CMBlu’s batteries competitive with li-ion after 5 hours, but more data, experience needed: US CEO

A “cost-optimal” global net-zero energy system will require deployments of long-duration energy storage, or LDES, to scale 400 times over 2021 levels by 2040, according to the Long Duration Energy Storage Council. 

LDES technologies capable of discharging power for periods ranging from four hours to several days will need to scale as dispatchable fossil-fuel generation retires, grid operators and regulators say. For example, California’s grid could require up to 37 GW of LDES by 2045 if the state’s gas-fired power plant fleet retires, the California Energy Commission said earlier this year.

Giovanni Damato, the California-based president of CMBlu Energy, Inc., CMBlu Energy AG’s U.S. subsidiary, agrees with these ambitious projections and believes his company’s Organic SolidFlow battery technology will meaningfully contribute to the expected LDES boom. It’s a strong endorsement from a civil engineer who’s spent more than a decade studying energy systems in general and energy storage in particular, most recently as principal project manager for energy storage and sistributed energy resources at the Electric Power Research Institute.

“[Working for CMBlu] is my first time hitching my horse to a technology cart, so to speak,” Damato told Utility Dive. Damato joined CMBlu Energy, Inc. in December 2022 and became its president this January. 

Damato’s timing is auspicious. CMBlu Energy AG plans to deliver its first commercial project next year at a Mercedes-Benz plant in Germany, Damato said. Its U.S. subsidiary inked agreements last year with Argonne and Idaho national laboratories to test its batteries’ performance and utility for specific applications like EV charging resiliency, along with pilot projects for utilities in Arizona and Wisconsin.

“Twists” on conventional battery storage

CMBlu’s product is a redox flow battery with “some twists that set us apart,” Damato said.

The first twist is organic chemistry. The battery’s active chemistry is a “hydrocarbon polymer chain that is conductive,” Damato said. Though its precise composition is proprietary, its components are readily available “wherever there’s an existing plastics industry” and are fully recyclable, which improves battery economics and reduces supply chain risk, he added. 

The second twist is the presence of “stationary solids in the energy storage tank,” which no other flow battery has, Damato said. The solids dramatically increase energy density by allowing “more surface area on the chemicals themselves and more ions per liter inside the tank,” ultimately achieving per-square-foot energy densities on par with Tesla’s lithium-ion Megapack battery, he said.

Ben Kaun, Damato’s predecessor as CMBlu’s U.S. president, told Utility Dive last year that the company is especially focused on utility applications. But CMBlu’s deal with Mercedes-Benz shows that the company’s technology appeals to commercial and industrial customers looking to ensure that their operations are powered by clean energy on a 24/7 basis, Damato said. 

But other “clean firm” technologies like advanced nuclear and enhanced geothermal, which can provide round-the-clock, zero-carbon power without the intermittency issues of wind and solar, remain in their infancy despite high-profile corporate efforts to stimulate their development. That makes longer-duration battery storage compelling for sustainably-minded users eager to decarbonize soon, Damato said.

According to Damato, these commercial and industrial users “want more than the typical four-hour storage.” For now, they’re looking for five to six hours of storage, which “pairs well with solar,” but CMBlu’s economics can work for up to 24 hours, Damato said.

Improving on lithium-ion

Redox flow batteries in general, and CMBlu’s product in particular, have key advantages over lithium-ion batteries in utility and commercial/industrial applications beyond the fact that they’re economical at longer durations, Damato said.

For starters, flow batteries are more stable than lithium-ion, with no risk of the spontaneous heating reaction known as thermal runaway.

“[Our batteries] can burn, but they won’t be the cause of the fire,” Damato said. And CMBlu batteries’ nonmetallic chemistry means that if one does catch fire, the result won’t be as toxic as lithium-ion battery combustion, he added.

Flow batteries’ stability was a key selling point for Arizona’s Salt River Project, SRP Manager of Innovation and Development Chico Hunter said. Hunter noted that utility-scale lithium-ion batteries need active cooling, creating “a big energy penalty” from the associated air conditioning load. 

