This summer, there's a higher likelihood than ever that Texas might not have enough electricity to go around. If you turn on the AC and nothing happens, you’ll want to know why. It helps to remember legendary Led Zeppelin drummer John Bonham.
Let me explain.
The electric grid is a network of transmission lines that connects power generators to users. The grid has a beat. It doesn't sound very pretty, kind of a low hum. It is the sound of 60 hertz, the frequency electricity runs over transmission lines.
“It’s like a heartbeat on the grid. It’s 60 cycles per second, 60 beats per second,” says Warren Lasher, planning director for the Electric Reliability Council of Texas (ERCOT).
In the same way that John Bonham manages the beat of Led Zeppelin, Lasher says, ERCOT manages the beat of the grid.
"It's a drummer; it's that beat that needs to be maintained," he says.
If ERCOT doesn’t keep that beat steady, bad things happen. And keeping it steady is a balancing act: All the electricity going on the grid must equal the amount that's coming off it.
“That’s one of the real focusses of what goes on here at ERCOT ... making sure that the power plants are producing, every second of the day, exactly the same amount of power as what the customers are using,” Lasher says. “That’s kind of difficult.”
If there's more power on the grid than people use, he says, “that rhythm of the grid will start speeding up.”
That change in speed can knock power plants offline and damage factories. Worst case scenario? It can cause grid-wide blackouts.
At ERCOT headquarters, there's a control room that looks a little like NASA’s Mission Control. It's staffed 24 hours a day by people trying to make sure something like that grid-wide blackout never occurs.
Because of the way the grid is managed in Texas, though, that “speeding up” is unlikely. ERCOT really worries about the opposite: People using more electricity than the state has available. That would slow the beat down, which would likewise create the risk of a grid-wide blackout.
Avoiding that, Lasher says, means focusing on one day: the hottest day of the year, when everyone in the state cranks up their ACs.
“That’s the day when customer demand is going to be the highest,” he says. “That’s kind of our benchmark. What is our demand going to be on that hottest day of the summer? Do we have enough generation resources to meet that demand?”
To avoid grid failure, ERCOT wants enough power to meet that demand – with some extra in reserve. Officials call it the "electricity reserve margin." But this summer, there’s less of that extra “just in case” electricity than ever before. In fact, there’s less of it in Texas than in any other grid in the country.
The reasons for that are complicated; they have to do with the decline of coal-power generation and the way the state set up its unregulated electricity market. But it means grid operators are more likely to declare an emergency this summer.
What does that mean?
“In order to maintain the reliability of the grid, you, in essence, have to reduce your customer demand,” Lasher says.
The people in the ERCOT control room have a lot of ways to do that. They pay big industrial users to shut down, which can lower electricity demand and keep the grid stable. They can also issue a call for residential customers to conserve.
But the last-ditch thing they can do is what you might know as rolling blackouts. Basically, ERCOT shuts off the power in different parts of the state for small chunks of time.
“What the customer will actually see is that their lights will go out for like 15 minutes and then their lights will come back on again,” Lasher says. “What they won’t see is then the next neighborhood over has lost their power for 15 minutes. So, in that way it rotates through the system.”
Grid experts and managers still say rolling blackouts are highly unlikely. But if your power goes off some hot day this summer, that could be why.
It's all about keeping the beat steady, John Bonham style.
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