SABATLE - Safety assessment of flow battery electrolytes

Redox flow batteries are an emerging technology for medium and large-scale stationary energy storage and are considered as a viable option to buffer fluctuations in the energy grid. These fluctuations are caused by the increasing share of renewable energy (e.g. solar and wind energy) whose production is dependent on weather and seasonal conditions. The core elements of a redox flow battery (RFB) are two tanks filled with the electrolytes. Currently used electrolytes feature several issues such as limited regional availability, stability, volatile price, lack of sustainability and – often neglected – significant toxicity. In SABATLE, we aim at investigating the safety and (nano)toxicity aspects of current and emerging electrolytes in redox flow batteries as well as the corresponding environmental impacts by performing a life cycle assessment of the whole life cycle from resource extraction to the end-of-life. We will investigate electrolytes from the following commercially available RFB technologies: vanadium, zinc-bromine/chlorine, iron, and compare them to emerging electrolytes based on organic compounds derived from lignins, so called quinones, currently being developed at one of the partners. The lignins as well as decomposition products of the electrolytes may contain also nanoparticles which may pose an additional risk for the environment. Human toxicity and ecotoxicity of electrolyte solutions will be assessed using algae, daphnia, and zebrafish biological models. Exposure scenarios upon accidents during operation of the battery and after end-of-life will be considered, and realistic doses for human exposure and ecotoxicity will be developed. Further, high impact will be generated by developing a tailored safe-and-sustainable-by-design (SaSbD) concept. Through the implementation of this concept a mitigation of potential hazards will be secured and more sustainable and inherently safe electrolytes will be provided. Public concerns, including risk assessment and stakeholder engagement will be covered in the project.