Replacing raw materials by secondary materials is a current issue and the use of waste or, better still; “bio-waste” (biodegradable green space residues, food and kitchen waste) is a promising way to do it. Producing energy from bio-waste is relatively known especially thanks to anaerobic digestion (AD) process which produces a biogas but producing chemicals is quite more technically complex. The BIORARE project (financed by the French National Research Agency – Investments for the future” call) has been aspired to provide an environmentally relevant solution to produce chemicals from bio-waste. The challenge of BIORARE project is a synergy between an innovative technology (microbial electrosynthesis process, also called bioelectrosynthesis (BES)) and a waste management option (AD plant). The AD plant provides renewable electricity from biogas burning and volatile fatty acids (VFAs) from bio-waste hydrolysis which are both send to the BES. In the BES, microorganisms convert VFAs into chemicals. This coupling technology, called BIORARE concept, has a low TRL (4) and needs to be driven by technical and environmental strategies. The Life Cycle Assessment methodology was chosen to eco-design the BIORARE concept based on expert’s opinion and prior experimentations. Performing LCA on such a low TRL concept was based on core issues all along the LCA methodology. The first question is what the function is. We assume a theoretical production of two types of chemicals: bioethanol or succinic acid thanks to BES and a waste treatment thanks to AD. The second question is what the scenarios for the comparison are. Two types of scenarios were built-up: a business as usual (BAU) scenario and a transition scenario (with the BES but using a simpler substrate than bio-waste: water). The next issue was to model and quantify theoretical synergies throughout the whole system. Synergies help reducing the use of external resources and could be achieved since AD allows the production of required input of the BES such as energy through biogas combustion, VFAs and CO2 via waste hydrolysis. Since no BES coupled with anaerobic digestion exists at pilot scale, the calculation approach to model these synergies has progressed with the upgraded skills and knowledge during the project. To identify the key parameters or synergies, sensitivity analyses have been carried out for the BES design and operating conditions. The LCIA showed that the BIORARE concept is environmentally competitive compared to the BAU and transition scenarios regarding the theoretical production of bioethanol or succinic acid. The results highlight the influence of current density on energy efficiency of the BES, and the hydrolysis rate to provide sufficient VFAs to the BES. In other words, we managed to model a low TRL industrial symbiosis through an eco-design approach based on LCA methodology aiming different potential chemical markets.