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How many Fusion Power Plants to power humanity?

  1. Jun 9, 2015 #1
    I watched that documentary by Dr. Brian Cox about nuclear fusion development and in one segment Dr. Saul Griffith tries to calculate how much would World need renewable power sources like wind farms, solar panels, hydroelectric generators etc. to substitute oil use completely in like 20 years and he came up with impossible numbers, so that in the end he said "Nuclear fusion would be a jail free card for humanity."

    So I was wandering how much nuclear fusion power plants would you need to substitute current electrical consumption in the world? Would it be enough something like five fusion power plants for the whole Europe?
    But then I presume you would expect to use the power to make methanol to substitute oil use for cars and other vehicles.
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  3. Jun 9, 2015 #2


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    A fusion power plant would probably have similar output to a fission or coal power plant. So you would need several hundred to replace all the current power plants.

    With plentiful electricity generated by fusion (or fission for that matter) you can use electrolysis to split water into hydrogen for clean burning fuel for vehicles. To replace all transportation fuel with hydrogen generated by electrolysis (or just for electric cars with batteries) you would need roughly double the number of power plants as we have now as transportation energy is around the same as grid energy usage.
  4. Jun 9, 2015 #3
    Well it doesn't seem to me that fusion is even comparable to fission, because in the documentary they conclude that combined humanity today uses around 30 terawatts of energy (all energy from electricity to cars and planes), so they make an experiment to see what it would take to substitute all that energy with clean resources in 25 years period.
    They divide the 30 terawatts number and assign that just 5 terawatts gets produced in next 25 yrs by fission and they get that it would take 5000 nuclear power-plants or 2,5 new fission power plants every week. Or every 3 minutes new full sized wind turbine.

    So my guess is that fusion generator would produce much more energy, because I don't think they or anybody else sees fusion power plants working in tandem with fission or solar or wind even.
  5. Jun 9, 2015 #4


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    Those numbers don't sound right to me. Nuclear today amounts to about 10% of all electric production over ~400 reactors. So 5000 reactors should be enough to supply all electric demand, and another 5000 could be enough to supply transportation demand (only in the raw numbers sense though, in reality it wouldn't be that simple). Over 25 years that comes out to 400 reactors per year. No small feat, but within the realm of feasibility if it really came down to that.

    There is nothing special about fusion power that would suggest that it would have a greater power density compared to fission or fossil power plants. Both fission and fusion power plants could probably be scaled up indefinitely, but why would you want to? That would put all your eggs in one basket.
  6. Jun 9, 2015 #5


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    Since fusion power has been 20 years away for at least 50 years I wouldn't depend on it for the near future.
  7. Jun 10, 2015 #6
    The medium and long term potential of D-D fusion to power the world at a level of 60 TW giving everyone living on the planet fair access to energy -

    The complete conversion of deuterium nuclear fuel releases an energy content of 250 x 10^15 joules per metric ton of deuterium. The quantity of deuterium in the world’s oceans is estimated at 4.6 x 10^13 metric tons. Deuterium present in seawater will yield around 5 x 10^11 TW-year of energy. In the year 2014 the entire planet consumed around 17 TW-years of energy, which means that the energy content of the deuterium in seawater would be enough for 29.4 billion years of energy supply.

    To give all 10 billion people expected to live on the planet in 2050 the level of energy prosperity we in the developed world are used to, a continuous average use of power of 6 kilowatts per person as is typical in Europe, we would need to build 60,000 one gigawatt fusion power plants to generate 60 terawatts as a planet—the equivalent of 900 million barrels of oil per day.

    The time since the earth first formed = 4.54 billion years. The time until the sun burns out = 5 billion years. The deuterium in the sea is capable of completely powering planet earth at a level of 60 Terawatts for 8.33 billion years (longer than the earth has existed or the sun will burn)
  8. Jun 10, 2015 #7
    Scientifically power density might be similar, but there is one huge difference between the two technologies.

    In fission, all the fuel is together inside the reactor thingie. If there's a problem, the fuel requires management to allow a cold shut down. The default state of an operational reactor is to continue with fission until positive controlled external action is taken. It's fail deadly. There are psychological /political reasons why you might not want a super dooper huge mega reactor next to the city where your mother lives. Consider German's nuclear strategy vis-a-vis Fukushima.

    In fusion, the majority of the fuel is outside the reactor. In an emergency you can just shut the fuel off. In extremis, you can cut the fuel line with a hot spanner and fusion will cease with only minimal damage /possible limited melt down. Similarly the highly sophisticated ignition /containment system can be easily disrupted. The tendency of an operational fusion reactor is to stop unless positive controlled external action continues. It's fail safe(ish). It's hugely safer.

    If fusion is perceived as being safer, Mother might be happy to have larger fusion reactors than fission reactors. So you might have less of them.

    (Just be careful where you site the exhaust port.)
  9. Jun 11, 2015 #8
    OK I get it. I did a little research and the answer is that there should also be lots of fusion power-plants made but they will be cheap and electricity will be cheap considering that today you don't just pay for electricity bill and pump bill but also devastation of environment, medical bills because they pollute your body and of course war for oil that is costing trillions of dollars. All fusion needs is some sea water which is free and always will be free.
    And then the next generation of nuclear fusion reactors will be even more stable and productive. Some day the inhabitants of this planet will look back at the clumsy magnetic bottle, the D–T tokamak, which will seem like an old IBM Selectric typewriter with font balls compared to Microsoft Word on a 3-GHz notebook computer. The deuterium–tritium reaction is a terrible fusion reaction, but we have to start with it because it is easy to ignite. I mean look how far we made from Wright Brothers to Space Shuttle in just one century or from the first computers till ipads.

