global warming – savemaple.org

In the prior post, I finally tracked down and read the Commonwealth of Virginia’s plans for fully de-carbonizing its electrical grid by mid-century. It boils down to replacing the existing natural-gas fired electrical capacity with a combination of wind, solar, and … great big batteries. You need the batteries because solar and wind are intermittent power sources.

That’s my reading of the law.

Literally, the law calls for the construction of “energy storage” facilities. While there are ways of storing electrical energy other than batteries, practically speaking, I’m pretty sure that means batteries of some type.

Source: Wikipedia

For example, Dominion (Virginia’s main electric utility) already owns the largest pumped-storage facility in the world, the Bath County Pumped Storage Station (shown above, per Wikipedia). That site stores energy by using electricity to pump water uphill from one reservoir to another, and then generates electricity as needed by allowing that water to flow downhill through generating turbines.

Sites suitable for pumped-storage facilities are few and far between. And other alternatives to batteries tend to be grossly inefficient (e.g., converting electricity to hydrogen, and back again). So it’s not beyond reason to expect that most of the energy storage that is required to be in the pipeline by 2035 will be battery-based storage of some sort.

The point of this post is to ask whether that seems even remotely feasible and plausible.

And, surprisingly — to me at least — the answer is yes. Yes, it does seem feasible to produce the required battery-based storage in that timeframe. Producing and installing (my guess for) the amount of battery capacity required to be in the works by 2035 would be the equivalent of adding grid-connected battery capacity required for manufacturing 400,000 Chevy-Bolt-size electric vehicles. That much, over the course of more than a decade. Where Virginia’s current stock of EVs is about 56,000 registered EVs.

Roughly speaking, on a per-year basis, those grid-based batteries will add as much to the demand for batteries as the current manufacture of EVs does. Given the rapid growth in EVs, and concomitant expansion of world battery manufacturing capacity, filling that amount of demand, in that timeframe, seems completely feasible to me.

That involves some serious guesswork on my part, due to the way the law was written (next section). But if that’s anywhere in the ballpark, then yeah, then Virginia’s path toward a carbon-free grid isn’t outlandish at all.

Big batteries, and an error in Commonwealth statute?

1. By December 31, 2035, each Phase I Utility shall petition the Commission for necessary approvals to construct or acquire 400 megawatts of energy storage capacity. ... 

2. By December 31, 2035, each Phase II Utility shall petition the Commission for necessary approvals to construct or acquire 2,700 megawatts of energy storage capacity.

Source: Commonwealth of Virginia statute, emphasis mine.

Virginia law appears to call for our public utilities to build or buy at least 3,100 megawatts of electrical storage capacity as part of this process.

Those of you who are well-versed on the difference between energy and power will have already spotted the problem. Megawatts is not a measure of electrical storage capacity. So the law is written oddly, or possibly incorrectly, no matter how you slice it.

Power is a rate of energy flow per unit of time. In particular, for electricity, the watt is a unit of power, not an amount of energy. The electrical unit of energy is the watt-hour.

E.g., the brightness of an old-fashioned incandescent light was determined by its wattage. But the amount of energy it used was based on its wattage, times the amount of time it was turned on, or total watt-hours used to light it.

When in doubt, just remember that you pay your public utility for the energy you use. And in Virginia, we pay about 12.5 cents per thousand watt-hours. (A.k.a. kilowatt-hours. Or KWH.)

Returning to the Bath County pumped storage facility referenced above, it has a peak power output of 3,000 megawatts, and a total storage of 24,000 megawatt-hours. Doing the math, if it starts out full, that facility can run at full power for eight hours before all the water has been drained from the upper reservoir.

But if that pumped-storage facility had been built with an upper reservoir ten times that size, or one-tenth that size, it would still produce 3,000 megawatts. But under those scenarios, the total energy storage could be anything from 1,200 to 120,000 megawatt-hours.

In other word, the section of Virginia statute that specifies the energy storage requirements does not actually specify an amount of energy storage. It specifies the (instantaneous) amount of power that those facilities must provide (megawatts).

I don’t know whether that’s a mistake, or whether they actually had something in mind. The nomenclature — megawatts — is what is used to size power plants. But that makes sense. Power plants produce electrical power, by transforming something else (coal, gas, sunlight, wind) into electricity. The assumption with gas and coal-fire plants is that they could produce that power for an indefinitely long period of time.

By contrast, electrical storage facilities don’t produce power, they simply store and release it. Telling me the amount of (instantanous) power they can release says nothing about how much energy they can store. It says nothing about how long they can keep up that power flow. Unlike gas and coal-fired power plants, there’s an expectation that they can only keep up that rate of power release for a relatively short period of time.

