[scott_ci]

Pumped storage analysis: https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/

spoiler: not remotely possible to scale large enough for total world needs.

"If we drained one meter from every upper lake, we would get 54 billion kWh of energy: about a sixth of the target capacity. If performed over seven days, the flow would be 375,000 cubic meters per second, or 125 times the normal flow over the falls."

"We would need 10,000 Raccoon Mountains to meet my baseline energy capacity"

[dragontamer]

> spoiler: not remotely possible to scale large enough for total world needs.

Yeah, not with those assumptions.

Storing enough energy for 7-days worth of zero-sun and zero-wind is going to be basically impossible across all known energy storage technologies. We'll likely have to run peaker plants during such an extended outage.

But we're not even trying to solve the 7-days worth of energy problem. We're starting with: lets save 3-hours worth of energy, so that the 6pm sun can be used for air-conditioning until 9pm or so.

Which we're not at yet (see the "Duck Curve" or "Nessie curve").

Besides, being able to store energy for 1 or 2 hours is still SUPER useful. Wind is strongest at night, while Solar is strongest during noon. Having energy at dawn (sun isn't strong yet) or twilight (sun is setting, but the wind hasn't picked up yet) is going to be a huge portion of our future energy strategy.

-----------

A huge part of the problem can be solved behaviorally and economically. We can change the price of electricity based on how easy it is to produce. 12:00 noon (highest sun power) can be cheaper, and 3am power (max wind energy) can also be cheaper.

Night-time energy can be used to power electric cars. 12:00 noon power can be used for factory work and other high-energy tasks (Air Conditioning, Washing Machines).

We all can change our behavior to reduce our energy demand between 5pm and 8pm, to reduce the Nessie curve / duck curve. And we can use economics to set the price higher to encourage others to follow our lead.

---------

Throw down a bit of nuclear, and keep a few natural gas peaker plants active for emergencies, and I think we've got a strong future for energy.

At the end of the day: Pumped Hydro is the ONLY GW-hr solution to this energy storage question. CAES is hundreds-of-MW-hrs, while Lithium Ion is also only hundreds-of MW-hrs.

That's just how the cookie crumbles: we don't have any other technology to store GW-hrs of energy.

[Gibbon1]

> Storing enough energy for 7-days worth

Thank you for pointing that out so I don't have to. He's tossing an insane requirement in there and hoping you don't notice. So instead of needing storage to shift about 20-30% of power needs on a daily basis he claims an absolute requirement of 700% of daily usage. Making any solution 20-30 times more costly.

Consider the alternative, as we have snow days. We could have 'energy days' where non-essential demand gets cut off and we fire up some combined cycle plants.

Also I'm not wading through his website again but last time I looked he was studiously ignoring thermal storage. Running that calculation is pretty easy. But he doesn't. Because it's doable even with his deranged 7 day requirement.

[WalterBright]

"being able to store energy for 1 or 2 hours is still SUPER useful."

Of course, which is why variable minute-by-minute pricing of electricity can serve as a "battery". The air conditioner, for example, can cool the house to the lowest comfortable temperature while power is cheap, which will then act as a zero-cost "battery" when the electricity gets more expensive in the evening.

[Gibbon1]

Someone I know in Arizona says a lot of people crank up the air conditioner in the morning and early afternoon and then just coast through late afternoon and evening. Basically using the house's thermal mass as a 'battery'

[WalterBright]

I bet a lot more people would do that if electricity was cheaper when the sun was high and more expensive when it was lower.

I'd certainly do that.

In fact, if I was designing a house under such a regime, I'd design it to incorporate lots of thermal mass within the envelope of the house to make it more effective.

[Gibbon1]

Time of use is definitely coming.

What I noticed when looking at this stuff is 'green building' codes are really about green washing natural gas and expensive toxic high R value insulation. Last thing I saw before I stopped researching was an article where and industry shill was crowing that they'd closed the loophole that allowed builders and home owners to use solar energy to offset insulation requirements.

The loophole was centered around, instead of spending $50,000 to install thick foam insulation with it's attendant issues with mold. Install $20k worth of solar panels, a heat pump and thermal mass inside the house.

[WalterBright]

My house has icynene foam,

https://www.icynene.com/en-us

which doesn't support mold. I've been very pleased with it. My house is shaded by large trees, so solar would never pencil out.

I'm just kinda sad that my idea of concrete "batteries" with variable pricing never gets any traction. People just can't seem to get past the notion that consumer electricity rates must be constant 24/7 despite enormous expense to make that happen.

[WhompingWindows]

When is there zero sun? I didn't realize that was a possibility on our spinning planet

[dragontamer]

> When is there zero sun?

I mean, its not my argument. But... something like the Dust Bowl of the 1930s or even a large volcanic eruption (like the 1980s Mount St. Helen eruption) would block out the sun in a local area for multiple days.

But my point being: such disasters are beyond our storage capabilities by several magnitudes. Most energy storage projects are at best, aiming for a few hours of energy storage.

Many (ie: Flywheels, typical Batteries, etc. etc.) are aiming for minutes, or even just seconds of grid-energy storage. This idea of days-long or even a week-long energy storage is just devoid from reality.

[Pxtl]

There also just aren't that many people above the Arctic circle. 90/10 rule applies here.

[elabajaba]

Extreme north or south. Barrow Alaska gets over 60 days without sun in the winter. A bit further south in more populated regions you only get a few hours of sunlight during the shortest days of the year.

[galuano1]

Cloudy days.

[pjc50]

A far more serious consideration for solar is the changing seasons, especially at non-tropical latitudes. I graphed the output of my solar panels (56 north, Scotland) and it's really apparent: https://flatline.org.uk/daystats.html

[PhantomGremlin]

So those panels are basically useless for 3 or 4 months of the year, i.e. November, December, January, February.

Would there be much improvement if you could tweak the orientation to match the seasons? E.g. tilt them down toward the horizon during the winter?

It's certainly a huge complication to have motorized panels that move all the time to track the sun. But maybe it wouldn't be that much of a hassle to go out there and manually reorient them (just in 1 axis) a few times a year?

[pjc50]

They're fixed to the roof, so making them movable would be a risk to their safety and wind resistance while being fairly difficult to access (and ladders are dangerous). For a fairly small benefit. It's not just the angle but the sunrise and sunset are a lot closer together.

[Retric]

Solar still provides power on Cloudy days, just less.

Storage is still a poor solution to this problem it’s much cheaper to have excess renuables.

[JoeAltmaier]

Isn't that about covering for outages? Those may never be solved.

This article was about storing off-peak green energy for peak usage. We're talking only about an hour or two of usage? Not 7 days. Those number may pencil out very well.

[mirekrusin]

Can you "decorate/boost" those dams with inflatable ballons on the lake's floor?

[Pxtl]

Compressed air is cheaper and has less geographic needs but it's even less efficient.