have is tough enough, and the exploding energy seems like it is always going to find a weak point.
- Fusors
No-one has forgotten how the magnetron was a hundred times more powerful than the most enormous valves that went before it. There is always the hope that you can use the squiggliness of plasmas and magnetic fields to work for you rather than against you. This seems to work to a point. Unfortunately, the point is usually where the device starts returning significant amounts of energy, which don’t fit into your confinement schemes.
- Laser driven implosion
This has got to be amazingly symmetric to work. The first thing a laser does is to generate a cloud of plasma, which is very opaque. You can drive the implosion of a D-T filled micro balloon via a plasma, and the plasma will actually even out the energy distribution a bit. But it is too slow, and Rayleigh-Taylor instabilities will grow and mess things up. I did a bit on this.
- Meson catalysed fusion
Mesons are like super-heavy electrons. If you are slamming a deuterium nucleus at a tritium nucleus, then a lot of work is wasted against electrostatic repulsion. If you can replace your hydrogen electron with a meson, then you can get a lot closer before the electrostatic repulsion starts to bite. But mesons decay rapidly so you have to make a lot of them, and get them orbiting your hydrogen nuclei. But it might work.
- Imploding hollow wires.
This was my favourite. In the last few picoseconds as a bulb filament burns out, it gives out hard thermal X-rays. The surrounding magnetic field tries to keep the current flowing, but there is vanishingly little material to pass the current through. In then end, metal goes straight to insulating plasma at hundreds of millions of degrees anything without changing density. This has density and temperature, but probably is tight on volume. This was my particular favourite. One day, when I get a shed big enough, I would like to build a Marx generator and give this a decent go.
- Conventional reactors
Not the ordinary sort. Use fast breeders. Or wave reactors (fast breeder and conventional reactor in the same tin. Or Thorium reactors. Old tech, but works, and can be made to consume a lot of its own waste. This could probably be cleaner than clearing up a fusion reactor at the end of its life. If your fusion solution isn’t better than this, then it’s not worth it.
I dunno. One big project like ITER that fails, or a hundred alternative projects that don’t come close to working. Not much of a choice, is it? We would all like a dramatic solution that Gets Us Out Of This Mess ™, but it is wise to put some big money behind something that has decent odds of working (albeit less dramatically) too.
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