Redox Flow Batteries Market 2024-2034: Forecasts, Technologies, Markets

As the volume of variable renewable energy (VRE) energy sources penetrating electricity grids increases globally, as does the need to manage the increasing uncertainty and variability in electricity supply. Grids will be relying on different solutions to manage this, which could include building of overcapacity and interconnections, but also energy storage solutions. Redox flow batteries will be a key energy storage technology to support increasing VRE penetration, with IDTechEx forecasting that the RFB market will be valued at US$2.8B in 2034.

 

Aside from pumped hydro, Li-ion batteries currently dominate the global stationary energy storage market, and they are suitable for large, grid-scale installations to provide ancillary and utility services. As VRE penetration increases however, demand for long duration energy storage (LDES) technologies is expected to increase. These technologies will be needed to dispatch energy over longer timeframes when energy from VRE sources is not available. Li-ion batteries start becoming less suitable for storing energy at durations greater than 6 hours, due to unit system cost increasing with duration of storage proportionally. Instead, RFBs only require the scaling of electrolyte storage tanks and electrolyte volumes to increase duration of storage, whereas cell stack configurations can remain unchanged, i.e., power and energy are decoupled. This results in a smaller and non-proportional increase in CAPEX with increasing duration of storage. This is part of the reason why redox flow batteries will start becoming useful for providing durations of storage greater than 6 hours.

 

It is also important to recognize that RFBs can provide a lower levelized cost of storage (LCOS) than Li-ion batteries. This is mainly due to the increased lifetime of RFBs, and many RFB manufacturers pride themselves on the fact that RFBs are reliable systems, with no significant degradation being observed over 20,000+ cycles for some chemistries. As a result, RFBs can dispatch greater volumes of energy capacity (approximately 4-5x) over their lifetime than Li-ion batteries, resulting in a lower LCOS.

 

 

However, there are some factors limiting the rate of RFB deployments in the current stationary energy storage market. Firstly, while RFBs present a lower LCOS than Li-ion, the CAPEX per kWh of the most widely deployed RFB, the vanadium RFB (VRFB), is higher. This will naturally act as a blocker for stakeholders looking to deploy energy storage technologies for grid-scale applications where CAPEX is already expected to be in the tens- or hundreds-of-millions of dollars for Li-ion. The cost of VRFBs is limited by expensive vanadium electrolyte, as this comprises ~30-50% of unit cost. Other substantial costs come from materials and components in the cell stack (see below) including the membrane, bipolar plates, electrodes, gaskets, etc. VRFB cost reductions are only likely to come in the longer term and from increasing economies of scale, as well as improved and more automated manufacturing processes.

 

A second factor limiting RFB deployments is that, in the current market, most RFBs will be competing with Li-ion batteries for 4-hour grid-scale applications. Li-ion batteries are a widely deployed and well understood technology for these grid-scale ancillary and utility services, such as energy shifting, voltage and frequency control, peaker plant/transmission and distribution (T&D) deferral, etc. Therefore, most RFB deployments in the mid-2020s RFBs are likely to continue being pilot and demonstration projects and competing with Li-ion. This will be at least until demand for long duration energy storage (LDES) technologies starts to increase in the later part of the decade in some key countries. Such countries may have higher penetration of VRE, greater blackout risks, LDES targets and tenders, or are where funding into LDES technologies is already starting to be seen - such as in the US.

 

As well as VRFBs, other competing RFB technologies could look to take increasing RFB and stationary battery storage market share. These include all-iron, zinc-bromine (Zn-Br), zinc-iron (Zn-Fe), organic, hydrogen-bromine (H-Br) and hydrogen-manganese (H-Mn) RFBs. Some of these technologies offer a much lower CAPEX compared to VRFBs, due to the more widely available and cheaper materials used in the electrolyte. However, they may of course pose some technical downsides which could limit their commercial feasibility. For example, zinc-based RFBs will be prone to zinc-plating on the anode surface, resulting in dendrite growth. Therefore, more highly engineered materials will need to be used in the cell stack to either limit dendrite formation or resist their penetration. This IDTechEx report includes a benchmarking analysis, comparing RFB technology metrics such as CAPEX, electrolyte costs, energy density, energy efficiency, dendrite formation, etc.

 

 

While other RFB technologies may compete, there are far fewer companies developing any one of these specific RFB chemistries. For instance, the only companies developing all-iron, H-Br or H-Mn RFBs are ESS Inc, Elestor and RFC Power, respectively. Therefore, it is more likely that most RFB capacity installed globally will be from vanadium RFBs over the next few years, as 18 companies identified by IDTechEx are developing these systems. Of the key players identified, Rongke Power's large 400 MWh VRFB installation dwarfs all installations made by other players over the past decade. In 2022, Sumitomo Electric Industries installed a 51 MWh VRFB in Japan, and another notable player, Invinity, installed ~22 MWh of VRFBs across various locations in the UK, US, Canada, South Korea and Taiwan. CellCube also made some smaller installations. The only company to make non-VRFB installations in 2022 was Redflow, with their Zn-Br RFB technology, but these only accumulate to ~3 MWh installed in 2022. This IDTechEx report includes market analysis, including RFB player announcements, supply partnerships, company and chemistry market shares, historical RFB installations by region since 2010, and planned projects and production facilities.

 

This IDTechEx report also provides ten-year market forecasts on the redox flow battery market for the period 2020-2034, in both capacity (MWh) and market value (US$B). Capacity forecasts are provided by regional and chemistry splits. Regions include China, United States, Europe, Japan, Rest of Asia, and Rest of the World. Chemistry breakdowns include vanadium, all-iron, Zn-Br, Zn-Fe, H-Br, and organic redox flow batteries.

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