Life cycle assessment of different production routes for polyunsaturated fatty acids

Polyunsaturated fatty acids (PUFAs), like long-chain ω-3 compounds such as eicosatetraenoic acid and docosahexaenoic acid, are essential for human health. Traditionally, they are derived from fish oil but a growing demand is increasing pressure on aquaculture supply chains at unsustainable levels. Here, life cycle assessment (LCA) is applied to evaluate the potential environmental sustainability of alternative pathways for PUFAs production. To this aim, first a critical review of existing LCA studies relevant to PUFA production has been carried out; second, the critical review outcomes have been used as a basis for further selection of three production routes of PUFA-rich oils to model through LCA. The inventory data collected from the literature is rebuilt into a cradle-to-gate system model resulting into a comparable set of scenarios, namely marine fish oil (MFO ), sugar based microalgal oil (SdMO), and waste derived microalgal oil (WdMO). Life cycle impact assessment (LCIA) is performed with the Environmental Footprint 3.1 method based on 1 kg of refined PUFA-rich oil set as functional unit. Characterization results indicates that WdMO has the highest environmental impacts, particularly for climate change, freshwater ecotoxicity and resource use (fossils). SbMO performs better than WdMO despite similar impact for climate change and resource use (fossils). MFO shows the lowest LCIA results mainly thanks to avoided fishmeal production. Impact category results aggregation at the single score level resulted in the following order of environmental preference: MFO (0.4 mPt), SbMO (1.3 mPt), WdMO(w/o infra, 20.1 mPt), and WdMO/w infra (34.3 mPt). However, uncertainty analysis did not significantly distinguish between SbMO and MFO scenarios. These findings are expected to inform and guide improvements in energy efficiency, infrastructure utilization, and system-level integration as critical determinants for the environmental viability of PUFA oil production pathways.