Integrated System for Capturing CO₂ as Feedstock for Algae Production

Abstract

In view of its promise as sustainable process for CO₂ capture and its potential in the production of feed, food and natural high value products such as omega-3 fatty acids and anti-oxidants such as astaxanthin, large scale algae cultivation is gaining commercial interest. Currently, most systems are based on directly contacting CO₂ containing gas, e.g. flue gas, with the algae culture. However, applicable on small scale, this approach is not applicable on a commercially relevant large scale due to mass transfer limitations. There is need for a cost effective and scalable system. TNO has developed a scalable system for efficient capture of CO₂ as feedstock for algae production. In this system, CO₂ is absorbed in an absorption liquid as bicarbonate. Subsequently, the enriched absorption liquid is fed to the algae, which convert the solubilized CO₂ into biomass and biobased products. Finally, biomass is recovered and the lean absorption liquid is recycled. TNO's integrated process concept was successfully demonstrated with continuous algae cultivation on a 2 L-scale for more than 150 days of which 40 days using flue gas as CO₂ source.