Salt River Project and Aypa Power have brought the Pediment Battery Energy Storage System online in Mesa, Arizona — a 250 MW / 1,000 MWh facility now serving customers in the Elliot Road Technology Corridor. The project arrives as the Phoenix metropolitan area continues to rank among the fastest-growing regions in the country, adding pressure to a grid already managing rapid population and commercial expansion.
Pediment BESS enters service in Mesa
SRP and Aypa Power confirmed that the Pediment BESS is now operational, making it the first of two battery storage contracts the two companies hold together. The project was jointly bid by Eolian and Aypa Power from SRP’s 2023 All-Source Request for Proposals, with Aypa Power purchasing the late-stage project from Eolian to complete development and construction. The 250 MW / 1,000 MWh system carries enough capacity to power over 50,000 average-sized residential homest for four hours—a scale that reflects the level of demand SRP must now plan for routinely.
The facility sits within the Elliot Road Technology Corridor, a stretch of Mesa that has become a hub for large commercial and data center operations. Its location is deliberate. Aypa Power CEO Moe Hajabed noted that the site is “well-positioned to support growing demand from large-load customers, while strengthening overall grid reliability.”
Why SRP is expanding battery storage capacity
The Phoenix metropolitan area is not growing slowly. It consistently ranks among the fastest-growing regions in the United States, and that trajectory is placing sustained upward pressure on electricity demand. SRP expects to more than double its total system capacity over the next decade just to keep pace.
Two forces are driving that growth. Population increases keep bringing new residential load onto the grid, while large commercial customers—particularly data centers—are expanding their footprint in the region, adding significant and concentrated demand in the process. Battery storage has become a central tool for managing both, especially during peak hours when the grid faces its sharpest stress.
Bobby Olsen, SRP Associate General Manager and Chief Power System Executive, framed the strategic value directly: “This project is an important addition to SRP’s energy portfolio and supports SRP’s commitment to providing reliable, affordable, and sustainable power as the Valley continues to experience record growth.”
Impact on SRP’s grid and customers
Pediment adds flexible, dispatchable capacity to an energy mix that already includes nuclear, hydroelectric, natural gas, coal, solar, wind, biomass, and geothermal resources. That diversity is intentional—SRP relies on the ability to shift resources quickly, and battery storage enables that in ways other generation types simply cannot.
With Pediment online, SRP now has more than 1,570 MW of battery storage supporting its grid. That figure will grow. A second Aypa Power project, rated at 250 MW / 2,000 MWh, is already under contract and expected to come online in December 2028. When both are fully operational, Aypa Power’s contribution to SRP’s system will total 500 MW and 3,000 MWh—a meaningful share of the flexible resources SRP is counting on through the next decade.
Economic and carbon reduction context
The Pediment project carries economic weight beyond the grid itself. Construction supported more than 200 jobs, and the project is expected to generate over $16 million in direct economic impact over its lifetime. Approximately $14 million of that will flow to Maricopa County as property tax revenue during the project’s first 20 years of operation.
SRP has set two formal carbon targets: reduce carbon intensity from 2005 levels by 82 percent by 2035, then reach net zero carbon emissions by 2050. The utility currently utilizes 2,300 megawatts of carbon-free resources to serve its customers, a total set to expand significantly with over 1,500 MW of additional large-scale solar under development. Battery storage does not generate power on its own, but it allows cleaner resources to be dispatched more efficiently—cutting reliance on carbon-intensive peaking plants when demand spikes.
3,000 MWh of storage added to the portfolio
The Pediment BESS represents a 250 MW / 1,000 MWh addition to SRP’s grid, located in Mesa’s Elliot Road Technology Corridor and now fully operational. It is the first of two projects Aypa Power has under contract with SRP. The second—a 250 MW / 2,000 MWh system—is expected online in December 2028. Together, the two projects will add 500 MW and 3,000 MWh of storage to SRP’s portfolio. Pediment created over 200 construction jobs and is projected to deliver more than $16 million in direct economic impact, including roughly $14 million in property tax revenue to Maricopa County over 20 years.
Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.
