Air conditioners whir during heat wave, but power systems hold up

Air conditioners kept pumping out the cool air for the most part on Tuesday. Utilities have reported minor outages during the heat wave, but power systems have largely been able to handle the load.

In the man versus heat wave competition, the winner is: the power systems.

Yes, on Tuesday, despite temperatures that climbed into the triple digits, the electric grid in the scorched Eastern part of the United States was pretty much able to handle the load. Utilities reported minor outages, but for the most part, air conditioners kept pumping out the cool air without interruption.

But since Wednesday is supposed to be almost as hot, the utility industry continues to carefully watch the load on the electric grid.

IN PICTURES: Beating the summer heat

“So far, so good,” says Jim Owen, a spokesman for the Edison Electric Institute in Washington. “But we are watching it carefully.”

Things haven’t gone quite so smoothly north of the US border. On Monday, about 250,000 Toronto residents lost their electricity for about four hours after a fire at a transformer station. Subways were shut down, and high-rises lost their elevator service, requiring firefighters to rescue stranded residents. The shutdown coincided with a visit by Queen Elizabeth II, whose state dinner was briefly delayed.

The triple-digit temperatures in the Eastern US can put a lot of physical stress on the electrical system, Mr. Owen says. Feeder cables, for example, can melt or stop working. And transmission lines can sag and stretch, with the danger that they come into contact with tree limbs.

“Everyone is at full battle stations; this is what we train for,” says Owen.

The nation’s electrical-system operators, he says, have learned a lot since Aug. 14, 2003, when a cascading blackout resulted in 50 million people in the Eastern US losing their power.

Two years after that blackout, Congress passed legislation that authorized strict new rules for utilities.

“If they don’t comply with the new standards, they can be fined or even sanctioned,” Owen says.

As part of the legislation, utilities were tasked with mandatory tree trimming, since it was determined that a tree bough brought down a transmission line, starting the 2003 blackout. And as part of new training, grid operators are instructed on when an area has to be isolated and blacked out to prevent another cascade.

According to some system operators on Tuesday, demand had already gone beyond the forecasted summertime peak. In New York State, the load hit 33,413 megawatts, above the peak forecast of 33,025, according to Dave Flanagan, a spokesman for the New York Independent System Operator (NYISO), a nonprofit that operates the state’s electric grid. A megawatt is the amount of electricity needed to serve 750 to 1,000 homes, depending on the size of the house.

To accommodate the high demand, Mr. Flanagan says, some large customers were required to reduce demand under their contracts or were asked to reduce demand.

Still, New York has some margin for even more demand: It has just over 43,000 megawatts available to it.

“We do have plenty of resources,” says Flanagan.

The New England utilities also seemed to be meeting a high level of electricity demand. “We’ve been able to meet robust consumer demand,” says Ellen Foley, a spokeswoman for ISO New England in Holyoke, Mass.

If they can get through Wednesday, system operators expect some relief as temperatures start to moderate slightly later in the week.

IN PICTURES: Beating the summer heat

Related:

• Heat wave: Triple-digit temperatures push East Coast to pools, malls
• Progress on preventing blackouts