Abstract
Innovative protein sources, such as single cell protein (SCP) derived from unicellular organism biomass, are emerging as promising solutions to address food scarcity and meet global nutritional needs. This article aims to estimate the environmental impacts of SCP production using biomethane from fish industry waste through an ex-ante Life Cycle Assessment (LCA), focusing on scaling up a lab-scale process. The proposed scenarios include SCP production with biofertilizer recovery (baseline scenario) and the additional valorization of biomethane as grid gas, electricity, and/or heat (modified scenarios). The analysis follows a cradle-to-gate approach, and recovered materials and energy were included by expanding the system boundaries to account for avoided primary production. Results revealed significant differences between laboratory-scale and industrial-scale impacts, with reductions ranging from 60% to 96% across all impact categories when scaled up. Focusing on the industrial scale, the baseline scenario showed the poorest environmental performance, mainly due to biogenic methane emissions from unutilized biogas. In contrast, modified scenarios that incorporated various biomethane utilization pathways achieved substantial reductions across all impact categories. These findings suggest that the optimal system configuration combines the recovery of biomethane, heat, and electricity, underscoring the need for further research into its technical and economic feasibility within the food sector. This research highlights the utility of LCA in evaluating emerging technologies, identifying key environmental challenges, and guiding decision-making at early development stages.