Iron flow battery startup ESS raised an additional $30 million to take its technology from pilots to commercial scale.
Since 2011, the company has been developing a low-cost, nonflammable long-duration storage technology to compete across domains where the dominant lithium-ion battery chemistries are weaker. Flow batteries have been one of the more prominent lithium-ion alternatives, but companies working in the space have struggled to stay afloat financially and move beyond the pilot stage.
With the new Series C investment, ESS has won a vote of confidence from prestigious and well-heeled backers. SoftBank’s SB Energy and Bill Gates-funded Breakthrough Energy Ventures led the round, which also brought in Evergy Ventures and PTT Global Chemical, in addition to previous investors.
“SB Energy and Breakthrough Energy Ventures both bring teams with deep experience and resources across multiple areas,” said Hugh McDermott, ESS senior VP for business development and sales, in an email. “This will contribute to our company’s growth on several levels, from board level leadership, to joint development, to renewable energy project development.”
ESS will use the funds to enhance its manufacturing facility in Wilsonville, Oregon and to prepare to serve utility-scale projects worldwide.
Since the company closed a $13 million Series B in 2017, it finished a second generation of its flow technology and worked with reinsurance giant Munich Re to craft a bankable warranty for the unusual product.
Its deployments so far have been behind the meter, using the containerized Energy Warehouse product. ESS has contracted 8 megawatt-hours of new Energy Warehouse orders, with the largest single project providing 2 megawatt-hours of storage capacity, McDermott noted.