January 26, 2006

Nuclear fusion and the energy debate

I was reading through bits of the BBC News site this morning as I do these days and found a short (video) report in the Sci-Tech section about the government launching a 3-month public debate about our future energy supplies. The general impression I get is that the government wants to re-invest in the nuclear power program (nuclear fission). I was slightly disconcerted that the BBC News' coverage and also the DTIs report on the subject contains no information about nuclear fusion. I've noticed in general that the vast majority of people have no idea what nuclear fusion is, which is slightly worrying considering the fact that the energy supplies and CO2 emissions debates have become important matters in the past few years.

The DTIs energy review does make one single reference to it:

The following pages provide an overview of those technologies that have a proven capability to generate significant amounts of electricity. It does not include technologies that are still in the early stages of Research and Development, such as nuclear fusion.

While it is a valid point that commerical production of electricity by nuclear fusion is a long way off, I wouldn't say it's "in the early stages of R&D". It's been in R&D since before 1950 and construction is about to begin on the latest large-scale experimental reactor . While I understand that it isn't going to be a direct factor anytime soon and cannot be entirely relied upon to save us from our energy problems, it will almost certainly have a huge impact on descisions made about the long term of energy production for the entire planet so people should at least be aware of it.

The currently known uranium fuel supplies for nuclear fission will only last about 50 years (DTI report) which leads to the reasonable argument that we perhaps shouldn't be building a host of new fission power plants when in half a centuary we will have the same problem all over again and have to start looking to more sustainable sources. Why not just build hundreds of wind turbines and such right now? Well, if fusion will be viable in 50 years time (ok, that's a bit of a stretch, 80 is more likely), in order to take over from fission, using all of our uranium supplies doesn't seem such bad idea. In fact, using all the uranium is surely a good idea since it will become increasing more sensible and economically preferable to use uranium for power rather than for nuclear weapons. In fact the DTI report does suggest that the fuels in old plants and bombs could increase the fission fuel supplies by up to 30 years.

So why does no one know anything about fusion? It's possible that I'm just mistaken and that they really do but just arn't interested. It's a shame really because energy and emmissions are likely to be two of our generation's greatest problems and nuclear fusion, given enough funding and help will be an almost certain and complete end to both for the imaginable future.


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  1. I was under the impression the there are hundreds of years of uranium left. Furthermore, most of it in nice places like Canada and Australia, rather than potentially unstable regimes like Russia and the Middle East (as with gas and oil).

    26 Jan 2006, 19:50

  2. Apparently not, the DTIs report, which can be found here says:

    The world’s major exporters of uranium ore are Australia and Canada, and deposits are known to exist elsewhere.75 Known recoverable uranium reserves would last around 50 years at current levels of demand and a further ~30 years is available from decommissioned plants and weapons.76 A global expansion of nuclear power stations would reduce this, but there has been little exploration for uranium since the mid-1980s and it is likely that further deposits exist. Today, mine expansions and new mines are planned in Australia, Canada, Kazakhstan, Russia, Brazil and Namibia.

    26 Jan 2006, 20:26

  3. Hopefully similar-minded people will point this out during the 3-month public debate and fusion will known about and deamed important.

    26 Jan 2006, 21:09

  4. Fusion really is far too far in the future to even be considered. A pretty sizeable energy crunch will happen in the next 15–20 years, and Fusion just won't be around (as you said) for at least another 50, perhaps 100, perhaps never. Although in princiiple Fusion power could work, there is still a sizeable camp of scientists saying it will never work, and a productive fusion plant will never be built.

    The ITER is called an "experimental" reactor not just because they are trying to work out the kinks, but work out whether fusion power is even possible. As far as I know the best fusion reactor so far has produced more useable energy than it consumed for about 1 millisecond (or something equally silly). The UK is involved in ITER, and has provided it's "share" of the money to building it (finally), but in 10 years time we may find it was all a waste of time. Quite what the DTI could say about fusion power now other than "look out for it in 50–100 years" I don't know. We'll certainly be decommisioning the next "batch" of fission power stations long before we're ready to start building the fusion ones.

    27 Jan 2006, 04:03

  5. Visiting Atheist

    The last thing I read was that to kick off fusion in the lab it required more heat and more pressure than exists at the centre of the sun, itself a natural fusion reactor, of course. It might be me, but might some current fusion research be going down the wrong line of investigation? (Not that I suggest that every country should just install a main sequence yellow star in every neighbourhood!)

