How far away are we from building functional fusion power plants? When we do, what will happen to the current big energy suppliers (e.g. oil, natural gas, coal)?
https://www.sciencemag.org/news/2021/02/road-map-us-fusion-power-plant-comes-clearer-focus-sort
It’s perpetually 10-20yrs away.
Well, the official web site says construction will be finished by 2025, with full-power D-T fusion scheduled by 2035, so they are slightly more optimistic, but only by a bit 
Here’s this week’s picture:
ETA NB that’s an experimental 500 MW fusion tokamak, not a commercial power plant that will actually produce any power
Yep. I won’t live to see it.
It’s really difficult for new energy sources to displace old ones. What has tended to happen is that new energy sources are much more efficient than older sources, and thus drastically increase the total available energy because older, less efficient energy sources continue producing just as much. We’ll use more power instead of replace old power sources.
That trend may change if modern societies decide to do more than pay lip service to climate change, but that would be a positively enourmous endeavor that’s not likely to be completed within the next 50 years.
Remember, without any subsidies, Wind and Solar are cheaper than fossil fuels and non-renewables. They haven’t magically replaced them, though. Likewise, even if fusion reactors were a viable market technology today they wouldn’t displace fossils, they’d run in parrallel.
I’m an (amatuer) energy investor, and my current bet is on renewables for growth and fossil fuels for value. Oil companies will continue yielding profits for quite some time and may even have a bull run if the current trend in commodities continues. Renewables will capture more and more market share from here on out, however. It’s waaay to early to identify front runners on commercial fusion. Eventually, however, if a corporation can get its hands on significant patents, some kind of regulatory monopoly, or just seize a huge market share, that’ll be a great investment. Not for now though.
I can’t answer the first question, but it will have minimal impact on oil, which we don’t use much for generating electricity.
AIUI, there are two reactors in development that are claimed will have a net positive energy. This is a significant development, and suggests that the jokes about fusion power might be obsolete in our lifetimes.
But
In the case of ITER at least, the claim is controversial, as some analysts have suggested that there has been pressure on scientists and engineers to inflate the figures and ignore probable energy losses elsewhere.
And even under optimistic scenarios, we’re talking about one or two proof of concept reactors in the first 20 years and probably at least a couple decades after that to actually make it a significant part of the energy mix.
I’m just writing this on my phone, I’ll provide cites later 
The comparison you make is problematic. Wind and solar are variable sources of power which can leave you in the dark if the sun don’t shine and the wind don’t blow. So the common wisdom is that you still need the old power plants for those events. Fusion wouldn’t be in that same category.
Fusion, when it finally arrives will remove the need for new Fission & Coal plants at very least. It should accelerate the closing of coal plants which has been very slow. It should slowly but surely supplant most other forms of electrical production and potentially steam production for cities like NY.
Obviously Iceland will be happy with their geothermal production they currently have.
Fission plants are good for fighting Climate Change but bad in almost every other way. Coal, well Coal should already be gone.
Except that coal is, in fact, already getting displaced. Not by solar or wind, but by natural gas. Granted, a lot of that is just refitting existing power plants, rather than completely replacing them, but maybe when fusion becomes practical, it’ll be possible to refit those, too.
As for the old saw about fusion being perpetually 20-30 years away, that estimate has always been based on continual support and funding for that entire timespan. Which has never been the case.
Sorry, I think you misunderstood. The trend to which I’m referring predates the existence of solar, wind, etc. I don’t have a good source because google has become so awful of a search engine lately and it’s burried beneath a bunch of oil funded solar bashing, but generally speaking the total power generated from any source does not go down (and in fact tends to go up) even when vastly superior tech is around.
That is, we still use wood and even primitive energy sources more than we used to. In fact, the only source I know we don’t use as much as before is whale oil, and that’s because it was almost completely exhausted.
Society and technology expands to consume the newly available power source in addition to the previously existing sources. Market forces might steer most new development/exploitation into newer sources, but those same forces kick in when the new tech is saturated and diminishing returns let the old tech catch back up in terms of profitability.
Most fusion predictions, for instance, say we need Helium-3 to do it with any sort of cost efficiency, and that’s found almost exclusively on the moon. That limits the economical scalability for some time until extra-terrestrial infrastructure can be built. So for a long time, there might be a few fusion plants using the limited earth-bound supplies of He-3 while we continue to use old sources and of course during that time, if power gets cheaper people will buy & use more of it (and if it doesn’t get cheaper, then there’s more incentive to burn fossil fuels).
