# Is a viable fusion power reactor still "only 20 years" away?

Discussion in 'General Science & Technology' started by Oystein, Dec 24, 2016.

1. ### OysteinRegistered Senior Member

Messages:
890
Ever since the 1950s, scientists and engineers have been saying that a viable fusion reactor is only 20 years in the future. 60 years later and it still seems to be 20 years away. Billions of dollars spent on laser and magnetic bottles and what to show? So, maybe by 2100? Maybe?

danshawen likes this.

3. ### Xelasnave.1947Valued Senior Member

Messages:
2,919
Its like playing a poker machine.
No matter how big the jackpot a point comes where maybe it is best to walk away.
At least with a poker machine you can reasonably expect a jackpot one day.
I think until we have a theory on quantum gravity we play the game at a disadvantage.
Alex

5. ### SeattleValued Senior Member

Messages:
2,200
Fusion power is here and has been here. The problem was that more energy was expended than produced.

They can scale up and be at the point where they are producing more than expending. They mainly do this by increasing the magnetic power field that contains the plasma. The other issue to be practical is how to take that energy that was generated and get it into the power grid and to do it economically.

The technology is there and projections are that it can be done at close to the costs of traditional power. It's still more but in the range that a commercial operation would be viable with government subsidies while costs were brought down.

The main roadblock is that this technology isn't being funded the way it should be. There is the ITER project in Europe but it's a multi-year (decades I believe) project and it's huge. Too large to be commercially feasible.

However, during the time that this has been under construction smaller research generators have been constructed using newer technology that could generate the same power on a much smaller scale.

What needs to happen is for more smaller generators to be constructed over much shorter periods of time so that "we" can learn from and incorporate improvements in each new generation just like any other technology improves.

7. ### Q-reeusValued Senior Member

Messages:
2,497
WTF would a theory of quantum gravity have to do with solving the MHD issues plaguing hot fusion?!

8. ### Xelasnave.1947Valued Senior Member

Messages:
2,919
I was thinking as fussion occurs in the Sun presumably in the presence of considerable gravity then to understand how gravity works may be helpful.
Alex

9. ### Q-reeusValued Senior Member

Messages:
2,497
Wow. As a matter of well known fact fusion is greatest at the very centre of the sun where 'gravity' as you would likely mean it i.e 'g' forces are negligible. Gravity obviously plays a role but Newtonian gravity is perfectly adequate to account for the gravitational component of the overall stellar fusion process. Gravity btw has zilch to do with e.g. Tokamak or such fusion reactor schemes.

10. ### Xelasnave.1947Valued Senior Member

Messages:
2,919
.
So your position is that we know sufficient about gravity such that we need not think there is more to know that may assist in understanding fussion.
My position is ...until we fully understand gravity and how it works at a quantum level we may be missing out on an important part of how fussion works.
If we do not know what we do not know I don't think the importance of that unknown knowledge can be assessed.
Alex

11. ### Q-reeusValued Senior Member

Messages:
2,497
I've said there is not even a connection beyond stellar fusion.
Well Alex SF allows you to voice that opinion, and I wouldn't want to have it stifled just because it's not MAINSTREAM THINKING. However, you will have an impossible task objectively justifying it. Try checking for yourself the huge energy density orders of magnitude gulf between fusion (any variant) and where quantum gravity 'comes into it's own'. Which is not even addressing the fact that terrestrial fusion schemes have no role for gravity to play at all.

12. ### Xelasnave.1947Valued Senior Member

Messages:
2,919
I do not think I will be called upon to justify my opinion and nor could I.
That's why they don't continue to work.

I don't wish to go on with this. I know I can't win and I know its not mainstream.
I will withdraw my comments if you like if they make nonsence out of this thread.
Alex

13. ### Q-reeusValued Senior Member

Messages:
2,497
You know and I know Alex this is just one back for your (unjustifiable) treatment of me in another thread. That's how it goes at SF. Whatever rationalizations and denials are made, such is the norm. Oh, lest it pass without anyone saying it in this thoroughly leftist PC forum - merry Xmas.

