Since fission might, in the wake of the Japanese disaster, to be forsaken in favor of other alternate forms of energy, I am curious as to what the current state of the art is in fusion, obstacles overcome, status of certain key projects, etc.
So far away from practicality, that you might as well check back in 30 years.
Practical fusion has always been 25 years away and looks like it always will be 25 years away.
I came in here to say, “About 20 years or so away from being commercially viable, same as it’s been for the last 50 years.”
When I was in college I got a chance to go to the Laboratory for Laser Energetics at the University of Rochester. That seemed to be the future. Obviously, they were just around the corner from getting it to continual production of electricity.
That was in 1970. They’re still boasting about being just around the corner. I believe it’s the same corner hiding Herbert Hoover’s recovered economy.
If things go well, maybe 40 years. But I don’t think that even the people working directly in the field think that it could be 20 years. The 40 year figure is based on current plans to build something that could be a working prototype by 2040 or so, and allowing another decade for the technology to be made practical enough for mass production.
Alan Boyle covers some of the dark horse candidates for fusion. One that he missed, dense plasma focus, is projecting break even sometime this year.
I visited JET (Joint European Torus), the world’s largest experimental fusion reactor (well, still the world’s largest - they’re currently building a bigger one in Cadarache, France) at Culham, Oxfordshire, England a few years ago. From what I recall from the tour given to us by a physicist, the state is that (1) they are doing very well at containing the plasma magnetically in the torus; (2) they routinely do up to several dozen ignitions a day; (3) they can’t keep the thing running permanently, they’re only doing individual ignitions that wuill last about 30 seconds each; and (4) that item (3) is one of the largest impediments when it comes to commercial utilisation, since a power plant would be expected to run continuously. They don’t have power generating capabilities at Culham, but the ignitions themselves run smoothly.
We were also shown charts according to which there is an estimated threshold of annual investments which you would have to put into fusion to boost it to a level of commercial viability, and that throughout the past decades the investment in fusion research has continuously been below this threshold. Of course, there is some interest on the part of the nuclear fusion research community in lobbying for more public spending, but it sounded plausible to me.
And where is my flying car, I’ve been promised a flying car. (and all i got is an Iphone)
I hear some old scientist in California is working on a miniature fusion reactor that is able of producing the still-amazing output of 1.21 gigawatts.
Currently, the international fusion reactor in Cadarache is being build. The goal is to produce more energy than is used for the reaction (until now, fusion reactors use more energy than they can produce). However, I’m talking about small amounts of energy for a short time.
So, in some years, it will be build. Scientists will play with the thing for some years, and draw conclusions from it. Let’s say they’re finished in 2025 or so, and it has been a success. Then the plan would be to build the first experimental fusion reactors, producing energy on a more or less constant basis. Planning, building, etc… them, will probably bring us to 2035 or so. Then, they’ll be run for some years. If it’s again a success, it will be time for planning to build actual serviceable fusion plants.
So, assuming everything works smoothly, I guess there might be such fusion reactors around…2040-2050, maybe. So, not exactly tomorrow. Of course, it could be a failure or at the contrary, meanwhile, a new, stunningly efficient way of harnessing fusion power could be discovered, resulting in fusion plants earlier.
Nevertheless, I still have faith that I will see a functional fusion reactor in my lifetime, providing I live long enough (I’m 45). A poster said that fusion power is permanently 25 years in the future, which, in my experience, is true. However, it has been said for decades that “Brazil is a country with a bright future and will stay so” and it seems that finally, they begin to achieve success. I hope it will be the same for fusion power. 
SimCity 2000 said that large-scale fusion would become available in 2050. So, 39 years.
So what is the current status of time travel technology? Because that would obviously solve the practical fusion problem.
Does anyone here know anything about Polywell Fusion? Beyond the wikipedia entry, of course. I also watched the video of Bussard’s presentation to Google. I certainly sounds promising to this EE anyway (which pretty much makes me a layman on things nuclear).
While there were reports of a successful test in California in 1985, there is no evidence that other scientists have been able to replicate the experiment.
Declaration of interest - I work at the UK/European fusion lab at Culham. **Clairobscur’s **summary is about right, there is a good explanation of the different machines being built and proposed and the possible timescales at this page. Note that this is looking at magnetic confinement which is the most mature technology but the inertial confinement people are making great claims for the strides they are making.
The crucial question is funding. The physics is mostly understood but there are massive engineering challenges to overcome and the present plans put all our eggs in one basket. When fission was being developed as a power source there were multiple prototype reactors in many countries whereas there is only one ITER and, in the Fast Track roadmap, there is only one DEMO - the proposed first electricity generating fusion plant. Having said that, if ITER does what it is meant to and the materials problems are overcome I can see several counties pushing ahead with building a version of DEMO - China, India, etc.
If anyone wants more there are multiple previous threads on this topic. Two I’ve found quickly are hereand here
But you gotta admit, an iphone *is *better than a flying car when everybody else has one.
If I might ask what are the major hurdles that need to be overcome to make fusion a viable energy source?
My understanding (which is admittedly lacking in technical skill) is it is impossible to inject more fuel into the reaction.
This seems reasonable since, as mentioned above, they can achieve ignition with regularity these days. But to get a working reactor it need to run non-stop (or at least for long lengths of time) to be viable. They cannot get more energy out because all they can do is start the reaction. They have no way to keep it going (i.e. feed more fuel to the reaction to keep it operational).
Is that about right or are there other issues? If I am right are there notions about how to add more fuel to the “fire”? Admittedly I am not a nuclear engineer but squirting more hydrogen into a fusion reaction seems near impossible. Hell, my understanding is even the sun only fuses what is in the core and the other 90% outside cannot add itself to the reaction. Sounds like an impossible task.