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Draft plan outlines how power will get from offshore wind farms in Northern California to the grid

Power lines in Sacramento County

Posted on April 17, 2024

A draft plan estimates it could cost up to $4.5 billion dollars to connect a future offshore wind energy project on the Northern California coast with the rest of the state’s electric grid.

The California Independent System Operator, which oversees the operation of most of the state’s power grid and transmission lines, released the 2023-2024 transmission plan on April 1.

Almost all of the proposed $6.1 billion in spending to meet reliability and green energy needs would go to connecting planned offshore wind projects on the Northern California coast.

Arne Jacobson from the Schatz Energy Research Center at Cal Poly Humboldt, who was not involved in the transmission plan, said the decision was made to transmit all the power over land using two new high-voltage lines. He said they chose not to use massive undersea cables to transport energy down the coast.

“The undersea routes may be possible a bit out into the future,” Jacobson said. “But the technology for the undersea routes isn’t yet commercially available.”

The undersea routes would also be more expensive, and there are environmental problems transporting energy from Humboldt County to places like the Bay Area.

Jacobson said there are a number of ecologically sensitive locations and undersea canyons that would be impractical to cross with cables.

He said the technology for deep undersea cables hasn’t been developed yet.

“So, it might be there in 20 years but we’re thinking of something that would be built over the next 10 years,” Jacobson said.

Jacobson and his team released a study late last year looking at possible options for offshore wind transmission on the West Coast.

Two 500 kilovolt power lines are being constructed to connect wind power to the rest of the grid. One will connect at a substation East of Redding, and the other further south in Collinsville, according to the transmission plan.

The California ISO anticipates the projects in this plan will take about a decade to be completed. The projects will be paid for through increased rates for consumers. Those would be phased in by utilities through their rate-setting process as the new infrastructure comes online.

The draft transmission plan will be presented for final approval by the Board of Governors at California ISO in May.

Jacobson said he’s happy to see that the plan also includes a connection between the new high-voltage lines and the local power grid that’s managed by PG&E.

“That will improve the reliability of electricity in the Humboldt Bay region,” he said. “And will also provide a pathway for either phasing out or at least greatly reducing the use of the natural gas power plant.”

Much of the Humboldt Bay’s electricity needs are currently supplied by natural gas power plants through a substation in Cottonwood, around 120 miles away.

The electric system in Humboldt County has also been plagued by reliability issues, in part because it’s so isolated from the rest of the energy grid.

2022 electric reliability report from PG&E shows the Humboldt region has seen longer and more frequent outages in recent years. According to the report, some outages have been because of increased wildfire mitigation efforts.

But, Jacobson said some of these problems will remain past the advent of offshore wind energy. He said that’s because local power lines are outdated, and need replacing by PG&E.

Jacobson said his team at the Schatz Energy Research Center is working on a study to explore additional ways to relieve reliability issues in these rural areas, including power storage systems and micro-grids.


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