The SABATLE project was one of the first of its kind to adapt and employ  the use of the Safe-and-Sustainable-by-Design approach to energy  storage systems. As energy storage system we chose organic flow  batteries, which aim at replacing the electrolyte, namely commercially  available vanadium against biobased redox active molecules. The SSbD  considerations included the value chain from cradle to grave, included  social LCA impacts as well as toxicity testing of some compounds.  Application of the SSbD approach showed that by analysis of all process  steps, the safety of the overall process can be significantly increased.  The main outcome of the project was a case study which was presented at  the EuroNanoforum in Lund 2023 and submitted for publication in  December 2023. It highlighted that the implementation of SSbD during  technology development is capable to design better processes from both  economic, ecologic and safety point of view. Another important outcome  of the project was the analysis of current LCA methods to assess flow  battery technoeconomic and environmental performance where we identified  several methodological shortcomings which were summarized in a  ChemSusChem Paper published in early 2023. In addition, the project was  presented to a variety of stakeholders and was disseminated in many  conferences on national and international level (e.g. American Chemical  Society meeting). SABATLE also served as the seed for two more funding  initiatives which both started in September 2023 (Safera SUESS, SSbD,  LCA of post-lithium ion batteries and EIC VanillaFlow, toxicity of redox  active molecules).

Providing sustainable energy storage is a challenge that must be  overcome to replace fossil-based fuels. Redox flow batteries are a  promising storage option that can compensate for fluctuations in energy  generation from renewable energy production, as their main asset is  their design flexibility in terms of storage capacity. Current  commercial options for flow batteries are mostly limited to inorganic  materials such as vanadium, zinc, and bromine. As environmental aspects  are one of the main drivers for developing flow batteries, assessing  their environmental performance is crucial. However, this topic is still  underexplored, as researchers have mostly focused on single systems  with defined use cases and system boundaries, making the assessments of  the overall technology inaccurate. This review was conducted to  summarize the main findings of life cycle assessment studies on flow  batteries with respect to environmental hotspots and their performance  as compared to that of other battery systems.