4 ms·

Even that is not true, since you can always combine electricity from multiple sources to form your base load, and there's no law of nature saying that the base

by jhgb 5y ago

Even that is not true, since you can always combine electricity from multiple sources to form your base load, and there's no law of nature saying that the base load must come from a single source. But even more importantly, the need for storage arises at much higher renewable penetration levels than you observe in the current world. It will take multiple decades to get to the point where you need large amounts of storage in the first place.

throwaway894345 5y ago
> Even that is not true, since you can always combine electricity from multiple sources to form your base load, and there's no law of nature saying that the base load must come from a single source. No one is saying it must come from a single source? Combining electricity from multiple reliable sources is fine, but there will be times when the sun isn't shining and the wind isn't blowing so you need to be able to meet energy demands in those cases. The only clean solution is nuclear (and hydro where available).
- jhgb 5y ago
  > but there will be times when the sun isn't shining and the wind isn't blowing so you need to be able to meet energy demands in those cases. The only clean solution is nuclear (and hydro where available). That claim is highly debatable. Lots of people claim that the storage necessary to overcome these generation troughs make it infeasible but they seem to completely ignore holistic cost minimization approaches using overgeneration and then conclude that the amount of storage required makes it impossible. Meanwhile it's been calculated that modest overgeneration squashes storage amounts (and costs) in massive ways. People have actually studied these things, you know... See for example the 2018 article On the economics of electrical storage for variable renewable energy sources by Zerrahn et al.
  - politician 5y ago
    We can't assume overgeneration will be sustainable since there is profit to be made by idling or scrapping generators to reduce costs.
    - jhgb 5y ago
      We can safely assume that. First, if the deployed mixture of generators is the cheapest mixed solution devised, there's money to be wasted "by idling or scrapping generators", since by definition that would increase costs, not reduce them, so it would be an irrational step to make. Second, opportunistic consumers not included in the base load can take advantage of these peaks, to the benefit of both sides (generators AND consumers -- consumers get power for peanuts and generators get some extra money they otherwise wouldn't get), for example for charging BEVs on demand -- and you'll need lots of power for that.
      - politician 5y ago
        Are you assuming grid-scale storage exists and is deployed widely in your scenario?
  - throwaway894345 5y ago
    It's not like overgeneration is free either, and I'm very skeptical that overgeneration can squeeze blood from a stone on regionally cloudy, still weeks; however, I'll read your source when I have a free moment, thanks for sharing, etc.
    - jhgb 5y ago
      Nobody says that overgeneration is free. But for example if your wind power costs are $20/MWh and your nuclear power costs are $80/MWh, even 100% overgeneration capacity for wind is still cheaper compared to the nuclear alternative. And if it achieves the desired effect cheaper than storage, then it will be preferred over storage as well. The optimal ratio of storage and overgeneration needs to be modeled for every grid independently; I believe the article I mentioned models it for the German grid. In practice, though, I expect that you won't even get energy waste from overgeneration if flexible energy consumers like BEVs or flexible hydrogen electrolyzers are connected to the grid. These will account for a major portion of electricity consumption and it will be possible to move their consumption around very considerably.
      - throwaway894345 5y ago
