Stellarator vs tokamak: The path to nuclear fusion

Posted: January 19, 2017 by oldbrew in Energy, innovation, Nuclear power, research

The latest contenders for the elusive fusion crown are reviewed here. Chasing the ‘holy grail’ of energy is an expensive and time-consuming business, as IB Times reports.

In a world struggling to kick its addiction to fossil fuels and feed its growing appetite for energy, there’s one technology in development that almost sounds too good to be true: nuclear fusion, writes Matthew Hall.

If it works, fusion power offers vast amounts of clean energy with a near limitless fuel source and virtually zero carbon emissions. That’s if it works. But there are teams of researchers around the world and billions of dollars being spent on making sure it does.

In February last year a new chapter of fusion energy research commenced with the formal opening of Wendelstein 7-X. This is an experimental €1 billion (A$1.4bn) fusion reactor built in Greifswald, Germany, to test a reactor design called a stellarator.

It is planned that by around 2021 it will be able to operate for up to 30 minutes duration, which would be a record for a fusion reactor. This is an important step en-route to demonstrating an essential feature of a future fusion power plant: continuous operation.

But the W-7X isn’t the only fusion game in town. In southern France ITER is being built, a $US20 billion (A$26.7bn) experimental fusion reactor that uses a different design called a tokamak. However, even though the W-7X and ITER employ different designs, the two projects complement each other, and innovations in one are likely to translate to an eventual working nuclear fusion power plant.

Fusion energy seeks to replicate the reaction that powers our Sun, where two very light atoms, such as hydrogen or helium, are fused together. The resulting fused atom ends up slightly lighter than the original two atoms, and the difference in mass is converted to energy according to Einstein’s formula E=mc².

The difficulty comes in encouraging the two atoms to fuse, which requires them to be heated to millions of degrees Celsius. Containing such a superheated fuel is no easy feat, so it’s turned into a hot ionised gas – a plasma – which can be contained within a magnetic field so it doesn’t actually touch the inside of the reactor.

What makes the W-7X particularly interesting is its stellarator design. It comprises a vacuum chamber embedded in a magnetic bottle created by a system of 70 superconducting magnet coils. These produce a powerful magnetic field for confining the hot plasma.

IB Times report continues here.

  1. gwaigau says:

    Well lets hope they don’t run out of power and lose control of their superconducting magnet coils because imploding stars are not a thing we need to be a part of.

  2. Climatism says:

    Reblogged this on Climatism and commented:
    The estimated $1Billion/day spent on “climate crisis Inc.” should be diverted asap to nuclear fusion R&D.
    This WILL be the future of genuine “clean and green” energy where the primary source of fuel is sea water!

  3. oldbrew says:

    Don’t assume there won’t be any snags with fusion power, if it arrives. Some tech ideas just don’t take off…

    ‘Electric vehicles first appeared in the mid-19th century’
    ‘for most of the 20th century the majority of the world’s battery electric road vehicles were British milk floats’

    Even ‘standard’ nuclear power hasn’t expanded as much as the pundits thought it would.

  4. Harry Passfield says:

    “But there are teams of researchers around the world and billions of dollars being spent on making sure it does.”

    But, then again, my conspiracist-mind tells me that many Green alarmists, wishing for CO2 Armageddon, would spend many billions making sure it doesn’t work. They really hate mankind that much that the thought of 100% clean power would be anathema to them.

  5. Steve says:

    To what purpose are they spending all this money? To be able to boil water into steam to make turbines move. Hundreds of billions of dollars being spent to boil water. The money would be better spent building more coal power plants and thorium powered nuke plants.

  6. Bitter&twisted says:

    Fusion power, like dangerous climate change, is always in the future.

  7. p.g.sharrow says:

    By the start of the 1960s it was plain that plasma fusion could NOT yield a positive outcome. 50 years of effort of the finest minds and 100s of $billions have proved this to be true. Still we are promised that given greater efforts and funding for more R&D they can change the laws of physics. Even GOD does NOT use plasma fusion to power our Universe!
    Fusion happens when the energy/mater density exceeds proton/electron repulsion and a Neutron is created. Fission happens under the opposite conditions. Plasma fusion requires far too high energy levels to be sustainable due to the huge amount of pinch energy needed to reach the needed density at a useful level.

    Solid state fusion under relatively low temperatures can yield useful energy at low radiation risk. A balance of Fusion/Fission can be maintained while yielding useful amounts of energy with a low amount of long term radiation hazard.

    Time to quit wasting resources on this “scientific” scam. Time to create real energy production facilities. Plasma fusion is an even bigger waste then wind and solar as energy suppliers for an industrial society.

  8. oldbrew says:

    If fusion tech were to appeal to the US military for some reason, that would speed things up at least in terms of effort and resources.

  9. peterandnen says:

    Fusion is future energy. Mankind needs a collaborative effort to build one enormous fusion reactor capable of providing all the energy we could ever need and if we locate it about 93m miles away for safety, etc.

  10. RoswellJohn says:

    The downside of any fusion reactor is that the container gets radioactive after 10-20 years of neutrons hitting it and has to be disposed of (Neutron Activation). The collective waste from hundreds of these reactors would overwhelm any radioactive storage facility, of which we have NONE. Good luck with that!

