Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple Question about Fusion For Power

  1. Feb 22, 2010 #1
    Why the hell don't we put more money into this? I mean, infinite free clean energy you think would be a drive but it don't seem to be.

    I mean, the more I think about it the more I wonder why...
  2. jcsd
  3. Feb 22, 2010 #2
    man i hear ya. maybe because it doesnt produce more power than it uses yet and not enough people know about it. but with more money things would definitely start moving faster. fusion is the future.
  4. Feb 22, 2010 #3


    User Avatar

    Staff: Mentor

    Fusion power is not infinite, free, or completely clean but we do already put a considerable amount into researching it.
  5. Feb 22, 2010 #4
    what's stopping you from putting all of your money into it? I know that sounds pissy, but I mean really, can you answer that question?
  6. Feb 22, 2010 #5
    I cant tell if this is a joke? You do realize that outputting more energy than is inputted breaks the laws of physics...
  7. Feb 23, 2010 #6


    User Avatar
    Gold Member

    Not in the sense he means. He means sustaining a reaction using less energy than you get out of the reaction.
  8. Feb 23, 2010 #7
    Not so.

    From the knowhow we have gained in the past few years, we can estimate that we would have fuel (on Earth) for nuclear fusion for the next few hundred years.

    This energy is definetly not free. Without talking about the cost of the nuclear fuel, or any other installation: to sustain nuclear fusion, on Earth, you need to reach a temperature of 100'000'000K (100million degree). Try to imagine how much that cost.

    The idea of clean is also relative. At this temperature, the particles collision and produce an outstanding amount of energy, but not only in its purest form. There are many particles, very exotic, created from reactions like these, that carry energy of many MeV, which it might even reach the TeV in some case. No one knows how these particles would react with the sheilding environment. Therefore, if you believe that existing nuclear power plant create radioactive waste, just wait for the exotism created from fusion power.

    But, there is energy available, which is not too expensive. Work is being done on research reactors, that could see a commercial version in a near future.

  9. Feb 23, 2010 #8
    From WIKI (Yes, I know, if you want better sources I can certainly oblige): "Assuming a fusion energy output equal to the 1995 global power output of about 100 EJ/yr (= 1 x 1020 J/yr) and that this does not increase in the future, then the known current lithium reserves would last 3000 years, lithium from sea water would last 60 million years, and a more complicated fusion process using only deuterium from sea water would have fuel for 150 billion years."

    People would be more likely to fund if it they saw the government take the lead. It's never even mentioned, we are instead funding corn power, wind power, possibly more nuclear power (which is cool with me), light power and other things like that that we all know can't output enough power to do it alone (except of course nuclear power, but we only have fuel for a few hundred years for that).

    A considerable amount is very subjective. Just a tiny pinch of the money from the war in Iraq and Afghanistan and we could all be flying around in space cars because we have so much energy from fusion.

    And yes, I know it's not strictly infinite (but longer than the life of the earth), strictly clean (but pure deuterium plants would be extremely clean I imagine) and strictly free (we only need water for deuterium plants)... but it's better than anything else possible right? I'm assuming we would find methods to extract lithium with no trouble from the sea and in time the initial cost of research/construction will be forgotten and power will be flowing pretty hard.

    Or, where have I gone wrong? Is the greatest source of ridiculous energy sitting right in front of us but no-one wants to put a reasonable effort?

    EDIT: I guess it could be that this thing is such in it's infancy that it's just not a reasonable thing to push it to quickly. We may not be able to see the same results in a reasonable time frame and it's better we use low hanging fruit for power in the near future. But I dunno.
    Last edited: Feb 23, 2010
  10. Feb 23, 2010 #9


