Starting with the launch of the state’s first California’s Community Choice Aggregator (CCA), Marin Clean Energy in 2010, CCAs have led the way on integrating renewable sources into the state’s energy supply mix.
With energy storage becoming the conduit through which more renewable energy is getting to the grid during peak times when it’s needed, three recently-announced projects across several CCA territories exemplify the different ways battery energy storage systems (BESS) are changing the grid for the better.
The first of these is the Tumbleweed Energy Storage facility in Kern County, California, the state’s first 8-hour BESS, which will serve eight CCA organizations throughout northern California. The second is a new 4 MW solar and 16 MWh solar plus storage facility built for the Sonoma Clean Power CCA. The third is the latest virtual power plant (VPP) managed by Lunar Energy on behalf of Central Coast Community Energy (3CE).
All three projects further the CCAs’ collective goals of providing more renewable energy to residents. According to the state’s annual report on utility compliance with the California Renewable Portfolio Standard (RPS) law, 73% of electricity procured by CCAs in 2024 came from RPS-eligible sources. None of the CCAs procured less than 40% renewable energy, while on the high end, CleanPowerSF offered 90% renewables to its customers.
Importantly, CCAs in California operate within the territory of the state’s three large IOUs. They are established by local government entities and become the area’s default providers of energy once established. The IOUs still deliver the energy to the end users, but the CCA model allows local officials to prioritize procurement of clean energy resources on behalf of their local residents.
The 73% number is more than double than the 35% delivered to customers by the state’s investor-owned utilities during that same time period. Despite being responsible for around 36% of the total energy served within California IOU territories, CCAs have an outsized effect on the state’s compliance with its RPS law because of projects like these:
Tumbleweed eight-hour storage
On June 18, project developer REV Renewables announced the commissioning of the Tumbleweed Energy Storage facility, a 125 MW, 1,000 MWh facility built by Mortenson in Kern County.
The facility, under development since 2018, has undergone a great deal of growth in its history. REV Renewables originally signed an energy storage service agreement for the project with California Community Power (CC Power) in 2022, with a pledged capacity of 69 MW / and storage size of 552 MWh.
Since then, the project has entered a second phase, bringing its total energy storage to 1,000 MWh, and adding Ava Community Energy as an additional offtaker.
“As a not-for-profit public agency, we’re committed to providing cleaner energy at competitive rates to the communities in Alameda and San Joaquin counties that we serve,” said Ava Community Energy CEO Howard Chang in a statement. “Long-duration storage projects like Tumbleweed are critical to delivering on that commitment. Our partnership with REV on this eight-hour battery helps us strengthen grid reliability and accelerate California’s clean energy transition.”
Seven California CCAs — CleanPowerSF, Peninsula Clean Energy, Redwood Coast Energy Authority, San José Clean Energy, Silicon Valley Clean Energy, Sonoma Clean Power and Valley Clean Energy — are the project’s original offtakers. The CCAs are all members of CC Power, an umbrella organization covering nine California CCAs.
Eight-hour batteries are incredibly important in the transition to a 100% renewable grid. That amount of discharge time is the minimum for what is known as “long-duration energy storage” (LDES) — an energy storage system designed to act as a “bridge” that can both discharge during peak evening hours and also keep renewable electrons from solar and wind resources flowing when the sun isn’t shining and the wind isn’t blowing.
Following the announcement of the Tumbleweed facility’s commissioning, the California Public Utilities Commission published a news release celebrating the project as the state’s first LDES facility.
“This project shows that California’s renewable energy goals, while ambitious, are achievable,” said CPUC executive director Leuwam Tesfai in a statement. “Developers, utilities, community choice aggregators, and regulators all play an important role in turning California’s clean energy vision into reality.”
Redemeyer road local solar and storage
The second recent energy storage system announcement — the 4 MWac/16 MWh Redemeyer Road Solar project — may not be as large as the Tumbleweed facility, but it is another beat in the steady rhythm of advancing energy storage prominence in California.
The project was developed by Renewable Properties for Sonoma Clean Power, which serves Sonoma and Mendocino counties. The system is set to generate an estimated 10,000 MWh of energy every year, which Sonoma Clean Power says is enough to supply 1,739 homes with electricity.
“The Redemeyer Road Solar project reflects Renewable Properties’ ongoing commitment to developing small-scale utility renewable energy projects that expand solar access to the communities where we operate,” said Renewable Properties CRO Brian von Moos in a statement. “We’re pleased to support Sonoma Clean Power, a pioneer in delivering locally generated renewable energy, with projects like this one.”
The CPUC lists the Sonoma Clean Power CCA’s 2026 load forecast as 2,216 GWh, meaning the Redemeyer Road project could generate approximately 0.45% of the organization’s total annual energy needs, but much of the energy will be delivered during the key evening peak hours in which California once used a great deal of natural gas for electricity.
“Our largest local solar project to date shows what’s possible when we invest in clean energy right here in our community,” said Sonoma Clean Power CEO Geof Syphers in a statement. “By pairing solar with battery storage, we can provide that power when it’s most needed, supporting reliability and keeping the benefits of that energy local.”
Sonoma Clean Power will use the energy from the project for its EverGreen 100% renewable energy service offering. According to a comparison of the Sonoma Clean Power offering to energy served by PG&E, the total cost to the average customer is about $15 per month higher on the EverGreen plan ($187 vs $172), but the IOU alternative features only 23% renewable energy, with 63% coming from the Diablo Canyon nuclear plant, 12% from large hydro plants and 2% from natural gas.
The Redemeyer Road facility, located in Ukiah, will be officially opened in a ribbon-cutting ceremony on July 14.
Central coast virtual power plant
On June 24, the Central Coast Community Energy (3CE) and hardware and software developer Lunar Energy announced a three-to-four-year agreement to launch a virtual power plant across the CCA’s central coast territory to optimize customer-sited home batteries for broader grid reliability.
Lunar Energy will deploy its Gridshare distributed energy resource management system (DERMS) platform to remotely coordinate home batteries across a network of participating customers. Through the program, 3CE will be able to coordinate the activation of customer-sited batteries to reduce strain on the grid when demand is highest.
The program will initially use batteries with up to 5 MW of combined power output, which the program aims to bring online by the end of 2026. In the future, other devices like heat-pump water heaters, EV chargers and smart thermostats will be used to bring the total capacity under management to 30 MW by 2030.
Rates from 3CE are currently very similar to those from PG&E, with the average customer paying $169 per month for energy from 3CE compared to $156 from the IOU. The difference allows ratepayers to get 55.8% energy from renewable sources, compared to 22.9% from PG&E in the same territory.
In the announcement of the Lunar Energy VPP, 3CE CEO Robert Shaw laid out why the CCA can be so effective at procuring clean energy. “As a locally controlled public agency, 3CE has the flexibility to move quickly and try new approaches when the opportunity is right,” said Shaw. “This agreement with Lunar Energy is a perfect example; we’re taking the next logical step beyond our battery rebate program and building something that benefits our customers directly while strengthening the grid for everyone on the Central Coast.”
The 3CE VPP program is the latest in a series of such programs Lunar Energy has inked with CCAs. The company also applies its Gridshare platform for Ava Community Energy, Peninsula Clean Energy, Silicon Valley Clean Energy and the California Choice Energy Authority, a group of CCAs located within Southern California Edison (SCE) utility territory.
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