Flow Batteries Under Fire: What’s Happening?

There has been an uptick in news surrounding flow batteries over the past year. On the positive front, ESS, Inc. recently raised $13 million in funding from investors and announced that it will deliver two of its systems to chemical manufacturer BASF. On the negative front, Vizn Energy scaled back its business, citing the loss of one its leading investors.

Guidehouse Insights expects flow batteries to be a major competitor to lithium ion (Li-ion) for both front-of-the-meter and behind-the-meter applications in the next several years. In fact, Guidehouse Insights expects them to be the fastest growing electrochemical energy storage device over the next 10 years. However, short-term hurdles still exist. In this blog, I’m discussing some of the major issues.

Cost and Use Case

CAPEX of flow battery systems compared to Li-ion batteries is higher. The cost over the lifetime of the storage asset is heavily dependent on the type of applications the device will serve. We see flow batteries being utilized for long duration energy applications (over 4 hours) as opposed to short duration power applications (less than 4 hours). As their discharge duration is directly correlated with the amount of electrolytes stored in the tank, the levelized cost of energy decreases as the discharge duration increases. At present, we generally see advanced energy storage being deployed for use cases less than 4 hours. Consequently, Li-ion batteries can provide the same services that flow can at a lower CAPEX.

Component and material costs are also an issue. Current commercial flow battery chemistries are limited to vanadium-based and zinc-based chemistries. Their redox pairs yield competitive but lower power densities compared to Li-ion. Exploring different chemistries that yield higher power density and are safer, engineering better separator and electrode materials and architectures to improve chemical conversion, and decreasing other balance-of-system costs are key to improving the competitiveness of flow batteries in the current energy storage market.

Project Timelines

From signing letters of intent to the ribbon cutting of the system, Li-ion batteries are deployed on increasingly shorter timelines relative to other advanced battery technologies. This is because they have been studied more by both the public and private sectors and are well understood. Flow battery systems can be a bit bulkier and require special permitting by players across the value chain. Most customers are not as educated on flow systems compared to Li-ion or lead-acid batteries. Consequently, it is difficult to convince flow battery customers (utilities and C&I customers, mostly) to invest when they can purchase a Li-ion system at a lower CAPEX and have the system up and running faster.

Economies of Scale

Most commercial flow battery vendors outsource component manufacturing to other companies and assemble the final product in house. The demand for flow batteries has not yet boomed, and companies have not found a need to scale up production. As medium- to long-duration markets begin to open for flow batteries as they did for other types, manufacturing synergies will be developed and consequently drive the price down.

How Do Companies Plan for Success?

Going forward, it is increasingly important that flow battery companies continue to educate customers on the benefits of deploying these systems while continuing to improve on the issues outlined above. Being able to back up the 20-year warranty that most commercial flow battery vendors offer will be contingent on these improvements. Because of this, we see the players best positioned to deploy these systems in the short term as large companies that have other business units and resources to support their flow battery business. This way, if business slows or fails, the company will not be set back significantly.