Sustainable microalgae cultivation: A comprehensive review of open and enclosed systems for biofuel and high value compound production

Microalgae have emerged as a promising feedstock for biofuels and high-value compounds, offering potential solutions to global energy and resource challenges. This comprehensive review examines the latest advancements in microalgae cultivation technologies, focusing on both open systems and enclosed photobioreactors (PBRs). We analyze various configurations including open raceway ponds, tubular PBRs, flat panel PBRs, and novel designs such as the Light Exchange Bubble-column (LEB). The review encompasses key performance indicators such as biomass productivity, energy efficiency, and water usage, as well as life cycle assessment (LCA) results for different cultivation systems. We also discuss the challenges and opportunities in scaling up microalgae production, the potential for integrating wastewater treatment and CO2 mitigation, and the prospects of biorefinery approaches. By synthesizing recent research findings and identifying knowledge gaps, this review aims to provide a comprehensive understanding of the current state and future directions in sustainable microalgae cultivation for researchers, engineers, and policymakers in the field of renewable energy and biotechnology.