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Flow battery maker behind ‘US’ biggest project’ closes Series B funding round

Rendering of H2 Inc Enerflow VRFB units with electrolyte tanks and balance of plant equipment. Image: H2 Inc.

An US$18 million Series B funding round has been closed by H2 Inc, a South Korea-headquartered manufacturer of redox flow battery energy storage systems.

The company secured the funds before the end of 2022, it said last week. It noted that of US$44 million raised since launching its first vanadium redox flow battery (VRFB) product line in 2013, US$32 million of that funding has come in the past two years.

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Contributors to the latest investment round included POSCO New Growth Fund, backed by POSCO, one of South Korea’s largest conglomerates and managed by private equity fund manager Korea Growth Investment Corp.

H2 Inc broke ground on a VRFB manufacturing plant with 330MWh annual production capacity last year in Gyeryong-si, South Korea, planning to bring it online during 2023, as reported by

That start of construction came just under a year after H2 Inc announced that it was planning the largest VRFB project in the US to date, a 5MW/20MWh (4-hour duration) system in California at the site of a former gas peaker plant.

While the claim was accurate at the time it was made, other larger flow battery projects in the country have since been announced. Nonetheless, if it comes online as planned towards the end of this year after a pilot phase, it may well hold the ‘country’s largest’ crown for a while.

That project is significant in other ways, H2 Inc founder and CEO Dr Shin Han said, calling California a “perfect test bed” for transitioning from natural gas for peaking capacity applications to long-duration energy storage (LDES) assets like flow batteries.

The CEO said that while it was likely other US states would be watching the project closely, South Korea’s government would also be watching to see if flow batteries could play a bigger role in renewable energy integration there, too.

The newest iteration of H2 Inc’s proprietary flow battery product, called Enerflow, is available for larger-scale applications with 250kW rated power output and up to 2.5MWh capacity (10-hour duration).

As with other flow battery providers, H2 Inc’s systems are designed to last about 20 years in the field, capable of performing more than 20,000 cycles at full depth of discharge, versus about 5,000 to 10,000 typical of lithium-ion batteries, albeit lithium-ion technologies tend to have considerably higher roundtrip efficiency, at more than 90% and often closer to 95%. reported yesterday on steps forward taken by two other flow battery companies, US-headquartered Stryten Energy and Germany’s CMBlu Energy, that are looking to take on the US market.

A confluence of factors included targeted programmes and funding to specifically support LDES in California, the general need for larger capacity energy storage systems in many parts of the country, and the expected impact of the Inflation Reduction Act (IRA), have led various industry players and observers to see future opportunities ahead for flow batteries in the country.

Read our August 2022 article, “Will the Inflation Reduction Act mean opportunities for flow batteries?” here.’ publisher Solar Media will host the 5th Energy Storage Summit USA, 28-29 March 2023 in Austin, Texas. Featuring a packed programme of panels, presentations and fireside chats from industry leaders focusing on accelerating the market for energy storage across the country. For more information, go to the website.

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