Emergent green technologies for cost-effective valorization of microalgal biomass to renewable fuel products under a biorefinery scheme

Abstract The current COVID-19 pandemic is forcing radical change in the global energy economy. All energy sectors have experienced profound economic contraction in 2020, with the notable exception of renewable energy, which has grown by nearly 3%. These unprecedented circumstances offer a pristine opportunity to create new jobs, technologies, and infrastructure, aimed at engineering a climate-friendly and sustainable energy future. This review explores several pathways to renewable bioenergy by developing microalgal biorefinery systems which capitalize upon the unique abilities of microalgae to sequester carbon and produce biomass for bioenergy feedstock, without compromising food security or land use. This review further highlights the necessity of synergistically coupled upstream and downstream techniques to realize the economic viability of microalgal biorefinery systems, and details possible product pathways using either whole or fractionated biomass. The zero-waste circular biorefinery approach, when specifically tailored to local conditions, in terms of regional climate, economics, infrastructure, and available resources, is the answer to economically competitive microalgal bioenergy. The most promising emergent methods for microalgal biomass valorization to fungible bioenergy are reviewed herein.