A system for growing algae includes a gas concentrator configured to receive a first gas containing CO2 at a first concentration and discharge a second gas containing CO2 at a second concentration higher than the first concentration, and a photobioreactor containing algae in an algae slurry and fluidically coupled to the gas concentrator to receive the second gas. A recycling line extends from a gas outlet on the photobioreactor to remove a third gas from the photobioreactor for future use in the photobioreactor.