The generators in Yuba City and Roseville are reserved for extreme energy needs, like this week's historic heat wave.
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At 4 pm Tuesday, a level 2 Energy Emergency Alert went into effect.
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It was issued by the California Independent System Operator (ISO) and triggered the generators to be powered up.
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"Within 10 minutes, we can be at full capacity with these units. And full capacity right now for what we have got is 120 megawatts of generated capable power," said Tony Myers of the Department of Water Resources. "That's equivalent to 120,000 homes that can be powered by just these four units."
He says they provide much-needed support to the state's grid when people need to use their air conditioning most. The generators were powered up for the first time Monday night from 6 to 9 pm, one of many assets that prevented outages that night.
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"To help make sure that we got the peak demand with enough supply," he said. "Keep everybody happy and keep their homes comfortable."
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In the summer of 2020, a heat wave triggered rolling blackouts up and down the state. State energy leaders hope putting six additional emergency generators online next summer could prevent that.
"So that we can have that much more dependability and reliability for the grid," said Myer.
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On Tuesday, California ISO continued to update the severity of energy emergency alerts. Even with extra power on deck, conserving between 4 to 10 pm will still be critical to keeping the power on in California.
"It's been tight for several days. [Tuesday] is expected to be the tightest day given the hot temperatures," said Jeff Smith with PG&E. "Not only through California, but the west."