Assessment of the use of vanadium redox flow batteries for energy storage and fast charging of electric vehicles in gas stations

A network of conveniently located fast charging stations is one of the possibilities to facilitate the adoption of Electric Vehicles (EVs). This paper assesses the use of fast charging stations for EVs in conjunction with VRFBs (Vanadium Redox Flow Batteries). These batteries are charged during low electricity demand periods and then supply electricity for the fast charging of EVs during day, thus implementing a power peak shaving process. Flow batteries have unique characteristics which make them especially attractive when compared with conventional batteries, such as their ability to decouple rated power from rated capacity, as well as their greater design flexibility and nearly unlimited life. Moreover, their liquid nature allows their installation inside deactivated underground gas tanks located at gas stations, enabling a smooth transition of gas stations' business model towards the emerging electric mobility paradigm. A project of a VRFB system to fast charge EVs taking advantage of existing gas stations infrastructures is presented. An energy and cost analysis of this concept is performed, which shows that, for the conditions tested, the project is technologically and economically viable, although being highly sensitive to the investment costs and to the electricity market conditions.The authors would like to thank Petrotec S.A. for the support given to the present work. This project was funded by Project MOBI-MPP (MIT-Pt/EDAM-SMS/0030/2008) supported by the MIT Portugal Program and FEDER funds through the Programa Operacional Factores de Competitividade - COMPETE and National Funds through FCT - Foundation for Science and Technology. Francisco P. Brito benefited from post-doctoral grants SFRH/BPD/51048/2010 and SFRH/BPD/89553/2012 supported by the MIT Portugal EDAM and FCT, respectively.