California electrical grid operator OK’d $89 million in Sonoma, Napa reliability upgrades

Planners for California’s electrical grid have eyed up to $88.6 million in needed upgrades to transmission lines and equipment in Sonoma and Napa counties to prevent forecast overloads in certain segments in coming years.

The California Independent System Operator Board of Governors on Thursday unanimously approved those North Bay projects amid a “historic” slate of transmission system upgrades totaling 45 projects and $7.13 billion in estimated cost.

The local projects include an estimated $37 million to $74 million to replace 115,000-volt lines between the Fulton and Lakeville substations in north Santa Rosa and south Petaluma, and $7.3 million to $14.6 million to swap out the 60,000-volt lines and certain equipment between the Tulucay and Basalt substations in southern Napa Valley.

If approved, the projects would go out for competitive construction bids, and the California Public Utilities Commission would coordinate sites and line routes, according to spokesperson for the grid operator.

Those projects are among two dozen reliability-focused efforts statewide in the agency’s 2022-23 transmission plan, updated May 10, at an estimated cost of $1.76 billion. The grid operator annually analyzes the suitability of the network of high-voltage lines that connect suppliers such as power stations to points where the power is stepped down for distribution to commercial and residential users.

But emphasis on reliability in the current transmission planning cycle was ratcheted up in December by the utilities commission, which said the focus must be on preparing the grid for electrification of transportation and buildings.

The current transmission plan’s assessment of reliability of Pacific Gas & Electric Co.’s North Coast and North Bay lines found undisclosed “contingencies” that starting next year would lead to overloads between the Corona and Lakeville substations in Petaluma, Santa Rosa and Corona substations, and Fulton and Santa Rosa substations. Details on those problems are in a confidential section of the plan.

Replacing the Santa Rosa-Petaluma lines, called reconductoring, would take care of the potential for overloads issue in 2028, when the new lines are expected to be in service, according to the plan.

To deal with the local overloads, the grid operator had considered implementing what’s called a remedial action scheme, currently used in Southern California to balance power production and demand in a given area. But the agency said in the plan that it was “not feasible” because of the number of systems to be monitored was more than its standards allow.

PG&E said Sonoma County transmission capacity wouldn’t impact interconnections of new homes or businesses to the grid.

“The identified issues in the CAISO transmission plan at this time are not expected to affect new electrical customer connections in the Santa Rosa, Petaluma or surrounding areas,” the company said in a statement. “PG&E continues to monitor actual demand development in the area and develop interim mitigation plans as needed until newly identified projects become operational.”

That’s in line with the unspecified “operating action plans” the grid operator’s draft transmission plan said would be a stopgap measure until 2028.

Grid capacity has become and issue locally and statewide in recent months.

As the Business Journal reported in December and March, a few warehouse projects in the Sonoma County airport industrial area have received notice from PG&E that interconnecting the new buildings to the grid could be delayed until late 2025. The utility said that was because of needed upgrades to distribution lines from the Fulton substation.

Santa Rosa Chief Building Official Jesse said only a few projects in the city have been affected by power interconnection delays.

As for the Napa Valley transmission line project, it adds to a $5 million to $10 million project the grid operator approved in 2020 to deal with projections at the time of overloads starting in 2024. The new switches and jumpers, set to come on line by the end of 2025, are forecast to push back the overload problem to 2032. The new transmission lines, expected to come on line in 2028, are set to deal with the overloads at that later date.

Further on the horizon in planning for moving power around in the state needed upgrades to handle the offshore wind project off Humboldt Bay and innovation projects envisioned for The Geysers geothermal field along the borders of Sonoma, Mendocino and Lake counties.

Sonoma Clean Power, an energy supplier for Sonoma and Mendocino counties, is promoting a geothermal opportunity zone, or GeoZone, to create 85% more power in The Geysers area using cutting-edge low-water-use and lower-heat technologies.

The power agency in March voted to move forward with up to 60 megawatts of demonstration geothermal projects from Cyrq Energy, Eavor and Chevron New Energies, scaling up to as much as 600 megawatts if the technologies prove economically viable.

The agency also requested the grid operator plan for the coming geothermal power, and 79 megawatts were factored into the current transmission plan.

“We found that you have to put resources into long-range planning on faith they will study the transmission needs,” said Geof Syphers, CEO of Sonoma Clean Power.

He said that’s similar to how the grid operator included in the transmission plan 4,400 megawatts from Humboldt offshore wind project, after analysis found more potential output than the 80 megawatts of power production originally envisioned.

Jeff Quackenbush covers wine, construction and real estate. Reach him at jquackenbush@busjrnl.com or 707-521-4256.

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This story was updated to reflect that the California Independent System Operator on May 18 approved the 2022-2023 transmission plan on a 5-0 vote.