In a future circular economy, biorefineries will produce chemicals and fuels from renewable feedstocks. A key part of this transition is the use of advanced fermentation concepts like electro-biosynthesis. The ELF4GREEN project explores this process to efficiently utilise bio-waste, poorly degradable residues, and CO₂-rich gas streams. These materials are inexpensive and widely available in the EU, but their effective use requires innovations to address feedstock variability and enhance bioavailability.

At the core of ELF4GREEN is electrobioconversion, an advanced technology in which fermentation processes are specifically supported by the application of electrical energy. Electroactive microorganisms interact with electrodes to convert substrates such as organic waste or CO₂ into chemicals and biofuels. This approach enhances the efficiency, sustainability, and cost-effectiveness of conventional fermentation processes.

ELF4GREEN investigates three bioelectric transformation routs for the conversion of waste or residues into green chemicals and fuels:

• Treatment of biologically recalcitrant materials (e.g. mixed plastic waste or sewage sludge) through gasification followed by electro-fermentation of synthesis gas. CO₂, CO and H₂ are utilized for the biosynthesis of environmentally friendly products. (Project 2)
• Fermentation of biologically convertible feedstocks, such as wastewater from the food industry, to produce medium-chain organic acids or alcohols. Electro-fermentation is used to selectively enhance product specificity and yield. (Project 3)
• Electro-biomethanation of CO₂ for biogas upgrading and for the treatment of CO₂-rich off-gas streams, with the goal of producing biomethane. (Project 4)

These three routs are supported by two cross-cutting projects that provide

• essential core knowledge through fundamental theoretical and experimental investigations for the effective utilization of electro-active microorganisms in technical applications. (Project 1)
• a comprehensive technoeconomic and ecological evaluation of the three technology concepts for green fuel or chemical production. (Project 5)

By combining electrochemical and biological catalysis, ELF4GREEN opens up new, resource-efficient pathways for the utilization of biomass and CO₂. In addition, electro-biosynthesis enables the storage of surplus renewable electricity in the form of gaseous or liquid energy carriers that are compatible with existing energy infrastructures and supply chains.

ELF4GREEN lays the foundation for application-oriented research aimed at developing novel biotechnological solutions for a sustainable energy supply based on biogenic fuels and for the climate-friendly transformation of the chemical industry