He3 is ideal in that it creates no radioactive waste, however it is not ideal from an energy standpoint or ease of implementation. I don’t believe that early fusion plants will be using it due to this. Perhaps one day, and yes moon mining can do wonders here.
Again you come up with a problematic example. You use wood as a technology that was being replaced by a ‘vastly superior tech’. But wood is still used because, location depending, no other energy source for heat can match woods prices. There is simply no superior tech available in that category of price. In fact woods price is artificially high in my area due to the even higher cost of alternatives. For many places wood fuel is a byproduct of tree trimming, so it is essentially not just free but paid for, that’s going to be hard to beat. In that wood has gone high tech, from being a chore just to gather for heat, to a reuse of a waste stream product. Wood also is simply unbeatable in cost of any fuel for a person willing to harvest it themselves.
What wood does not have is convenience, it is one of the most inconvenient fuels period, however even their wood has gone high tech and we have wood pellets which compete with alternatives on that basis as well added convenience at the cost of some cost.
So I don’t think wood qualifies under the point you are trying to make. Wood still holds advantages over other fuels.
Just to add there is one thing that falls under the category that I can think of and that is energy conservation. Energy efficiency has been used as a source of power. Get enough people to be energy efficient and you saved the equivalent of a power plant, thus the energy efficiency is considered a virtual power plant that needs continuous efforts and incentives to keep a population efficient.
But there comes a point where a population gets so energy efficient that they no longer feel the need to conserve power, or are too inconvieneced by it, that there simply is no longer felt a need to conserve.
It depends on how much fusion power costs and the particular operating parameters. I personally haven’t seen any such estimates. I also don’t know how much unsafe waste they create… yes, the obvious waste product is helium, but what about induced radiation in the coolant or structural materials or whatever.
If it’s convenient and small like in the movies, of course it will be revolutionary, but reality is going to be different and complicated.
Hopefully, by the time fusion becomes realistic as a power supply hopefully many people will have transitioned to solar which is nice because it doesn’t require large amounts of grid infrastructure.
Solar with battery backup.
We can refit coal-fired plants with the ability to use natural gas because both use a basic boiler system to generate mechanical work, and natural gas plants are actually more compact (although mechanically more complex than coal do to the necessity of handling a flammable and potentially detonable fuel). Nuclear fission plants are more complex because they have inner and outer working fluid (coolant) loops that have a heat exchanger between them to prevent the potential for radioactivity being released into the environment; this and other safety and reliability requirements necessitate a very different basic layout of a fission plant.
A nuclear fusion plant, on the other hand, is going to be radically different, as you can’t simply run coolant pipes through the middle of a fusion plasma core or stream, and thus the conversion of the energy output from fusion will be quite different. In deuterium-tritium fusion (the most likely fuel for a near-term fusion power reactor) charged alpha particles (3.52 MeV) can be run through an electrostatic grid or otherwise captures to generate electricity directly, while the energetic neutron output (14.06 MeV) can hopefully be used to breed more tritum or perhaps absorbed by fissionable materials lining the reactor as a secondary means of producing energy or breeding fission fuel. Whatever mechanism for energy conversion is used, it won’t be simple thermal conversion into mechanical work like a conventional combustion power plant.
It is certainly the case that assuring consistent funding for nuclear fusion power production research has always been a challenge (as is consistently funding any research project or development program for decades on end) but the problems aren’t just linear to funding. There are both some fundmaental issues with the necessary precise control of plasma to maintain a stable or cyclic state of fusion energy output, as well as the unsolved problems in engineering, materials science, power conversion, et cetera to turn a theoretically overunity fusion reaction into a practical source of power. By some guestimates, it will require a Q>10 (that is, more than ten times overunity output) to actually get usable fusion power. And if fusion plants are all of the scale of ITER or the planned size of DEMO, they will be enormous construction projects that rival the Large Hadron Collider in complexity which is obviously not well-suited to quickly offsetting conventional hydrocarbon combustion energy production. There is a lot of technological maturity across various systems required before it is reasonable to declare that nuclear fusion power production can replace or even supplement conventional energy sources:
https://www.sciencemag.org/news/2021/02/road-map-us-fusion-power-plant-comes-clearer-focus-sort?utm_campaign=news_daily_2021-02-19&et_rid=372394086
“It’s credible and doable,” says William Madia, vice president emeritus at Stanford University, who has often been critical of DOE’s fusion efforts. However, Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists, notes the report also points to numerous key technologies that are in a low state of technical readiness and questions whether they can be developed in time. “Reading between the lines, I didn’t feel that it gives you a lot of confidence that these time tables are realistic,” Lyman say.
