Salt River Project proposes Marigold Energy Center 45 miles south of Phoenix: 400 MW battery storage, 600 MW solar, and up to 675 MW gas generation.

Salt River Project plans to seek board approval in September to develop the Marigold Energy Center, a mixed-resource facility located approximately 45 miles south of Phoenix. The project is designed to serve growing electricity demand across Maricopa and Pinal counties in Arizona.

The Marigold Energy Center will comprise 400 MW of battery storage, 600 MW of solar generation, up to 675 MW of natural gas generation, a new substation, and four miles of 230-kV transmission lines. SRP announced the project last year alongside community informational sessions in Stanfield, Arizona.

To gather public input before the board decision, SRP will host an in-person open house in Stanfield on July 28 and a virtual open house on July 29. Previous informational sessions were held at Stanfield Elementary School in December and March.

According to SRP, the project "will build on SRP's commitment to provide Arizona with reliable and affordable power to keep up with economic growth." The utility is also exploring a potential partnership with Electrical District No. 3, a regional public power utility. "ED3 is evaluating a potential partnership with SRP to procure a portion of the energy generated by the Marigold Energy Center, enhancing its ability to serve local customers with reliable and competitively priced electricity," SRP stated.

The Marigold project supports SRP's broader strategy to expand storage resources on its system to meet rising demand while maintaining reliability, affordability, and cleaner energy objectives. In June, SRP announced an agreement with Energy Dome, a Google-backed company, to add a 19-MW, 10-hour carbon dioxide-based battery system co-located at SRP's Coronado Generating Station in St. Johns, Arizona. The project was selected through a 2024 request for proposals.

Additionally, SRP selected ESS Tech in October to develop a 5-MW/50-MWh iron flow battery through a pilot project and storage purchase agreement.