4 ms·

Commercial fusion will not be competitively viable at any Q. Even unlimited free heat is not valuable if it costs too much to make power from it. A volcano, ear

by ncmncm 4y ago

Commercial fusion will not be competitively viable at any Q. Even unlimited free heat is not valuable if it costs too much to make power from it. A volcano, earthquake, or hurricane releases many TWh of energy, but not usefully so, for reasons. Once you start to get enough neutron kinetic energy out, those neutrons have to be captured and their kinetic energy degraded to heat in thousands of tons of molten lithium pumped in big pipes snaking around inside your magnets, which you must then use to boil water and drive a turbine. The cost of operating such a plant would be at least 10x the equivalent fission plant. But fission is already not competitive, and gets less so every day. Part of operation would need to be purifying grams of tritium, daily, out of those thousands of tons of radioactive molten lithium, for the fuel needed to continue operating. That might not be possible. No one is even trying it yet. The power density of your D-T plasma would be much less than fissioning uranium (Th, Pu, etc.), which means you need a great deal of it, and a huge plant. If superconducting magnets squeeze it smaller, you have the problem that all this neutron flux has to come through a wall of limited area, destroying it in short order. Magnets so strong would need thousands of tons of steel to hold them in place, which would weaken rapidly under heavy hot neutron bombardment. So, the D-T fusion chased is a series of fascinatingly hard technical problems, but there is no plausible prospect of ever getting any commercially valuable power out. And, they are not even safer than a regular nuke; the thousand tons of molten radioactive lithium is hugely inflammable, even explosive, and the smoke turns into radioactive drain opener on contact with anything damp, e.g. lungs.