        I agree with your first paragraph, but I’m still far from optimistic that the cost analysis will work out in favor of renewables in the near term unless perhaps we continue to keep nuclear costs artificially high. In particular, I’m not sure that 100% over provisioning (absent storage) gets us anywhere near the same reliability of nuclear.
  - jjk166 5y ago
    It doesn't matter how many solar panels you build, when the sun is down none of them are generating power. Likewise when the wind stops, it doesn't matter how many turbines are in the windfarm. Overgeneration certainly does not squash storage amounts.
    - ben_w 5y ago
      It reduces but does not eliminate storage. You’ll still have some windless nights, but enough overproduction means that you don’t have to worry about mere cloudy days or low-wind periods — One suggestion in another comment was needing weeks of storage, and overproduction can reduce that to a day of storage, perhaps even less.
  - blitzar 5y ago
    The solution will inevitably be distributed overstorage rather than overgeneration. 10% of everyones car and home battery will be annexed by the grid when needed.
- derriz 5y ago
  Combining sources from multiple _unreliable_ sources is actually fine - as long as the failure/intermittency isn't correlated. Defining "fine" as reasonably low variance - i.e. guaranteeing X amount of capacity will be available for Y% of the time. Nuclear doesn't give you 100% for Y above - there are times when your nuclear reactor will also be unavailable - the average is about 32 days per year in the US. So nuclear has a similar problem - as has all generation types - albeit with different statistical properties.
  - throwaway894345 5y ago
    > Combining sources from multiple _unreliable_ sources is actually fine - as long as the failure/intermittency isn't correlated. This is true for a sufficiently large number of uncorrelated sources, but all solar plants in a region are correlated and all wind plants in a region are correlated so effectively you have only two renewable sources in a region that are decoupled, which is wholly inadequate considering the relatively low reliability of either source. Maybe over-provisioning would help, but I don't know how much you would have to over-provision to get power on a still night, and anyway the whole point is accounting for costs so if it's not storage then you have to account for the over-provisioning costs. > Nuclear doesn't give you 100% for Y above - there are times when your nuclear reactor will also be unavailable - the average is about 32 days per year in the US. So nuclear has a similar problem - as has all generation types - albeit with different statistical properties. These aren't similar problems. With wind and solar power, bad weather shuts down all "plants" in a region. With nuclear, you have maintenance windows on individual plants which can be coordinated with other plants in the region such that base load is maintained. > different statistical properties Technically true, but doing a lot of rhetorical labor.
    - derriz 5y ago
      You but your claim was that it was only possible to provide reliable supply by combining _reliable_ sources. This is not the case. Wind and solar are largely anti-correlated in most regions. Depending on the geography, differences in wind output can vary significantly over distances in as little 100km and offshore and on-shore capacity factors also tend to show divergence. At distances above 1,500km wind is uncorrelated in Europe. The stochastic failures of nuclear reactors are largely independent but not always - a natural catastrophe like Fukushima can take out a bunch of reactors. Or extreme weather (heat), like last summer's drought took out a bunch of reactors in a few northern European countries. It's not rhetorical labor to point out that it's simplistic to present nuclear as completely reliable (it's not) and that unreliable sources can contribute to a reliable grid. It's pointing out that the problem is more subtle. Unlike 10 years ago, we have now concrete examples of grids which operate with very high shares of wind and solar without any decrease in reliability and have developed practical techniques for incorporating such sources into grids.

