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Rob debriefs with colleagues on the latest climate news.
In a special episode of Shift Key, Rob interviews Representative Sean Casten about his new energy price bill, plus Emerald AI’s Arushi Sharma Frank.
Rob and Jesse talk to Ember’s Kingsmill Bond about how electricity is reshaping global geopolitics.
Rob and Jesse riff on the state of utility regulation in America — and how to fix it.
Rob talks to Peter Brannen, author of the new book The Story of CO2 Is the Story of Everything.
Rob and Jesse revisit the basics of the ultra-clogged electricity interconnection queue.
Rob and Jesse quiz Mark Rothleder, chief operations officer at the California Independent System Operator.
So far on Shift Key Summer School we’ve covered how electricity gets made and how it gets sold. But none of that matters without the grid, which is how that electricity gets to you, the consumer. Who actually keeps the grid running? And what decisions did they make an hour ago, a day ago, a week ago, five years ago to make sure that it would still be running right this second?
This week on Shift Key, Rob and Jesse chat with Mark Rothleder, senior vice president and chief operating officer of the California Independent System Operator, which manages about 80% of the state’s electricity flow. As the longest-serving employee at CAISO , he’s full of institutional knowledge. How does he manage the resource mix throughout the day? What happens in a blackout? And how do you pronounce CAISO in the first place?
Shift Key is hosted by Jesse Jenkins, a professor of energy systems engineering at Princeton University, and Robinson Meyer, Heatmap’s executive editor.
Subscribe to “Shift Key” and find this episode on Apple Podcasts, Spotify, Amazon, YouTube, or wherever you get your podcasts.
You can also add the show’s RSS feed to your podcast app to follow us directly.
Here is an excerpt from our conversation:
Jesse Jenkins: To make this a little bit more concrete, walk through how you’re orchestrating the generation fleet. What is the typical mix of resources that you’re calling on at different times of day, on a typical California day. Let’s start at 8:00 a.m. and, you know, move through the day.
Mark Rothleder: So if it’s like today, it’s a moderate summer day, there would be in the. There would be some thermal resources, gas resources that would already be on, probably near their minimum load, which is probably about 30%, 40% of their full operating capability. And they would be sitting there waiting for dispatch instructions as the load increased.
And I talk about the morning because people start turning lights on. This is when the load starts to increase, in that morning hour. So to balance the system as that load increases relatively quickly, you’re going to have a combination of probably solar starting to come up and produce, naturally, because the sun is coming out. You may have a little bit of wind production starting to increase because the wind’s starting to blow because the temperatures and the system are driving that wind. If that’s not enough energy, we’re dispatching probably thermal resources, probably doing some exchanges through the Western Energy Imbalance Market with the neighbors.
And then you get to about probably 9 o’clock, 10 o’clock ,and things stabilize. And then what ends up happening, at least in our system, is you start to see solar production continue to go up, but the load is not increasing. It’s kind of flattened out. We start to probably see some backing off of thermal resources that were brought up during that morning load pull. And now we’re starting to back off on those, and maybe even getting to the point where surplus energy in the middle of the day — we’re exchanging and maybe exporting some of our energy to our neighbors because we have surplus. We’re probably starting to see batteries charge up in the middle of the day because now we’ve got this cheap energy. And this is going to probably go on until about 4 o’clock, 5 o’clock in the afternoon, when the traditional peak of the day is, and this is when the highest gross load is.
And then we start to see another dynamic happen, and that is, at least in our system, the sun starts to set and then the solar production starts to decrease. What’s interesting about that is, as the solar production decreases, it happens over about a three-, four-hour period, and it’s a relatively fast ramp out of those solar resources. The load is not dropping. And in fact, if you think about —
Jenkins: It’s rising often, right?
Rothleder: It’s actually still rising because some of the load that was previously served by behind the meter rooftop solar, that load is also coming back on the system because the solar production is decreasing. So again, to rebalance the system and keep that balanced and straight, we have to start ramping up a couple things. We start to turn, maybe, what was exports around, and we start importing energy from our neighbors. We start discharging the batteries that we just charged up earlier. And to the extent we still need other energy, we probably have a combination of thermal gas resources that we’re bringing them off their minimum load, dispatching them up during the day, and probably some hydro resources that are able to be dispatched during the day.
Between 6 p.m. and 7 p.m. we hit what we call our net peak. We call it net peak because it’s the gross load minus wind and solar production. And that tends to be the most critical time when we need — since the ramp out of wind and solar, more solar, that kind of is the highest where we need other resources to be available and dispatched. And so once we get through that net peak, come around 6:30, 7 o’clock, things just start to gradually turn around. And then we’re ramping out over the rest of the day the thermal resources, the interchange, and the hydro resources that we previously dispatched up to get to that net peak. And this all starts over again the next morning.