jhrmnn 4y ago
Are you suggesting that all those people doing fusion research don’t know about this, or that they make false promises to the public to fund their research?
- ncmncm 4y ago
  At least many know and do not care. Many deceive themselves, as often seen here. Others don't think about it, considering it Somebody Else's Problem. Promises of commercial power are naked lies they will never be called to account for.
- tsimionescu 4y ago
  Probably a mix of both, and other stuff. For an example of other stuff, look at the inertial confinement fusion reactors. Those are only plausibly useful for fusion weapons research (as fusion-based nuclear weapons work on the same principle, but are somewhat harder to study up close). However, that's unfashionable to talk about, so they are touted as a potential source of energy. Given that a single shot costs many tens of millions of dollars (because of the incredibly precisely machined piece of gold, called a target, that gets heated up by lasers until it emits X rays that cause the fuel pellet to implode in a perfectly symmetrical fashion), and is over in nanoseconds. So, a continously operating plant would literally spend millions of dollars per minute even with optimistic improvements in the cost of the targets - not exactly a promising new "free energy" generation technology.
gradschoolfail 4y ago
Effectively harnessing volcanos and earthquakes really should be a milestone on our path to Kardashev status. Elon, if you are reading this, we need drone swarms that can eat and store explosive geoenergy release. > A volcano, earthquake, or hurricane releases many TWh of energy, but not usefully so, for reasons.
- ncmncm 4y ago
  /s
weregiraffe 4y ago
> The cost of operating such a plant would be at least 10x the equivalent fission plant. But fission is already not competitive, and gets less so every day. People keep repeating this (fission is not competitive) like it's a law of nature, but the reason they are not competitive are entirely human-made.
- epistasis 4y ago
  They don't repeat it "like a law of nature" but as an empirical description of our technological capacity. If there is a large advancement of construction productivity that may make nuclear more cost effective, it would be good to know about, but nobody who claims this is possible seems to have some sort of methodological description of this advancement. Similarly, those that claim that it's just regulations getting in the way of nuclear don't seem to have an answer for why Flamanville in France has issues, or have the specific change of regulations that will alleviate the construction issues that we regularly see in the Western Hemisphere. Personally, I believe an advancement in construction productivity is quite possible, but that it will take an entirely new generation of bright, ambitious, and innovative individuals entering the field, as well as compensation to attract them from other fields that currently outpay construction by quite a bit. But that's a loooong and expensive change of economies.
  - DennisP 4y ago
    Here is a peer-reviewed global survey of nuclear reactor costs: https://www.sciencedirect.com/science/article/pii/S0301421516300106 https://www.sciencedirect.com/science/article/pii/S030142151... For a quick overview, skip down to figure 12, which shows a plot of overnight construction costs across time and countries. Note that the bulk of them are below $3000/kW, quite a bit less than the most expensive reactors in the US. So here's an optimizer that finds the lowest overall grid cost, based on various assumptions you can modify: https://model.energy/ https://model.energy/ Pick a country. "Show advanced assumption settings." Check the box for "dispatchable technology 2." Set the overnight cost down to $3000. The lifetime of 25 years is unrealistic, given that the average age of US reactors is 40 years. Set that to a more accurate value, like 60 years. Finally, give it the same discount rate as everything else. You'll find that in many countries, nuclear does quite well. In countries without good wind/solar resources, even a higher capital cost can result in a 100% nuclear grid.
elevaet 4y ago
So what you're telling me is that fusion is 20 years away? /s
- ncmncm 4y ago
  "How about never? Is never good for you?"
roenxi 4y ago
> A volcano, earthquake, or hurricane releases many TWh of energy, but not usefully so, for reasons. I don't quite follow your point here. Presumably the issue with earthquakes and hurricanes is that they aren't dispatchable and the work environment for operating a plant is quite hazardous. The issue with volcanoes (although I'd bet we already do use volcanoes for power) could very easily be as simple as that they tend to be in difficult to reach locations because of the plate tectonics (ie, mountains) & the hot parts take a lot of drilling to get to. If there is energy, we can find a use for it.
- ncmncm 4y ago
  We do not try to capture and bank energy from more or less reliably annual hurricanes because we are not fucking insane. They are rightly classed as natural disasters, not resources. Nukes will rightly come to be seen much the same way, a phenomenon to hope people elsewhere suffer, if anyone must.
  - roenxi 4y ago
    That isn't an argument or a reason. The problem is they aren't reliably available. If hurricanes were an ongoing phenomenon we would harvest the energy - like we do for wind. Using volcanoes for power is absolutely on the cards. Apparently the hard part is finding the magma chambers [0]. The barriers are entirely practical in that these power sources don't scale well and aren't easy to get on demand. None of the problems there are similar to having a tokamak - it isn't like we are going to struggle to find the tokamak (it will be marked on the map with something like "tokamak here") and it will likely have a big on/off switch. [0] https://www.science.org/content/article/could-volcanoes-power-world https://www.science.org/content/article/could-volcanoes-powe...
    - ncmncm 4y ago
      We reliably get multiple hurricanes every year, each releasing far more energy than we could use. We do not, in fact, extract that energy. We also never, ever drill into magma chambers. Drilling into a magma chamber is a good way to get a new, vitrified surface, several feet deep, for miles around what was once your drilling rig.
DennisP 4y ago
> Magnets so strong would need thousands of tons of steel to hold them in place, which would weaken rapidly under heavy hot neutron bombardment. I'm just going to nitpick this part. In ARC, the magnets go outside the blanket, which is a molten salt, fully surrounding the inner wall. The salt has to absorb almost all the neutrons, to generate enough tritium. The steel outside of that shouldn't be getting many neutrons.
smopecakes 4y ago
The ARC proposal argued for a cost per kWh of 26 cents, for a pilot plant not necessarily optimized to full commercial configuration. This requires a fairly revolutionary further advance for general commercial relevance but note that the current cost for ratepayers in Germany is 32 cents. A much cheaper or much stronger structural material than steel 216 would quickly change the cost as the strength determines the operating magnetic field which increases output to the fourth power. More interestingly there appears to be a similar revolution newly predicted. Based on a first principles simulation it was projected that density can be doubled over current limits in a reactor as powerful as ARC. I believe density translates directly to pressure which increases output to the second power - possibly quadrupling output over what was expected. Roughly speaking this should mean a cost of less than 10 cents for ARC if that pans out. Hinkley Point C is guaranteed a price of 14 cents, which is the world average for electricity. The doubled density prediction appears to bring a conventional tokamak in line with the projected costs of various alternative designs such as General Fusion's 8 cent projection. None of the alternatives have been tested at the scale of tokamaks but there are a few with the potential of a revolutionary price - Helion projects 1-6 cents based on reactor survivability, and don't use tritium. In fact they may be able to produce it fairly efficiently if they fall short of standalone electricity production. Fusion is generally a more expensive, more of a longshot competitor to SMRs, but with the very dramatic advantage of zero meltdown risk that makes it worth a shot
- ncmncm 4y ago
  Cost to extract power does not scale with power density of plasma. No optimistic projections for cost of extraction are better than idle speculation. Practicality of extracting diffuse 3H from a molten metal blanket, needed for fuel, is as previously noted purely speculative. Renewables are driving cost per kWh well below any plausible, or even aspirational, figures. The only fusion technology that has any chance of competitive extraction cost is Helion's, which does not depend on a round trip through heat. But it depends on a regular supply of 3He, a decay product of 3H which must be produced via operation, filtered from the working plasma, and then held for its 12y decay half life. It is anyway not clear if its process can be achieved at all. SMRs depend on the round trip through heat and incur all the other costs of traditional nukes, so offer no prospect of keeping up with plummeting cost of renewables. Fission's fuel rod meltdown is not the only catastrophic failure mode available. Fukushima demonstrated hydrogen detonation. Breached containment of thousand-ton inflammable, caustic, radioactive molten metal neutron absorption blanket would be adequately catastrophic.

