Comparative life cycle assessment of industrial and artisanal spirulina production systems.

Conventional food production, particularly animal protein, exerts considerable pressure on the environment. As part of the protein transition and global efforts towards sustainable agricultural practices, it is relevant to study low-impact protein alternatives and compare their environmental profiles with those of conventional animal sources. This study examined spirulina, a protein-rich edible cyanobacterium. It compared the environmental impacts of four spirulina production systems (industrial, geothermal, artisanal and permacultural), with those of beef, poultry and eggs. The assessment used Life Cycle Assessment methodology, with a cradle-to-consumer scope and a functional unit of 1 kg of protein content. The results showed that spirulina production, whatever the production system, has significantly lower environmental impacts than beef production, with up to 98 % lower greenhouse gas emissions (4.56 vs. 187.17 kg CO₂-eq) and over 99 % lower land use (0.25 vs. 116.95 m²a crop eq). These benefits were less marked in comparison with poultry and eggs. Of the spirulina systems studied, the permacultural system performed best on five out of eight environmental indicators - including global warming, land use, and human toxicity - followed by the artisanal system, the geothermal system and, finally, the industrial system. Compared to the industrial system baseline, global warming impacts were reduced by 56-82 %, land use by 26-73 %, and human toxicity by up to 77 %, depending on the spirulina system. These results highlight the potential of spirulina as a promising alternative for the protein transition and the promotion of sustainable agricultural practices, particularly if produced in a permacultural way.