SRP to Add 340 MW of Additional Battery Storage to its System with Two New Projects From Plus Power

Salt River Project announced signed contracts with Plus Power to bring online two grid-charged battery storage systems with a total combined output of 340 megawatts (MW) by early summer 2024. This is enough energy to power more than 76,000 average size residential homes over a four-hour period.

The first project, called Sierra Estrella, will be a 250-MW, four-hour battery storage system located in Avondale. The second, called Superstition, will be a 90-MW, four-hour battery storage system located in Gilbert.

“SRP is proud of our early investments in battery storage and clean energy,” said Kelly Barr, SRP’s Chief Strategy, Corporate Services and Sustainability Executive. “These early deployments will help both SRP and the industry gain experience with this technology, which will play a major role in reducing carbon emissions.”

SRP selected these projects from its most recent all-source request for proposals (RFP) process and both will be owned and operated by a subsidiary of Plus Power. SRP will have dispatch control of the storage systems, which means SRP will have the ability to decide at what point each day it will deploy the four-hour energy output from each system onto its grid. This will typically be done during peak energy demand periods, during the early evening timeframes when demand is high and renewable resources are not available.

“Adding more large-scale batteries on our system and working with developers so SRP controls the times of day we deploy batteries onto our grid greatly improves our operational experience with this technology while providing us opportunity to manage charging and discharging as it fits our customer needs,” said Barr.     

Both battery systems will utilize Tesla lithium-ion technology, and Plus Power will design and build these projects to updated national codes and standards for Battery Energy Storage Systems, which incorporate lessons learned from incidents at other battery facilities. Additionally, Plus Power is engaged with both the Gilbert and Avondale Fire Departments, working to prepare a thorough Emergency Response Plan and to ensure that local first responders are directly engaged throughout project design, construction, operation, and training.  

“We are thrilled to partner with SRP on the Sierra Estrella and Superstition Battery Energy Storage Systems projects which will greatly enhance local grid reliability and provide a variety of tax and jobs benefits to the nearby communities,” said Molly Emerson, Director of Project Development at Plus Power. “At a total of 340 MW, these projects represent a bold step forward for the Southwest energy market, and will act as a cornerstone to Plus Power’s growing portfolio of operating projects.”

With these two new battery projects, SRP’s total commitment to battery storage will surpass 800 MW by 2024, which is enough to power more than 180,000 average size homes and represents over 10 percent of SRP’s anticipated peak-hour electricity demand from customers in 2024. This is among the largest utility-scale battery investments in the Western U.S.

Other soon-to-be developed projects include the Sonoran Energy Center, which will be the largest solar plus battery project in the state. SRP has also contracted for an additional utility-scale solar and battery storage project called the Storey Energy Center and will be adding a battery to the Saint Solar project site, both of which will be located near Coolidge. All three projects are scheduled to become operational in 2023.

In 2021, SRP placed into service a 25-MW battery storage facility at its Bolster Substation, which is adjacent to its Agua Fria Generating Station, located in Peoria. SRP also receives output from the Pinal Central Energy Center, a 20-MW solar plant paired with a 10-MW solar-battery system located in Pinal County.

SRP will continue to develop and deploy evolving storage technologies safely and cost-effectively as part of SRP's commitment to reducing carbon intensity (from 2005 levels) by more than 65 percent by 2035 and 90 percent by 2050. SRP has also closed the largest coal plant in the Western U.S. and will have retired approximately 2,600 MW of coal-fired generation by 2032. With these strategic resource additions and decisions, nearly half of all retail energy delivered to SRP customers will come from carbon-free resources by 2025.

About SRP

SRP is a community-based, not-for-profit public power utility and the largest provider of electricity in the greater Phoenix metropolitan area, serving more than 1 million customers. SRP is also the metropolitan area’s largest supplier of water, delivering about 750,000 acre-feet annually to municipal, urban, and agricultural water users.

About Plus Power

Plus Power develops, owns, and operates battery energy storage systems that enable a more efficient and reliable electrical grid. With an over 8,000 MW pipeline across nearly 25 states, Plus Power applies an intentional mindset to energy storage development by prioritizing local relationships, optimal siting considerations, and environmental stewardship. Proudly American-owned, Plus Power is headquartered in Houston with offices across the country.