The carbon dioxide (CO2) sequestration potential of two microalgae, Chlorella pyrenoidosa and Scenedesmus abundans was evaluated in a tubular batch photobioreactor with provision for continuous flow of 10% CO2 enriched air through the headspace. CO2 sequestration and biomass growth was affected by gas flow rate over the range 20-60 ml/min and 40 ml/min was found to maximize algal growth and CO2 sequestration. Moles of CO2 sequestered over 20 h at a gas flow rate of 40 ml/min was estimated using a novel rapid screening approach as 0.096 and 0.036, respectively, for C. pyrenoidosa and S. abundans. At this gas flow rate the maximum growth rate was 4.9 mg L-1 h(-1) and 2.5 mg L-1 h(-1) for C. pyrenoidosa and S. abundans, respectively. The CO2 sequestration and growth rate were comparable at height/diameter ratio of 8 and 16. (C) 2015 Elsevier Ltd. All rights reserved.