Chlorella vulgaris biorefineries: sustainable biofuels and high-value carbon capture

Abstract

Global reliance on fossil fuels has created urgent economic and environmental challenges, yet large-scale use of algal biomass remains limited by production costs. Industrial scaling is constrained by inefficient harvesting and the technical challenges of processing recalcitrant cell walls. This review proposes that Chlorella vulgaris-based biorefineries can become economically viable through integrated multiproduct valorization aligned with circular economy principles. A synthesis of literature, patents, and techno-economic studies – supported by bibliometric analyses of the Web of Science and WIPO PATENTSCOPE – highlights multidisciplinary trends spanning biology, engineering, and market dynamics. Academic research primarily focuses on biofuels, whereas patent trends emphasize nutraceutical and cosmetic applications. This divergence reveals opportunities for hybrid cascade-extraction approaches that integrate biotechnology, artificial intelligence-assisted process optimization, and the valorization of residue into biochar. High-value co-products, such as lutein and astaxanthin, support projected profit margins of 40% to 45%, a 3.5- to 4.5-fold increase over biodiesel-only routes, while potentially offsetting up to 4.1 million t CO2 annually. Future development could include metabolic engineering (e.g., CRISPR/Cas9) to enhance yields, pilot-scale demonstrations in semi-arid regions using brackish water and industrial CO2 streams, and measures to address regulatory, investor, and certification challenges. Ultimately, C. vulgaris-based biorefineries can foster circular bioeconomies, recover nutrients from waste, and leverage the expanding global market, positioning the species as a versatile and profitable platform for sustainable technological transitions.