By Conrad Nichols
Vanadium redox flow batteries (VRFBs) have been developed for decades and are the most widely understood and commercialized redox flow battery (RFB) technology. It is an energy storage (ES) technology with reasonably sufficient performance metrics, across energy efficiency (70-80%), cycle life (20,000+), and the ability to decouple energy capacity and power output, making for potentially lower cost ($/kWh) systems at longer durations of storage.
However, their wider adoption in grid-scale energy storage markets has been inhibited by the high cost of vanadium electrolyte. In this market, Li-ion battery energy storage systems (BESS) continue to dominate, given that this technology’s costs continue to fall. High VRFB cost has been a key driver for the development of alternative flow battery technologies, using cheaper and more abundant materials, such as organic- and iron-based technologies. If these various technologies can be commercialized and brought to market, and as shown in their newly updated market report “Redox Flow Batteries Market 2026-2036: Forecasts, Markets, Technologies and Players”, IDTechEx predicts that the global redox flow battery market will be valued at US$9.2B in 2036.
Vanadium demand and electrolyte leasing
Supply of global vanadium has slightly outweighed demand in recent years, and this tight surplus is a key driver for high prices of both vanadium electrolyte and final VRFB systems. Approximately 90% of vanadium is currently supplied to steel industries, with other sectors including titanium alloys for rotating applications, ballistic missiles, and oxidation catalysts for chemicals. This leaves a marginal proportion of global vanadium supply available for vanadium electrolyte production and flow battery developers, giving rise to high system costs.
To combat this, electrolyte leasing models could be offered by electrolyte suppliers to VRFB developers, reducing the upfront cost of electrolyte. These models are starting to be adopted commercially, e.g., in the US, Storion Energy will be supplying vanadium electrolyte to Terraflow Energy for a 9.6 MW / 48 MWh VRFB project.
However, with the declining cost of Li-ion BESS technologies, this reduction in upfront VRFB cost may not always result in a VRFB technology that is cheaper than a containerized Li-ion BESS. In the long-term, exploitation of new vanadium mines outside China may be needed to increase global vanadium supply and reduce vanadium costs; players are indeed exploring new mines across Canada and Australia.
Alternative flow battery technologies
Given the high-cost of VRFB technologies, other players are looking to develop cheaper organic and iron-based chemistries. Organic redox flow battery technologies are starting to move out of the lab, and into pilot- and early commercial demonstration projects. To keep costs of ORFB technologies down, their electrolytes will need to have short synthesis routes, and their production will need minimize the use of catalysts and organic solvents. Performance of the final technology is also key, with minimal degradation over extended cycling needing to be demonstrated, as well as the technology needing to exhibit non-flammable electrolyte, as these can act as key advantages over Li-ion BESS technologies in applications such as data centers.
Indeed, several organic and iron-based players are upscaling their electrolyte production capacities. Quino Energy is a key player in the US, developing an organic flow battery technology, based on quinones. As written in IDTechEx’s market report and through an interview with IDTechEx, Quino Energy explained that they have ~25 MWh/annum of quinone anolyte production, and the company is looking to scale production over the coming years.
Similarly, Redox One is a developer of an iron-chromium flow battery chemistry. With its sister company, Arxo Metals, the company is hoping to scale its electrolyte production capacity to multi-hundred-MWh scale in the near future. However, the company is continuing its search for and development of profitable business models for its technology, for example in long duration energy storage (LDES) applications.
The redox couples that can be developed are vast, and many other flow battery chemistries are at early stages of commercialization. Some chemistries may have also ceased development amidst technical barriers or company financial difficulties. These chemistries, at various stages of development, include hydrogen-, bromine-, CO2-, and saltwater-based chemistries. In principle, these chemistries offer theoretically lower material and system costs than vanadium RFBs, though performance metrics vary across all chemistries. Flow battery Capex and key performance metrics are benchmarked across 10 flow battery technologies in IDTechEx’s newly updated market report.
Flow battery technology outlook
Since most players in the global RFB market are vanadium technology suppliers deploying systems commercially, IDTechEx expects this chemistry to continue dominating RFB installations over the next few years. Vanadium electrolyte leasing models could support VRFB uptake to some degree, though the exploitation of new mines would increase global vanadium supply and may help to more significantly reduce final VRFB system costs.
The wider deployment of cheaper, alternative RFB technologies is likely to occur, and could take more substantial RFB market share in the longer-term. The commercialization prospects of these technologies are tied to material, component, and electrolyte costs, as well as technology bankability. Developers will also look to pursue clear routes to market through targeting key RFB applications where the technology can pose key advantages over Li-ion BESS.
•By Conrad Nichols, Principal Technology Analyst at IDTechEx
