AC power grid eyes supply as weather warms

Temperatures are about to soar and California’s electricity supply is about to tighten.

California’s Independent System Operator, or ISO, which operates the state’s power grid, on Friday asked generators and transmission line operators to delay any scheduled maintenance.

The advisory goes into effect Monday through Thursday, from noon to 10 p.m. each day, when temperatures are expected to exceed 100 degrees in much of the state.

“Avoid actions that could compromise production and/or transmission availability,” the organization said.

Although the ISO has not yet issued a call for conservation, the advisory illustrates the fragility of the California network. Two years ago, the state suffered two nights of power outages during a 110-degree heat storm that engulfed much of the West. The power outages exposed grid vulnerabilities in the early evening – when the solar power supply fades, but homeowners continue to start their air conditioners. Solar power can account for a third or more of California’s electricity supply during the summer.

Since then, state officials have rushed to fortify the network, forcing PG&E Corp. and other utilities to line up additional power supplies. California is also promoting the development of “battery farms,” facilities with utility-sized batteries that can store unused electricity generated during the day for use during the evening hours.

While that has helped, state officials have warned that supply remains limited and power outages are possible this year. The drought wipes out much of California’s hydroelectric power, putting further pressure on supplies.

Next week is shaping up to be one of the hottest of the year, with high temperatures forecast to peak at 104 on Tuesday, according to the National Weather Service.