SAN FRANCISCO (Reuters) - California's electricity grid operator called off its appeal for residents and businesses to reduce their consumption through the weekend on Friday, as the state's fragile power system appeared to pass one of its toughest tests in years.
While California's Independent Grid Operator maintained a rare "flex" alert through 6 p.m. local time on Friday after a heat wave caused a spike in demand, it said the warning was no longer needed through Sunday thanks to cooler temperatures.
"We're looking at a better situation going into the weekend," said Steven Greenlee, a CAISO spokesman. "We promised Californians we would only use flex alerts when we really need them and we don't need them through the weekend, at least not at this time."
But he also warned that a new test loomed on Monday.
"On Monday people will be coming back to work, it's still going to be hot, and we'll have the residual heat buildup."
The CAISO issued the alert on Thursday, raising the alarm for what promised to be the grid's toughest test since a heat wave in 2007 drove demand within 7 percent of the state's power capacity, prompting a "stage 1" emergency declaration.
Although demand for electricity is still well below that record high, production has also been cut by outages at several key power plants, including the 2,150 MW San Onofre nuclear power plant in Orange County, which hasn't produced electricity since a small radiation leak was discovered in late January.
The state is capable of producing up to 58,600 MW of electricity. Thursday's demand peaked at 45,325 MW. Friday's demand was forecasted to be around 46,685 MW, a relatively comfortable 20 percent below max capacity.
Greenlee hailed Thursday's alert as a success, with conservation by residents and businesses freeing up 900 MW of electricity.
"We are very grateful and thrilled with the response," Greenlee said Friday. "And we're hoping to see something similar today."
The grid operator is working around three unplanned power plant outages, which total 6,402 MW.
(Reporting By Rory Carroll; Editing by David Gregorio)