EDP Renewables North America and Salt River Project (SRP) have commissioned Flatland Energy Storage, a 200-MW/800-MWh battery energy storage system (BESS) in Coolidge, Arizona. The standalone facility, located in Pinal County, is capable of powering roughly 44,500 homes, according to the company.
The project represents a major addition to standalone storage capacity in the region, with no co-located solar or wind generation. Its 800-MWh capacity provides significant grid flexibility, allowing SRP to store energy during low-demand periods and discharge it when demand peaks.
EDP Renewables handled the development and construction of the system; SRP, a not-for-profit public power utility serving over 2 million people in central Arizona, is the off-taker. The project did not disclose specific investment figures, but similar BESS projects typically involve capital costs in the hundreds of millions of dollars.
The facility bolsters Arizona's energy resilience, particularly as the state faces growing electricity demand from population growth and extreme heat events. Standalone storage such as this can help integrate variable renewables without requiring direct renewable generation on site.
Critics caution that large-scale battery storage remains expensive and that its economic viability depends on evolving market rules and battery cell pricing, which have seen volatility from raw material supply chains. The project's long-term cost effectiveness relative to natural gas peaker plants remains a point of debate.