    User Avatar

    Staff: Mentor

    Have you looked for information on fusion funding? It's out there. Google it. And recognize, there is a difference between funding fission and fusion. Fusion funding is for research and fission funding funds actual power plants.
    That's absurd.
    It isn't too bad, but understand that the reactor would turn itself and anything around it inside its containment system radioactive.
    You still need to turn that water into nuclear fuel - its not like you can just pump it out of the ocean and into the power plant. And you still need to build the power plant!
    Maybe, but only maybe: we don't even know if it is "possible" yet!
    Extracting one chemical from another requires energy - there is no way around the first law of thermo. And construction cost is never forgotten in a good economic analysis. Fusion plants will no doubt be extremely expensive.
    What's reasonable? It's already in the hundreds of millions of dollars a year. Here's a single international project that is funded for a projected cost of $14 billion over 30 years, or $450 million a year (probably front-end loaded for construction). http://en.wikipedia.org/wiki/ITER
  11. Feb 23, 2010 #10
    I suggest reading what Eric Drexler wrote about it. Also read the comments. He had some good feedback. The bottom line is that the capital costs for tokamak style fusion are extremely high and there doesn't appear to be any prospect for reducing the costs anywhere close to a fission power plant.

    http://metamodern.com/2010/01/20/why-fusion-won%E2%80%99t-provide-power/" [Broken]
    Last edited by a moderator: May 4, 2017
  12. Feb 24, 2010 #11
    Whelp, that was fun.

    There are some serious problems but all of the problems have solutions with separate problems so we just need to get to problem solving.

    "Why fusion won’t provide power" Should be called, why fusion won't provide power in the near future. I imagine as fusion becomes more and more attractive because development costs go down, we run out of easy oil/uranium and power requirements go up we will start building them seriously. There were surely similar problems with our current systems when they were in their infancy... possibly not as complex but problems none the less.

    But it's just too soon to be practical.
  13. Feb 24, 2010 #12
    So when do you all think that we will have fusion power of any kind (tokama, polywell, etc) be a put to real use? Or do you think that it will never be viable?
  14. Feb 24, 2010 #13


    User Avatar
    Gold Member

    For D+T fusion? With the available deuterium, a few hundred years is many orders of magnitude too low assuming today's energy load. Are you assuming some extraordinary increase in load?

    There are difficult neutron activation and tritium handling issues, but this makes no sense. Other than neutrons and alphas, to what 'many' and 'very exotic' particles are you referring? What D+T fusion reaction or side reaction makes TeV particles? The interactions of neutrons with materials is well documented.
  15. Feb 25, 2010 #14
    Hi there,

    Were you ever in an environment of more than 100 million degrees? If not, I can tell you that no one has. Therefore, it is difficult to know what type of particles will be created from such fusion.

    Theory tells us many things, but without any experimental facts, it is hard to know precisely what will be the end result of such fusion.

    Secondly, by clean I understand that it has no or very little radioactivity (that could be dangerous to humans). With such high energy particles, how will the sheilding resist over the years. It is also quite known that the danger of fission power plant does not only reside in the fission products, but also in the residual shielding materials, that has to be dismantled at the end. This is where the workers from a NPP get alot and alot of radiation exposure. To come back to the fusion, how do you know that the shielding material will not react in a very ackward way when exposed to this type of super high energy particle flux???

  16. Feb 25, 2010 #15
    My take is that tokamak style fusion won't be a practical power source during the current century. I would continue tokamak research, but spend more money on other approaches that probably won't work, but the cost of investigating them is low enough to make it cost effective to do the research to figure if they will work or not.

    The solution isn't urgent. With breeder reactors we have enough Uranium and Thorium to last for thousands of years.
  17. Feb 25, 2010 #16


    User Avatar
    Science Advisor
    Gold Member

    100 million kelvin is only ~10 keV average per particle. That is not very high energy nuclear-ly speaking.

    Nuclear fission spent fuel and structural materials have long-lasting radioactivity mainly due to fission products and transuranics. Generally the products of direct neutron activation are shorter lived isotopes.
  18. Feb 25, 2010 #17


    User Avatar
    Science Advisor
    Gold Member

    By the time the NRC gets around to licensing a new fast reactor design, all the third world dictators will have nuclear weapons anyway. :grumpy:
  19. Feb 25, 2010 #18
    Hey guys,

    When I commented that we had plenty of time to solve the problem of fusion power I wasn't trying to hijack the thread. Let's try to get back on topic.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Simple Question about Fusion For Power
  1. Question about fusion (Replies: 11)

  2. Fusion power (Replies: 2)