Two New Batteries on SRP’s Grid will Advance Reliable and Sustainable Power for SRP Customers

Facilities include the largest standalone battery facility to date in Arizona
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Salt River Project (SRP) and Plus Power LLC today celebrated two new grid-charged battery storage systems, Sierra Estrella Energy Storage and Superstition Energy Storage. Together, these facilities will add 340 megawatts (MW) / 1,360 megawatt-hours (MWh) of additional battery storage capacity to SRP’s system – enough to power 76,000 residential homes for a four-hour period. The batteries will absorb excess energy when customer demand is lower and store it for use during times of peak demand.

The 250 MW Sierra Estrella Energy Storage facility, located in Avondale, AZ, is SRP’s largest grid-tied battery and now the largest standalone battery in Arizona. The project is sited on nine acres in Avondale and unaffiliated with a specific type of power generation. It will store enough energy to power more than 56,000 homes for a four-hour period.

The 90 MW Superstition Energy Storage facility, located in Gilbert, will store enough energy to serve more than 20,000 Valley homes for a four-hour period. This project is expected to come online this week.

When both facilities are operational, nearly 1,300 MW of battery and pumped hydro storage are helping serve SRP customers with affordable, reliable and sustainable power.

“We appreciate our partnership with Plus Power to develop these resources, which will provide flexibility and resource diversity to help maintain reliable power during Arizona’s hot summers,” said Jim Pratt, SRP chief executive officer. “We are proud to be leading the way with integrating new energy technology to serve our customers.”

Plus Power designed the facilities in consultation with Avondale and Gilbert first responders and will operate them to national safety codes and standards for Battery Energy Storage. The facilities feature lithium-ion battery energy storage systems that were designed and manufactured in the U.S. by Tesla. A majority of the EPC work was performed by union labor. Both facilities were supported by a federal investment tax credit from the Inflation Reduction Act.

“We are proud to partner with SRP to bring the Sierra Estrella and Superstition battery storage projects online to help meet growing summer peak demand, while creating local jobs and tax benefits for Avondale and Gilbert,” said chief executive officer Brandon Keefe at Plus Power. “Plus Power is in the business of solving hard climate problems for our customers; we are excited to provide these projects as solutions to SRP and Greater Phoenix to help meet their growing electrical needs with zero emissions and zero water sources of electricity.”

SRP is continuing to develop and deploy safe, cost-effective storage technology as part of the company’s commitment to reducing carbon intensity (from 2005 levels) by 82 percent by 2035 and achieving net zero carbon emissions by 2050. Through its Integrated System Plan, SRP found it will need 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 as it moves forward with the planned retirement of 1,300 MW of coal resources. 

More than 2,300 MW of carbon-free energy resources, including over 1,000 MW of solar, are currently serving SRP customers. SRP also has significantly more solar energy capacity under development and over 1,100 MW of additional battery storage resources will be online by the end of 2024.

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