Beyond this confusion between units of power and units of energy, something about the energy storage part of the statute still does not quite add up. Per the U.S. Energy Information Agency, Virginia’s grid has a peak summertime output of about 30,000 megawatts (reference). So the Commonwealth seems to be requiring that new energy storage facilities have to be able to supply about 10% of peak load. Which, along with the existing Bath pumped-storage facility, would mean that total storage capacity would be able to supply 20% of peak summertime load. But for no more than eight hours (the amount of time that the existing Bath facility can run flat-out at 3000 megawatts.)

By contrast, the fossil-fuel-fired equipment that must be retired by 2045/2050 accounts for about 65% of current generating capacity, as of 2020. Acknowledging that nighttime demand is below peak daytime time, it still seems like a breezeless summer night would still result in more electricity demand than the Virginia grid could produce.

So they’re cutting it pretty close, that’s all I’m saying. Sure, we’re on a multi-state grid. Sure power can flow in from out-of-state. But if we’re having still and sultry summer nights, it’s a pretty good bet that all our neighboring states are as well.

I guess I should take the 3,100 as a minimum. Nothing bars out electric utilities from producing more than that.

Enough batteries to power 400,000 Chevy Bolts?

So let me assume a storage capacity, since the law does not actually specify one. And let me do that by patterning the new facilities on the characteristics of the existing Bath pumped-storage facility.

Let me then assume that the 3,100 megawatts of “storage” means that the new storage facilities have to match the existing Bath facility, and produce at that rate of power for eight hours. That would require about 25,000 megawatt-hours’ worth of battery capacity.

My Chevy Bolt, by contrast, has about 60 KWH of battery storage. Doing the arithmetic, and rounding, that’s enough battery capacity to manufacture 400,000 Chevy Bolts.

Virginia already has about 56,000 EVs registered in-state (reference). So that would be enough battery capacity to produce a seven-fold increase in EVs on the road, in Virginia, in a more-than-decade timespan.

Absent some huge unforseen bottleneck in the current ramp-up in battery production, that seems completely feasible. Not cheap. But clearly feasible.

Conclusion: This is a good start.

It’s fashionable to say that we aren’t doing anything about global warming.

While I would agree that we aren’t doing enough, and we aren’t doing it fast enough, the planned conversion of the electrical grid to carbon-free electricity (in just under half the U.S. states) is an example of a material change that is in the works.

Source: National Conference of State Legislatures.

There’s pretty clearly a red-state/blue-state divide in plans for a carbon-free grid. And it’s possible that the next time Republicans take power in Virginia, or nationally, they’ll put a stop to grid de-carbonization. In exactly the same way that they killed the Obama Clean Power Plan. That was a set of EPA rules that would require all states to have some plan in place for reducing the C02 emissions from their electrical grids. In effect, it was a national plan for decarbonizing the grid, with states given the freedom to implement those reduction targets as they saw fit. Republicans did their best to block it, and Republicans eventually successfully killed it once Trump took power (reference).

When you look at the details, the statement that we are unwilling to do anything about global warming is not true. In the U.S., in terms of Federal and state policies that could matter, Republicans are unwilling to do anything about it.

I have to admit, at first blush, Virginia’s plans for decarbonizing its grid seem kind of nuts. But when I looked in detail, well, it’s not so nutty after all. In the grand scheme of things, what’s nutty is all the states — in white and brown above — that have absolutely no plans, whatsoever, to address this issue.

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Source: Maps are from USDA. I added the line marking the boundary between hardiness zones 5 and 6.

… and nobody cared.

Which is a good thing. I think. On balance.

On the one hand, it’s good that they released it. That’s my take on it, knowing the controversial history of the USDA hardiness zone map.

On the face of it, the red lines on the map above simply mark a data-defined boundary. Below that line is the area where winter temperatures should be expected to stay above -10F. That’s based on the 30 years of local weather data, prior to the map date. As the U.S. winter nighttime temperatures have warmed, those lines are moving north about 5 miles per year, in Missouri. And, as I understand it, at roughly that rate, averaged across the entire U.S.

Back to the here-and-now, if you look at the illustration above and immediately say, hey, what happened to the circa-2002 map? Why did they skip a decade? Then you get an interesting story.

The answer is, Republican administration. The Bush Jr. administration just somehow couldn’t quite seem to get around to allowing the public to see the updated version of that map. The widely-held presumption is that they withheld the information precisely because it showed what I’ve highlighted above: the USDA hardiness zones are migrating north. That’s easily-grasped evidence of the early impact of global warming on the U.S. And so that information was suppressed.

