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It's clear that right now we should roll out wind and solar as fast as we can. However, once those reach high penetration, costs increase rapidly as you attemp

It's clear that right now we should roll out wind and solar as fast as we can. However, once those reach high penetration, costs increase rapidly as you attempt to reach 100% clean energy. At that point it helps a lot to have clean dispatchable power. Nuclear plants we start today can fill that role, in areas without available hydro. https://www.sciencedirect.com/science/article/pii/S2542435118303866 https://www.sciencedirect.com/science/article/pii/S254243511...

est31 6y ago
Nuclear power isn't very "dispatchable", it takes long times to be turned on vs off. But it might be useful for seasonal use in the winter when there is less sun.
- pfdietz 6y ago
  No. Unless you run your nuclear power plant at high capacity factor, the cost of power from it inflates unacceptably. It's an economic issue, not a technical issue.
  - piva00 6y ago
    That's the whole point of nuclear, hydro or coal though, they need to be run at high capacity to be economically viable, have long spin up and down times and are costly to maintain. You use them as the basis of the grid and use wind and solar that are more prone to fluctuations to fill up the demand when necessary, less batteries needed as the base load can always be delivered by nuclear/hydro. Coal is basically dead in the next decade or so.
    - dTal 6y ago
      >use them as the basis of the grid and use wind and solar that are more prone to fluctuations to fill up the demand when necessary Er, how does this work? You can't control when wind and solar produce power, so how can you use them to "fill up the demand when necessary"? If anything, using a fluctuating source on top of already fluctuating demand just increases the amount of power storage you need. A power source that ramps up and down quickly is more convenient than one that ramps up and down slowly, but both are miles more convenient than one which ramps up and down uncontrollably.
      - DennisP 6y ago
        At least with solar you know when it won't produce power. You could have enough nuclear for nighttime demand, and build enough solar for the extra daytime demand. You'd have some remaining discrepancies to make up but relatively small ones.
  - est31 6y ago
    Well then you should ask yourself: is building this nuclear reactor cheaper than buying some batteries or converting excess energy to LNG to store it for later? If it is, then a nuclear power plant is economical, if it isn't, you should do the alternatives instead.
    - pfdietz 6y ago
      Hydrogen underground, not LNG, but yeah. For some simulations to help answer when those two options are best: https://model.energy/ https://model.energy/
      - labawi 6y ago
        The model doesn't support methane generation. Hydrogen is cool, but we should also be investing in efficient methane production. AFAICT it's not too hard to make and has immense advantages - existing transport, storage and use infrastructure and market as a heavily traded good. We can use it for most of our energy or carbon needs with today's technology and existing machines with no or easy modifications. Hydrogen can be more efficient and probably simpler when appropriate but is more finicky, still needs research and will take a lot of time to ramp up.
        pfdietz 6y ago
        Sorry, the two options were nuclear vs. renewables + storage (batteries and hydrogen). I don't think very large methane storage makes much sense; where does the carbon come from?
        AnthonyMouse 6y ago
        > where does the carbon come from? https://en.wikipedia.org/wiki/Biogas https://en.wikipedia.org/wiki/Biogas
        pfdietz 6y ago
        Biomass is fundamentally limited by the very low efficiency of photosynthesis, so that it requires very large areas. It should probably be limited to providing liquid transportation fuels and feedstock for chemicals.
- DennisP 6y ago
  Perhaps that wasn't the best term for the point they're making. From the abstract: "This paper presents a comprehensive techno-economic evaluation of two pathways: one reliant on wind, solar, and batteries, and another also including firm low-carbon options (nuclear, bioenergy, and natural gas with carbon capture and sequestration). Across all cases, the least-cost strategy to decarbonize electricity includes one or more firm low-carbon resources. Without these resources, electricity costs rise rapidly as CO2 limits approach zero. Batteries and demand flexibility do not substitute for firm resources."
