Potential of Algal Biomass and Their Cultivation for Biofuels Production as Plausible Bio-resource for Economic Sustainability

Depletion of conventional energy resources necessitates the exploration of new alternative raw materials for sustainable biofuel production to improve socio-economic development. This research focuses on the cultivation of specific algae varieties, biomass quantification, fatty acid profiling, and their potential application in biodiesel production. The study examines diverse emerging algal species, including Ulothrix, Stigeoclonium, Chlorellavulgaris, Cladophora, Oedogonium, Oscillatoria, Spirogyra, and H.reticulatum. Over a 4-week cultivation period, all species demonstrated increased dry biomass, with Ulothrix exhibiting the maximum growth (19 g) and Stigeoclonium the minimum (5 g). Lipid composition analysis by microwave-assisted extraction (MAE) indicated varying percentages (% DW) among strains, with Ulothrix sp. displaying the highest lipid content (62.4%). Lipid yields, crucial for biodiesel, followed the order: Ulothrix > Stigeoclonium > C.vulgaris > Cladophora sp. > Oedogonium > Oscillatoria > Spirogyra sp. > H.reticulatum. Further analysis of fatty acid methyl esters (FAMEs) composition using GC–MS revealed 24 detected FAMEs, with percentage ranges for specific fatty acids. The total FAMEs yield reached approximately 98% (w/w) from algal biodiesel, showcasing variations in saturated, monounsaturated, and polyunsaturated FAMEs content among strains. Fatty acid profiles, emphasizing linoleic, stearic, and oleic acids, were analyzed, identifying Cladophora sp., Chlorellavulgaris, and Stigeoclonium sp. as promising biodiesel candidates based on growth rates and fuel properties. All algal strains met or exceeded specifications, except for H.reticulatum in cetane number. Despite highlighting challenges in large-scale algal cultivation for cost-effective biomass production, this study underscores the potential of expanding the algae biorefinery value chain to include advanced biofuels and valuable co-products, presenting a significant global impact on the gross domestic product. Graphical abstract: (Figure presented.)