US Department of Defense-funded study finds vanadium flow batteries worthy of further scrutiny
Vanadium redox flow batteries are almost as reliable as diesel generators in providing resiliency, but won’t be competitive against lithium-ion unless cost reductions can be achieved with the scaling up of manufacturing and deployment.
A study funded by the US Department of Defense (DOD) appears to confirm some broad conclusions about vanadium redox flow batteries that may perhaps not be particularly surprising to those in the industry that have followed the energy storage space for some time. Nonetheless studies of its type could form an important step in validating the technology for further investigation and in then gaining market traction.
The DoD contracted energy solutions corporation Ameresco to undertake the study, in partnership with consulting services and project development company 2ndPath Energy, funded via the Department’s Environmental Security Technology Certification Program (ESTCP). The programme seeks to “promote the transfer of innovative technologies from proof-of-concepts to field or production use,” Ameresco said.
Vanadium redox flow batteries enjoy some advantages over lithium-ion including the capability of storing electrical energy for long durations of 10 or 12 hours a day without significant degrading of battery electrolytes, which are liquid and pumped through tanks. However, they also have some disadvantages such as lower round-trip efficiency, while in economic terms they have yet to realise potential cost reductions of the kind enjoyed by lithium-ion by the latter’s ubiquitousness across the world not only in recent renewable or standalone stationary energy storage projects but also in electric vehicles, phones, laptops and more.
The study sought to determine the reliability aspects of vanadium redox flow batteries (VRFB) versus diesel generators for covering outages of up to 168 hours as well as assessing the VRFB versus lithium-ion for critical load coverage both on a technology as well as economic basis.
The full report, which can be downloaded here along with an executive summary, admits that while VRFB’s could cover reliability and resilience metrics almost as well as diesel generators, dipping below diesel’s critical load coverage at 168 hours by only 1.6% to 3%, the VRF technology merits further investigation in order to validate and test its “true reliability metrics”, which Ameresco study author Benjamin Leveaux said will now take place in Phase 2 of the study.
The Ameresco team went on to find that at the moment, the higher operating cost of flow batteries makes lithium-ion a better choice for covering critical loads at large-scale, but that it “is important to recognise that VRF BESS technology is early on in its development and deployment lifecycle and has not yet appreciated the vast cost reductions due to economy of scale that Li-Ion has enjoyed.”