4 ms·

Nuclear power costs about as much to run 24/7 as it does to run intermittently, because the vast majority of its cost is in construction. So building enough nuc

Nuclear power costs about as much to run 24/7 as it does to run intermittently, because the vast majority of its cost is in construction. So building enough nuclear power to satisfy demand when intermittent sources aren't producing makes those intermittent sources totally redundant.

AnthonyMouse 3y ago
Not exactly. Suppose you have renewable sources that on average generate 100GW. Well, some weeks they're going to average 90GW -- and that will be quite common -- in which case you'd need 10GW of something else. The long-term average (e.g. over 48 hours) is what matters because you'd always need to smooth out the short-term load with batteries. Some weeks you'll need to make up 20GW, but that will be less often than a 10GW shortfall. Even less often, 30GW. Sometimes, but very rarely, the whole 100GW, or at least say 90GW. This means that the first 10GW of peaker plants will be quite economical because they get used e.g. 15% of the time, but the last 10GW will only get used <1% of the time and not be competitive with nuclear running ~100% of the time. So what you end up with is, say, 60GW of renewables, 40GW of nuclear and 50GW of peaker plants that run the ~5% of the time when you have low renewable generation. Instead of needing 100GW of renewables and 90GW of peaker plants, of which 40GW is almost never used.
- fragmede 3y ago
  That's one side of the equation. The other side that's being explored is to vary the demand side. Only use 90 GW when 90 GW is available, and run the aluminum smelters undercapacity when there isn't the solar power to run them at full capacity. It's an interesting balancing equation that someone could make an interesting game out of.
  - AnthonyMouse 3y ago
    > Only use 90 GW when 90 GW is available, and run the aluminum smelters undercapacity when there isn't the solar power to run them at full capacity. That gets you a few percent for the things that work like that, but most of the load on the power grid isn't able to do that. You can't turn off the heat in the winter, which is going to be an even larger proportion of the load in the future than it is now as we transition from fossil fuel heating systems to electric. People demand hot water. Refrigeration is a significant load but you turn it off and your food spoils. Electrifying transportation is also a mixed blessing here. It helps smooth out the day/night load because you can charge them whenever generation exceeds demand, but after a couple days you can't put it off anymore and then you've just got more unsuppressible demand.
    - notyoutube 3y ago
      I would expect heating to be one of the electricity use that you _can_ adapt the easiest. First by using heatpumps instead of resistors, and then with some inertia management to buffer (e.g. water tanks, or something) Isn't that the case?
      - AnthonyMouse 3y ago
        We're largely not using resistors now, we're using oil and gas. Heat pumps use less than resistors but not less electricity than burning hydrocarbons on site. Buffering systems can be effective for intra-day load shifting. You want to use electricity at noon and have heat at night. It doesn't work when you want to use electricity on Monday to have heat on Friday (tank would have to be too big and losses are too high) and it definitely doesn't work when you need heat on Monday but won't have the generation capacity until Friday.
- Manuel_D 3y ago
  > Suppose you have renewable sources that on average generate 100GW. Well, some weeks they're going to average 90GW Renewables' fluctuations are way, way bigger than 10%. Solar, by definition, is going to be producing 0% of output 12 hours a day on average. Wind has fluctuations of over 10x as well: https://ars.els-cdn.com/content/image/1-s2.0-S0306261917308346-gr10.jpg https://ars.els-cdn.com/content/image/1-s2.0-S03062619173083... https://www.sciencedirect.com/science/article/abs/pii/S0306261917308346 https://www.sciencedirect.com/science/article/abs/pii/S03062... It's more like, you have renewable sources that produce 100 GW at their times of peak output. And for a couple months of the year they're producing 10GW. If you built 90 GW of nuclear power, then you could just scrap 90% of your renewables and run your nuclear plants all year round. Again, nuclear power plants are just as cheap to run constantly as it is to run them intermittently.
  - AnthonyMouse 3y ago
    I reiterate that we're talking about the daily average and not the instantaneous generation. You have solar panels that generate 100GW average, i.e. 200GW during sunlight and nothing at night. You have batteries to match this up with the daily load. But then it's more cloudy than usual for a couple weeks, so your average generation from solar is 50GW, or 10GW, or what have you, depending on how cloudy it is. You need something to make up the difference that week or the batteries run down and the power goes out. But because averaging 90GW over a day (when the typical average is 100GW) is a lot more common than averaging 10GW, the first 10GW of peaker plants is economical against nuclear and the last 10GW is not. And the total of nuclear + peaker plants has to add up to ~90GW because there will be times when you only average ~10GW from renewables.
    - zozbot234 3y ago
      > the first 10GW of peaker plants is economical against nuclear and the last 10GW is not. I'm not sure how well this works given that peaker plants have to pay for their fuel whereas nuclear - to a first approximation - does not; everything is factored in the building cost. So it's more like the first 10GW of nuclear baseload can displace a lot of gas use, whereas the last 10GW shortfall might still be efficiently covered by peaker plants if they're cheaper to build for the same capacity and almost never have to burn fuel. It works out to mostly the same outcome, though.

