3 ms·

I get that, 100% props for the experience. And I totally respect it. The GP question was "what makes fusion different", and the only thing that is different rea

I get that, 100% props for the experience. And I totally respect it. The GP question was "what makes fusion different", and the only thing that is different really is the economics of how much it costs vs how much energy you get out. Energy out is, by definition, the amount of heat differential you can generate. Cost is, again by definition, the total operating cost of the heat source. So this is where the author and I see things differently, the author wrote: ... the "levelized cost of electricity", dominated by the capital cost of the plant, will still be much higher than other sources of electricity. I agree with that statement, the difference with fusion is that the amount of energy produced after accounting for the capital cost of the plant will be a million times greater. And as I related in a later comment if you compare things on a dollars/BTU level the fusion plant will produce extremely cheap BTUs. Much cheaper than even the cheapest natural gas plant. The key here is that the cost to build such a plant is much higher (and it is), but the energy produced by that plant is way higher. That is the ratio that makes fusion different.

rfrey 5y ago
But the LCOE is a normalized (usually to $/kwh) price that accounts for the amount of energy produced for a given capex, plus the operating costs, plus the cost of capital, plus the lifetime of the plant. It tries to bake that all in. Your position is that LCOE will be much lower, because (as I understand you) the plant cost will scale much better than, say, 100MW natural gas plants. I totally accept that my assertion about LCOE might be wrong because it only costs 2x as much money to build a fusion plant that's 100x bigger.
- ChuckMcM 5y ago
  Exactly. The future of whether or not fusion becomes the next big thing will be watching the LCOE for fusion plants vs everything else. It is interesting to compare fusion plants to fission plants in this regard. Fusion fuel extraction is much cheaper, fusion waste byproducts are minimal, plant failure risk and mitigation is much much cheaper (no fallout, no long live nucleotides etc), and the energy cycle produces 10 - 20x as much energy as fission. Edit: And when things get going you can get around Carnot Efficiency by converting the high speed particles directly[1]. This experiment was built at LLNL as well and shown to actually give > 50% conversion efficiency. [1] http://www.ralphmoir.com/wp-content/uploads/2012/10/venBlnd.pdf http://www.ralphmoir.com/wp-content/uploads/2012/10/venBlnd....
  - pfdietz 5y ago
    > plant failure risk You don't have to worry as much about major accidents as in fission, but the risk of minor accidents that aren't a public safety risk but are a risk of ruining the plant is arguably much larger. A fusion reactor puts a large, very complicated thing, with many non-redundant parts, into a hot zone where hands on repair is impossible. The lesson of TMI is that even if the public is unharmed, an accident that destroys a multibillion dollar investment is ruinous for a utility.
    - ChuckMcM 5y ago
      Absolutely agree. We don't know a LOT about how these things would go together once we get past making energy. If the probability of destroying your plant was such that the lifetime expectancy was shorter than the 20 - 30 years a typical plant is expected to operate then it would definitely raise the effective cost.
- tuatoru 5y ago
  Fusion plants cannot be 100x bigger. The grid doesn't cope well with current 2GWe plants going offline suddenly. It would not cope at all with a 200GWe plant doing that. Besides the waste heat dissipation issues...
  - pfdietz 5y ago
    Also, fusion plants have inherent diseconomy of scale, from the square-cube law. There is a limit to the energy flux through the surface of the reactor, and because of that the volumetric power density of the reactor is inversely proportional to its linear size.
grkvlt 5y ago
are you suggesting that fusion plants will be petawatt sized? because that's really not the case. i think the lcoe of fusion is predicted to be around the same as natural gas, with the DEMO reactor costing twice as much.
- ChuckMcM 5y ago
  No. There are a lot of unknowns around fusion plants (with the current big one being is it even feasible to build one). The last time I was looking at grid infrastructure questions the largest power plants on US grids stayed below 3GW because, as I was informed but cannot cite/verify, that was the limit on infrastructure carrying capacity of the western grid. One of the unknowns is what is the minimum cost to build a plant capable of sustained nuclear fusion. Once you know that, you will also know what its net energy output is as well. Next you will want to know what is smallest practical increment of net energy output and what is the marginal cost of that increment. Then, as we've been discussing here, what is the sweet spot with respect to total plant cost versus kW capacity (it's LCOE). I have chosen to use as a base estimate the cost of building a nuclear plant (the discussion of nuclear LCOE is here[1], here[2], and here[3]). I base that assumption that if we're going with heat conversion then the primary differences between fusion and fission plants will be reactor construction and fuel efficiency. If we take it as a given that the LCOE for nuclear is approximately 10 cents per kWh, if our Fusion plants cost the same and can generate twice the power that is 5 cents per kWh. Given the difference in energy production between fusion and fission I'd