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The problem with 100% solar+batteries is that you need to massively overbuild for the system to meet demand. It's far more cost-effective to have some portion o

The problem with 100% solar+batteries is that you need to massively overbuild for the system to meet demand. It's far more cost-effective to have some portion of generation come from a firm, weather-independent source. The main options are fossil fuels, hydro, geothermal, and nuclear. Since fossil fuels emit carbon and hydro and geothermal are geographically limited, nuclear is the best option in a lot of places.

bryanlarsen 20d ago
> firm That's the opposite of what you want. You want something that is cost-effective to operate at a 10%, 1% or 0.1% duty cycle. Like nat gas or hydro. Not nuclear. And overbuilding isn't the only lever you have to ensure coverage meets your target 99.99% level -- geographic diversity works really well (the wind is always blowing somewhere), and wind power production is usually negatively correlated with solar power production.
- fasterik 20d ago
  Natural gas and hydro are firm power. You're correct that nuclear is not a good backup power source, but that's not the suggestion. The question is whether adding high-capacity-factor firm generation reduces total system cost. In regions where hydro and geothermal are unavailable, nuclear is the next best low-carbon option. I think you're underestimating the costs and difficulties associated with 100% renewables, especially transmission capacity between regions.
  - bryanlarsen 20d ago
    I think you're underestimating the costs and difficulties associated with 99.99% renewables and/or using it as a straw man against the highly inexpensive and achievable 95% renewables. You're also underestimating the costs of using nuclear to achieve 99.99% reliability on top of a grid with 95% renewables: in that scenario you need nuclear capable of supplying ~100% of your power. In which case you might as well ditch the renewables. But the world does not have the quadrillions needed to go 100% nuclear. The world does have the 10s of trillions needed to go 95-99% renewable.
    - fasterik 20d ago
      >in that scenario you need nuclear capable of supplying ~100% of your power. Where are you getting that from? Again, nuclear doesn't need to be a full backup, and nobody is suggesting we ditch renewables for nuclear. A perfectly viable solution would be a grid with a majority of power coming from renewables and storage, with enough nuclear generation to reduce the amount of overbuild necessary and to stop burning natural gas. From this article: https://www.sciencedirect.com/science/article/pii/S2666278721000234 https://www.sciencedirect.com/science/article/pii/S266627872... >Individually, each firm technology delivers substantial cost reductions relative to portfolios restricted to wind, solar, and energy storage alone. Additionally, because each technology occupies a distinctive functional niche in the electricity system, having all of these technologies available optimizes the utilization rate of each resource and reduces system costs by up to 10% relative to cases with just one class of firm resource.
      - bryanlarsen 19d ago
        If you're using nuclear as a backstop in that way, you're using the same statistical techniques that let you use cheaper, less reliable sources of power for backstop.
- UltraSane 19d ago
  You are very wrong. US base load demand is around 400GW that must be provided 24/7
  - bryanlarsen 19d ago
    Baseload is a cost optimization strategy only relevant if your non-dispatchable power generation is cheaper than your dispatchable power generation. https://en.acatech.de/publication/baseload-power-plants/ https://en.acatech.de/publication/baseload-power-plants/
