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.

It is generally recognized, that algae could be an interesting option for reducing CO₂ emissions. Based on light and CO₂, algae can be used for the production various economically interesting products. Current algae cultivation techniques, however, still present a number of limitations. Efficient feeding of CO₂, especially on a large scale, is one of them. Current methods for CO₂ feeding to algae cultures rely on the sparging pure CO₂ or directly from flue gas. The limiting factor in this system is the solubility of CO₂in water, which demands a considerable amount of energy for an effective gas to liquid transfer and leads to losses to the atmosphere. Due to the current ineffective methods for CO₂ introduction into algae ponds very large surface areas would be required for enough ponds to capture a considerable amount of the CO₂. At TNO, an amine-based method have been developed for algae production utilization of CO₂ where algae is used as photochemical desorber of CO₂ from an absorption liquid. This methods brings the advantage of higher CO₂ removal efficiencies compared to current CO₂ feeding systems for algae and lower operational cost compared to both conventional CO₂ removal using amines and conventional autotrophic algae cultivation.