The two BESS projects will be the largest in TEP’s portfolio and among the largest in the state, helping TEP manage supply and demand in the state. They will be built side by side next to a TEP substation near Tucson, Arizona’s capital city.
“Our new Roadrunner Reserve II system will help us make the most of intermittently available resources, especially during the summer when usage is highest and customers count on us the most,” said Susan Gray, TEP President and CEO. “We need additional energy storage as part of a diverse energy portfolio to support service reliability.”
Both projects are being built by engineering, procurement and construction company DEPCOM using lithium iron phosphate (LFP) based BESS units. DEPCOM’s Vice President of Business Development for Energy Storage explained in an interview with Energy-Storage.news recently (Premium Access), including the combination of EPC with Operations and Maintenance (O&M).
TEP, an Arizona-only utility, has 50 MW of BESS in operation today, including the Wilmot Energy System’s 30 MW unit pictured above.
The Roadrunner Reserve projects, which will increase that capacity fivefold, are aligned with the utility’s 2023 Integrated Resource Plan (IRP), part of its plan to achieve net-zero direct greenhouse gas (GHG) emissions by 2050.
It will also source power from the Winchester Solar project, which combines 80 MW of solar and an 80 MW BESS and is being developed and operated by Torch Clean Energy, when it comes online in 2027.
Roadrunner Reserve II was selected through the utility’s 2024 All-Source Request for Proposals (ASRFP) process, which sought 825 MW of “firm capacity” alongside 625 MW of renewable energy. TEP and sister company UniSource Energy Services are currently reviewing additional proposals submitted for the ASRFP.
Utilities are driving the BESS market in Arizona by either building the projects themselves, like TEP, or by procuring their power under long-term tolling contracts. Salt River Project (SRP) and Arizona Public Service (APS) recently secured power from 1,000 MWh and 600 MWh of BESS projects, respectively, through tolling. California-based utilities, including PG&E, are doing the same for projects across the state line.
