Comparative Evaluation of Growth Dynamics, CO₂ Sequestration, and Bio-Oil Production in Three Microalgae Species under Controlled Conditions

Abstract

Microalgae represent a promising biological platform for carbon capture and renewable fuel production. This study compared the growth performance, CO₂ sequestration efficiency, pigment accumulation, and lipid/bio-oil productivity of Chlorella vulgaris, Nannochloropsis oculata, and Spirulina platensis cultured under controlled conditions. Growth was monitored for 20 days, and biomass increased significantly in all species, with C. vulgaris exhibiting the highest final dry weight (2.90 g/L), followed by S. platensis (2.72 g/L) and N. oculata (2.18 g/L). CO₂ removal was greatest in C. vulgaris (64% at 10% CO₂), compared with Nannochloropsis (25%) and Spirulina (22%). Chlorophyll a content peaked in C. vulgaris (18.4 µg/mL). Lipid content was highest in Nannochloropsis (40.8%), although Chlorella achieved competitive lipid yield due to higher biomass. FAME analysis revealed dominance of desirable biodiesel fatty acids (C16:0, C18:1, C18:2). The comparative analysis indicates that Chlorella vulgaris is best suited for biomass-driven CO₂ sequestration applications, whereas Nannochloropsis oculata is optimal for high-yield bio-oil production.  Integrating high-biomass (Chlorella) and high-lipid (Nannochloropsis) species may provide a synergistic strategy for maximizing CO₂ fixation and biofuel output in commercial microalgal systems. Future work should explore scale-up dynamics and optimization of CO₂ delivery.