Environmental sustainability analysis of a protein-rich livestock feed ingredient in The Netherlands: Microalgae production versus soybean import

Abstract

Sustainability in terms of the natural resource demands of protein-rich algal meal for livestock feed applications was examined. In The Netherlands, an integrated microalgal biorefinery delivered the following products: digestate, electricity, heat available for a nearby bio-ethanol facility and algae oil and meal. Pilot scale (500m2) data were used to conduct an exergy analysis (EA), which revealed the process inefficiencies of energy-intensive processes such as drying (44.01%) and inoculum production (54.98%). An attributional life cycle assessment (LCA) using system expansion exposed the high contribution of biomass digestion to the total resource footprint of the biorefinery (72.74%) due to the high daily demand for biomass and electricity consumption of the dosage system. In this study, algal meal was compared with soybean meal, which is the most commonly used protein-rich animal feed ingredient; it is produced in Brazil and transported to The Netherlands. Because algae production is a young, small-scale technology, the resource footprint of the large-scale soy meal production was a factor of 102 lower, mainly as a result of the energy-intensive algae cultivation stages. A sensitivity analysis showed that the resource footprint of algal meal production could be comparable with soy meal when, overall, the areal biomass productivity increases, electricity production is based on more renewable sources (wind) and the energy consumption from mixing and blowing flue gases into the ponds decreases.