California grid sets record, with 67% of power from renewables

Wind turbines dot the hills outside of Rio Vista, Ca. on Wed. April 19, 2017. Wind turbines dot the hills outside of Rio Vista, Ca. on Wed. April 19, 2017. Photo: Michael Macor / The Chronicle Buy photo Photo: Michael Macor / The Chronicle Image 1 of / 4 Caption Close California grid sets record, with 67% of power from renewables 1 / 4 Back to Gallery

A stretch of sunny, windy days, combined with brimming reservoirs at hydroelectric plants across the state, helped California reach a renewable energy milestone last weekend.

Early Saturday afternoon, renewable sources produced a record 67.2 percent of the electricity on the portion of the state’s power grid controlled by the California Independent System Operator. That figure does not include large hydropower facilities, which added another 13.5 percent. Based in Folsom, the ISO runs 80 percent of the state’s grid.

More than half of the renewable energy flowing across the grid at that moment on Saturday came from large solar facilities and wind farms. The ISO’s numbers do not even account for electricity from rooftop solar arrays.

Overall, renewables accounted for 42 percent of the California grid’s power on Saturday, not counting the large hydropower plants.

“The fact that the grid can handle 67 percent renewable power from multiple sources — it’s a great moment, and it shows the potential we have,” said Sachu Constantine, the director of policy at the Center for Sustainable Energy, a nonprofit clean energy advisory firm in Berkeley.

Sustaining such high levels, however, will be challenging, he said.

California law requires utilities to get 33 percent of their electricity from renewable sources by 2020, rising to 50 percent by 2030. Last year, California's three large electric utilities collectively got 32.3 percent of their electricity from renewables. (Neither the state requirement nor the 2016 figure includes large hydropower facilities.)

Saturday’s numbers are the latest benchmark in what is expected to be a record-setting year for renewable energy production in California, because of the growing number of solar power plants in the state, the seasonal increase in sunshine and the flush hydroelectricity reserves produced by last winter’s rain.

For a span of three hours on March 11, solar power met roughly half of all electricity demand across much of the state, according to the federal Energy Information Administration, the Energy Department’s statistics division. The proportion of power produced from renewables that day peaked at 56.7 percent — a record at the time.

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The torrents of rain that fell in the state have filled hydroelectric dams to levels not seen in decades. Up to 21 percent of the state’s total electricity output could come from hydroelectricity this year, according estimates from the California Energy Commission.

And on Tuesday, the state set a new record for wind power generation, producing 4,985 megawatts. A megawatt is a snapshot figure roughly equal to the amount of energy used by 760 homes at any given moment.

“It’s going to be a dynamic year for records,” said Steven Greenlee, a spokesman for the ISO. “The solar records in particular are falling like dominoes.”

It is possible, Greenlee said, that the state could cross the 70 percent threshold for renewable production this summer.

The steady stream of record-breaking days is a positive sign that the grid is adapting well to the influx of renewable energy, according to Greenlee. “That shows how our grid is shifting from the old paradigm, the old grid we used to have,” he said.

Given current weather forecasts, it is not out of the question that the state could push past the new record by this weekend, Greenlee said.

Constantine hopes the state’s clean energy milestones will show that California can continue to wean itself off fossil fuels.

Still, “there’s a lot of work before we see 60-70 percent renewables (on a sustained basis), even in the summer months,” he said.

Dominic Fracassa is a San Francisco Chronicle staff writer. Email: dfracassa@sfchronicle.com Twitter: @dominicfracassa

Energy sources on the California grid, May 13

Wind

16.3%

Solar

17.2%

Hydro

19.2%

Other

renewables

6.1%

Nuclear

5.1%

Natural gas

11%

Imports

25.1%