The heat has yet to break, but Californians are being urged to turn down their air conditioners.

Operators of the state's electricity grid have declared a Flex Alert for Tuesday, telling customers to curb their power use as California's inland regions face yet another day of sky-high heat.

The California Independent System Operator (ISO) says conservation will be critical. Customers are being asked to set their air conditioners to 78 degrees or higher, to wait until after 7 p.m. to use major appliances and to turn off anything that isn't necessary.

The call for conservation led a KQED News Twitter follower to ask if Californians could do more to avoid Flex Alerts:

http://twitter.com/DebWTrotter/status/235462514811482112

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The answer is: probably not. California ISO Spokesperson Stephanie McCorkle explained that you can't store energy conserved at other times of the year to use in the summer. There is no battery big enough to store power for the Golden State.

"You can't bottle up electricity right now," McCorkle said. "We are creating energy as soon as it's provided."

McCorkle said Flex Alerts are called whenever increased demand threatens to put additional stress on the power grid. That increased demand risks causing fatigue in the power equipment.

Of course, Californians might be able to avoid Flex Alerts by following the Flex Alert conservation recommendations throughout the summer, even when alerts aren't called. Peak demand for energy today is forecast at 47,500 megawatts; the state has the resources to produce about 54,000 megawatts of power, according to the CISO website.

McCorkle said Flex Alerts typically reduce demand by about 1,000 megawatts. She noted that conservation is particularly important this summer due to the loss of the San Onofre nuclear power plant, which has been shut down since January due to a damaged generator. The plant had been generating about 2,200 megawatts at any given time.

Californians have never demanded more power than the state can provide in the 10 years since Flex Alerts were created, McCorkle said.

flexalert — California's power outlook as of 2 p.m. Image courtesy of the California ISO.

You can find up-to-date information about power use in California on the CISO website; for more about Flex Alerts, head to FlexAlert.org.

The National Weather Service has issued excessive-heat warnings from Santa Barbara County through southeastern California and in much of the San Joaquin Valley.

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