Sammendrag
Improving sustainability in agriculture and aquaculture production systems is paramount to global food security and maintaining healthy, diverse ecosystems. One way to reduce pressure on terrestrial food production systems is looking towards the ocean for food production. With its extensive coastline and intensive salmon aquaculture, Norway is experimenting with macroalgae as a new feedstock for a circular bio-economy. This study compares the environmental performances of two similar aquafeed ingredients: Brazilian Soy Protein Concentrate (SPC) derived from Glycine max, and Norwegian Seaweed Protein Concentrate (SWPC) extracted from Saccharina Latissima. The efficiency and sustainability of these two production systems are assessed using a comparative Material and Substance Flow Analysis (MSFA) accounting for the transfers of primary energy and Phosphorus (P). Through an environmental product comparison, this research aims to increase the understanding of the SPC and SWPC value-chains, compare their efficiencies using key environmental indicators, and assess the potential of SWPC as an alternative aquafeed ingredient for the aquaculture industry. Both the SPC and SWPC systems integrate cradle-to-customer gate system boundaries. Leading sources originated from published environmental assessments as well as private companies, and both systems were modelled with sets of assumptions and generic datasets. To compare commodities with similar protein contents, the primary energy and P demands of 1 ton of SPC is compared to 2 tons SWPC. The primary energy requirement of SWPC (172,133 MJ) is found 11.68 times larger than for SPC (14,733 MJ). However, the SWPC primary energy consumption can be reduced to 34,010 MJ by utilising secondary heat from a waste incineration plant during the late spring harvest. The SWPC system outperformed the SPC system in terms of fossil P consumption since 1 ton of SPC requires 25.75 kg fossil P while 2 tons of SWPC require as little as 0.008 kg fossil P input. Furthermore, results suggest that, while allocation of soybean co-products environmental burden reduces SPC’s overall impacts, SWPC co-product bio-fertilisers can replace the production of mineral fertilisers at a ratio of nearly 1:1 and reduces the SWPC fossil P -into negative values, -26.36 kg. Results show that with today’s technology, substituting SPC by SWPC is an environmental trade-off. Such substitution would dramatically increase the primary energy demand of protein-rich feed ingredients, while also likely reduce freshwater and marine eutrophication, mitigate mineral P depletion, and decrease pressure on arable lands. The overall conclusion of this study is that SWPC holds a competitive advantage based on P management performances; however, based on the results from current technology, replacing SPC with SWPC will require extensive innovation and optimisation to become energy competitive.
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