Microbially charged redox flow batteries for bioenergy storage

Electrochemical energy conversion and storage technologies are always seeking new renewable sources of energy. Electrochemical energy conversion is the common basis in bioelectrochemical systems (BESs) and redox flow batteries (RFBs), although the first technology is not able to promote energy storage. RFBs are an electrochemical storage technology where the energy is stored in soluble redox pairs (electrochemical fuel), and in this form is available for exchange in electrical energy. The fundamental principle for RFB is that power and energy are independent, a great difference over other systems. Several organic active molecules are a great novelty as redox pairs with their energy capacity and higher efficiencies reached in organic RFBs, lowering the cost and toxicity of the system. There are responsible for a new direction of research and applicability for these devices, and this opens the door for their coupling with other technologies. Microbially charged RFBs are an innovative research technology with a potential new approach for the bioconversion of waste biomass energy and the promotion of bioelectrochemical fuels, to combine these with RFBs with the aim to produce and store bioenergy. Efficient storage technologies can be reached with these newest approaches for converting biomass into storable energy.M.S.S. Santos is grateful to the Portuguese Foundation for Science and Technology (FCT) for her PhD fellow (reference no. SFRH/BD/104087/2014) and C. Dias‐ Ferreira to the FCT fellowship by POCH (Programa Operacional Capital Humano) within ESF (European Social Fund) and by national funds forms MCTES (SFRH/BPD/100717/2014). The authors would like to acknowledge the FCT under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE‐01‐0145‐FEDER‐000004) funded by the European Regional Development Fund (ERDF) under the scope of Norte2020 – Programa Operacional Regional do Norte. The authors also acknowledge the following projects: (i) UID/EQU/00511/2019 – Laboratory for Process Engineering, Environment, Biotechnology and Energy – LEPABE funded by national funds through FCT/MCTES (PIDDAC), through COMPETE2020 (Programa Operacional Competitividade e Internacionalização [POCI]) and by nationals funds through FCT; (ii) Project SunStorage – “Harvesting and storage of solar energy,” with reference to POCI‐01‐0145‐FEDER‐016387, funded by ERDF, through COMPETE 2020, and by national funds, through FCT; and (iii) NORTE‐01‐0145‐ FEDER‐000005 – LEPABE‐2‐ECO‐INNOVATION, supported by North Portugal Regional Operational Program (Norte 2020), under the Portugal 2020 Partnership Agreement, through ERDF.info:eu-repo/semantics/publishedVersio