by ncmncm 4y ago

jhrmnn 4y ago

Are you suggesting that all those people doing fusion research don’t know about this, or that they make false promises to the public to fund their research?

ncmncm 4y ago
At least many know and do not care. Many deceive themselves, as often seen here. Others don't think about it, considering it Somebody Else's Problem. Promises of commercial power are naked lies they will never be called to account for.
tsimionescu 4y ago
Probably a mix of both, and other stuff. For an example of other stuff, look at the inertial confinement fusion reactors. Those are only plausibly useful for fusion weapons research (as fusion-based nuclear weapons work on the same principle, but are somewhat harder to study up close). However, that's unfashionable to talk about, so they are touted as a potential source of energy. Given that a single shot costs many tens of millions of dollars (because of the incredibly precisely machined piece of gold, called a target, that gets heated up by lasers until it emits X rays that cause the fuel pellet to implode in a perfectly symmetrical fashion), and is over in nanoseconds. So, a continously operating plant would literally spend millions of dollars per minute even with optimistic improvements in the cost of the targets - not exactly a promising new "free energy" generation technology.

gradschoolfail 4y ago

Effectively harnessing volcanos and earthquakes really should be a milestone on our path to Kardashev status. Elon, if you are reading this, we need drone swarms that can eat and store explosive geoenergy release. > A volcano, earthquake, or hurricane releases many TWh of energy, but not usefully so, for reasons.

ncmncm 4y ago
/s

weregiraffe 4y ago

> The cost of operating such a plant would be at least 10x the equivalent fission plant. But fission is already not competitive, and gets less so every day. People keep repeating this (fission is not competitive) like it's a law of nature, but the reason they are not competitive are entirely human-made.

epistasis 4y ago
They don't repeat it "like a law of nature" but as an empirical description of our technological capacity. If there is a large advancement of construction productivity that may make nuclear more cost effective, it would be good to know about, but nobody who claims this is possible seems to have some sort of methodological description of this advancement. Similarly, those that claim that it's just regulations getting in the way of nuclear don't seem to have an answer for why Flamanville in France has issues, or have the specific change of regulations that will alleviate the construction issues that we regularly see in the Western Hemisphere. Personally, I believe an advancement in construction productivity is quite possible, but that it will take an entirely new generation of bright, ambitious, and innovative individuals entering the field, as well as compensation to attract them from other fields that currently outpay construction by quite a bit. But that's a loooong and expensive change of economies.
- DennisP 4y ago
  Here is a peer-reviewed global survey of nuclear reactor costs: https://www.sciencedirect.com/science/article/pii/S0301421516300106 https://www.sciencedirect.com/science/article/pii/S030142151... For a quick overview, skip down to figure 12, which shows a plot of overnight construction costs across time and countries. Note that the bulk of them are below $3000/kW, quite a bit less than the most expensive reactors in the US. So here's an optimizer that finds the lowest overall grid cost, based on various assumptions you can modify: https://model.energy/ https://model.energy/ Pick a country. "Show advanced assumption settings." Check the box for "dispatchable technology 2." Set the overnight cost down to $3000. The lifetime of 25 years is unrealistic, given that the average age of US reactors is 40 years. Set that to a more accurate value, like 60 years. Finally, give it the same discount rate as everything else. You'll find that in many countries, nuclear does quite well. In countries without good wind/solar resources, even a higher capital cost can result in a 100% nuclear grid.

elevaet 4y ago

So what you're telling me is that fusion is 20 years away? /s

ncmncm 4y ago
"How about never? Is never good for you?"

