Project Details


Increasing the concentration of CO2 delivered to photosynthetic microbes can greatly improve their productivity. We propose a novel direct air capture (DAC) technology that integrates newly developed CO2-capture polymers to continuously and rapidly deliver inorganic carbon (ICi) directly into the cultivation medium to maximize photosynthetic growth rates and produce sustainable fuels and high-value products with the CO2 delivered by DAC; we call this technology ASUs DAC polymer-enhanced cyanobacterial bioproductivity (AUDACity, Figure A). The CO2-capture polymer builds on the principles of moisture-swing sorption observed in well-established quaternary ammonium-based anion exchange resins; they capture CO2 from air when dry and release ICi when exposed to moisture. The DAC-polymer material introduces quaternary ammoniums for rapid CO2 capture into high-surface-area, porous poly(arylene ether sulfone)s (PAES) polymers for rapid CO2 capture from air, with high flexibility and stability to withstand tensions and torsion as it is continuously circulated between exposure to air and the cultivation medium (Figure A). AUDACity will be used to provide IC Ci to cultivate biofuel-producing cyanobacteria, specifically Synechocystis sp. PCC 6803 strains developed at ASU that have been engineered to excrete methyl laurate ($1k/ton) and that contain phycocyanin, a high-value natural dye for food and cosmetics ($150k/ton). To further improve performance, the DAC-polymer will be optimized to resist biofouling, minimize salt exchange with the cultivation medium (including seawater) that could degrade its performance, and minimize polymer drying time to maximize the polymers cycling frequency between air and cultivation medium. AUDACity systems, which are integrated to cover both polymers and cyanobacterial culturing, will be evaluated in terms of DAC-polymer material performance, biocompatibility, kinetics of CO2 delivery from air to the culture, and pH stability. Scales of cyanobacterial culturing will range from laboratory scale to outdoor ponds.

The projects ultimate objective is to demonstrate a pathway for delivering CO2 from air to photosynthetic microbes for ~$50/ton or less at rates that do not limit their growth. This low cost is enabled by the use of low-cost polymers and by eliminating forced air movements and CO2 compression and delivery. Our AUDACity concept overcomes significant CO2 losses associated with sparging (up to 70% loss) and significantly reduces the CO2 delivery cost compared to other emerging DAC technologies.
Effective start/end date10/1/209/30/21


  • US Department of Energy (DOE): $1,999,051.00