Even with active cooling, lithium-ion batteries’ performance can suffer in hot weather, and in extreme conditions may need to be limited or shut down altogether for safety reasons, Hunter said.

“You think you’ll have a battery to save you on a summer day, but it might not be there,” Hunter said.

The lack of metals in CMBlu’s batteries leads to another key advantage: a less complicated, more predictable supply chain that’s easier to onshore. The Organic SolidFlow battery uses an oil- or bioplastics-derived feedstock that contains no lithium, nickel, cobalt or other critical minerals, so it’s less reliant on international suppliers and less vulnerable to volatile commodity prices, Damato said. 

The battery’s nonmetallic chemistry is also a boon for durability, thanks in part to a low operating pressure of about one atmosphere that puts less wear and tear on battery components like valves and pumps, Damato said. Metal-based flow battery technologies require higher pressures for efficient ion exchange, he added. 

Additionally, Damato said, CMBlu’s core chemistry degrades more slowly than lithium-ion batteries. CMBlu’s website touts its batteries’ “potentially unlimited [lifespan] with proper maintenance,” though Damato said the expected service life is 10 to 20 years with “daily discharge.” 

A final advantage of CMBlu’s technology — and another selling point for utilities like SRP — is its modularity. An individual Organic SolidFlow battery is “about the size of a standing desk,” Damato said, but the modules are easy to stack into megawatt-scale configurations. 

CMBlu’s 5-MW SRP pilot project, which is expected to come online late next year, will have 80 modules that can be disconnected individually if a single module malfunctions, reducing the risk of a catastrophic failure, Hunter said. Modularity also creates economies of scale in contrast to alternatives like pumped hydro and lithium-ion, which “scale linearly with cost,” he added.

Yet despite flow batteries’ inherent advantages over other storage technologies, some potential users and financing partners want to see more evidence that they work as promised in real-world conditions. 

Though the Organic SolidFlow battery is “competitive with lithium today” for durations longer than five hours, the biggest hurdle for CMBlu right now is “getting more data and experience to finance these projects,” Damato said.

For its part, SRP wants to see “a few years” of performance before committing to any storage technology that hasn’t yet been deployed at commercial scale, Hunter said. 

“The chance of guessing right on the first try is not high,” he said.

Building a market for longer-duration storage

CMBlu’s two U.S. utility pilots aim to utilize its flow batteries in different ways, underscoring the technology’s broader potential to support a lower-carbon electricity system. 

SRP’s 5-MW, 10-hour pilot is all about maintaining grid stability as more solar comes online in the Phoenix area, Damato and Hunter said.

“They need to bridge the late evening peak and into the early morning,” Damato said, noting that air-conditioning load remains high through the night during the steamy Arizona summer. 

SRP is taking a “technology-agnostic” approach to its long-duration storage procurement but prefers technologies that have better economies of scale, such as flow batteries and compressed-air systems, Hunter said. Like the process that led to the CMBlu partnership, future SRP storage procurements at the Copper Crossing Energy and Research Center will come from competitive RFPs, he added. SRP put out a request for information last October, targeting non-lithium ion technologies ready for deployment in 2027 or 2028.

CMBlu’s Wisconsin pilot is a “1-2 MWh” project that will test its flow batteries in partnership with EPRI over five- to 10-hour discharge durations, according to CMBlu’s website. It’ll be based at the WEC Energy Group’s Valley Power Plant, a Milwaukee cogeneration facility that supports one of the country’s biggest district steam heating networks, Damato said.

As a cogeneration plant, Valley Power Plant often generates too much electricity when demand for steam is high, Damato said. Rather than discharge that energy into the grid right away, WEC wants to store it for use when electricity demand is higher. 

Damato believes both use cases are compelling and expects other utilities to recognize the value of non-lithium long-duration storage technologies in the coming years — for shifting peak loads, making good on decarbonization promises and hardening grids amid increasingly frequent extreme weather events.