like to believe it would be closer to 10x more power for the same cost or an LCOE for 1 cent per kWh. The optimism here stems from an assumption that plant costs scale with size so smaller more powerful plants win in two ways, more power and less cost. And yes, nobody knows if we can even build these things yet. So it really is all just speculation at this point. [1] https://www.britannica.com/technology/nuclear-power/Economics#:~:text=Nuclear%20power%20-%20Nuclear%20power%20-%20Economics%3A%20A,plant%E2%80%99s%20generators%20and%20other%20components%20to%20the%20 https://www.britannica.com/technology/nuclear-power/Economic... [2] https://world-nuclear.org/information-library/economic-aspects/economics-of-nuclear-power.aspx https://world-nuclear.org/information-library/economic-aspec... [3] https://www.energy.gov/sites/prod/files/2015/08/f25/LCOE.pdf https://www.energy.gov/sites/prod/files/2015/08/f25/LCOE.pdf
AlbertCory 5y ago
I will admit that I'm not an engineer of any relevant area here. So I offer this only as a matter of general judgment & experience, which you are welcome to say "does not apply." (But please say why it doesn't.) It's always been my impression that building things on a huge, factory-wide scale is a radically different problem than building a demo, or even reasoning about it. The latter is what you are all doing. As long as "energy crisis" has been a Thing, I've been hearing about some uber-cool new thing a scientist did, which has the potential to transform everything. Usually that's the last you ever hear of it. I always wonder "whatever happened to X?" I figure that "X" might look good in the lab, but no one can build a factory around it. The people who build factories (or power plants) are much less starry-eyed than we all are. That's what we mean by "skin in the game (SITG)." Don't tell me what stocks to buy -- tell me what's in your portfolio. So if I'm deciding whom to believe in an area where I know next to nothing, I'm much more likely to listen to someone who has, or had, SITG. Obviously if no one's ever built a fusion plant before, then exactly no one has had SITG. That makes it a tough one.
- ChuckMcM 5y ago
  Communication is a difficult thing, especially written communication. I work proactively to get better at it when the opportunities to do so arise. In your initial response, and in this one, what I "hear" is that what you heard was somehow either dismissive or disrespectful of the experience the OP brought to the table. I am interested in understanding what it was about my words that gave you that impression. I do understand that reality is very complicated and building systems as ones $dayjob in a competitive environment gives you a depth of knowledge that is unmatched. What I heard in the OP comment was a question, "What makes fusion different?" and in this case the context was why might it be a step change versus other things (some of which the author was involved in) have not gotten traction. And the specific driver was how to compete with costs from extractive technologies like natural gas that are quite mature. I shared my point of view and reasoning from the perspective that I expected the ratio of the plant construction and operation cost relative to the energy output to be much higher than pretty much any other technology so it's LCOE will be lower. Do I know that to be the case? No I don't. Can I reason to that position from first principles? I think so, and calling me out on my reasoning as pfdeitz has done a couple of times in this thread is awesome (the most relevant for this thread being that so far we only know how to make fusion plants with a much lower energy/m3 ratio than say nuclear plants) To your comment about 'whom to believe' I would say I'm not asking you to believe me (and I hope that wasn't a take away from my responses). I was sharing how I thought fusion was different, others have other takes on this, and nobody knows for sure because well it doesn't exist yet. I am curious though, if you feel okay sharing it, if there is anxiety with your belief system. When I am presented with information and I don't know how much confidence to put into it, I often do similar things which is to look at the source, and to consider how the source arrived at that belief. Ideally I like to hear how they got to that belief which probably comes from reading a bunch of scientific papers that are basically one long essay that use the form: "This is what we believe, this is why we believe it, and this is the evidence we have to support our beliefs." But even in a paper I still hold that belief "lightly." If you see me passing such things on it will usually be of the form, "here is a reference to a paper or article I've read that posits this." As opposed to some definitive statement of truth. For me, I'm not invested in being "right". I can easily say that most of the best conversations I've had, started with "Chuck you are completely wrong about that and here's why ..." I love conversations like that because it means I'm likely to learn something new, and every time we re-examine what we "know" we often come away with a better understanding of the limits of what we "know" and what we "think" or hypothesize. Throughout this conversation it has been my intent to be clear that these are things I "think" based on what are, to me, comparable but "solved" problems. Still there are a lot of unknown unknowns such as it is and everything I think could easily be invalidated by one of them. I am always on the lookout for this sort of information. It helps keep me grounded. Always working on improving communications and critical thinking skills and always open to feedback.