Mentioned:
Jesse’s slides on long-run equilibrium and electricity markets
Shift Key Summer School episodes 1, 2, 3, and 4
Also on Shift Key: Spain’s Blackout and the Miracle of the Modern Power Grid
This episode of Shift Key is sponsored by …
Accelerate your clean energy career with Yale’s online certificate programs. Gain real-world skills, build strong networks, and keep working while you learn. Explore the year-long Financing and Deploying Clean Energy program or the 5-month Clean and Equitable Energy Development program. Learn more here.
Join clean energy leaders at RE+ 25, September 8–11 in Las Vegas. Explore opportunities to meet rising energy demand with the latest in solar, storage, EVs, and more at North America’s largest energy event. Save 20% with code HEATMAP20 at re-plus.com.
Music for Shift Key is by Adam Kromelow.
Jesse gives Rob a lesson in marginal generation, inframarginal rent, and electricity supply curves.
Most electricity used in America today is sold on a wholesale power market. These markets are one of the most important institutions structuring the modern U.S. energy economy, but they’re also not very well understood, even in climate nerd circles. And after all: How would you even run a market for something that’s used at the second it’s created — and moves at the speed of light?
On this week’s episode of Shift Key Summer School, Rob and Jesse talk about how electricity finds a price and how modern power markets work. Why run a power market in the first place? Who makes the most money in power markets? How do you encourage new power plants to get built? And what do power markets mean for renewables?
Shift Key is hosted by Jesse Jenkins, a professor of energy systems engineering at Princeton University, and Robinson Meyer, Heatmap’s executive editor.
Subscribe to “Shift Key” and find this episode on Apple Podcasts, Spotify, Amazon, YouTube, or wherever you get your podcasts.
You can also add the show’s RSS feed to your podcast app to follow us directly.
Here is an excerpt from our conversation:
Jesse Jenkins: If I’m just a utility operating on my own, I want to basically run my fleet on what we call economic dispatch, which is rank ordering them from cheapest to most expensive on a fuel or variable cost basis, and trying to maximize my use of the less expensive generators and only turn on the more expensive generators when I need them.
That introduces this idea of a marginal generator, where the marginal generator is the last one I turned on that has some slack to move up or down as demand changes. And what that means is that if I have one more megawatt-hour of demand in that hour — or over a five-minute period, or whatever — or 1 megawatt-hour less, then I’m going to crank that one generator up or down. And so the marginal cost of that megawatt-hour of demand is the variable cost of that marginal generator. So if it’s a gas plant that can turn up or down, say it’s $40 a megawatt-hour to pay for its fuel, the cost on the margin of me turning on my lights and consuming a little bit more is that that one power plant is going to ramp its power up a little bit, or down if I turn something off.
And so the way we identify what the marginal value of supplying a little bit more electricity or consuming a little bit more electricity is the variable cost of that last generator, not the average cost of all the generators that are operating, because that’s the one that would change if I were to increase or decrease my output.
Does that make any sense?
Robinson Meyer: It does. In other words, the marginal cost for the whole system is a property of the power plant on the margin, which I realize is tautological. But basically, the marginal cost for increasing output for the entire system by 1 megawatt-hour is actually a property of the one plant that you would turn on to produce that megawatt-hour.
Jesse Jenkins: That’s right, exactly. And that can change over the course of the day. So if demand’s really high, that might be my gas plant that’s on the margin. But if demand is low, or in the middle of the day, that gas plant might be off, and the marginal generator during those periods might be the coal plant or even the nuclear plant at the bottom of the supply curve.
Mentioned:
Jesse’s slides on electricity pricing in the short run
Jesse’s lecture slides on electricity pricing in the long run
Shift Key Summer School episodes 1, 2, and 3
This episode of Shift Key is sponsored by …
Accelerate your clean energy career with Yale’s online certificate programs. Gain real-world skills, build strong networks, and keep working while you learn. Explore the year-long Financing and Deploying Clean Energy program or the 5-month Clean and Equitable Energy Development program. Learn more here.
Join clean energy leaders at RE+ 25, September 8–11 in Las Vegas. Explore opportunities to meet rising energy demand with the latest in solar, storage, EVs, and more at North America’s largest energy event. Save 20% with code HEATMAP20 at re-plus.com.
Music for Shift Key is by Adam Kromelow.