  11. tchannon says:

    The article is incomplete (also applies to the better linked articles). I have a huge article here which I was preparing for publishing a couple of years ago, then outside matters and illness stopped me.

    The structure becoming radioactively hot is long known. This is part of all the nuclear machine problems, fission reactors, accelerators and fusion devices. This is why exotic materials are used, often at much high purity than is usual. (the impurities are the problem)

    The root of ITER is JET and prior developments here in England. JET at Culham was designed and built to answer some major research questions so that the remaining problems can be passed to pre-production engineering. JET seems to have succeeded. It continues working. This includes now acting as a teaching facility… the fusion project has been so long in gestation the originators are dead.

    JET was powered by a considerable part of the output of the coal fired Didcot power station, the whole thing located there at a sweet spot of rail transport (Didcot rail facility), existing nuclear expertise (Harwell, Rutherford, Aldermaston, Culham, etc.) and on a disused WW2 fighter airfield… the triangular runway layout is visible to this day.

    The whole job should and would have been done in England but for our ghastly civil servants, infested from the landed gentry, old hands, etc., plus dreadful politicians acting to kill nuclear power, specifically nothing is allowed, hence the lack of infrastructure in this country. Why it is all broken, overloaded.

    ITER is the pass over to EU funding production engineering, specifically materials engineering.

    Last I heard JET _did_ get a positive yield but this was casual, not official. Damage was the risk so it wasn’t authorised.

    The idea is producing a “bang-bang” system with a fairly rapid repeat rate. This sidesteps the continuous operation problem (we don’t know how to extract energy a such a high energy density under the circumstances in there) This also allows power output modulation.
    I think the figure is a 75% yield (output to grid, the rest is what was put in to wind it up)

  12. oldbrew says:

    World’s first commercial fusion reactor could be ready by 2027

    Read more:

    We’ve heard these claims before 😐

  13. oldbrew says:

    Another option…think small and local.

    DM: The nuclear plant that can fit on the back of a truck: Radical mini reactor could power cities

    NuScale, based in Portland, Oregon, has submitted a design application to the Nuclear Regulatory Commission to be able to construct their nuclear power plant.

    Each small NuScale reactor has a 50-megawatt output. To give perspective, the smallest nuclear plant in the US, the Fort Calhoun plant in Nebraska, has one reactor with a capacity of 479 megwatts.

    An actual power plant based on these reactors would require more than one reactor hooked together and would need to be run by engineers. The modules of the power plant would be pre-assembled at a factory and then transported to a specific site.

    Read more:

    Also: The company behind the radical design says it is far safer
    – – –
    Whiff of sales talk 😉

  14. gallopingcamel says:

    Most of the time I find myself nodding in agreement with p.g.sharrow but not today!

    Back in 1970 I was building instruments for fusion research in the confident expectation that we would have large scale fusion power plants within 40 years. Back then “Inertial Confinement” looked promising.

    Clearly the optimism we felt in 1970 was not justified. In my opinion the “Pot of Gold” at the end of the fusion rainbow is at least 50 years in the future yet I reject p.g’s idea that it will never happen.

    Our understanding of nuclear physics is primitive given that most of the universe can’t be explained under current theories. We imply the existence of “Dark Matter” by its gravitational effect and “Dark Energy” is even more mysterious. Theoretical physics will advance dramatically as long as we continue to “Waste” money on ITER and the projects that will follow.

    Remember how people objected to the ridiculous waste of money represented by the Hubble Space Telescope? Against all the odds and in spite of technical blunders Hubble is so successful that it has transformed our understanding of the universe while spawning a multitude of space and terrestrial telescopes.

  15. gallopingcamel says:

    While I advocate continuing fusion research, small “Generation IV” fission reactors are more likely to take over when fossil fuels dry up as suggested by DM and “oldbrew”. Fusion reactors are like a “Hail Mary” pass into the end zone. They may win the game but the odds of success are low.

    Small fission reactors solve many problems.

    There would be tens of thousands of them making it virtually impossible to shut down our economy using EMP weapons. Small reactors mean less dependence on a distribution grid.

    Small reactors are easy to secure as they can be built entirely below grade level with no personnel access required to the reactor building during normal operation

    Many small reactor designs are “Intrinsically Safe” which means that they will shut down safely even if all back up systems fail.

    Small reactors can operate at temperatures high enough to take of advantage of Brayton cycle heat engines (gas turbines) with greater than 60% efficiency.

    Small reactors can be cheap if they are built in a factory and delivered to site on a single truck.

    Generation IV reactors can consume our 80,000 tonnes of “Nuclear Waste” from Generation I & II reactors while generating 200 times more electricity than those earlier reactors produced from the same fuel rods.

    The only thing that makes nuclear power expensive is stupid government:

    Greenies love to talk about “Renewables” as if that matters. What matters is the ability of a technology to power our industrial civilization for a significant time at an affordable cost. Given our current understanding of physics and material abundance in the Earth’s crust small fission reactors can support our current civilization for at least 100,000 years and much longer if we can extract Uranium from sea water.

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