AnthonyMouse 3y ago

Not exactly. Suppose you have renewable sources that on average generate 100GW. Well, some weeks they're going to average 90GW -- and that will be quite common -- in which case you'd need 10GW of something else. The long-term average (e.g. over 48 hours) is what matters because you'd always need to smooth out the short-term load with batteries. Some weeks you'll need to make up 20GW, but that will be less often than a 10GW shortfall. Even less often, 30GW. Sometimes, but very rarely, the whole 100GW, or at least say 90GW. This means that the first 10GW of peaker plants will be quite economical because they get used e.g. 15% of the time, but the last 10GW will only get used <1% of the time and not be competitive with nuclear running ~100% of the time. So what you end up with is, say, 60GW of renewables, 40GW of nuclear and 50GW of peaker plants that run the ~5% of the time when you have low renewable generation. Instead of needing 100GW of renewables and 90GW of peaker plants, of which 40GW is almost never used.

fragmede 3y ago
That's one side of the equation. The other side that's being explored is to vary the demand side. Only use 90 GW when 90 GW is available, and run the aluminum smelters undercapacity when there isn't the solar power to run them at full capacity. It's an interesting balancing equation that someone could make an interesting game out of.
- AnthonyMouse 3y ago
  > Only use 90 GW when 90 GW is available, and run the aluminum smelters undercapacity when there isn't the solar power to run them at full capacity. That gets you a few percent for the things that work like that, but most of the load on the power grid isn't able to do that. You can't turn off the heat in the winter, which is going to be an even larger proportion of the load in the future than it is now as we transition from fossil fuel heating systems to electric. People demand hot water. Refrigeration is a significant load but you turn it off and your food spoils. Electrifying transportation is also a mixed blessing here. It helps smooth out the day/night load because you can charge them whenever generation exceeds demand, but after a couple days you can't put it off anymore and then you've just got more unsuppressible demand.
  - notyoutube 3y ago
    I would expect heating to be one of the electricity use that you _can_ adapt the easiest. First by using heatpumps instead of resistors, and then with some inertia management to buffer (e.g. water tanks, or something) Isn't that the case?
    - AnthonyMouse 3y ago
      We're largely not using resistors now, we're using oil and gas. Heat pumps use less than resistors but not less electricity than burning hydrocarbons on site. Buffering systems can be effective for intra-day load shifting. You want to use electricity at noon and have heat at night. It doesn't work when you want to use electricity on Monday to have heat on Friday (tank would have to be too big and losses are too high) and it definitely doesn't work when you need heat on Monday but won't have the generation capacity until Friday.
Manuel_D 3y ago
> Suppose you have renewable sources that on average generate 100GW. Well, some weeks they're going to average 90GW Renewables' fluctuations are way, way bigger than 10%. Solar, by definition, is going to be producing 0% of output 12 hours a day on average. Wind has fluctuations of over 10x as well: https://ars.els-cdn.com/content/image/1-s2.0-S0306261917308346-gr10.jpg https://ars.els-cdn.com/content/image/1-s2.0-S03062619173083... https://www.sciencedirect.com/science/article/abs/pii/S0306261917308346 https://www.sciencedirect.com/science/article/abs/pii/S03062... It's more like, you have renewable sources that produce 100 GW at their times of peak output. And for a couple months of the year they're producing 10GW. If you built 90 GW of nuclear power, then you could just scrap 90% of your renewables and run your nuclear plants all year round. Again, nuclear power plants are just as cheap to run constantly as it is to run them intermittently.
- AnthonyMouse 3y ago
  I reiterate that we're talking about the daily average and not the instantaneous generation. You have solar panels that generate 100GW average, i.e. 200GW during sunlight and nothing at night. You have batteries to match this up with the daily load. But then it's more cloudy than usual for a couple weeks, so your average generation from solar is 50GW, or 10GW, or what have you, depending on how cloudy it is. You need something to make up the difference that week or the batteries run down and the power goes out. But because averaging 90GW over a day (when the typical average is 100GW) is a lot more common than averaging 10GW, the first 10GW of peaker plants is economical against nuclear and the last 10GW is not. And the total of nuclear + peaker plants has to add up to ~90GW because there will be times when you only average ~10GW from renewables.
  - zozbot234 3y ago
    > the first 10GW of peaker plants is economical against nuclear and the last 10GW is not. I'm not sure how well this works given that peaker plants have to pay for their fuel whereas nuclear - to a first approximation - does not; everything is factored in the building cost. So it's more like the first 10GW of nuclear baseload can displace a lot of gas use, whereas the last 10GW shortfall might still be efficiently covered by peaker plants if they're cheaper to build for the same capacity and almost never have to burn fuel. It works out to mostly the same outcome, though.