(This, despite the nonsensical CYA language that the USDA insists on including in the footnotes to the description of the map methodology. They seem to say that “climate change” requires 50 years of data, and since each individual map only covers 30 years, you can’t infer that this is the impact of climate change. Despite the fact that the underlying span of data across the full set of maps is now more than 50 years.)

On the other hand, I think those changes ought to get more press coverage. This isn’t natural variation. This is a clear and understandable signal of global warming’s initial effects. And as slow as these changes are, relative to a human lifetime, there’s nothing on the horizon to suggest that they are going to stop any time soon. Five miles a year doesn’t sound like much, until you realize that the U.S. is only 1000 mile north to south, and that things will move a lot faster once global warming really gets rolling. And that it’s fairly hard to grow corn and wheat in a sagebrush and cactus desert.

So, even though I’m still in Zone 7, I think this deserves more press than it has gotten. And I think that the Bush-administration suppression of the circa-2002 map needs to be remembered, right alongside the temperature data.

What are we talking about?

Source: USDA. I removed some details from the map (e.g., degrees C scale) to make it clearer. Thus, I must say that: a) the map is not the official USDA Plant Hardiness Zone Map, and (b) the USDA-ARS and OSU logos are eliminated. If you want to see the full official map, follow the link.

The map above shows the coldest wintertime temperatures in each year, averaged across 30 years of data. The 2023 map literally uses weather data from 1991 to 2020.

The map provides guidance as to what perennial plants can usually be expected to survive the winter, unprotected, in each location.

That’s guidance, not certainty. As the owner of a lime tree, I am acutely aware that citrus trees will typically die back to the ground if they go below about 28F. Plausibly, you need to live somewhere near Zone 10 or higher (e.g., Florida) before you can expect your citrus trees to survive reliably, out-of-doors, unprotected. Even so, the occasional freeze will hit Florida, so significant frost damage to Florida citrus groves seems to occur every few decades or so (reference).

More generally, if you ever buy a perennial plant from an on-line nursery, they’ll let you know the hardiness zones in which the plant is expected to survive. Or they’ll give you information such as “hardy down to 0F”, and leave it up to you to know what USDA hardiness zone you live in.

It’s not hard to get your hands on the underlying data from which these maps were created, for example, via NOAA. I’ve plotted the annual wintertime lows before, for the weather station at Dulles Airport. Here’s 60 years of wintertime lows, as recorded at Dulles.

The obvious upward trend that you see above is pretty much the norm for most of the U.S. So it’s no surprise that the revised USDA map shows those plant hardiness zones creeping northward.

In fact, my location (Vienna VA) graduated from Zone 7A (expected annual low of 0F to 5F) to Zone 7B (5F to 10F). I was firmly in the middle of 7A, now I’m barely at the edge of 7B. That’s reasonably consistent with the increase in wintertime minimums shown in the Dulles data above.

Footnote: Hardiness zone creep exaggerates average warming

One final footnote is that, due to the nature of C02-driven global warming, the northward creep of the hardiness zones exaggerates average warming.

The reason for this is simple: The largest impact of global warming is on nighttime temperatures. (E.g., via Scientific American). And on winter temperatures (E.g., via Axios). By inference, the biggest impact of all should be on nighttime winter temperatures. And, typically, the annual low temperature in an area is set during the course of some winter night.

If nothing else, knowing this is a quick way to dismiss denialist arguments that, somehow, the observed warming on earth is due to changes in the sun. (That, despite direct satellite measurement of solar irradiance, dating back to the 1970s, showing no such thing.) The fact is, the warming is more pronounced at night, and in the winter, both times of limited sunshine. Heuristically, if enhanced atmospheric C02 is a blanket, that blanket matters more when it’s cold and dark.

Conclusion

The real lesson here isn’t the map, per se. Anyone who cared to analyze the publicly-available weather data — as I did above — would already have a strong expectation that the official USDA climate zones would continue to move northward, in this most recent update of the USDA map.

Really, the big lesson here is the missing circa 2002 map. There was a time when Republicans so thoroughly insisted in keeping their heads in the sand, on global warming, that they found excuses not to update this map.

Has that changed? Are Republicans on board now, with the idea that global warming is real? I doubt it, but there’s no way to know. The last two iterations are both dated to periods with Democrats in control of the administrative branch of government. So, as to whether or not a Republican administration would allow this to be updated on a once-a-decade schedule, I guess we just won’t know until we see it. Or not.