The most common oil extraction methods for Chlorella include solvent extraction (typically using hexane), supercritical CO₂ extraction, and mechanical cell disruption followed by filtration. Ultrasound- or microwave-assisted extraction enhances lipid recovery from tough algal cell walls. After extraction, oil is filtered and may be degummed or neutralized before transesterification. Supercritical methods yield high-purity oil but are costly. For commercial viability, combining mechanical pre-treatment with solvent extraction offers an effective balance of yield, cost, and oil quality for biodiesel production.