The rapid growth of solar power in the central San Joaquin Valley and peak electricity use shifting to later parts of the day are prompting the operators of California’s power grid to reconsider the need for a major transmission line project in Fresno County.
Several years ago, the California Independent System Operator deemed that another high-voltage line, called the Central Valley Power Connect project, was needed between Pacific Gas & Electric Company’s Gates Substation near Coalinga and its Gregg Substation south of Madera, to move electricity more effectively in the Valley. PG&E already has one set of 230-kilovolt lines between the two substations, but no capacity on the existing poles or towers to carry another line.
But a lot can change in a couple of years. Now, the California ISO is rethinking the need for the line, which would cost between $115 million and $145 million to build.
“There does not appear to be sufficient economic benefits to support the Gates-Gregg 230 kV transmission line project,” said Jeff Billinton, the ISO’s regional transmission manager for Northern California, in a November presentation to power industry stakeholders.
He added that the ISO is considering canceling the project, but “may consider deferring the cancellation and putting the project on hold to further assess uncertainties” about future economic benefits.
The 70-mile stretch of power lines originally was anticipated to serve as a two-way street for electricity to and from the Helms Hydroelectric Project in the Sierra Nevada east of Fresno.
During periods of high power demand, electricity from the Helms project would be shipped out to the statewide power grid; at slower times, power would be channeled up to Helms to pump water from its lower reservoir back uphill to be stored in its upper reservoir to produce more electricity later.
During the early stages of the planning process, PG&E representatives noted that no new high-voltage transmission lines had been built in the Central Valley since the 1980s.
Throughout 2014 and 2015, PG&E studied a range of routes between the two substations, and held a series of open-house meetings for communities and property owners along the route options.
PG&E was in the process of preparing an application to the California Public Utilities Commission to build the line when the ISO put its planning process on hold.
“We appreciate the community’s input and support of the Central Valley Power Connect transmission line project over the last two years of the planning process,” PG&E project manager Mark Schexnayder said in a statement posted on the utility’s website. “Our most recent analysis takes into account the state’s new renewable energy goals and evolving energy landscape.”
Part of the ISO’s assessment of need for the high-voltage line was based on the forecast growth of residential rooftop and industrial-scale solar power – also known in the industry as “distributed generation” – as well as larger utility-scale solar installations to generate more and more electricity during the daytime hours.
Billinton’s report noted California Energy Commission forecasts showing the installed production capacity of distributed-generation solar projects in the Fresno area growing from nearly 60 megawatts in 2016 to almost 600 megawatts in 2026. One megawatt is typically estimated to meet the energy demands of between 500 and 800 homes.
“Due to currently forecasted increases in the development of distributed energy resources and a later peak energy demand in the greater Fresno area” to between 4 and 7 p.m. daily, “the reliability need for the project will be pushed out,” he added.
PG&E and its project partner, BHE, “have placed all development work on hold and will await the ISO’s decision to cancel the project or place it on hold.” Schexnayder said a decision could come sometime in the next few months.