A Deep Dive on an Old Idea: Invinity’s Bruce Herzer Breaks Down Flow Battery Fundamentals
Storage With a Long Memory
On September 10, 2026, the Women in the Global Battery Industry (WGBI) hosted a webinar titled Flow Batteries 101, featuring Bruce Herzer, Director of Marketing at Invinity Energy Systems. Moderated by BCI Technical Programs Manager Courtney Greco, the session gave members a foundational look at flow battery technology, how it stacks up against lithium-ion, and where it’s being deployed. Greco traced the session back to BCI’s Flow Battery Industry Group, formed to “advance the US supply chain and overall grow and educate the public on flow battery technologies, especially stakeholders and policymakers, but also interested parties such as yourself,” and flagged the upcoming Flow Batteries North America event, October 1921 in Phoenix.
Herzer, with Invinity for about six years, framed his talk around the technology itself, its benefits versus lithium-ion, and real business cases. He noted that in his time at the company, “we’ve seen the flow battery segment and share of the stationary [energy] storage market really take off.”
An Old Idea Getting a Second Look
Flow batteries aren’t new. The concept dates to 1879, when a zinc-bromine chemistry first proved energy could be stored and cycled in a liquid; NASA revisited the technology in the 1970s for space applications, drawn to its fire safety. The breakthrough for Invinity’s chemistry came in 1985, when Dr. Maria Skyllas-Kazacos at the University of New South Wales found that vanadium “has this unique chemical property that is well suited for flow batteries, and that it has a considered different states of charge, and it’s a very simple non degrading reaction. It’s just a magical metal in that regard.”
Early commercialization followed in Japan through the 1990s and 2000s. Today, Herzer said, the industry is “really at this point of hockey stick growth in the segment,” with China building toward gigawatt-hour-scale systems. Vanadium itself is “fairly ubiquitous” in the earth’s crust, usually mined as a byproduct of iron ore and best known for strengthening rebar and steel and it’s fully recyclable at end of life.
How a Flow Battery Actually Works
Stripped to basics: two tanks of liquid electrolyte, positive and negative, pumped into a “cell stack” where an ion exchange membrane lets charge move between them without the liquids mixing. “So it’s actually a fairly simple machine,” Herzer said. “There are pumps fundamentally moving that a liquid around the flow of the current… creates the means to produce the current. That’s why it’s called a flow battery.”
Power and energy are decoupled add bigger tanks for more energy, more cell stacks for more power. “That flexibility is often exploited and is very useful for sizing a flow battery to exactly the needs of the application,” Herzer explained. Invinity’s modular units, sized like shipping containers, house the tanks, pumps, and cell stacks, overseen by a battery management system that integrates many modules into one dispatchable fleet.
Flow vs. Lithium-Ion
Herzer grouped the comparison into operation, safety, and end of life. On operation, vanadium flow chemistry doesn’t degrade like lithium-ion: “You can run a battery for over 30 years without losing any energy capacity,” giving operators far more freedom to cycle as often as an application demands. On safety, he was direct: “flow batteries, vanadium flow batteries have no fire risk,” simplifying permitting and cutting fire suppression costs. Flow batteries are also quieter, using simple fans rather than an HVAC system.
On end of life, Invinity’s systems are “about 99% of components recyclable by weight,” versus a still-evolving path for lithium-ion. The trade-off is weight and density lithium-ion remains the better fit for anything mobile. Herzer cited Modo Energy modeling: a lithium-ion battery cycled twice daily needs augmentation around 11 years in, versus a flow battery’s 30-year runway on the same duty cycle.
Where the Batteries Are Going
Herzer walked through five use cases: co-located and standalone grid assets, commercial and industrial sites, data centers, standalone grid batteries, and transmission/distribution. A commercial and industrial case in France cycled a battery twice daily charging overnight and off midday solar, discharging into morning and evening price peaks for a reported 42% reduction in annual electricity costs, while doubling usable solar.
Data centers are a fast-growing segment given their stochastic loads. Herzer described a project in Laufenburg, Switzerland near the historic “Star of Europe” substation, where the French, Swiss, and German grids first interconnected set to be “the world’s largest flow” battery, built beneath the data center itself for load smoothing and grid stability.
On standalone grid assets, Herzer cited Great Britain and Hungary as active markets, with revenue shifting “towards merchant, i.e. trading and trading revenue” as more storage comes online. For transmission and distribution, he cited a project near Golden, BC, where batteries at a constrained grid spur avoid upgrade costs, plus a Midwest deployment with Dairyland Power Cooperative backed by DOE funding.
Q&A: Cost Curves, Residential Limits, and Leaks
Asked where flow will take the most share from lithium-ion, Herzer pointed to microgrids, where dispatch needs are uncertain: “it’s it’s that’s a really great segment for us because it leans into the… utility and flexibility to the battery.” Lithium-ion keeps the edge on shorter project lifespans and mobile uses.
On cost, Herzer pointed to supply chain scale, not labor: components are “sourced at low cost from from Asia, China, India, etc.” Government-backed certainty around large US projects, he argued, would let manufacturers negotiate bigger supply contracts: “there’s going to be ten gigawatt hours of flow, battery deployments planned and backed and guaranteed through government incentive… next five years.”
On residential use, he said the technology could work at home, but economics favor utility-scale volume over “thousands of smaller ones,” and the real constraint is space, since the electrolyte can’t be compressed. On failure modes, leaks remain the toughest challenge; Invinity is now on its “sixth generation of stacks,” has adapted hose-fitting designs from automotive, and has added secondary containment inside the tank’s outer shell.
Closing Note
Herzer closed by thanking attendees, underscoring how far the technology has traveled from its 19th-century origins to today’s gigawatt-hour-scale deployments. Committee Week follows October 5 in Philadelphia, with BCI’s Flow Batteries North America event close behind in Phoenix.