    - UltraSane 19d ago
      You need to have dispatchable capacity equal to or greater than your base load in order be able to guarantee you will be able to deliver it with 100% reliability year round. I am very dubious of any energy policy coming form Germany because they have managed to make their electricity among the most expensive in the world while STILL being high carbon.
      - bryanlarsen 19d ago
        > You need to have dispatchable capacity equal to or greater than your base load in order be able to guarantee you will be able to deliver it with 100% reliability year round. Just one word change needed: You need to have dispatchable capacity equal or greater than your peak load in order be able to guarantee you will be able to deliver it with 100% reliability year round.
        deleted 18d ago
        [deleted]
  - dalyons 19d ago
    Solar produces incredibly cheap power for the daytime hours, pushing any nuclear off the grid (why would a data center buy expensive nuke power in the hours when cheap renewables are available?). Nuclear needs to be running and selling power at its high price 24/7 for it to be even close to economically viable. Only supplying power that people want(due to its high price) during the night is fatal to nuclear. base load demand does not mean it has to be met with a constant matched source, and in fact that no longer works economically.
- Mawr 19d ago
  > Like nat gas or hydro Since hydro is impossible to "just" build, that's gas only. No, there's no "nat" gas. > geographic diversity works really well "Give up your energy independence :)" I'm sure world leaders are eager to jump on that great idea. "and wind power production is usually negatively correlated with solar power production" Well, that should be fine, I only usually need electricity.
  - bryanlarsen 19d ago
    You don't need to cross oceans to get good geographic diversity.
fpoling 19d ago
If solar becomes 2 times cheaper, it will be economical to capture nitrogen from atmosphere and produce ammonia and use that for long-term energy storage and fuel. And with that one does not need massive solar overbuild. This does not require any magic technology, just scaling up what is available today is enough and will definitely happen within the next 20 years, before small nuclear will have any effect.
- chickenbig 19d ago
  > If solar becomes 2 times cheaper It would be good to see a techno-economic analysis of this. For instance, taken to the limit, if solar were free what would be the CAPEX and OPEX to produce the ammonia? In addition, the plant to consume the ammonia to produce electricity would not be free.
  - fpoling 19d ago
    Ammonia does not require a plant to generate electricity. While fuel cells running on it require temperatures over 600 Celsius to get to 70% percent of efficiency and not exactly small, with cheap way to produce ammonia they would provide energy dense batteries that could run for months if necessary.
    - chickenbig 18d ago
      > Ammonia does not require a plant to generate electricity. While fuel cells running on it OK, so it requires a plant of fuel cells. And the cost per kW (i.e. discharge capacity) is? And it requires some facility to produce the ammonia; what is the cost per kW of electricity consumed, and at what efficiency? Numbers would help to assess the proposal, given the claim that a halving of the cost of electricity from solar would make all the economics for ammonia work.
- istjohn 19d ago
  If I recall correctly solar panels are already so cheap that to halve the installed cost again will require most of the efficiencies to be found in other costs like manufacture of associated hardware and equipment and installation. I don't know if those costs will be so easy to reduce.

