INTRODUCTION
Demand for long duration energy storage is expanding for application in remote area power supply, wind and solar farms, grid-scale load-levelling and load-shifting, as well as emergency power back-up installations. The use of batteries in electric vehicles (EV) is rapidly expanding resulting in supply shortfalls of energy metals. Longer cycle life and higher energy densities are needed for portable energy applications such as EV while long-duration static applications are more sensitive to cost.
Lithium and nickel metal hydride emerged more recently as excellent high energy density alternatives to conventional lead-acid and nickel-cadmium batteries, although the relatively high cost of metal hydride has limited use to smaller-scale portable equipment and hybrid electric vehicles.
The redox flow cell appears to offer great promise as a low cost, high efficiency system for long-duration static energy storage and the next-generation vanadium redox battery (VRB) is rapidly moving towards full commercialisation in a wide range of stationary applications.
The VRB system employs vanadium redox couples in sulphuric acid in both half-cells and was pioneered by Prof. Maria Skyllas-Kazacos and her team at the University of New South Wales in Australia. The electrolyte used in vanadium redox batteries is a mixture of vanadium and sulphuric acid of acidity similar to lead-acid batteries.
VRB BATTERIES
Vanadium redox batteries are widely hailed as a strong contender for the alternative energy storage requirements. This technology could also potentially replace lead-acid batteries in UPS and other back-up uses, subject to competitive pricing of the vanadium-based electrolyte. The VRB market promises steady growth over the next few decades constrained mainly by price volatility of vanadium in steel alloying as its primary application. It follows that the successful commercialisation of VRB is contingent on access to low cost vanadium from sources decoupled from cyclical price and demand fluctuations of the construction industry globally.
The SMB IX process of IPEX Solutions promises high purity vanadium suitable for niche markets such as VRB electrolyte. Ongoing R&D to further improve product optionality and purity promises a novel VRB electrolyte flowsheet at lowest costs globally. Vanadium electrolyte below $5 per lb V2O5 contained will be essential for utility-scale deployment of VRB as preferred platform for long-duration energy storage. VRB is widely considered one of the most promising candidates for the energy transition to renewables.