ESS Tech, Inc.

ESS Tech, Inc., commonly known as ESS, is a leading manufacturer of long-duration energy storage solutions based in Wilsonville, Oregon, USA. Established in 2011, the company's mission is to accelerate decarbonization safely and sustainably by providing longer-lasting energy storage, thereby delivering clean and reliable energy to meet growing global demand.

ESS specializes in iron flow battery technology, utilizing earth-abundant, environmentally benign materials such as iron, salt, and water for its electrolyte. This technology underpins its key product lines, including the Energy Warehouse™, Energy Center™, and the newer Energy Base systems, which are designed for commercial, industrial, and utility-scale applications, as well as microgrids and off-grid solutions. The company's solutions are noted for their safety, sustainability, and ability to provide energy discharge for extended periods, with the Energy Base product line offering up to 22 hours of energy storage.

Under the leadership of CEO Drew Buckley, ESS continues to expand its market presence and technological offerings. Recent developments include a strategic partnership with Alsym Energy in May 2026 to integrate sodium-ion cells and modules, enabling ESS to enter the short and medium-duration battery energy storage market. In January 2026, the company secured a $9.9 million contract with Concurrent Technologies Corporation and the U.S. Air Force Research Laboratory for a large capacity energy storage system. Additionally, ESS acquired intellectual property and assets from VoltStorage GmbH in March 2026. While the company reported a net loss of $63.4 million in fiscal year 2025, an improvement from the previous year, it continues to position itself as a critical enabler of the clean energy transition with a focus on American-made products and a U.S.-centered supply chain.

Latest updates

ESS Expands Storage Portfolio with Sodium-Ion Partnership

Event summary

  • ESS, Inc. signed a letter of intent to partner with Alsym Energy.
  • The partnership will integrate 8.5 GWh of Alsym’s sodium-ion batteries into ESS’s portfolio.
  • ESS is entering the short- and medium-duration Battery Energy Storage System (BESS) market.
  • The deal combines ESS’s iron flow technology with Alsym’s sodium-ion batteries.
  • Alsym utilizes a proprietary AI platform for battery development.

The big picture

ESS’s move into the short- and medium-duration BESS segment represents a strategic expansion beyond its long-duration storage focus, directly challenging the lithium-ion dominance in a rapidly growing market. The partnership with Alsym provides ESS with a non-flammable, potentially lower-cost alternative, addressing safety concerns and supply chain vulnerabilities associated with lithium-ion batteries. This signals a broader industry shift towards diversifying energy storage chemistries to enhance resilience and sustainability.

What we're watching

Market Adoption
The success of this partnership hinges on the ability of ESS to effectively integrate Alsym’s sodium-ion technology and gain traction in the short- and medium-duration BESS market, historically dominated by lithium-ion.
Technology Integration
How ESS manages the technical integration of Alsym’s sodium-ion batteries with its existing iron flow platform will be critical, particularly in delivering on the promised performance and cost benefits.
Supply Chain
The reliance on non-FEOC sourced materials for Alsym’s batteries, while a positive, will need to be consistently maintained to avoid disruptions and maintain a competitive advantage.
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