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This article describes fusion power as "the ultimate energy source -- abundant heat, low price, an almost infinite supply of raw materials, no dangerous leftovers and no pollution." None of those things are correct. First off, the power plant itself is going to be grossly expensive, and that's got to be paid for somehow. Fission plants are cheap by comparison because they don't require things like cryogenic superconducting magnets. Much of the cost for modern fission power is amortized payment for the plant. And those costs have risen enormously; one of the reasons no-one builds fission plants anymore is that they are so costly in the US as to not be economically viable. (A lot of that is due to regulatory burdens; elsewhere in the world they're being built all the time.) Given that the expense will be enormous this means that in practice "abundent" will be limited by capital investment. Nor is it true that the fuel is "nearly infinite" in any practical sense. The fuel for these plants is deuterium (H2) and tritium (H3), and the main source of those is actually reprocessed cooling water from fission plants. Protium (H1) is useless in a plant like this, and though deuterium makes up just 0.015% of naturally occurring hydrogen (16 grams per metric ton of water) that still means there are millions of tons of deuterium readily available in the ocean. However, there is no natural source of tritium because tritium has a half-life of 12.26 years. I don't believe their claim to being self-sufficient in tritium. The idea of lining the chamber with lithium is problematic because metallic lithium is not stable in contact with oxygen; it's more volatile than sodium or potassium metal. To build it and work on it you'd have to pressurize with dry nitrogen and work in atmosphere suits. That's too unforgiving an environment for my taste. And you wouldn't want the lining of the chamber to be outgassing anyway because it would interfere with the formation and maintenance of the plasma. The biggest canard here is "no dangerous leftovers". In actuality, these plants will be creating a great deal of hazardous waste. The plasma which creates the energy is confined by a magnetic field, but the reaction liberates neutrons which have no charge. It is impossible to have a fusion reaction which does not create a huge number of neutrons; fusion is inherently "dirty". Neutrons are not affected by the field and will strike the inner wall of the chamber and be absorbed by atoms there. This can be ameliorated some by lining the chamber with a substantial thickness of Boron-10 which is capable of capturing up to 3 neutrons per atom without becoming radioactive. However, after two hits it beta decays to Carbon 12, and a enough of that will weaken the metal. The lining will have to be replaced periodically. And there will necessarily be other things in the chamber needed to inject plasma and control and sense and mediate the flow, and those things will become fiercely radioactive in a fairly short time. Finally, the "no pollution" claim is also false. It is not possible to harvest 100% of the heat produced by a plant like this, and a great deal of heat will have to be vented to the environment just as with all existing power plants, including coal. What I think they mean by "no pollution" is "no smoke" and that is certainly true. It's also true that it won't be fed by mines, at least directly. But a fusion plant is going to need a cooling tower, just as a fission plant does, and it's going to vent a heck of a lot of water vapor into the air. This article is really just another in a long line of "It's just around the corner" claims for fusion that I've been reading all my adult life. There's always been just one more problem to solve for tokamaks to become practical, but each time they solve that one another pops up. It is, as we engineers say, a non-trivial problem. No fusion plant on earth has ever been exothermic. None has even come close. But every so often they have to have an "almost there" breakthrough so as to guarantee a continued flow of research money from the US Government. This has been going on for thirty years. (discuss) Update: Just in passing, something that I bet people may be curious about: Fusion combines atoms together, releasing energy. Fission breaks atoms apart, releasing energy. Why not combine them, then break them, then combine them, and by so doing create perpetual motion? Wouldn't that violate the laws of thermodynamics? There isn't actually any contradiction. The energy comes from conversion of mass to energy, but where that mass comes from is a bit surprising. It turns out that not all hadrons (protons and neutrons) weigh the same. Weigh two atoms of deuterium (each consisting of a proton and a neutron) and compare to an atom of He4 (consisting of two protons and two neutrons) the He4 weights marginally less than two deuterium atoms, even though the count of particles is identical. Combine two atoms of deuterium into a helium atom and the lost mass is converted to energy. Equally,
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