bryanlarsen 20d ago

> firm That's the opposite of what you want. You want something that is cost-effective to operate at a 10%, 1% or 0.1% duty cycle. Like nat gas or hydro. Not nuclear. And overbuilding isn't the only lever you have to ensure coverage meets your target 99.99% level -- geographic diversity works really well (the wind is always blowing somewhere), and wind power production is usually negatively correlated with solar power production.

fasterik 20d ago
Natural gas and hydro are firm power. You're correct that nuclear is not a good backup power source, but that's not the suggestion. The question is whether adding high-capacity-factor firm generation reduces total system cost. In regions where hydro and geothermal are unavailable, nuclear is the next best low-carbon option. I think you're underestimating the costs and difficulties associated with 100% renewables, especially transmission capacity between regions.
- bryanlarsen 20d ago
  I think you're underestimating the costs and difficulties associated with 99.99% renewables and/or using it as a straw man against the highly inexpensive and achievable 95% renewables. You're also underestimating the costs of using nuclear to achieve 99.99% reliability on top of a grid with 95% renewables: in that scenario you need nuclear capable of supplying ~100% of your power. In which case you might as well ditch the renewables. But the world does not have the quadrillions needed to go 100% nuclear. The world does have the 10s of trillions needed to go 95-99% renewable.
  - fasterik 20d ago
    >in that scenario you need nuclear capable of supplying ~100% of your power. Where are you getting that from? Again, nuclear doesn't need to be a full backup, and nobody is suggesting we ditch renewables for nuclear. A perfectly viable solution would be a grid with a majority of power coming from renewables and storage, with enough nuclear generation to reduce the amount of overbuild necessary and to stop burning natural gas. From this article: https://www.sciencedirect.com/science/article/pii/S2666278721000234 https://www.sciencedirect.com/science/article/pii/S266627872... >Individually, each firm technology delivers substantial cost reductions relative to portfolios restricted to wind, solar, and energy storage alone. Additionally, because each technology occupies a distinctive functional niche in the electricity system, having all of these technologies available optimizes the utilization rate of each resource and reduces system costs by up to 10% relative to cases with just one class of firm resource.
    - bryanlarsen 19d ago
      If you're using nuclear as a backstop in that way, you're using the same statistical techniques that let you use cheaper, less reliable sources of power for backstop.
UltraSane 19d ago
You are very wrong. US base load demand is around 400GW that must be provided 24/7
- bryanlarsen 19d ago
  Baseload is a cost optimization strategy only relevant if your non-dispatchable power generation is cheaper than your dispatchable power generation. https://en.acatech.de/publication/baseload-power-plants/ https://en.acatech.de/publication/baseload-power-plants/
  - UltraSane 19d ago
    You need to have dispatchable capacity equal to or greater than your base load in order be able to guarantee you will be able to deliver it with 100% reliability year round. I am very dubious of any energy policy coming form Germany because they have managed to make their electricity among the most expensive in the world while STILL being high carbon.
    - bryanlarsen 19d ago
      > You need to have dispatchable capacity equal to or greater than your base load in order be able to guarantee you will be able to deliver it with 100% reliability year round. Just one word change needed: You need to have dispatchable capacity equal or greater than your peak load in order be able to guarantee you will be able to deliver it with 100% reliability year round.
      - deleted 18d ago
        [deleted]
- dalyons 19d ago
  Solar produces incredibly cheap power for the daytime hours, pushing any nuclear off the grid (why would a data center buy expensive nuke power in the hours when cheap renewables are available?). Nuclear needs to be running and selling power at its high price 24/7 for it to be even close to economically viable. Only supplying power that people want(due to its high price) during the night is fatal to nuclear. base load demand does not mean it has to be met with a constant matched source, and in fact that no longer works economically.
Mawr 19d ago
> Like nat gas or hydro Since hydro is impossible to "just" build, that's gas only. No, there's no "nat" gas. > geographic diversity works really well "Give up your energy independence :)" I'm sure world leaders are eager to jump on that great idea. "and wind power production is usually negatively correlated with solar power production" Well, that should be fine, I only usually need electricity.
- bryanlarsen 19d ago
  You don't need to cross oceans to get good geographic diversity.

fpoling 19d ago

If solar becomes 2 times cheaper, it will be economical to capture nitrogen from atmosphere and produce ammonia and use that for long-term energy storage and fuel. And with that one does not need massive solar overbuild. This does not require any magic technology, just scaling up what is available today is enough and will definitely happen within the next 20 years, before small nuclear will have any effect.

chickenbig 19d ago
> If solar becomes 2 times cheaper It would be good to see a techno-economic analysis of this. For instance, taken to the limit, if solar were free what would be the CAPEX and OPEX to produce the ammonia? In addition, the plant to consume the ammonia to produce electricity would not be free.
- fpoling 19d ago
  Ammonia does not require a plant to generate electricity. While fuel cells running on it require temperatures over 600 Celsius to get to 70% percent of efficiency and not exactly small, with cheap way to produce ammonia they would provide energy dense batteries that could run for months if necessary.
  - chickenbig 18d ago
    > Ammonia does not require a plant to generate electricity. While fuel cells running on it OK, so it requires a plant of fuel cells. And the cost per kW (i.e. discharge capacity) is? And it requires some facility to produce the ammonia; what is the cost per kW of electricity consumed, and at what efficiency? Numbers would help to assess the proposal, given the claim that a halving of the cost of electricity from solar would make all the economics for ammonia work.
istjohn 19d ago
If I recall correctly solar panels are already so cheap that to halve the installed cost again will require most of the efficiencies to be found in other costs like manufacture of associated hardware and equipment and installation. I don't know if those costs will be so easy to reduce.