Photosynthetic algal cultivation has been intensively studied for CO2 capture and utilization for several decades. The footprint for using algae to capture CO2 emitted from carbon-intensive industrial processes (power plants, cement plants, and fermentation processes) is extremely large, which creates serious technical and economic hurdles that must be cleared if algal technologies are to be commercially implemented. Fortunately, algal biomass is rich in proteins, carbohydrates, and lipids, providing a good chemical source for organic absorbents and other value-added chemical feedstocks. In particular, amino acids from algal protein can be used to generate amino acid salt solutions that have been proven to be effective for capturing CO2. In order to take advantage of both algal cultivation and biomass utilization, the goal of the proposed project is to develop a combined biological and chemical system for coal-fired power plants for sequestering CO2 in biological absorbents and generating value-added products. This approach significantly reduces the land and energy footprint of CO2 capture, and minimizes capital and operational expenses. Three specific objectives are targeted: 1) optimizing the growth of the selected algal strain to maximize biomass accumulation from the coal-fired flue gas
2) developing a cascade biomass utilization to produce amino acid absorbents, polyurethanes, biodiesel, and methane
and 3) conducting techno-economic analysis (TEA) and life cycle assessment (LCA) of the proposed process. Three key technical outcomes were achieved: (1) With the selected robust algal strain and unique photobioreactor design, long-term culture stability can be extended, and algal biomass productivity reached 0.5 g dry biomass/L/day year-round at a biomass concentration of 1.2 g/L in the pilot photobioreactor
(2) The biomass utilization process led to complete utilization of the algal biomass to produce amino acid salt absorbent, polyurethanes, and methane
and (3) The combined biological and chemical flue gas utilization process concluded a technically and economically feasible commercial-scale system that completely captures CO2 in coal-fired flue gas with greatly reduced energy consumption.