Salt River Project will add a 5-MW/50-MWh iron flow battery to its system through a pilot project and storage purchase agreement with developer ESS Tech, the two announced on Thursday.
ESS’ stock price jumped 85% to $3.20/share in early Friday trading. The company’s technology uses a combination consisting mainly of iron, salt and water to store and discharge energy and is made with over 90% domestic content.
The battery project is the result of a request for proposals issued by SRP in 2024 for long-duration energy storage pilots, and will be installed at the utility’s Copper Crossing Energy and Research Center in Florence, Arizona. The capacity will be sold to SRP under a 10-year energy storage agreement.
The research center currently includes a 99-MW gas generator and a 55-MW utility scale solar project that is under construction. The site will also host CMBlu Energy's Desert Blume 5-MW, 10-hour project.
“As the Valley continues to see rapid commercial and residential growth, projects like this allow us to better understand the efficacy and impact of different kinds of LDES technologies as they mature,” Chico Hunter, SRP manager of innovation and development, said in a statement. “This is another opportunity for SRP to evaluate the real-world performance of emergent technologies on our grid and in the Arizona climate.”
The utility said wants to “at least double” the number of generating resources on its power system in the next 10 years to meet increasing energy demand in the Phoenix metropolitan area. SRP already has almost 1,300 MW of energy storage currently supporting its grid, including 1,100 MW of battery storage.
ESS and SRP said the project is expected to be online by December 2027.
“Design is already underway, and manufacturing will begin in 2026. SRP and ESS will work with the Electric Power Research Institute to monitor performance data of the project,” they said.