rfrey 5y ago

But the LCOE is a normalized (usually to $/kwh) price that accounts for the amount of energy produced for a given capex, plus the operating costs, plus the cost of capital, plus the lifetime of the plant. It tries to bake that all in. Your position is that LCOE will be much lower, because (as I understand you) the plant cost will scale much better than, say, 100MW natural gas plants. I totally accept that my assertion about LCOE might be wrong because it only costs 2x as much money to build a fusion plant that's 100x bigger.

ChuckMcM 5y ago
Exactly. The future of whether or not fusion becomes the next big thing will be watching the LCOE for fusion plants vs everything else. It is interesting to compare fusion plants to fission plants in this regard. Fusion fuel extraction is much cheaper, fusion waste byproducts are minimal, plant failure risk and mitigation is much much cheaper (no fallout, no long live nucleotides etc), and the energy cycle produces 10 - 20x as much energy as fission. Edit: And when things get going you can get around Carnot Efficiency by converting the high speed particles directly[1]. This experiment was built at LLNL as well and shown to actually give > 50% conversion efficiency. [1] http://www.ralphmoir.com/wp-content/uploads/2012/10/venBlnd.pdf http://www.ralphmoir.com/wp-content/uploads/2012/10/venBlnd....
- pfdietz 5y ago
  > plant failure risk You don't have to worry as much about major accidents as in fission, but the risk of minor accidents that aren't a public safety risk but are a risk of ruining the plant is arguably much larger. A fusion reactor puts a large, very complicated thing, with many non-redundant parts, into a hot zone where hands on repair is impossible. The lesson of TMI is that even if the public is unharmed, an accident that destroys a multibillion dollar investment is ruinous for a utility.
  - ChuckMcM 5y ago
    Absolutely agree. We don't know a LOT about how these things would go together once we get past making energy. If the probability of destroying your plant was such that the lifetime expectancy was shorter than the 20 - 30 years a typical plant is expected to operate then it would definitely raise the effective cost.
tuatoru 5y ago
Fusion plants cannot be 100x bigger. The grid doesn't cope well with current 2GWe plants going offline suddenly. It would not cope at all with a 200GWe plant doing that. Besides the waste heat dissipation issues...
- pfdietz 5y ago
  Also, fusion plants have inherent diseconomy of scale, from the square-cube law. There is a limit to the energy flux through the surface of the reactor, and because of that the volumetric power density of the reactor is inversely proportional to its linear size.

grkvlt 5y ago

are you suggesting that fusion plants will be petawatt sized? because that's really not the case. i think the lcoe of fusion is predicted to be around the same as natural gas, with the DEMO reactor costing twice as much.

ChuckMcM 5y ago
No. There are a lot of unknowns around fusion plants (with the current big one being is it even feasible to build one). The last time I was looking at grid infrastructure questions the largest power plants on US grids stayed below 3GW because, as I was informed but cannot cite/verify, that was the limit on infrastructure carrying capacity of the western grid. One of the unknowns is what is the minimum cost to build a plant capable of sustained nuclear fusion. Once you know that, you will also know what its net energy output is as well. Next you will want to know what is smallest practical increment of net energy output and what is the marginal cost of that increment. Then, as we've been discussing here, what is the sweet spot with respect to total plant cost versus kW capacity (it's LCOE). I have chosen to use as a base estimate the cost of building a nuclear plant (the discussion of nuclear LCOE is here[1], here[2], and here[3]). I base that assumption that if we're going with heat conversion then the primary differences between fusion and fission plants will be reactor construction and fuel efficiency. If we take it as a given that the LCOE for nuclear is approximately 10 cents per kWh, if our Fusion plants cost the same and can generate twice the power that is 5 cents per kWh. Given the difference in energy production between fusion and fission I'd like to believe it would be closer to 10x more power for the same cost or an LCOE for 1 cent per kWh. The optimism here stems from an assumption that plant costs scale with size so smaller more powerful plants win in two ways, more power and less cost. And yes, nobody knows if we can even build these things yet. So it really is all just speculation at this point. [1] https://www.britannica.com/technology/nuclear-power/Economics#:~:text=Nuclear%20power%20-%20Nuclear%20power%20-%20Economics%3A%20A,plant%E2%80%99s%20generators%20and%20other%20components%20to%20the%20 https://www.britannica.com/technology/nuclear-power/Economic... [2] https://world-nuclear.org/information-library/economic-aspects/economics-of-nuclear-power.aspx https://world-nuclear.org/information-library/economic-aspec... [3] https://www.energy.gov/sites/prod/files/2015/08/f25/LCOE.pdf https://www.energy.gov/sites/prod/files/2015/08/f25/LCOE.pdf

