CHARLOTTE -- Temperatures should be down a few degrees this week, but Duke Energy's struggle to provide power for the Charlotte region isn't over.
On Friday, a new problem arose when Duke had to curtail power generation at two coal-powered plants on the Catawba River, Duke spokeswoman Paige Sheehan said. The river's water temperature is too high to use for cooling.
Low lake levels already had cut the hydro generation that Duke usually taps at peak times.
Duke uses river water to cool its coal-powered steam operations. That heats the water, which then is discharged back into the waterway.
But when the water is too hot to begin with, the state won't allow Duke to add to the heat because the resulting temperature would be too hot for wildlife and cause other environmental concerns.
The temperature at which Duke can't use the water for cooling differs by station, said Duke spokeswoman Mary Kathryn Green.
Only two stations -- Riverbend Steam Station in Mt. Holly, N.C., and Allen Steam Station in Belmont, N.C. -- have been impacted so far, but other plants that do not have cooling towers are vulnerable if water temperatures climb, Sheehan said. It's unclear how long it will take for the water to cool down.
Both the heat wave and the drought have caused the water temperature problem. The drought has lowered water levels in the lakes, and smaller amounts of water heat up more quickly.
"People think that because the temperatures are down that we're OK," Sheehan said. "The drought is having a much bigger impact on us."
Duke hit its all-time peak for power usage on Wednesday. Thursday would have been another record, but the company implemented a program in which some big customers stop using Duke power. The program was continued Friday. Power customers have experienced scattered outages as demand taxed the system.
Conservation efforts by customers could help the utility meet power demand and also allow some generators to rest, Sheehan said.
"If everybody turns off one light bulb, that makes a huge difference," Sheehan said.
Duke Energy suggests ways residents can conserve electricity:
• Turn up the thermostat on air conditioning.
• Use fans to circulate air.
• Close blinds and curtains to keep out heat.
• If you experience a power outage during a peak demand time (mid-afternoon), turn off lights and appliances. That makes it easier for Duke to restart the power.
More conservation tips are available at www.duke-energy.com.