US Patent 7763457 High photoefficiency microalgae bioreactors

A system and method are provided for growing algae with improved photoefficiency. The system includes a bioreactor formed with a conduit for growing algae cells in a medium. Further, the system is provided with a paddle wheel for moving the medium through the conduit at a predetermined fluid flow velocity. In order to ensure that algae cells are efficiently converting light energy to chemical energy, a plurality of barriers is positioned in the fluid stream. Specifically, the barriers are separated by predetermined distances to create von Karman vortices in the medium. As a result, algae cells are sequentially flowed to the surface of the fluid stream to receive light energy for predetermined intervals of time.