Weather

Flex Alert urges Californians to conserve energy Tuesday amid heat wave

The California Independent System Operator’s nerve center in Folsom, where it runs the state’s main electricity-transmission grid.
The California Independent System Operator’s nerve center in Folsom, where it runs the state’s main electricity-transmission grid. Sacramento Bee file photo

California’s energy grid operator has issued a “Flex Alert,” calling on residents to conserve power on Tuesday, when hot weather is expected to propel energy demand to its highest point so far this year.

Folsom-based California Independent System Operator is urging people to be especially energy-conscious between 2 and 9 p.m., when demands on the energy grid typically peak. California ISO expects energy usage to reach 48,000 megawatts Tuesday afternoon, surpassing Monday’s peak usage of 47,575 megawatts, the highest load the state’s power grid has had to handle in 2017.

“The Flex Alert is the first tool in our toolbox to manage grid stress, and it’s proven to be very effective over the years,” said Steven Greenlee, a California ISO spokesman.

Greenlee suggested that people wanting to conserve energy turn up their air-conditioning to 78 degrees, turn off unneeded lights and avoid using big appliances until the Flex Alert ends at 9 p.m.

California ISO has only issued an alert for Tuesday, but it may do so again on Friday, Greenlee said. The average temperature for non-coastal areas of utility PG&E’s service region in Northern California is expected on Friday to hit 108 degrees, significantly higher than Tuesday’s predicted average of about 103, according to Greenlee.

California ISO typically issues two or three Flex Alerts per summer, Greenlee said. The last alert was for June 20 and 21, in the midst a heat wave even more intense than the one hitting the state now.

The National Weather Service predicts that Sacramento will reach 103 degrees Tuesday, a dip from Monday’s high of 109 degrees. Weather may cool on Wednesday before rising until Friday, when temperatures are forecast to reach 110.

With the Flex Alert in place, the power grid should be able to meet demand, Greenlee said. But if issues besides heat arise – for example, if a generator breaks under strain or if a wildfire disrupts the grid – power utility companies may need to rotate short power shutdowns through their customers.

A Spare the Air day has been issued for Tuesday in the Sacramento region, with a 126 AQI forecast, which is unhealthy for sensitive groups.

Hannah Knowles: 916-321-1141, @KnowlesHannah

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