7 ms·

I could cite you things like this: (https://www.osti.gov/biblio/6276900 https://www.osti.gov/biblio/6276900) but they will likely be buzzword soup. The simples

I could cite you things like this: (https://www.osti.gov/biblio/6276900 https://www.osti.gov/biblio/6276900) but they will likely be buzzword soup. The simplest explanation is that the fusion reactor's energy output is the _primary_ heat source for a heat engine like a steam turbine. It sounded from your description that your company was targeting so called "waste" heat, which is a lower grade of heat (smaller delta between ambient so a smaller temperature differential to work with). There are limits to the efficiency of being able to convert heat into some other form of energy (kinetic, chemical, electric, Etc.) because that is how the universe works sadly. That said, when you have a very large heat differential, as you do from fusion or fission reactions, converting even a small percentage of that can be a net win in terms of production. So fusion is different in that it can take a small amount of widely available "fuel" and release a large amount of energy by "burning" it (in actuality fusing it into a new element, but the effect is that the original fuel is no longer available for use) and then using that heat to run heat engines that are producing electricity. The waste products are the fused result and heat in the form of highly energetic alpha particles.

AlbertCory 5y ago
Skin in the game [1]. OP has actually done it ("CTO of a company providing heat-to-electricity plants"). Have you? Or you just read about it? [1] https://www.amazon.com/Skin-Game-Hidden-Asymmetries-Daily-ebook/dp/B075HYVP7C/ref=sr_1_1 https://www.amazon.com/Skin-Game-Hidden-Asymmetries-Daily-eb...?
- hellohntoday 5y ago
  OP doesn't bring up the different temperature and pressure differential of heat sources. That's a huge red flag. For all we know the CTO role at that company was entirely focused on keeping the staff laptops running and is largely disconnected from the fundamentals of heat to electricity generation. Why the hell would she (or he) ask here when (s)he has current or former colleagues in the industry to ask. My BS detector went off immediately.
  - tuatoru 5y ago
    Please bring better data or logic to the discussion, not ad hominem attacks.
  - rfrey 5y ago
    I said several time in this discussion that waste heat sources are typically ~600C with flow rates of ~80-100kg/s. Do the math and that's about 100MW of energy in a stack. Off the shelf Organic Rankine Cycle engines can convert heat energy at that temperature at about 20% efficiency. Of course that varies by ambient temperature and pressure, but not significantly for the purposes of this discussion. A good rule of thumb is that for a given delta-T, current OTC tech can get you about half of Carnot efficiency at the optimal spot on the cost-efficiency curve. I wouldn't know how to fix a laptop if you offered me a yacht to do it. What I asked about was not waste heat to power tech, but fusion power economics, which I know nothing about. You don't seem nice.
- ChuckMcM 5y ago
  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....
rfrey 5y ago
Sure, I understand delta-T, and Carnot haunts my nightmares. My question about fusion isn't about thermodynamic efficiency, but about economics. Our waste heat solutions produced electricity at about 2x the LCOE of a natural gas turbine. Since it was carbon-free electricity, by selling the carbon credits we could get close to the ROI of a natural gas plant. A NG plant might have a 20 year IRR of 14-16% - we could get to 11 or 12. But that was enough to kill the project. And we have other technologies that produce carbon free electricity at a price close but not quite at NG turbines - renewables + storage, for example, or geothermal. But those aren't considered economic to build right now, despite being here and ready and understood. I might be wrong, but I can't imagine a nuclear fusion plant getting within spitting distance of a NG plant for capital cost. And if it's even twice as much money -- which seems wildly optimistic -- maybe nobody will build them. Or maybe they will, because there are other factors at play besides carbon free electricity and cost! That's what I'm asking - what are those other factors?
- Jensson 5y ago
  Coal plants runs on heat as coal isn't explosive enough to run turbines directly. If they are affordable then so is fusion heat. So the question is if we can generate fusion heat at low enough cost.
  - Gwypaas 5y ago
    They are not affordable. That's why they are being replaced by gas plants and renewables all over the place.

AlbertCory 5y ago

Skin in the game [1]. OP has actually done it ("CTO of a company providing heat-to-electricity plants"). Have you? Or you just read about it? [1] https://www.amazon.com/Skin-Game-Hidden-Asymmetries-Daily-ebook/dp/B075HYVP7C/ref=sr_1_1 https://www.amazon.com/Skin-Game-Hidden-Asymmetries-Daily-eb...?

hellohntoday 5y ago
OP doesn't bring up the different temperature and pressure differential of heat sources. That's a huge red flag. For all we know the CTO role at that company was entirely focused on keeping the staff laptops running and is largely disconnected from the fundamentals of heat to electricity generation. Why the hell would she (or he) ask here when (s)he has current or former colleagues in the industry to ask. My BS detector went off immediately.
- tuatoru 5y ago
  Please bring better data or logic to the discussion, not ad hominem attacks.
- rfrey 5y ago
  I said several time in this discussion that waste heat sources are typically ~600C with flow rates of ~80-100kg/s. Do the math and that's about 100MW of energy in a stack. Off the shelf Organic Rankine Cycle engines can convert heat energy at that temperature at about 20% efficiency. Of course that varies by ambient temperature and pressure, but not significantly for the purposes of this discussion. A good rule of thumb is that for a given delta-T, current OTC tech can get you about half of Carnot efficiency at the optimal spot on the cost-efficiency curve. I wouldn't know how to fix a laptop if you offered me a yacht to do it. What I asked about was not waste heat to power tech, but fusion power economics, which I know nothing about. You don't seem nice.
ChuckMcM 5y ago
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....

rfrey 5y ago

Sure, I understand delta-T, and Carnot haunts my nightmares. My question about fusion isn't about thermodynamic efficiency, but about economics. Our waste heat solutions produced electricity at about 2x the LCOE of a natural gas turbine. Since it was carbon-free electricity, by selling the carbon credits we could get close to the ROI of a natural gas plant. A NG plant might have a 20 year IRR of 14-16% - we could get to 11 or 12. But that was enough to kill the project. And we have other technologies that produce carbon free electricity at a price close but not quite at NG turbines - renewables + storage, for example, or geothermal. But those aren't considered economic to build right now, despite being here and ready and understood. I might be wrong, but I can't imagine a nuclear fusion plant getting within spitting distance of a NG plant for capital cost. And if it's even twice as much money -- which seems wildly optimistic -- maybe nobody will build them. Or maybe they will, because there are other factors at play besides carbon free electricity and cost! That's what I'm asking - what are those other factors?

Jensson 5y ago
Coal plants runs on heat as coal isn't explosive enough to run turbines directly. If they are affordable then so is fusion heat. So the question is if we can generate fusion heat at low enough cost.
- Gwypaas 5y ago
  They are not affordable. That's why they are being replaced by gas plants and renewables all over the place.