    I would also recommend an excellent book "An Indispensable Truth: How Fusion Power Can Save the Planet" by Francis Chen

    Because from what he writes it also depend on us when we will have fusion power-plants. We should press the politicians to devote more money and urgency to it. Even Dr. Brian Cox said that there should be Manhattan-like project but to develop fusion.

    Here is what Francis Chen says:

    The path is clear, but the rate of progress is limited by financial resources. In the USA, fusion has been ignored by both the public and Congress, mainly because of the lack of information about this highly technical subject. People just do not understand what fusion is and how important it is. Books have been written light-heartedly dismissing fusion as pure fantasy. The fact is that progress on fusion reactors has been steady and spectacular. The 50-year time scale presently planned for the development of fusion power can be shortened by a concerted international effort at a level justified by the magnitude of the problem. It is time to stop spinning our wheels with temporary solutions.


    A high-priority Apollo-like program to put fusion on a fast track will cost less than Apollo did and will solve the CO2 problem, the fossil-fuel shortage problem, and the oil dependence problem all at once.
  10. Jun 11, 2015 #9
    Yeah, and 20 years later fusion power is still 20 years away.
    But I hope ITER has some good news :smile:
  11. Jun 11, 2015 #10
    Fusion power is always fascinating me
    I'm imagining utopia already :smile:

    5 x 10^11 TW x (sec x min x day) joules for how many Q in power plant? 10?

    In what year level of world energy needs? 2010?
  12. Jun 12, 2015 #11


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    It would be more accurate to say that fusion power has always been 20 billion dollars away. But the funding has been stagnant or decreasing until recently when ITER finally got started.
  13. Jun 12, 2015 #12
    But 20 billions dollars is not that "much".
    If I remember correctly in Gulf War II, 1991. US spent 1 billion dollar per day.
  14. Jun 12, 2015 #13
    A very, very bright future!
    But the main question remains. When will we be able to build the box?
  15. Jun 12, 2015 #14
    This perception annoys me, and is a fallacy.

    The Zeitgeist suggests fusion = zero oil dependency = zero CO2. What am I typing this on? A plastic computer made from oil. I bought it by driving a car lubricated by oil, along an asphalt road made from oil. The trendy t-shirt I'm wearing is made from polyester with it's ancestry in a distillation column. And I cooked my dinner on a LPG powered cooker.

    Energy /transport only accounts for roughly 2/3rds of oil consumption. We'll by pumping out oil and CO2 for a good while yet, no matter how many fusion reactors we have :frown:
  16. Jun 12, 2015 #15


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    So...roughly the same number of fusion plants as invisible purple unicorns on hamster wheels?

    Seriously, how can we speculate about the capacity of a power source that doesn't exist?
  17. Jun 12, 2015 #16


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    Disagree. Cost estimating inventions is even less reliable than scheduling them.
  18. Jun 12, 2015 #17


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    And a processing facility and power plant, which are definitely not free....

    ....and the 50+++ years of development costs.
    Hopefully, we will be able to call the next generation the first generation of actual generators...

    ...and "produce" an output greater than 0.
    So it's cheap, when compared to the most expensive project in the history of the world? ...though already 5x longer, without success?

    Doesn't sound like a great deal to me. If we had chosen to, like France, we could have been 100% nuclear, 30 years ago and this issue should be moot.

    I've given up on fusion and come to the conclusion: why bother? It really offers nothing relevant that fission couldn't have already given us.
    Last edited: Jun 12, 2015
  19. Jun 13, 2015 #18
    Why do you think it's the most expensive? Keeping up Moore's law is far more expensive, every time you pull out your mobile phone it's trillions of dollars of research that went into it and yet it's in the palm of your hand.

    It is a good question: if we had fusion what makes it so different that it won't go the way of the fission?
    Possible reasons why there is not more fission power plants:
    1. people don't like them around. They are afraid
    2. it takes lots of time to build them: something like 6 years just to get the permits and then 4 years to build them
    3. you have to mine uranium and uranium mines are an ugly and expensive places
    4. radioactive waste. We all know that only one plant produces 30 tons of radioactive waste a year, if we had much more of them around then imagine all those trains and trucks driving around with nuclear waste: what if there is a train accident? What if they become target for terrorists?
    5. stigma of connecting it with nuclear weapons. Having fission power plant means you can easily make a big bomb
    6. they are a hazard and therefore not recommended to by built in "less developed" nations

    Differences and similarities that fusion will and will not confront:
    1. People would welcome them, they would not be afraid of them
    2. Probably very complicated to be built but likely not more then fission.
    3. No mining what so ever
    4. Waste in minute quantities and degradable in just few years
    5. no stigma of using it to make nuclear weapons
    6. They are not a hazard and they absolutely do not pose a danger to anyone around and could be built near towns, so even more electricity could be saved
  20. Jun 13, 2015 #19
    But we can build machines that purifies CO2 from atmosphere, and these machines are powered buy fusion power :smile:
  21. Jun 13, 2015 #20
    Yep, they could be built in the middle of town, or in an island three miles away :smile:
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