by jhgb 5y ago

throwaway894345 5y ago

> Even that is not true, since you can always combine electricity from multiple sources to form your base load, and there's no law of nature saying that the base load must come from a single source. No one is saying it must come from a single source? Combining electricity from multiple reliable sources is fine, but there will be times when the sun isn't shining and the wind isn't blowing so you need to be able to meet energy demands in those cases. The only clean solution is nuclear (and hydro where available).

jhgb 5y ago
> but there will be times when the sun isn't shining and the wind isn't blowing so you need to be able to meet energy demands in those cases. The only clean solution is nuclear (and hydro where available). That claim is highly debatable. Lots of people claim that the storage necessary to overcome these generation troughs make it infeasible but they seem to completely ignore holistic cost minimization approaches using overgeneration and then conclude that the amount of storage required makes it impossible. Meanwhile it's been calculated that modest overgeneration squashes storage amounts (and costs) in massive ways. People have actually studied these things, you know... See for example the 2018 article On the economics of electrical storage for variable renewable energy sources by Zerrahn et al.
- politician 5y ago
  We can't assume overgeneration will be sustainable since there is profit to be made by idling or scrapping generators to reduce costs.
  - jhgb 5y ago
    We can safely assume that. First, if the deployed mixture of generators is the cheapest mixed solution devised, there's money to be wasted "by idling or scrapping generators", since by definition that would increase costs, not reduce them, so it would be an irrational step to make. Second, opportunistic consumers not included in the base load can take advantage of these peaks, to the benefit of both sides (generators AND consumers -- consumers get power for peanuts and generators get some extra money they otherwise wouldn't get), for example for charging BEVs on demand -- and you'll need lots of power for that.
    - politician 5y ago
      Are you assuming grid-scale storage exists and is deployed widely in your scenario?
- throwaway894345 5y ago
  It's not like overgeneration is free either, and I'm very skeptical that overgeneration can squeeze blood from a stone on regionally cloudy, still weeks; however, I'll read your source when I have a free moment, thanks for sharing, etc.
  - jhgb 5y ago
    Nobody says that overgeneration is free. But for example if your wind power costs are $20/MWh and your nuclear power costs are $80/MWh, even 100% overgeneration capacity for wind is still cheaper compared to the nuclear alternative. And if it achieves the desired effect cheaper than storage, then it will be preferred over storage as well. The optimal ratio of storage and overgeneration needs to be modeled for every grid independently; I believe the article I mentioned models it for the German grid. In practice, though, I expect that you won't even get energy waste from overgeneration if flexible energy consumers like BEVs or flexible hydrogen electrolyzers are connected to the grid. These will account for a major portion of electricity consumption and it will be possible to move their consumption around very considerably.
    - throwaway894345 5y ago
      I agree with your first paragraph, but I’m still far from optimistic that the cost analysis will work out in favor of renewables in the near term unless perhaps we continue to keep nuclear costs artificially high. In particular, I’m not sure that 100% over provisioning (absent storage) gets us anywhere near the same reliability of nuclear.
- jjk166 5y ago
  It doesn't matter how many solar panels you build, when the sun is down none of them are generating power. Likewise when the wind stops, it doesn't matter how many turbines are in the windfarm. Overgeneration certainly does not squash storage amounts.
  - ben_w 5y ago
    It reduces but does not eliminate storage. You’ll still have some windless nights, but enough overproduction means that you don’t have to worry about mere cloudy days or low-wind periods — One suggestion in another comment was needing weeks of storage, and overproduction can reduce that to a day of storage, perhaps even less.
- blitzar 5y ago
  The solution will inevitably be distributed overstorage rather than overgeneration. 10% of everyones car and home battery will be annexed by the grid when needed.
derriz 5y ago
Combining sources from multiple _unreliable_ sources is actually fine - as long as the failure/intermittency isn't correlated. Defining "fine" as reasonably low variance - i.e. guaranteeing X amount of capacity will be available for Y% of the time. Nuclear doesn't give you 100% for Y above - there are times when your nuclear reactor will also be unavailable - the average is about 32 days per year in the US. So nuclear has a similar problem - as has all generation types - albeit with different statistical properties.
- throwaway894345 5y ago
  > Combining sources from multiple _unreliable_ sources is actually fine - as long as the failure/intermittency isn't correlated. This is true for a sufficiently large number of uncorrelated sources, but all solar plants in a region are correlated and all wind plants in a region are correlated so effectively you have only two renewable sources in a region that are decoupled, which is wholly inadequate considering the relatively low reliability of either source. Maybe over-provisioning would help, but I don't know how much you would have to over-provision to get power on a still night, and anyway the whole point is accounting for costs so if it's not storage then you have to account for the over-provisioning costs. > Nuclear doesn't give you 100% for Y above - there are times when your nuclear reactor will also be unavailable - the average is about 32 days per year in the US. So nuclear has a similar problem - as has all generation types - albeit with different statistical properties. These aren't similar problems. With wind and solar power, bad weather shuts down all "plants" in a region. With nuclear, you have maintenance windows on individual plants which can be coordinated with other plants in the region such that base load is maintained. > different statistical properties Technically true, but doing a lot of rhetorical labor.
  - derriz 5y ago
    You but your claim was that it was only possible to provide reliable supply by combining _reliable_ sources. This is not the case. Wind and solar are largely anti-correlated in most regions. Depending on the geography, differences in wind output can vary significantly over distances in as little 100km and offshore and on-shore capacity factors also tend to show divergence. At distances above 1,500km wind is uncorrelated in Europe. The stochastic failures of nuclear reactors are largely independent but not always - a natural catastrophe like Fukushima can take out a bunch of reactors. Or extreme weather (heat), like last summer's drought took out a bunch of reactors in a few northern European countries. It's not rhetorical labor to point out that it's simplistic to present nuclear as completely reliable (it's not) and that unreliable sources can contribute to a reliable grid. It's pointing out that the problem is more subtle. Unlike 10 years ago, we have now concrete examples of grids which operate with very high shares of wind and solar without any decrease in reliability and have developed practical techniques for incorporating such sources into grids.