Upscaling and environmental impact assessment of an innovative integrated multi-trophic aquaponic system

The increasing growth of the aquaculture sector has raised significant concerns regarding its environmental footprint, including nutrient discharge, substantial feed consumption, and high energy requirements. In response, innovative approaches such as aquaponics and integrated multi-trophic aquaculture (IMTA) are being developed as potentially more sustainable alternatives. This study aims to evaluate the environmental performance of an innovative Integrated Multi-Trophic Aquaponics system (IMTAcs) using the Life Cycle Assessment (LCA) approach. Given the experimental nature of the pilot plant, two distinct scaled-up scenarios were analysed: one utilizing an alternative feed (IMTAcs AF), and the other employing a commercial feed (IMTAcs CF). The functional unit was defined as 100 kcal and 1 kg of protein produced by the system, with a cradle-to-gate perspective defining system boundaries. Results revealed that IMTAcs AF has a higher global warming impact (0.234 kg CO2 eq./100 kcal) compared to IMTAcs CF (0.207 kg CO2 eq.). In both scenarios, electricity consumption was identified as the primary driver to environmental impact, exceeding 50%, in contrast to conventional systems where feed is the main hotspot. Moreover, while trends in impact categories such as net primary production use and eutrophication is opposite between the scenarios, the latter demonstrated substantial mitigation potential, attributable to the system's inherent nutrient recycling, in comparison with traditional aquaculture systems. While the findings are promising, certain limitations in the study (e.g. utilization of scaled-up data and inherent uncertainties analysed), with the scarcity of existing research, point to the opportunity for further exploration. This includes analysing real-scale implementations whenever feasible and conducting more detailed comparisons with traditional systems.