14. ### Xelasnave.1947Valued Senior Member

Messages:
2,919
I am sorry if I have been unfriendly or treated you unfairly it won't happen again.
Maybe because I am basically a shy type of person I sometimes try to be unnecessarily forceful.
I will be careful in the future.
I don't understand the implications of leftist I hope I am not leftist.
I believe in free health and education but that doesn't make me left does it?
I wish you and your family friends and loved ones Merry Xmas.
Best wishes
Alec

Q-reeus likes this.
15. ### Q-reeusValued Senior Member

Messages:
2,497
Thanks. And that's how I prefer to leave it. Except to say, I consider the future belongs to advanced fission reactors not fusion, to the extent either is an ultimately viable answer.

Xelasnave.1947 likes this.
16. ### SeattleValued Senior Member

Messages:
2,200
I disagree regarding fission reactors although current technology could be improved and many reactors that do exist are using older technology because of political pressure to not build any/many newer reactors.

They certainly could be much safer than many of them currently are but the nature of fission is inherently less safe than fusion.

Alex, gravity contains the plasma in the sun and Earth just doesn't have to mass to replicate that here so it's done with magnetic fields. The stronger the magnetic fields the smaller the reactor. This is why some university research reactors could reach the same efficiency as something like the ITER project.

I'm not expert in this field so if someone else is feel free to correct and inaccuracies in what I've written. I think I've been accurate enough given the context of this forum but if not so be it.

Regarding fission, in the U.S. reactors are not allowed to reuse the plutonium byproduct (for "security" reasons) so instead it is stored. It could be largely reused as fuel in the reactors and that is the case, I believe, in much of Europe.

Other radioactive byproducts, through nuclear transmutation, could be rendered less dangerous with half-lives that can be more safely stored underground or where ever I don't think much of this is currently going on either probably for economic reasons.

17. ### Russ_WattersNot a Trump supporter...Valued Senior Member

Messages:
5,051
Current best guess is 30 years, based on the suggested timeline for DEMO, which is the acronym for the proposed first demonstration power generating fusion plant. It is currently proposed to become operational in the mid 2040s: https://en.wikipedia.org/wiki/DEMO#Timeline

However, it is dependent on the success of ITER, which so far is delayed for longer than the project was supposed to last. We'll see if/when it gets finished and if it works...
If your point is that maybe we are wasting our money, I'm starting to agree. At this point it seems clear that even if it does eventually work it will be fabulously expensive (even not counting the fabulously expensive development process), so it may never be worth doing. And in the meantime we lost a generation of clean nuclear [fission] power on the promise that something similar but better was right around the corner.

Fortunately though, what they also told me was 20 years away in elementary school - Peak Oil - was wrong too.

18. ### Russ_WattersNot a Trump supporter...Valued Senior Member

Messages:
5,051
That isn't correct. The issue is containment and sustainment. Scientists don't know how to contain a fusion reaction in a way that it won't melt its enclosure. So they fire it up for only instants, to study it. It isn't as simple as just 'build a bigger one and it will work'.
That's not an issue at all. We've been doing that for over a hundred years.
Scientists seem optimistic, but they always seem optimistic. After 70 years, I'll believe the latest version of the technology works when it actually gets turned on and is shown to work.
Since no one knows what they will look like, how much power they will produce, how big they are -- or how much they will cost, such guesses are wild -- and always optimistic.
ITER will cost on the order of $20 billion. How much is reasonable? Didn't you start the thread by saying all that was needed was to scale-up? That's a contradiction and a big problem for fusion's viability. ITER will cost twice what a fission plant costs, produce half the power and won't be capable of continuous operation/power generation. The sunk costs will have to be considered long after fusion becomes viable (if it ever does). IE, if at some point 50 years from now we have 20 working fusion plants, each of them will be trying to defray$1 Billion of ITER's cost and an equal fraction of DEMO's cost.

19. ### SeattleValued Senior Member

Messages:
2,200
I'll get into more links and specifics as to what I was getting at later but I'll give a short response now.

