Integrating CO2 scrubbing from flue gas with its utilization in algae cultivation represents a potential means of lowering the cost of CO2 capture. Towards this goal, this study sought to assess the feasibility of using gaseous a CO2/NH3 stream, derived from CO2 capture using aqueous ammonia, as a C- and N-source for algae cultivation. Scenedesmus acutus was cultured in 800 mL photobioreactors using gaseous CO2/NH3 in mole ratios varying from 7 to 18. Excellent growth of Scenedesmus acutus was observed, the average growth rate for CO2/NH3 = 10 of 0.171 ± 0.015 g/L·day exceeding that obtained using 1% CO2/N2 and urea as the N-source (0.099 ± 0.28 g/L·day). Under optimal growth conditions (CO2/NH3 mole ratio of 10), CO2 utilization ranged from 57 to 72%, while the NH3 utilization was >90%. The CO2/NH3 feed rate was also found to exert a significant effect on algae productivity, with excessive feed rates leading to the accumulation of NH3 in the culture at concentrations that were toxic to the algae. Consequently, to avoid the toxic effects of high NH3 concentrations (>2.0 mM), it proved necessary to balance the NH3 supply with the algae growth rate so that excessive NH3 accumulation was prevented. This indicates that for practical applications, a CO2/NH3 feed control strategy would be required that takes into account the ammonium ion concentration in solution and the pH so as to avoid significant concentrations of free NH3. Analysis of the harvested biomass revealed a high protein (≥ 47 wt%) and a low ash content (< 3.6 wt%), suggesting it would be well suited for use as animal feed or as a feedstock for the production of bioplastics.
|State||Accepted/In press - 2023|
Bibliographical noteFunding Information:
This work was funded by the Department of Energy Office of Fossil Energy and Carbon Management under award number DE-FE0031921. This report was prepared as an account of work sponsored by an agency of the US government. Neither the US government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the US government or any agency thereof. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the US government or any agency thereof.
© 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
- CO capture
- CO supplementation
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Agronomy and Crop Science
- Energy (miscellaneous)