Polar Vortex provided some good metrics

[begreen]

Energy companies shared data on the recent cold wave to estimate requirements for keeping the lights on without fossil fuel.

https://insideclimatenews.org/news/...orage-need-worst-case-polar-vortex-wind-solar

 

[CaptSpiff]

There is something wrong with article's graph. This is the same graph shown in another post, and the WIND representation does not appear accurate. My recollection on prior wind production did not show it coincident with solar, and also not steady either. I recall a pattern similar to solar with a greater production at night, but I do not recall if the night was early evening, late evening, or early morning.

That production cycle is shown later in the article's "dynamic solar & wind vs time" gif.

 

[begreen]

The graph is only a one week period and only covers the eastern and central regions of the country. I don't think it includes the stronger midwest and southwestern winds where the animation indicates strong activity during non-solar periods.

 

[Corey]

There is something wrong with article's graph. This is the same graph shown in another post, and the WIND representation does not appear accurate. My recollection on prior wind production did not show it coincident with solar, and also not steady either. I recall a pattern similar to solar with a greater production at night, but I do not recall if the night was early evening, late evening, or early morning.

That production cycle is shown later in the article's "dynamic solar & wind vs time" gif.

View attachment 241263

I think that graph is showing 'wind + solar' ie the 'wind' isn't necessarily rising 'equal and greater than' solar during the day, the solar is making a large peak with a small amount of wind on top. Basically showing the total generation.

Still not sure how that graph explains how the grid would have coped. Seems like for a stable grid, 'demand - generation' needs to be zero or negative at all times. So in some instances ie - overnight Jan 31/Feb 1, that 'demand-generation' line rises up near the 200 GW... and being winter, seems like that could easily be a 12 hour dark period. So you'd basically need 2.4 terawatt hours of batteries charged and ready. And that is just the 'worst' in a 7 day period. I'm sure the 'absolute' worse is even worse than that!

Also not really clear how the area under the negative curve relates to the area under the positive curve. If they're equal, then you're generating as much charging as discharging, but if the area under the negative curve is smaller, then not generating enough charge to offset the demand on the positive side.

 

[DBoon]

"Littell says some of the most promising ways to operate a cleaner grid involve using technology to reduce demand during peak periods."

This is exactly where the creativity on the part of the utilities and regulators needs to come in. There are far cheaper ways to "store" power than putting it in a battery, and people and businesses would be happy to do these things if the utility structured their rates to their customer's benefit (saving them money) and their own benefit (reducing peak demand needs, reducing demand when renewable technologies are not producing as much, increasing demand when renewable technologies are producing too much).

For instance, today I have an electric water heater tank that I run only overnight (cheaper off-peak rate). Demand is low then and the utility wants to have a good base load to keep their base load plants running. I'm happy to do that. I've installed a slightly larger tank to make this possible, and I only use electricity for this during off-peak hours and run on storage throughout the day.

A new renovation I am completing has a geothermal heat pump coupled to a 180 gallon storage tank. Why 180 gallon? I can foresee a day when the utility reduces the rates in daytime in order to use up excessive solar PV or wind generation. A 180 gallon tank heated fully will keep my house heated for about 5 hours. It is less expensive to store those BTUs as hot water than as electrons in a battery. More customers would oblige if they were incentivized correctly.

Studies like the one referenced are interesting, but I am naturally suspicious of them because they assume only one solution - more battery storage - as the answer to the problem. There are lots of answers to the problem, but perhaps only one that benefits the people who did the study.