First of all ITER is just an experiment (a too costly one in my opinion). Even when completed it won't be adding any energy to the grid. It wasn't designed to be a commercial power generator.

It was designed to be huge to get around some of the limitations in small reactors at the time it was proposed. That is one of its problems. It costs so much and takes so long to be built that it is obsolete by the time it is completed.

By building it larger it is supposed to produce more energy than it requires but still not at a cost that compares to tradition power generation. However, building smaller reactors over shorter periods of time allows technology (and learning) to advance more rapidly.

The money would have been better spent to have advanced more research reactors at universities. The problem I was speaking of was not have to move energy to a power grid, of course that is not an issue.

It's dealing with containing the plasma at the same time as trying to transfer power to the grid. I'm not implying that it can't be done but it is not something that is currently being done in any fusion reactor.

Improvements in being able to increase the magnetic field is what have brought down the sizes of reactors and still kept the efficiency of a larger reactor like ITER. A research reactor in a university could now be much smaller than ITER and be just as efficient due to newer (newer than ITER) technology in increasing the magnetic field.

I disagree with your statement that scientists don't know how to contain the plasma.

20. ### billvonValued Senior Member

Messages:
12,713
They don't - if they knew how, they'd do it.

There are several problems with fusion power.
1) Ignition. You have to get the plasma hot/compressed enough to undergo fusion to begin with. That takes a LOT of power (gigawatts in the case of inertial-confinement systems.)
2) Breakeven. You have to have a high enough reaction rate to be able to maintain the temperatures/pressures to enable more fusion.
3) Containment. You have to contain the plasma and some of the reaction products for long enough (at least days) to make power from it.
4) Thermal transfer. You have to get the heat out of the reaction (the same reaction you have been trying to keep isolated and very, very hot) to run a Carnot cycle plant. This is actually not that hard; any containment solution will not be perfect, and imperfect containment will mean heat transfer. Managing it will be key.
5) Radiation. You have to deal with very high levels of primary (gamma and neutron) and secondary radiation within the reactor. Those levels of neutron bombardment, for example, will weaken any metal quickly. Then the reactor lining has to be replaced, and you have to dispose of tons of very radioactive metal.

All those are perhaps solvable, but there's a lot of work yet to be done. It's not a matter of scaling what we have now; it's that we can't do it at all now.

Messages:
890
22. ### DinosaurRational SkepticValued Senior Member

Messages:
4,584
The force of proton-proton repulsion is circa 10E37 times gravitational force. To grok this force, note that a magnet weighing less than an ounce can cause a needle to jump off the Earth.

In the core of a star, the gravitational force keeps protons from escaping while the heat indicates that they have a high velocity resulting in collisions in spite of the repulive force.

The above conditions seem impossible to create on on Earth without using more energy input to some device than obtained as output.

23. ### danshawenValued Senior Member

Messages:
3,942

The Sun is 4.6 billions years old, and showers us every day with pure clean, free fusion energy to warm the Earth and support life. It doesn't cost anyone a nickel to develop this fusion technology and anyone with or without solar panels can use it. It's just there, for 12 hours a day, in most locations and under most weather conditions. Solar energy provides us with all our food already. Planting and harvesting that food currently uses fossil fuels. That probably would not change even if practical fusion power to generate electricity happened tomorrow.

Even if we could produce and control fusion energy on the surface of the Earth, its use would no doubt present us with many new environmental concerns for which our planet is ill adapted, particularly in terms of global warming. No energy producing technology like this comes without that are hidden.

The only alternative I can fathom would be to scale such technology down to almost negligible energy output, and that would carry with it many other unacceptable risks, as well as making the payback less profitable. From a payback point of view, if fusion energy did happen on the scale its developers wish, it would cause revenues from other energy sources to drop precipitously, causing turmoil in the energy sector of the economy for as long as low cost fusion energy was a practical alternative.

So to answer the OP, no, it is not likely this will happen any time soon.

Last edited: Jan 1, 2017