The Energy Storage Report 2024

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Arizona utility SRP to arrive at 800MW battery storage by mid-2024 with two new deals


Salt River Project (SRP) has signed deals for two large-scale battery energy storage systems (BESS) that bring the Arizona utility to 800MW of energy storage contracted or owned.

SRP said yesterday that it has contracted for Sierra Estrella, a 250MW project, and Superstition, a 90MW system with their developer Plus Power. Both will feature four-hour duration BESS technology, meaning Sierra Estrella will be 250MW/1,000MWh and Superstition 90MW/360MWh.

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Targeted to come online by early summer 2024, the 1,360MWh of BESS was selected by SRP through an all-source request for proposals (RFP) which it launched in October 2021. The utility was seeking up to 400MW of new energy resources by summer 2024 and up to 1,000MW by summer 2026.

The battery storage systems will help meet peak capacity needs in summer, when demand for electricity spikes. They also support SRP’s plan to arrive at more than 2GW of utility-scale solar PV on its networks by 2025 as well as longer-term goals on decarbonisation, reducing emissions 65% by 2035 and 90% by 2050, against 2005 greenhouse gas (GHG) levels.

SRP will be able to control the dispatch of the systems, determining at which times every day their four hours of stored energy can be of most benefit to help manage peaks in power demand. As with California and Nevada in the US west and southwest, this is typically in the early evenings after solar PV production tails off.

Plus Power will own and operate Sierra Estrella and Superstition, set up as subsidiary LLCs. They are in the Arizona city of Avondale and town of Gilbert respectively, both in Maricopa County.

The developer specialises in transmission-connected standalone battery storage and has a few projects completed under its belt, particularly in Texas. However, its flagship project to date, thought to be nearing the end of the installation phase, is Kapolei Energy Storage in Hawaii.

Kapolei, on the Hawaiian island of Oahu, is the state’s biggest standalone BESS project to date at 185MW/565MWh and is being built to help replace Hawaii’s last remaining coal power station, which was on Oahu and closed a couple of months ago.

Plus Power won that project through a competitive solicitation held by state utility Hawaiian Electric (HECO). The developer closed US$219 million financing for the project in late 2021.

As with Kapolei Energy Storage, Plus Power’s projects for SRP will utilise Tesla Megapack lithium-ion BESS equipment.

Lessons learned on safety

Unfortunately, a fire occurred at an existing 10MW SRP BESS project earlier this year, and in 2017 a large-scale BESS in the service area of another Arizona utility, APS, became the subject of scrutiny after a fire and explosion which injured members of a fire crew at the scene.

SRP said that the new projects will be built to updated national BESS safety codes and standards, which incorporate lessons learned from fire incidents.

One major finding from the APS fire at its McMicken project was that first responders had not been prepared for what they might find at the scene and how to tackle it; SRP said it is engaging with the Avondale and Gilbert fire departments to prepare adequate plans for emergency response and involving the first responder community in the projects’ design, construction, operation, and training stages.

BESS output will match 10% of peak load by summer 2024

Meanwhile, SRP said the 800MW of BESS that it will be able to call on by 2024 represents 10% of customers’ anticipated peak-hour electricity demand. These include a large-scale new build solar-plus-storage project, a standalone battery storage project and a battery retrofit at an existing solar PV plant, all to come online during next year.

In September 2021, the utility brought online its own biggest BESS project to date, a 25MW/100MWh system also assembled with Tesla Megapacks, at a site adjacent to SRP’s Agua Fria Generating Station thermal power plant in the City of Peoria and connected to an existing SRP substation.

This article has been amended from its original form to reflect that Plus Power’s operational projects are largely focused in Texas, not California, and that the two projects are subsidiary LLCs.’ publisher Solar Media will host the 5th Energy Storage Summit USA, 28-29 March 2023 in Austin, Texas. Featuring a packed programme of panels, presentations and fireside chats from industry leaders focusing on accelerating the market for energy storage across the country. For more information, go to the website.

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