ARI SHAPIRO, HOST:
A heat wave has broken records this week from North Carolina to Massachusetts. Electric utilities are asking people to conserve energy as power demand surges. And higher demand is not the only challenge utilities face in these temperatures. From member station KUT in Austin, Mose Buchele reports how the heat itself can stop electricity from getting to your home.
MOSE BUCHELE, BYLINE: Michael Webber is a professor in the mechanical engineering department at the University of Texas at Austin. He says there is a cruel irony when it comes to electric grids in the heat of summer. They start to struggle right when customers need them the most.
MICHAEL WEBBER: What happens when it's really hot is everything underperforms, yet demand is higher than ever.
BUCHELE: It starts at the power plant. Coal and gas plants already get really hot generating electricity. Webber says doing it in a heat wave is like an athlete running a marathon.
WEBBER: It's the same. Like, the human experience in heat is the same as a power plant experience. They have trouble shedding the excess heat they generate in the process. They are just less efficient. They are more inclined to break down.
BUCHELE: Sometimes, they do break down. And to keep plants running, operators reduce how much electricity they generate - not ideal when everybody needs power to run their AC.
WEBBER: So that's part of the problem.
BUCHELE: But not the only part. Things don't get easier once that electricity reaches transmission lines.
ALISON SILVERSTEIN: So transmission lines - big wires between very tall towers that go across a state.
BUCHELE: Alison Silverstein is an energy consultant and former official with the Federal Energy Regulatory Commission, or FERC. She says those lines also get hot moving electricity. The more of it they move, the hotter they get. When they get too hot, they become less efficient, shedding power. It's called line loss.
SILVERSTEIN: Which means, even if you have a huge amount of generating capacity available, you're losing a huge amount by the time it gets to customers.
BUCHELE: Power lines, usually made of steel and aluminum, also expand and start sagging in the heat. That's dangerous because they can droop close to trees and other things that can start wildfires. But if it doesn't, the sag can also cause lines to just stop carrying power. In fact, drooping, overheated power lines were one of the causes of a huge blackout in 2003 that Silverstein investigated while at FERC.
SILVERSTEIN: The specific transmission lines started dropping out. The electricity started redistributing across other lines and, therefore, overloading other transmission lines.
BUCHELE: Then those lines sagged and stopped working.
SILVERSTEIN: It was slow until it was fast, and then it was really fast.
BUCHELE: Fifty million customers lost power in the northeastern U.S. and Canada.
MARK LAUBY: And so we got to watch sag.
BUCHELE: This is Mark Lauby. He's the chief engineer at the North American Electric Reliability Corporation, or NERC. He says after that blackout, NERC put new practices into place to monitor and mitigate the risk of sagging.
LAUBY: And so many times, what the utility will have to do is to ease off on the amount of flow because they got to manage that sag.
BUCHELE: He says new technologies and engineering are letting transmission utilities better monitor power lines and build a stronger system. Big utility-scale batteries can also help keep things running when the grid hits heat-related hiccups. But climate change is also making heat waves stronger and longer-lasting. That not only drives up energy demand, it places ever more strain on the system. Again, Alison Silverstein.
SILVERSTEIN: We're asking the grid to do, at minimum, heavy walking, if not flat-out sprinting, for more and more hours and days of the year.
BUCHELE: She and others say planning an energy system for a hotter future will be essential to keeping the lights on and the AC running. In the shorter term, the heat dome that's caused so much discomfort in the eastern U.S. is moving southwest. Triple digits are expected here in Texas by next week.
For NPR news, I'm Mose Buchele in Austin. Transcript provided by NPR, Copyright NPR.
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