AlbertCory 5y ago

I will admit that I'm not an engineer of any relevant area here. So I offer this only as a matter of general judgment & experience, which you are welcome to say "does not apply." (But please say why it doesn't.) It's always been my impression that building things on a huge, factory-wide scale is a radically different problem than building a demo, or even reasoning about it. The latter is what you are all doing. As long as "energy crisis" has been a Thing, I've been hearing about some uber-cool new thing a scientist did, which has the potential to transform everything. Usually that's the last you ever hear of it. I always wonder "whatever happened to X?" I figure that "X" might look good in the lab, but no one can build a factory around it. The people who build factories (or power plants) are much less starry-eyed than we all are. That's what we mean by "skin in the game (SITG)." Don't tell me what stocks to buy -- tell me what's in your portfolio. So if I'm deciding whom to believe in an area where I know next to nothing, I'm much more likely to listen to someone who has, or had, SITG. Obviously if no one's ever built a fusion plant before, then exactly no one has had SITG. That makes it a tough one.

ChuckMcM 5y ago
Communication is a difficult thing, especially written communication. I work proactively to get better at it when the opportunities to do so arise. In your initial response, and in this one, what I "hear" is that what you heard was somehow either dismissive or disrespectful of the experience the OP brought to the table. I am interested in understanding what it was about my words that gave you that impression. I do understand that reality is very complicated and building systems as ones $dayjob in a competitive environment gives you a depth of knowledge that is unmatched. What I heard in the OP comment was a question, "What makes fusion different?" and in this case the context was why might it be a step change versus other things (some of which the author was involved in) have not gotten traction. And the specific driver was how to compete with costs from extractive technologies like natural gas that are quite mature. I shared my point of view and reasoning from the perspective that I expected the ratio of the plant construction and operation cost relative to the energy output to be much higher than pretty much any other technology so it's LCOE will be lower. Do I know that to be the case? No I don't. Can I reason to that position from first principles? I think so, and calling me out on my reasoning as pfdeitz has done a couple of times in this thread is awesome (the most relevant for this thread being that so far we only know how to make fusion plants with a much lower energy/m3 ratio than say nuclear plants) To your comment about 'whom to believe' I would say I'm not asking you to believe me (and I hope that wasn't a take away from my responses). I was sharing how I thought fusion was different, others have other takes on this, and nobody knows for sure because well it doesn't exist yet. I am curious though, if you feel okay sharing it, if there is anxiety with your belief system. When I am presented with information and I don't know how much confidence to put into it, I often do similar things which is to look at the source, and to consider how the source arrived at that belief. Ideally I like to hear how they got to that belief which probably comes from reading a bunch of scientific papers that are basically one long essay that use the form: "This is what we believe, this is why we believe it, and this is the evidence we have to support our beliefs." But even in a paper I still hold that belief "lightly." If you see me passing such things on it will usually be of the form, "here is a reference to a paper or article I've read that posits this." As opposed to some definitive statement of truth. For me, I'm not invested in being "right". I can easily say that most of the best conversations I've had, started with "Chuck you are completely wrong about that and here's why ..." I love conversations like that because it means I'm likely to learn something new, and every time we re-examine what we "know" we often come away with a better understanding of the limits of what we "know" and what we "think" or hypothesize. Throughout this conversation it has been my intent to be clear that these are things I "think" based on what are, to me, comparable but "solved" problems. Still there are a lot of unknown unknowns such as it is and everything I think could easily be invalidated by one of them. I am always on the lookout for this sort of information. It helps keep me grounded. Always working on improving communications and critical thinking skills and always open to feedback.