- klyrs 6y ago
  https://www.usnc.com/ https://www.usnc.com/ This is one of the most compelling nuclear plans I've seen. From the sound of it, these would be fine for intermittent power supply Building a single one wouldn't be cheap, but the modular / standard design can benefit from economy of scale
- Manfredo_1 6y ago
  A nuclear plant costs the same to run at full capacity all year round as it does to run it at partial capacity. Just run the plant at full capacity all year round, and save money by building less solar.
  - DiogenesKynikos 6y ago
    You have to pay off the initial construction costs. Throwing away half the energy you generate means that you're wasting the large up-front costs.
    - Manfredo_1 6y ago
      Right. If we build nuclear plants to fulfill peak energy demand (which coincides with a lack of energy production from solar) then there's not reason not to just run the nuclear plants 24/7 and skip building solar altogether. This is why nuclear power and intermittent sources end up being a dichotomy in practice. Solar does provide a good way to mitigate carbon emissions in the meantime, even if it's role in a fully decarbonized economy is dubious. It's fast to build and makes a good complement for gas plants. Turn off the gas when the solar cells are collecting, and you can save a good deal of emissions. Solar also has niche use cases that make sense even with nuclear power. Rooftop solar is a good way to offset air conditioning energy use. In this case, the solar energy collected by the panels are intrinsically connected to the power demand of the air conditioning unit. Plus the energy production and energy demand are co-located.
      - AnthonyMouse 6y ago
        One of the interesting possibilities for new nuclear plants is on-site thermal storage. Store heat from the reactor in a heat sink when solar is generating, use the heat to generate power when it isn't. That handles the daily load variation and lets you trade half the required nuclear capacity for cheap solar. It also means you have more turbines on site than the reactor needs on its own, so you can add a furnace burning whatever you like (hydrogen, biofuels, synthetic methane), and that handles the days when renewable output is below average.
- dTal 6y ago
  It's strictly better than wind and solar, which take an indeterminate and totally uncontrollable amount of time to turn on and off.
pfdietz 6y ago
Nuclear would be utterly terrible for filling in the last part of a renewable-dominated grid. As in, ludicrously expensive, compared to other non-nuclear, non-fossil alternatives. The article you point to talks about "firm, low carbon sources". This kind of source for this last bit would be something like hydrogen, not nuclear. A nuclear reactor operating at 10% capacity factor to "fill in" for renewables would be producing power at $1/kWh or more, which is uncompetitive vs. hydrogen by a massive margin.
- DennisP 6y ago
  They specifically cited nuclear. I don't think operating it at 10% capacity factor is what they mean.
  - pfdietz 6y ago
    They very carefully didn't mention hydrogen at all. They compared nuclear vs. renewables + batteries. It's almost as if they were setting up renewables to fail. Imagine that, in a study where half the authors are from the Department of Nuclear Science and Engineering. Yes, if you had nuclear, you'd operate it at high capacity factor. That isn't nuclear filling in for renewables, that's using nuclear instead of renewables. It's really mostly one or the other.
- dTal 6y ago
  You can invert this and say that solar/wind would be utterly terrible at "filling in the last part" of a nuclear-dominated grid. The inability to generate constant, reliable power is a weakness, not a strength.
  - pfdietz 6y ago
    Right. It's one or the other generally (although some solar could help nuclear if demand peaks on sunny days). However, unless nuclear gets a lot cheaper, it's looking like the nuclear dominated grid is going to be more expensive than the renewable dominated grid, even taking the cost of intermittency into account.
sampo 6y ago
> costs increase rapidly as you attempt to reach 100% clean energy. France has been running at 75%-80% nuclear for 30 years.
- selectodude 6y ago
  Heck, the State of Illinois gets over 50 percent of its electricity from nuclear and 1/8th of the entire country's nuclear generation. We can do it, even in the USA.

