Comment by trunnell | Hacker News Reader

Comment by trunnell | Hacker News Reader

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Respectfully disagree -- solar isn't the big story here.

One could argue that batteries will have a bigger impact than solar. Batteries obviously let you decouple power generation and consumption, shifting anytime production to peak-time demand.

Less obvious is that local demand can fluctuate 2x. It usually dips mid-day and peaks 5-9pm (see the charts at www.caiso.com) when people come home and turn on their lights, oven, appliances, etc. This pattern happens throughout the year.

So forget solar for a moment; the ability to shift energy that was produced mid-day (even by a natural gas plant) to the evening would allow you to build fewer power plants. Nuclear + batteries might also be a good combination. Batteries get you closer to being able to solve for "average demand" rather than "peak demand."

This has nothing to do w/ California. California is just on the leading edge of battery installation. Solar just exacerbates the issue of the peak-to-trough ratio (evening vs. mid-day demand) due to mid-day solar "overproduction" causing it to be uneconomical to run gas plants mid-day. But solving for "peak demand" is still a problem in the absence of solar.

Still: most of the complaints about solar are answered when paired with large battery systems.

The mid-day peak of solar can be almost entirely mitigated by adding bifacial vertical east-west mounted solar panels.

It works really well: The vertical mounting means the panels stay cooler and are thus more efficient. The east-west mounting also does that, but additionally shifts the peaks of production to close to sundown and sunrise. The only real downside is that you are using (somewhat) more panel surface. And of course you're still not generating more electricity after sundown or on cloudy days, so it is not a panacea.

Sources:

- https://undecidedmf.com/298-vertical-bifacial-solar-panels/

- https://www.nature.com/articles/s41598-024-68018-1

Yup by far batteries are the bigger deal. If battery prices were minimal then it makes household solar far more feasible to begin with.

The OP numbers are fascinating. I wonder how the equivalent to the "station wagon full of tapes hurtling down the highway" looks for batteries.

> I wonder how the equivalent to the "station wagon full of tapes hurtling down the highway" looks for batteries.

Looks terrible.

I think the best are only about 500Wh/kg, so a shipping container* full of them would be 28870kg * 500Wh/kg = 14.44 MWh, so if it takes an hour to the destination it's about the capacity of one not particularly thick cable.

Cables are great for electricity. If the (aluminium) cable had a cross section of one square meter, you could get all the way around the planet and back to where you started with just 1Ω of DC electrical resistance.

* https://www.maersk.com/support/faqs/cargo-weight-limit

I seem to recall that one of the main reasons to doubt batteries was that they relied on minerals that are just too rare on Earth to consider scaling them up to the entire grid.

Was my understanding incorrect? Or perhaps have new technologies emerged that work around this limitation?

The linked article addresses that. Modern batteries are lithium-iron, without the rare cobalt and nickel. Sodium batteries are also in development, but lithium is turning out to be so cheap and abundant that investment in the sodium batteries isn’t economical.

Grid storage batteries don't have the same weight constraint as vehicle batteries which opens the door to many other combinations that have a lower energy density but are cheaper per GW despite weighing more per GW.

Sodium-ion batteries have extreme good performance in low-temperature environments. CATL is working on sodium-LFP dual-power batteries to get the best of both worlds:

https://www.catl.com/en/news/6401.html

That's mainly for EVs though.

That was never the case. Some people looked at "current reserve" amounts for lithium or other minerals and assumed that we had already discovered all usable deposits. That was a very incorrect assumption.

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