roenxi 4y ago

> A volcano, earthquake, or hurricane releases many TWh of energy, but not usefully so, for reasons. I don't quite follow your point here. Presumably the issue with earthquakes and hurricanes is that they aren't dispatchable and the work environment for operating a plant is quite hazardous. The issue with volcanoes (although I'd bet we already do use volcanoes for power) could very easily be as simple as that they tend to be in difficult to reach locations because of the plate tectonics (ie, mountains) & the hot parts take a lot of drilling to get to. If there is energy, we can find a use for it.

ncmncm 4y ago
We do not try to capture and bank energy from more or less reliably annual hurricanes because we are not fucking insane. They are rightly classed as natural disasters, not resources. Nukes will rightly come to be seen much the same way, a phenomenon to hope people elsewhere suffer, if anyone must.
- roenxi 4y ago
  That isn't an argument or a reason. The problem is they aren't reliably available. If hurricanes were an ongoing phenomenon we would harvest the energy - like we do for wind. Using volcanoes for power is absolutely on the cards. Apparently the hard part is finding the magma chambers [0]. The barriers are entirely practical in that these power sources don't scale well and aren't easy to get on demand. None of the problems there are similar to having a tokamak - it isn't like we are going to struggle to find the tokamak (it will be marked on the map with something like "tokamak here") and it will likely have a big on/off switch. [0] https://www.science.org/content/article/could-volcanoes-power-world https://www.science.org/content/article/could-volcanoes-powe...
  - ncmncm 4y ago
    We reliably get multiple hurricanes every year, each releasing far more energy than we could use. We do not, in fact, extract that energy. We also never, ever drill into magma chambers. Drilling into a magma chamber is a good way to get a new, vitrified surface, several feet deep, for miles around what was once your drilling rig.

DennisP 4y ago

> Magnets so strong would need thousands of tons of steel to hold them in place, which would weaken rapidly under heavy hot neutron bombardment. I'm just going to nitpick this part. In ARC, the magnets go outside the blanket, which is a molten salt, fully surrounding the inner wall. The salt has to absorb almost all the neutrons, to generate enough tritium. The steel outside of that shouldn't be getting many neutrons.

smopecakes 4y ago

The ARC proposal argued for a cost per kWh of 26 cents, for a pilot plant not necessarily optimized to full commercial configuration. This requires a fairly revolutionary further advance for general commercial relevance but note that the current cost for ratepayers in Germany is 32 cents. A much cheaper or much stronger structural material than steel 216 would quickly change the cost as the strength determines the operating magnetic field which increases output to the fourth power. More interestingly there appears to be a similar revolution newly predicted. Based on a first principles simulation it was projected that density can be doubled over current limits in a reactor as powerful as ARC. I believe density translates directly to pressure which increases output to the second power - possibly quadrupling output over what was expected. Roughly speaking this should mean a cost of less than 10 cents for ARC if that pans out. Hinkley Point C is guaranteed a price of 14 cents, which is the world average for electricity. The doubled density prediction appears to bring a conventional tokamak in line with the projected costs of various alternative designs such as General Fusion's 8 cent projection. None of the alternatives have been tested at the scale of tokamaks but there are a few with the potential of a revolutionary price - Helion projects 1-6 cents based on reactor survivability, and don't use tritium. In fact they may be able to produce it fairly efficiently if they fall short of standalone electricity production. Fusion is generally a more expensive, more of a longshot competitor to SMRs, but with the very dramatic advantage of zero meltdown risk that makes it worth a shot

ncmncm 4y ago
Cost to extract power does not scale with power density of plasma. No optimistic projections for cost of extraction are better than idle speculation. Practicality of extracting diffuse 3H from a molten metal blanket, needed for fuel, is as previously noted purely speculative. Renewables are driving cost per kWh well below any plausible, or even aspirational, figures. The only fusion technology that has any chance of competitive extraction cost is Helion's, which does not depend on a round trip through heat. But it depends on a regular supply of 3He, a decay product of 3H which must be produced via operation, filtered from the working plasma, and then held for its 12y decay half life. It is anyway not clear if its process can be achieved at all. SMRs depend on the round trip through heat and incur all the other costs of traditional nukes, so offer no prospect of keeping up with plummeting cost of renewables. Fission's fuel rod meltdown is not the only catastrophic failure mode available. Fukushima demonstrated hydrogen detonation. Breached containment of thousand-ton inflammable, caustic, radioactive molten metal neutron absorption blanket would be adequately catastrophic.