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Combining sources from multiple _unreliable_ sources is actually fine - as long as the failure/intermittency isn't correlated. Defining "fine" as reasonably lo

by 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 derriz 5y ago

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.