Productivity, carbon utilization, and energy content of mass in scalable microalgae systems

• Published in: Bioresource technology 2012-06, Vol.114, p.499-506
• Main Authors: Murray, Kyle E., Shields, Jeremy A., Garcia, Nicholas D., Healy, Frank G.
• Format: Article
• Language: English
• Subjects: Bioenergy; Biofuel; Carbon - metabolism; Carbon dioxide; Carbon emission reduction; Cell Proliferation; Computer Simulation; Energy Metabolism - physiology; Microalgae - physiology; Models, Biological; Pilot Projects; Sodium bicarbonate
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2012.03.012

► Biomass productivity was highest for CO2 supplemented systems. ► Mass produced by CO2 supplemented systems had highest heating values. ► Microalgae system without C supplementation had the highest percent C utilization. This study was designed to examine carbon utilization within scalable microalgae production systems. Neochloris oleoabundans was produced in replicated troughs containing BG11 nutrient formulation. Atmospheric CO2 was supplemented with ∼5% CO2 or with NaHCO3, and the pH of troughs receiving NaHCO3 was adjusted with HCl or H3PO4. Peak biomass concentrations reached 950, 1140, or 850mgL−1 and biomass productivities of 109, 96, and 74mgL−1 day−1 were achieved in the CO2, NaHCO3:HCl and NaHCO3:H3PO4 troughs, respectively. The highest productivity is expected in a scaled-up continuous batch process of the CO2 supplemented system, which was projected to yield 8948L lipids ha−1yr−1. Carbon utilization in the CO2, NaHCO3:HCl and NaHCO3:H3PO4 systems was ∼0.5, 15.5, and 12.9%, while the energy content of the combustible biomass was 26.7, 13.2, and 15.4MJkg−1, respectively. Techno-economic analyses of microalgal production systems should consider efficiencies and cost-benefit of various carbon sources.