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Comment by Vvector | Hacker News Reader

"But 2 hours in 2030 against a year's demand today is still a nudge."

How much battery storage do you think we need? Surely not a year's worth.

For solar, we'd likely need 10-16 hours of storage to power stuff overnight. Maybe a little more to cover a few cloudy days. Sounds like we are about 5% of that now?

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Generally the worst case is two weeks. In the middle of winter you often get cloudy low wind days for that long. Of course how you handle those worse cases are days need not be how you handle typical. If you can handle 16 hours of no input this will over the typical cases this will be enough to max a massive dent in carbon emissions and we can fall back to existing gas (or even coal) plants for the rest. Plus a lot of power use can turn off when needed - give my company a discount and we can turn the factory off.

10-16 hours is not enough at all. On a cloudy day, solar output will only be 15-20%. On top of that, your panels really only generate for 8 hours on a very good day - the sun is a lot dimmer in the early morning and late evening. Really, you need 2x storage for a good day, if you want to deal with two cloudy days you'd want 50-60 hours of storage.

Could you possibly read the article you're replying to again?

Even skimming through it discusses the coverage of wind and a not 50/50 system particularly to cover winter & night time. There is also discussion of a ~2% from "other" and how much storage capacity is required.

The article even goes into using wind & solar data for the simulation and reducing further the output to be conservative.

I obviously understand it's not a 100% solar system. If it was you would need to be able to deal with at least 2 weeks of bad weather, not two days, and you would have to take into account winter (dropping to about 5 hours instead of 8).

Additionally, mixing solar and wind is not as easy as it seems, because the two are correlated. If you have a major storm that makes wind energy impossible due to wind speeds above ~100km/h, you will also have clouds making solar energy unworkable. I'm not aware of any simulations modelling a 95+% solar/wind grid for storage needs, taking into account extreme weather patterns, grid topology, and equipment damage, but if you do then please link it.

I don't see any article linked in the comment I replied to. Perhaps you're mixing up two comment chains.

It's likely enough battery capacity if you combine batteries with e-fuels for longer term storage.

Assuming batteries are used for all storage use cases is one of the classic errors of energy system analysis.

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