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Thread: fusion reactor break even

  1. #1 fusion reactor break even 
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    As a lay person, not a physicist, I am trying to understand what is meant when the phrase "break even" is applied to fusion reactors. It seems to me (erroneously?) that it is meant to mean that the energy produced by fusion reactions equals the energy pumped into the plasma. In addition, it is usually implied that a fusion reactor would need to exceed break even to produce net energy, or in other words to be a useful energy source.
    However, it seems to me that a fusion reactor could still provide useful energy output if the energy produced by fusion was less than break even, provided most of the energy being pumped into the reactor could be recovered. The assumption always seems to be that all the energy being pumped into the plasma will be "lost" somehow, yet all the energy being pumped in must come out somehow (probably mostly in the form of heat). If nearly all the energy pumped into the reactor, together with the energy produced by fusion, is turned into heat, collected by the cooling system and used to drive a generator, then the criteria for a useful reactor is only that the energy output is higher than the energy input. If 100% of the energy input to the reactor was collected, and there were no subsequent losses (e.g. 100% efficiency), then a reactor where fusion energy was only 1 % of the total energy input could still be a useful power source (bearing in mind fusion energy being more than a million times more potent than chemical energy).
    Is this correct?


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  3. #2  
    Forum Radioactive Isotope MagiMaster's Avatar
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    If the energy pumped in could be recovered, it'd already be included in the energy output. The main idea is that once the break even point has been passed, a portion of the energy out can be used to restart the cycle while still having some left over to do work. In a fusion reactor, you don't want to let the plasma cool down (and extracting energy from it would cool it down).


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  4. #3  
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    You are correct, but the problem is recovering the energy. I know how to do it, and so do a number of other people, but they are in different fields than nuclear science and do not like to meddle with other fields. A multidisciplinary approach is key. MagiMaster is correct though, you do not want to pump all of the energy out; ideally the reaction would be self sustaining.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

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  5. #4 Re: fusion reactor break even 
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    Quote Originally Posted by magneticrabbit
    As a lay person, not a physicist, I am trying to understand what is meant when the phrase "break even" is applied to fusion reactors. It seems to me (erroneously?) that it is meant to mean that the energy produced by fusion reactions equals the energy pumped into the plasma. In addition, it is usually implied that a fusion reactor would need to exceed break even to produce net energy, or in other words to be a useful energy source.
    However, it seems to me that a fusion reactor could still provide useful energy output if the energy produced by fusion was less than break even, provided most of the energy being pumped into the reactor could be recovered. The assumption always seems to be that all the energy being pumped into the plasma will be "lost" somehow, yet all the energy being pumped in must come out somehow (probably mostly in the form of heat). If nearly all the energy pumped into the reactor, together with the energy produced by fusion, is turned into heat, collected by the cooling system and used to drive a generator, then the criteria for a useful reactor is only that the energy output is higher than the energy input. If 100% of the energy input to the reactor was collected, and there were no subsequent losses (e.g. 100% efficiency), then a reactor where fusion energy was only 1 % of the total energy input could still be a useful power source (bearing in mind fusion energy being more than a million times more potent than chemical energy).
    Is this correct?
    We do not at this time have any sustained fusion reactions. So the reactions are transient. It takes quite a bit of heat to cause fusion to occur and that must be input to the reactor from an outside source. Once there is sufficient temperature to cause fusion to occur, heat is generated by the reaction.

    Breakeven occurs when the energy output of the fusion reaction is equal to the energy input from outside sources.

    Below breakeven the operation is net energy consumer. At breakeven the operation creates as much energy as it consumes from outside sources. Beyond breakeven there is anet production of energy. In order to have an energy source, as opposed to a sink, it is necessary to operate beyond breakeven.

    The reason for interest in experiments that do not breakeven is simply to learn enough about creating the conditions necessary for fusion to develop scientific proof of principle for later application to development of a practical fusion system. As things stand now the problems are such that no one knows how to design a practical fusion system. There are several competing approaches.

    "No one" most certainly includes "Cold Fusion" and other delusional people.
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  6. #5 Re: fusion reactor break even 
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    Quote Originally Posted by DrRocket

    As things stand now the problems are such that no one knows how to design a practical fusion system. There are several competing approaches.

    "No one" most certainly includes "Cold Fusion" and other delusional people.
    And I thought you had mellowed!
    Still, I must say I have to agree with you.
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    Forum Ph.D. Dave Wilson's Avatar
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    I remember something called JET ( Joint European Torus ) It started off in the 70`s and it seems to be just plodding along, consuming vast amounts of energy and money. I am almost certain that there has been some valuable spin - off, but I do not know what, here is a link to JET.

    http://www.jet.efda.org/
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  8. #7  
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    .................................................. ...............................
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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  9. #8  
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    Quote Originally Posted by Cold Fusion
    HAHAHAHAHAHAHAHA!!!!!!!! You are very funny. Delusional? Really? Well, I'm glad it seems people intrinsically believe that; it will work in my favor in due time.

    You need to do more research. The mainstream scientific community is based off of mediocrity. No great feats, and no great plunders (they inadvertently strive for at least). It is the minority, composed of the great feats and plunders that is capable of vastly exceeding the common PhD's cognitive awareness....as I have demonstrated without a doubt so far. How many PhD's over how much time? Quite a bit on both ends, shame on the mainstream...someone as little as me making a mockery of them.
    Thank you very much for proving my point.
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