ESS

ESS develops and manufactures long-duration flow battery solutions for utility and industrial applications. ESS’s batteries use a recyclable iron-based electrolyte that provides over 20,000 cycles of power. ESS offers two long-duration battery solutions: Energy Warehouse (EW) and Energy Center (EC). 

EW is a 400 kWh modularized energy storage solution deployed in commercial and utility-scale applications that can provide 4 - 12 hours of energy capacity and an operating life of over 25 years with no capacity fade. EC is a design-build solution with a configurable range of power capacities starting at 3MW that can be tailored to the requirement of the customer and provides up to 6 - 12 hours of energy capacity. As of October 2019, ESS had reportedly shipped its battery solutions to customers on four continents. 

Key customers and partnerships

In October 2021, ESS partnered with SB Energy, a Japanese clean energy arm of Softbank, to deploy two-gigawatt hours of long-duration battery storage systems through 2026 in California and Texas. The first ESS system was delivered to the SB Energy project site in California and was commissioned in October 2021.

In August 2022, ESS and Energy Storage Industries Asia Pacific (ESI) announced a strategic partnership to distribute and manufacture iron flow batteries utilizing ESS technology in Australia, New Zealand, and Oceania. In September 2022, ESS partnered with Sacramento Municipal Utility District to provide up to 200 MW/ 2 GWh of energy warehouses and energy centers. 

In January 2023, the company partnered with Amsterdam Airport Schiphol to provide its Energy Warehouse solution for a pilot project carried out by the latter. In June 2023, ESS partnered with LEAG to construct a 50 MW iron flow battery system using ESS iron flow battery technology at LEAG’s Boxberg power plant site in Germany. In September 2023, the company partnered with Honeywell to build on ESS’ patented iron flow battery design with Honeywell’s expertise in advanced materials and energy systems to accelerate the development of battery solutions.

Funding and financials

In September 2023 , ESS secured an investment of USD 27.5 million from Honeywell as part of a broader collaboration aimed at enhancing the adoption and development of iron-flow battery energy storage. ESS intended to use the funding to advance the partnership with Honeywell, which included an agreement for Honeywell to purchase and resell ESS products, broadening the market footprint of ESS' long-duration energy storage solutions.

In October 2019, ESS raised USD 30 million in a Series C funding round led by Breakthrough Energy Ventures and SB Energy. The funds went to expanding and automating the manufacturing process of ESS’s second-generation flow battery technology.

In October 2021, ESS went public through a merger with ACON S2 Acquisition Corporation, a publicly traded special purpose acquisition company (SPAC). Following the transaction, ESS was listed on the New York Stock Exchange. The transaction was expected to generate USD 308 million, with proceeds being utilized to scale operations. The company reported revenue of USD 686,000 for the first time in Q2 2022 .