ESS, Salt River Project and Google Launch 50 MWh Iron Flow Storage Pilot to Advance Long-Duration Energy Storage
ESS Tech, Inc., a leading manufacturer of long-duration energy storage (LDES) systems for commercial and utility-scale applications, has announced a collaboration framework with Salt River Project (SRP) and Google to advance long-duration storage innovation through Project New Horizon. The initiative will center on a five-megawatt (MW), 50 megawatt-hour (MWh) energy storage system to be deployed at SRP’s Copper Crossing Energy and Research Center in Florence, Arizona.
The Project New Horizon pilot represents a significant commercial validation milestone for ESS and its next-generation Energy Base platform, which is built around the company’s proprietary iron flow battery technology. Designed specifically for utility-scale deployment, Energy Base is expected to demonstrate the performance, flexibility, and cost advantages required to compete in a rapidly evolving energy storage market increasingly focused on alternatives to lithium-ion systems.
Advancing Non-Lithium Long-Duration Storage
As utilities and large energy users seek to integrate greater volumes of renewable energy into their portfolios, the need for long-duration energy storage has become more pressing. Unlike conventional lithium-ion batteries, which typically provide four hours of storage, long-duration systems are designed to discharge electricity over extended periods—often eight to 12 hours or more—helping balance intermittent generation from solar and wind resources.
Project New Horizon will deploy ESS’s iron flow Energy Base system as part of SRP’s broader effort to evaluate emerging non-lithium LDES technologies. The five-MW/50-MWh installation will provide operational data under real-world grid conditions, supporting resource planning decisions and offering insights into how iron flow batteries perform at scale.
The pilot was selected through SRP’s competitive solicitation process for long-duration energy storage technologies, underscoring both the technical merits of ESS’s solution and growing interest among utilities in diversifying storage chemistries beyond lithium-based systems.
Design work on the project is currently underway. Manufacturing of the system is expected to begin in 2026, with delivery targeted for December 2027. Once operational, the system will serve as a cornerstone demonstration project for ESS’s next-generation platform.
A New Platform for Utility-Scale Deployment
ESS’s Energy Base platform marks an evolution from the company’s earlier containerized storage products. While previous solutions were delivered in standardized enclosures, Energy Base is engineered to allow more flexible configuration tailored to diverse grid and customer use cases. This modular architecture enables scalability for large utility projects while maintaining adaptability for varying discharge durations and power requirements.
The company anticipates that Energy Base will deliver cost advantages at larger scales, positioning iron flow technology as a competitive alternative in long-duration applications. By using abundant materials such as iron, the technology also seeks to mitigate supply chain constraints and price volatility associated with lithium and other critical minerals.
For ESS, the SRP collaboration represents more than a single project. It is a pivotal step in demonstrating the commercial readiness of its platform in partnership with a major utility and a global technology leader.
Drew Buckley, Chief Executive Officer of ESS, described this phase of Project New Horizon as a meaningful validation point for the company. He emphasized that utilities are actively exploring scalable, non-lithium long-duration storage as part of long-term planning strategies. According to Buckley, the partnership with SRP—alongside Google’s participation and cost-sharing support—reinforces the growing relevance of long-duration storage for enhancing grid reliability and supporting large energy users focused on carbon-free power.
Multi-Party Collaboration and Independent Oversight
Under the agreement, SRP intends to partner with the Electric Power Research Institute (EPRI) to support operational testing of the system. The initial scope includes a multi-year research program, with potential for future collaboration depending on results.
All tests required under the Energy Storage Agreement (ESA) will be performed by SRP and ESS throughout the term of the agreement. EPRI will provide independent oversight, helping ensure transparency, technical rigor, and credibility in performance evaluation.
This collaborative model—utility-led testing supported by independent research oversight and private-sector cost sharing—reflects a structured approach to advancing emerging energy technologies from pilot to broader commercialization.
Google’s Role in Accelerating Clean Energy Innovation
Google is participating in the Copper Crossing project through a cost-sharing arrangement with SRP, funding a portion of the project’s payments. The company has publicly committed to expanding clean energy procurement and supporting innovative technologies that can enable around-the-clock carbon-free electricity.
By engaging in Project New Horizon, Google aims to accelerate learning from real-world deployments of long-duration storage technologies. The company views long-duration storage as a critical enabler of grid resilience and renewable integration, particularly as electricity demand rises from data centers, electrification, and economic growth.
Lucia Tian, Head of Advanced Energy Technologies at Google, highlighted the importance of long-duration storage in improving grid resilience and unlocking continuous clean energy supply. She noted that the collaboration with SRP is intended to generate operational insights from a portfolio of emerging LDES technologies, with the ESS pilot serving as the first such project in this initiative. Tian also emphasized the importance of supporting diverse technologies and supply chains capable of delivering reliable, affordable, and clean electricity.
Supporting SRP’s Long-Term Mission
For SRP, Project New Horizon is part of a broader strategy to assess innovative technologies that can support its mission of providing reliable, affordable, and sustainable power. As one of the largest public power utilities in the United States, SRP is responsible for delivering electricity to a rapidly growing service territory in Arizona.
Chico Hunter, Manager of Innovation and Development at SRP, explained that the project will help evaluate how long-duration energy storage technologies could meet future system needs. By testing performance in real-world conditions alongside ESS, Google, and EPRI, SRP aims to deepen its understanding of how iron flow storage and other non-lithium solutions can enhance grid operations.
Arizona’s strong solar resource makes energy storage particularly valuable. As solar penetration increases, extended-duration storage can shift midday generation into evening peak periods, improve system flexibility, and reduce reliance on fossil-fueled peaking plants.
Broader Implications for the Energy Storage Market
Project New Horizon arrives at a time when the global energy storage sector is seeking alternatives that address cost, safety, supply chain, and duration challenges associated with lithium-ion technology. While lithium systems dominate short-duration applications, utilities are increasingly exploring complementary solutions capable of delivering multi-hour discharge at scale.
Iron flow batteries, such as those developed by ESS, use water-based electrolytes and are designed to offer long cycle life, enhanced safety characteristics, and flexible discharge durations. If the Energy Base platform performs as expected, it could provide a pathway for wider adoption of non-lithium storage technologies.
Successful execution of the Copper Crossing pilot could unlock follow-on commercial opportunities with utilities and large energy users seeking scalable long-duration solutions. For ESS, the project serves as both a technical validation and a strategic blueprint for broader deployments.
As manufacturing is slated to begin in 2026 and delivery targeted for late 2027, the coming years will be critical in demonstrating the operational performance and economic viability of the Energy Base platform. The results of this collaboration may help shape procurement decisions and resource planning strategies across the U.S. power sector.
In bringing together a technology innovator, a major public utility, an independent research institution, and a global corporate energy buyer, Project New Horizon illustrates how multi-stakeholder partnerships can accelerate the commercialization of next-generation energy infrastructure. If successful, the initiative could mark an important step toward enabling more resilient grids and expanding access to reliable, around-the-clock clean energy.
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