To boost lipid content in Chlorella, nitrogen-starvation is the most effective strategy. When nitrogen levels are limited, the algae shift metabolism from protein synthesis to lipid accumulation, especially neutral lipids ideal for biodiesel. Cultivation in photobioreactors or controlled open pond systems allows precise manipulation of nutrients, light, and CO₂ levels. Optimizing light intensity, pH, and temperature also enhances lipid productivity. Coupling nutrient stress with batch or semi-continuous cultivation and CO₂ supplementation maximizes lipid yield, making Chlorella a promising source for sustainable biodiesel production.