    27 Jan 2006, 10:12

  6. It's further along than you think. It is true enough that it's not going to directly effect the immeadiate problem but I think it should play a part in the long term strategy. As present research in the field goes there are not any single insurmountable problems, if there are no futher surprises then it will work. Obviously, success cannot be gaurenteed as such surprises may turn up, but it's looking fairly promising at the moment.

    The various measures of confinement and energy production in the latest reactors arn't a sensible measure of the progress of the science. JET, the larest reactor in the existance today (and where I worked last summer) was designed in the 1980s just before a major discovery in improving the process was made. The changes that had to be made to JET to make use of the new discovery put it's working capacity well below that needed to try to use it to produce any power.

    The power production capability is low today simply because the systems already built were just not designed to do it. For the reaction to take place at a reasonable rate the system just needs to be bigger and provided the physics scales up without changing dramatically it will work on a bigger reactor. The next issue – how long the reaction can continue for is limited in JET due to the way power is injected. The system which drives heat and electricity into the plasma in the reactor can only continue for a certain length of time, and this is the principal limit to its operation length (about 60 seconds).

    ITER, as well as being big enough to theoretically acheive the famed 'break-even' is designed to be mostly powered by heating and electricity drive systems which can continue running indefinately. Also ITER will use many technologies which simply weren't around in the 1980s, such as superconducting magnets which will provide much greater control of the plasma then JET could manage. So while it is still an experimental reactor, the basis for it is not the usual 'something to poke the physics with' as JET was desinged to be. ITER is really the first fusion experiment actually designed with establishing a continuous fusion reaction in mind.

    27 Jan 2006, 10:38

  7. Actually, the primary reaction in the sun is a different sort of fusion than is intended to take place in reactors here, the one intended does not require quite such high-energy conditions as that inside the sun's core. The sun manages fusion due to the intense pressure and temperature created by all that mass. Interestingly fusion on earth requires a much higher temperature (about 100 times) because we have no way of creating the immense pressure. However, creating this temperature in small plasmas is not as big a problem as you would think. And so, I believe the hottest point in the Solar system during certain very short periods is infact in Oxford, England!

    27 Jan 2006, 10:47

  8. Government consultations are strange things. Rather like "The Big Con(!)versation," consultation periods and public debate usually involve constructing a "time parachute," whereby, when they announce unpopular measures in 3 months time, they can argue that they had conducted an in depth investigation of public opinion.

    Also the DTI's report loses validity in my eyes due to the fundamental lack of scientific presentation and credible statistics. The Lib Dems wanted to abolish the DTI at the last election, perhaps one of the few things they have going for them.

    27 Jan 2006, 13:44

  9. I've sent over half of my PhD working on fusion (frequently at JET) and I'm pretty confident that, providing humans stay around for long enough, we'll be able to use fusion on earth to provide our energy one day. However, this doesn't mean it will necessarily be in the hoped for timescales.

    The problem here isn't necessarily the physics of getting a fusion reactor to work (although, until ITER is built we can't be sure there aren't big and undiscovered problems), but that there are a very large number of unsolved engineering and physics problems to which solutions are needed before we can actually build a commercial one. All the materials involved need to be able to withstand constant bombardment with huge nubers of high energy neutrons over long timescales, which most current materials can't, and also hopefully not end up too radioactive at the end (the process of fusion itself doesn't produce radioactive waste but the reactor will become radioactive over time). Current designs also require superconducting electromagnets (which need to be kept very, very, very cold) and liquid lithium (which needs to be at ~200 centigrade) in fairly close proximity, and I'm not aware of a technical solution to that problem which has had any kind of real world testing.

    None of this means that we, as a species, shouldn't fund the research into the one technology that could potentially provide all of our desired energy for as long as we can expect to want it, but we shouldn't rely on that research actually being successfull any time soon.

    27 Jan 2006, 22:55

  10. theostein

    The world already has all the pieces to the puzzle to free cleand cheap energy. The only thing lacking is a good theory. The way to put this pieces together.

