The High-Value Product, Bio-Waste, and Eco-Friendly Energy as the Tripod of the Microalgae Biorefinery: Connecting the Dots

A bio-based circular economy is fundamental to catalyzing the transition to a new economic model that thrives well within the planet’s ecological limits. The microalgae biorefinery, which consists of converting biomass into multiple products, operates in light of the principles of a circular economy. Therefore, as the pivot of a new economic paradigm that aims to promote ecological robustness, the main scope and motivation of this article are to use life cycle assessment to scrutinize the environmental sustainability of a microalgae-based biorefinery system. We assume β-carotene as the flagship of the microalgae industry and evaluate the sustainability metrics and indicators of two residual products: bulk oil and defatted biomass. The role of the use of renewable energy in the unit operations of the biorefinery was also evaluated. The results of this study show that waste products contribute an almost insignificant fraction of the ecological footprint and the cost and energy demand of the microalgae-based biorefinery. It is also confirmed from the results that the transition from coal-based energy to renewable is the most realistic path to production with significantly lower emissions. In sum, the consolidation of the microalgae biorefinery seems to be just around the corner, and our highlights can help make this a successful route.