Microalgae technology has the potential to make significant contributions to the circular economy and the transformation to a bioeconomy, thereby mitigating climate change. One of the key benefits of microalgae is their high capacity for CO2 capture by use of CO2 in photosynthetic growth and biomass production, turning a waste product into a valuable resource. The realization of the idea of a sustainable circular bioeconomy with microalgae stands and falls with the production process, which must be energy-efficient, robust and, above all, scalable in energy-efficient photobioreactors. In photobioreactors, the necessary process intensification can be achieved by improving light utilization and efficient CO2 conversion. CO2 utilization is closely linked to the light regime and nutrient supply, ensuring that the CO2 introduced is completely converted into biomass. Process control and automatization increase energy efficiency and cut costs. Algae biotechnology has the opportunity to turn residual products into a valuable resource.