    06 Feb 2006, 14:27

  11. If you're talking about fusion the theory isn't likely to be there any time soon and also isn't required in the strictest sense. Magnetically confined plasmas (the type in the mainstream fusion experiments) are a chaotic system so we just try to understand them by firing them up and seeing what happens. It is likely that we will learn to control this naturally unstable system well before we learn what excatly is actually going on inside.

    I don't think we do have all the pieces to the puzzle at all. As Nicholas points out, there are still some major technical issues to overcome but I think we will get over them eventually.

    I've tried to answer your comment sensibly and without jumping to conclusions and maybe I am wrong, but I get the impression from your website that you might not have anything sensible to contribute.

    06 Feb 2006, 21:05

  12. Firstly, as it appears currently fusion is at least 50 years into the future. Hopefully we will start dealing with CO2 emissions before that, or we will be in pretty bad trouble.

    Secondly, whereas pressent nuclear reactors only have fuel for a few hundred years, they only use about 0.01% the Uranium available ( Since todays reactors rely solely on Uranium 235 ). The newer generations of reactors, known as fast breeder reactors, could convert Uranium 238 into Plutonium that can be used in mixed-oxide fuel in the reactor. Using this technology ( which is not on the experimental level, some such powerplants already exist) the Uranium that has already been extracted, and is currently treated as waste, could supply the worlds energy needs for hundreds of years. If one were to extract all Uranium that is available and use this technology, the world's energy demand would be covered for a few thousand years. Plenty of time to get fusion, or something else, in other words.

    The main problem is politics. There are ways to construct these reactors and reprocessing plants so that the waste would decay back to safe levels within a few hundred years ( as opposed to several thousand with current technology). However, such power is currently more expensive than Oil and Gas, which is why it is not popular. In addition, building more reactors here will make it difficult to put pressure on countries like Iran and North Korea not to do the same, and a side effect of having a well developed nuclear infrastructure is the potential to develop nuclear bombs. So unless politics will allow world peace and a 300% tax on fossil fuel, nuclear energy will remain controversial despite the theoretical advantages.

    09 Feb 2006, 03:55

  13. I have to agree with Nick Young, that as far as a practical means of power generation for the next 50 to 100 years is concerned, fission is the only nuclear choice available. The physics problems of fusion power generation have not been solved yet, let alone the ridiculous engineering tasks it presents for high power, consistent energy supply to a grid system. Correct me if I'm wrong, but at root this is a problem of entropy right? It's easy enough to get a fusion reaction to take place, but leaving the entropy of the final state low enough to funnel the nuclear recoil energy into an electrical current down a tiny wire is nigh on impossible.

    09 Feb 2006, 23:59

  14. "The newer generations of reactors, known as fast breeder reactors"

    This is incorrect. All commercial reactors today use U-235 as a fuel. U-238 fuelled FBRs have only ever really reached experimental status, and never gained any great commercial acceptance. The UK pulled the plug on it's FBR programme at Dounreay in 1994 (the DFR, first operated in 1959, and the the PFR in the 1970's). The French have the one of the few operating FBRs today in their Phenix reactor (only 233MWe), which was designed for destruction of nuclear waste by transmutation. The Superphenix is the largest FBR ever built at 1200MWe, but was shut down in 1997 only 13 years after entering service; most of it's time was spent shut down for repair and mainenance work anyway, as is the case with most of the FBRs ever built. The USSR have several FBRs of which two are of note, the largest being 600MWe. Japan has one FBR which has been shut since 1995 following a sodium leak, and India has a test program but no commercial reactors that I know of.

    The chief problem with FBRs is the sheer magnitude of the technical difficulties. The power densities in the core are many times greater, and require cooling by liquid metal (all recent attempts have used liquid sodium), as water would soak up the fast neutrons. Due to the higher power densities of the core, the reactor design is altogether more dangerous, and should a coolant failure occur it would take something in the order of a minute for a full scale meltdown to occur. Whilst I agree that they present the only long term solution for fission (and indeed I would like to see more development work done with FBRs), there just simply isn't the economic case right now for the investment. Whilst uranium and enriched uranium costs stay comparatively low, fast neutron reactors will remain uncompetitive to themal reactor designs, namely PWRs, PhWRs and probably the new pebble bed type reactors being pioneered in South Africa. Long term, fusion is the answer.

    07 Apr 2006, 23:49


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