est31 6y ago

Nuclear power isn't very "dispatchable", it takes long times to be turned on vs off. But it might be useful for seasonal use in the winter when there is less sun.

pfdietz 6y ago
No. Unless you run your nuclear power plant at high capacity factor, the cost of power from it inflates unacceptably. It's an economic issue, not a technical issue.
- piva00 6y ago
  That's the whole point of nuclear, hydro or coal though, they need to be run at high capacity to be economically viable, have long spin up and down times and are costly to maintain. You use them as the basis of the grid and use wind and solar that are more prone to fluctuations to fill up the demand when necessary, less batteries needed as the base load can always be delivered by nuclear/hydro. Coal is basically dead in the next decade or so.
  - dTal 6y ago
    >use them as the basis of the grid and use wind and solar that are more prone to fluctuations to fill up the demand when necessary Er, how does this work? You can't control when wind and solar produce power, so how can you use them to "fill up the demand when necessary"? If anything, using a fluctuating source on top of already fluctuating demand just increases the amount of power storage you need. A power source that ramps up and down quickly is more convenient than one that ramps up and down slowly, but both are miles more convenient than one which ramps up and down uncontrollably.
    - DennisP 6y ago
      At least with solar you know when it won't produce power. You could have enough nuclear for nighttime demand, and build enough solar for the extra daytime demand. You'd have some remaining discrepancies to make up but relatively small ones.
- est31 6y ago
  Well then you should ask yourself: is building this nuclear reactor cheaper than buying some batteries or converting excess energy to LNG to store it for later? If it is, then a nuclear power plant is economical, if it isn't, you should do the alternatives instead.
  - pfdietz 6y ago
    Hydrogen underground, not LNG, but yeah. For some simulations to help answer when those two options are best: https://model.energy/ https://model.energy/
    - labawi 6y ago
      The model doesn't support methane generation. Hydrogen is cool, but we should also be investing in efficient methane production. AFAICT it's not too hard to make and has immense advantages - existing transport, storage and use infrastructure and market as a heavily traded good. We can use it for most of our energy or carbon needs with today's technology and existing machines with no or easy modifications. Hydrogen can be more efficient and probably simpler when appropriate but is more finicky, still needs research and will take a lot of time to ramp up.
      - pfdietz 6y ago
        Sorry, the two options were nuclear vs. renewables + storage (batteries and hydrogen). I don't think very large methane storage makes much sense; where does the carbon come from?
        AnthonyMouse 6y ago
        > where does the carbon come from? https://en.wikipedia.org/wiki/Biogas https://en.wikipedia.org/wiki/Biogas
        pfdietz 6y ago
        Biomass is fundamentally limited by the very low efficiency of photosynthesis, so that it requires very large areas. It should probably be limited to providing liquid transportation fuels and feedstock for chemicals.
DennisP 6y ago
Perhaps that wasn't the best term for the point they're making. From the abstract: "This paper presents a comprehensive techno-economic evaluation of two pathways: one reliant on wind, solar, and batteries, and another also including firm low-carbon options (nuclear, bioenergy, and natural gas with carbon capture and sequestration). Across all cases, the least-cost strategy to decarbonize electricity includes one or more firm low-carbon resources. Without these resources, electricity costs rise rapidly as CO2 limits approach zero. Batteries and demand flexibility do not substitute for firm resources."
klyrs 6y ago
https://www.usnc.com/ https://www.usnc.com/ This is one of the most compelling nuclear plans I've seen. From the sound of it, these would be fine for intermittent power supply Building a single one wouldn't be cheap, but the modular / standard design can benefit from economy of scale
Manfredo_1 6y ago
A nuclear plant costs the same to run at full capacity all year round as it does to run it at partial capacity. Just run the plant at full capacity all year round, and save money by building less solar.
- DiogenesKynikos 6y ago
  You have to pay off the initial construction costs. Throwing away half the energy you generate means that you're wasting the large up-front costs.
  - Manfredo_1 6y ago
    Right. If we build nuclear plants to fulfill peak energy demand (which coincides with a lack of energy production from solar) then there's not reason not to just run the nuclear plants 24/7 and skip building solar altogether. This is why nuclear power and intermittent sources end up being a dichotomy in practice. Solar does provide a good way to mitigate carbon emissions in the meantime, even if it's role in a fully decarbonized economy is dubious. It's fast to build and makes a good complement for gas plants. Turn off the gas when the solar cells are collecting, and you can save a good deal of emissions. Solar also has niche use cases that make sense even with nuclear power. Rooftop solar is a good way to offset air conditioning energy use. In this case, the solar energy collected by the panels are intrinsically connected to the power demand of the air conditioning unit. Plus the energy production and energy demand are co-located.
    - AnthonyMouse 6y ago
      One of the interesting possibilities for new nuclear plants is on-site thermal storage. Store heat from the reactor in a heat sink when solar is generating, use the heat to generate power when it isn't. That handles the daily load variation and lets you trade half the required nuclear capacity for cheap solar. It also means you have more turbines on site than the reactor needs on its own, so you can add a furnace burning whatever you like (hydrogen, biofuels, synthetic methane), and that handles the days when renewable output is below average.
dTal 6y ago
It's strictly better than wind and solar, which take an indeterminate and totally uncontrollable amount of time to turn on and off.

pfdietz 6y ago

Nuclear would be utterly terrible for filling in the last part of a renewable-dominated grid. As in, ludicrously expensive, compared to other non-nuclear, non-fossil alternatives. The article you point to talks about "firm, low carbon sources". This kind of source for this last bit would be something like hydrogen, not nuclear. A nuclear reactor operating at 10% capacity factor to "fill in" for renewables would be producing power at $1/kWh or more, which is uncompetitive vs. hydrogen by a massive margin.

DennisP 6y ago
They specifically cited nuclear. I don't think operating it at 10% capacity factor is what they mean.
- pfdietz 6y ago
  They very carefully didn't mention hydrogen at all. They compared nuclear vs. renewables + batteries. It's almost as if they were setting up renewables to fail. Imagine that, in a study where half the authors are from the Department of Nuclear Science and Engineering. Yes, if you had nuclear, you'd operate it at high capacity factor. That isn't nuclear filling in for renewables, that's using nuclear instead of renewables. It's really mostly one or the other.
dTal 6y ago
You can invert this and say that solar/wind would be utterly terrible at "filling in the last part" of a nuclear-dominated grid. The inability to generate constant, reliable power is a weakness, not a strength.
- pfdietz 6y ago
  Right. It's one or the other generally (although some solar could help nuclear if demand peaks on sunny days). However, unless nuclear gets a lot cheaper, it's looking like the nuclear dominated grid is going to be more expensive than the renewable dominated grid, even taking the cost of intermittency into account.

sampo 6y ago

> costs increase rapidly as you attempt to reach 100% clean energy. France has been running at 75%-80% nuclear for 30 years.

selectodude 6y ago
Heck, the State of Illinois gets over 50 percent of its electricity from nuclear and 1/8th of the entire country's nuclear generation. We can do it, even in the USA.