Carbon accounting of negative emissions technologies integrated in the life cycle of spirulina supplements

Carbon dioxide removal (CDR) technologies are considered essential to accomplish the Paris Agreement targets. Given the important contribution of the food sector to climate change, this study aims to investigate the role of two carbon capture and utilization (CCU) technologies in decarbonizing the production of spirulina, an algae product commonly consumed for its nutritional characteristics. The proposed scenarios considered the replacement of synthetic food-grade CO2 in Arthrospira platensis cultivation (BAU scenario) with CO2 from beer fermentation (BRW) and CO2 from DACC (direct air carbon capture) (SDACC), representing two alternatives with great potential in the short and medium-long term, respectively. The methodology follows the Life Cycle Assessment guidelines, considering a cradle-to-gate scope and a functional unit equivalent to the annual production of spirulina in a Spanish artisanal plant. Results showed a better environmental performance of both CCU scenarios as compared to BAU, reaching a reduction of greenhouse gas (GHG) emissions of 52 % in BRW and of 46 % in SDACC. Although the brewery CCU offers a deeper carbon mitigation of spirulina production, the process cannot reach net zero GHG emissions due to residual burdens across the supply chain. In comparison, the DACC unit could potentially supply both the CO2 needed in spirulina production and work as a CDR to compensate residual emissions, which opens the door for further research on its technical and economic feasibility in the food sector. [Display omitted] •Life cycle assessment is applied to assess the use of CDRs in spirulina production.•Direct air capture (DACC) and CO2 recovery from breweries (BRW) are evaluated.•DACC is the best method to remove CO2 and achieve a neutral spirulina production.•BRW is the most feasible way to mitigate climate change in the short term.•Future technical and economic evaluation of the scenarios is recommended.