Magnetohydrodynamic Vortex Photobioreactor Concept for Microalgae Cultivation in Space

With increasing durations of upcoming crewed space missions, bioregenerative life support systems based on microalgae are currently being researched for air revitalization, food production, as well as waste and water treatment. Under microgravity conditions, microalgae have been cultivated in closed-loop pump-driven photobioreactors that use membranes for phase separation. The specific gas diffusion rate, biofilm buildup, and algae damage by mechanical pumping pose limitations in these systems. This paper introduces a novel concept for a magnetohydrodynamically driven photobioreactor for microalgae cultivation. When exposed to a magnetic and perpendicular electric field, a Lorentz force can be introduced in the conductive algae-compatible nutrient solution. When the consequent flow is directed in a circular manner, a vortex is created, mixing the microalgae and acting as a phase separator, driving the liquid outwards and bubbles toward the inside. In- and outlets are required for water and nutrient supply and harvesting. The inlet may also be used to introduce additional gas. An analytical 2D axisymmetric model of the fluid vortex combined with numerical simulations on the flow field within a small-scale reactor demonstrator is presented for the Magnetohydrodynamic Vortex-Inducing Photobioreactor Experiment (MVIPER), scheduled to fly on a parabolic flight in September 2025 as part of the ESA Academy Experiments Programme 2024-2025. The results from the analytical and numerical models show good agreement over a large range of geometric and electrical parameters. Overall, this photobioreactor concept operates with minimal active parts and is expected to significantly reduce the weight of the overall system and required spare parts to improve reliability.