NEW YORK — A lengthy, blistering heat wave that is blanketing the eastern half of the United States is putting significant stress on the nation's power grid as homeowners and businesses crank up their air conditioners.
Utilities say they're ready for high power demand and widespread electricity shortages or outages are unlikely. Lines and equipment are not fully taxed and there is more generating and transmission capacity available than usual because of the weak economy. There are also few major storms in the forecast, meaning fewer downed power lines.
The heat wave began a week ago in the Plains states and is expected to spread east through the weekend. It is lasting longer than most heat waves and is spread over an unusually wide area, according to Travis Hartman, the Energy Weather Manager at MDA Earthstat, which proves forecasts for utilities and other weather-dependent businesses.
Hartman predicts 90- to 100-degree weather from Chicago to Boston from Wednesday through the weekend. The Midwest is expected to see peak heat on Thursday while thermometers in eastern states will top out on Friday and Saturday. Philadelphia may break a 1957 record of 100 degrees on Friday, while Washington, D.C., is expected to reach 103, tying a record from 1926.
Texas and the southern Plains states will extend a long streak of hot weather. On Wednesday, Oklahoma was expected to suffer its 30th day of triple-digit temperatures this year.
Nationwide, today and Friday will be hotter than any time since 1950, Hartman said.
"It's going to mean elevated power demand for an extended period of time for a lot of people," he said.
To meet demand, utilities are firing up special power plants used only a few days a year, delaying scheduled maintenance in order to keep all equipment on line and testing heat-sensitive switches and other equipment with high-tech devices like thermographers that can gauge temperatures to one-tenth of a degree.
"These are the days everyone wants to have their ACs on, their computers going while they watch TV," said Jon Jipping, chief operating officer of ITC Holdings Corp., a transmission grid operator that owns grids in Iowa, Michigan and four other Midwest states. "These are the days we get ready for."
Peak demand for most utilities usually happens on a late weekday afternoon in midsummer. That's when businesses are still open but people return home, turn on their air conditioners, lights and televisions and they start cooking dinner.
Problems can arise when the grid comes under maximum strain.
Equipment can't cool off, and it can't handle as much power as usual. Lines, transformers and switches are working at full capacity and can be overwhelmed by power surges that can result from a blown piece of equipment or downed power line.