“Solar with a battery backup” is fine for limited scale power like an off-grid home but it is nowhere near the capacity to actually drive an industrial civilization. People don’t realize the amount of power they use personally at home or work is dwarfed by the amount of energy that goes into manfacting, transporting, and distributing the products and services they use every day. Solar power is a potentially vast source of energy (provided you are in the temperate to equatorial latitudes) but being able to store the energy and access it as you need it is an enormous challenge, and conventional battery technology is inadequate on industrial scales, both because of the limited cycle life and because there just isn’t enough accessible litium in the world for everyone to have a Tesla Powerwall. Solar, while becoming very cheap to deploy thanks to the still-dropping costs of producing solar panels, also has a market problem of getting out of its own way because it can literally become “to cheap to meter”, which sounds great until you realize that this means it becomes unprofibable as the SunEdison fiasco shows.
Solar (and despite the Fox News winging about frozen turbines, wind) power are great sources because they have a relatively low carbon footprint and can be deployed in both an inexpensive and scalable manner, but until the energy storage problems can be solved they’ll never be a baseload solution on an industrial scale, which means we will still need some means of on-demand power production. Every conventional source has its downsides (coal and natural gas are net carbon producers; nuclear fission has limitations of fuel production and enrichment, radioactive waste disposal, and end-of-life retirement costs; biofuel has significant scalability problems) and renwable sources like solar and wind can significantly offset those if deployed strategically but they are not a near-term comprehensive solution to world energy demand.
Stranger
General observation only here: I get how fun it is to say “fusion is always 10-20 years away from reality” but serious progress has indeed been made over the decades. For one thing, no one questions the science any more and that was a yuge problem a few decades ago. Now, we’re (lots of reputable scientists, which is also a fairly recent development) just working on the technology. Which is extremely difficult and why we’re probably still, uh, 10-20 years away.
No one has questioned the scientific basis of nuclear fusion since November 1952. The question has always been how to maintain self-sustaining fusion reaction which is what has been perpetually two decades away. Every decade seems to come with the new promise that the hurdles of maintaining a stable plasma structure with proposed new configuration from linear inertial fusion and heavy ion beams (inertial confinement), various tokamaks and stellarators to biconic cusp and ELMO bumpy torus (for magnetic confinement), and a smattering of other concepts like electrostatic confinement, various z-pinch methods, and hypothesized cold fusion (now referred to as Low Energy Nuclear Reactions or LENR), muon-catalyzed fusion (which has a seemingly unsolvable alpha sticking problem), and a variety of other Rube Goldberg-esque concepts that seem unlikely to ever be workable even if they could theoretically achieve over-unity power output.
We are almost certainly more than ten or even twenty years away from practical fusion; the current schedule for the ITER follow-on, DEMO, is now estimated to be out in the 2050s which isn’t surprising because ITER was originally supposed to be at first plasma in 2015 and the current schedule has it now at 2025, which many people still think is optimistic. Unless one of the commercial fusion efforts pulls a rabbit out of a hat or some genius figures out how to overcome the alpha sticking problem with muon-catalyzed fusion, practical nuclear fusion is probably at least thirty-odd years out at best.
This is an excellent book on the fundamentals of nuclear fusion power production; it’s quite technical as it is intended for engineers or physicists at the upper undergraduate or graduate level but the text is clear enough for a reasonably knowledgeable layperson to get the gist. It’s a rare text in that it addresses low temperature muon-catalyzed fusion and ‘hybrid’ fission-fusion concepts, albeit in not extensive detail. I’ve followed developments in nuclear fusion and fission-fusion hybrids since I was at university (I was originally intending to go into high energy plasma and fusion research) and I’ve seen a lot of speculative promises fall by the wayside as technical issues cropped up over and over. I now temper any expectations with the quenching oil of looking for experimental results, which are rare.
Stranger
Here’s an interesting article about developing technology for fusion reactors:
I also wonder if some fusion-technology progress isn’t being shared yet. There are obvious reasons why it might not be.