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Comment by KennyBlanken | Hacker News Reader

At least in the US, no, for one simple reason: grids in the US rarely to never have an excess amount of renewable generation capacity.

In my area natural gas is a consistent 40-60% of generated power, with solar rarely reaching more than about 30-35% at high noon in the summer.

Right now (as in at this very minute, high noon) in CA ~70% of the power being generated is renewable. That's 30% that could be solar, and isn't.

When there's excess renewable generation capacity (or about to be), sure, let's talk about installations for storing it.

In the meantime utilities are deploying battery systems for virtual grid inertia, to avoid having to use "peaker" plants, reliability when transmission lines go down, and for transmission line maintenance.

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That might have to do with existing deal structures to maintain a non-renewable base load. Something like, if cloud cover/wind suddenly changes, we want to ensure there is already X% of natural gas running so there is a less sudden surge. There is a lot behind the scenes planning to try and ensure grid robustness.

California is certainly curtailing a lot of energy. EIA report[0] said 3.4 TWh in 2024, which was a 29% increase over 2023. If I am reading this[1] chart correctly, the 2024 California demand was ~275TWh.

CASIO also has pages dedicated to curtailment with much of the data available[2].

[0] https://www.eia.gov/todayinenergy/detail.php?id=65364

[1] PDF https://www.energy.ca.gov/sites/default/files/2024-11/2024_C...

[2] https://www.caiso.com/about/our-business/managing-the-evolvi...

Standby generation -- "spinning reserve" -- doesn't count as generated energy, because it's not. Until you're at that point you still can reduce natural gas consumption with more renewable.

California has huge amounts of excess renewable generation nearly every day, especially in spring and fall. Last April the grid operator curtailed 1.47 million MW/hrs of renewables, or about 2 GW per day. That's excess power the grid did not accept due to no demand. (source: https://www.caiso.com/documents/key-statistics-jul-2026.pdf)

In my mind the ideal solution is in addition to daily BESS time-shifting is seasonal time-shifting: long term storage of April excess for use in July.

I think you had me until you mentioned long term storage. How do you store significant amounts of energy across seasons? I'm just not aware of anything other than pumped hydro power that has anywhere near the cap as capacity to do such a thing.

Green hydrogen. Generate hydrogen from water during excess times and convert back later on.

Is is actively done at scale? I suspect not given the amounts of batteries being installed.

No because there’s lower hanging fruit. We’re still burning dinosaurs on windy days and in summer, seasonal storage is a long way down the list.

Is this curtailment due to overproduction, curtailment due to inadequate _grid_ capacity, or some mixture? In Ireland there's now a _lot_ of curtailment, but it's mostly driven by inadequate grid capacity (wind power in particular expanded quicker than the grid could).

Generators don't ramp up/down immediately. Especially when peak power usage is 4-5pm, people getting off work, but also closer to sunset. That's a lot of power that needs to be generated immediately for stability.

More solar (without batteries) makes that worse.

https://en.wikipedia.org/wiki/Duck_curve

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