Controlling the release of carbon dioxide (CO2) into the atmosphere is a major challenge facing global environmental sustainability. Fermentation off gases consist of mostly CO2 and are a major byproduct accompanying the production of biofuels. These can be better controlled and mitigated using complementary heterotrophic and photosynthetic microorganisms. An efficient CO2 delivery system is being designed to reduce carbon emissions, using a membrane carbonation system to deliver effluent CO2 to microalgal cultures to produce recyclable sugars. This novel bioprocessing strategy would result in an efficient biofuel production with virtually zero CO2 emissions.