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Established in 2011, ESS Inc. manufactures low-cost, long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring 4-12 hours of flexible energy capacity. Our long-duration energy storage platforms, the Energy Warehouse™ (EW) and Energy Center™(EC), use iron, salt, and water for the electrolyte, and deliver an environmentally safe, long-life energy storage solution for the world’s renewable energy infrastructure. Its non-flammable composition eliminates costly fire suppression systems. Combined with an innovative cell design, our customers benefit from increased power density and reduced O&M cost over our platform’s 20+ year lifespan. With its safe, earth-abundant, all-iron flow battery technology, ESS is helping project developers, utilities, and EPCs make the transition to more flexible non-lithium ion storage that is better suited for the grid and the environment. Our iron flow batteries are guaranteed with insurance backed by Munich RE.

Products & Services

  • Energy Warehouse™ Designed to serve commercial and industrial customers, this compact unit has an energy storage capacity of 400 kWh and a 25-year design life. It can be configured to provide storage durations of 4 to 12 hours.
  • Energy Center™ Created for utility-scale applications, this battery-in-a-building delivers a configurable range of power capacities starting at 3 MW and energy durations ranging from 6 to 12 hours. A one-acre footprint supports up to 6 MW and 74 MWh.

Industries Served

  • Utility Scale
  • Commercial & Industrial
  • Microgrids, DERMS & VPP's

Clients Include

  • Edelaysen, a GRUPO SAESA Company
  • California, investor owned utilities
  • US Army Core of Engineers
  • Sword and Stone Capital
  • SoftBank Energy
  • InoBat Energy
  • Engie (EU)
  • UC San Diego
  • Stone Edge Farms

Client Testimonials

“We stand firmly behind ESS Inc.’s iron flow battery technology as a commercially ready solution for long-duration energy storage at commercial and utility scale. Our goal in providing a comprehensive policy is to enable ESS Inc. to expand deployment of its environmentally sustainable energy storage solution at scale globally.”

– Michael Schrempp, Global Head of Green Tech, Munich RE

“As we are seeing market requirements for utility-scale energy storage moving from traditional 2-to-4-hour lithium-ion-based capability to longer 8-to-12-hour durations that emphasize flexibility and long life, it is clear that proven and practical flow batteries offer key design and cost advantages over lithium.”

– Mark Burton, Senior Engineer for Energy Storage, Enertis Solar

“A rapid and dramatic shift is occurring that favors pairing larger-scale battery installations with renewables. These projects are finding improved overall customer value from longer duration, daily cycling and the flexibility to adapt to evolving use cases that are not constrained by cycle life. We are excited about the economics, operating life and design flexibility that the ESS Energy Center solution offers.”

– David Brown, Senior Principal and Co-Founder, Obsidian Renewables
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