The fatty acid profiles of lipids extracted Sargassum hemiphyllum by supercritical carbon dioxide (SC-CO2) were compared with those obtained by Soxhlet solvent extraction using chloroform/methanol. For the pressure range (24.1−37.9 MPa) and temperature interval (40−50 °C), 37.9 MPa/40 °C and 37.9 MPa/50 °C gave the highest lipid yield, which was comparable to that of the Soxhlet method, and the highest concentrations of total and individual ω-3 fatty acids, which were significantly higher (p < 0.05) than the solvent extraction. However, SC-CO2 extraction at higher temperature but low-pressure levels (24.1 MPa/50 °C) gave significantly lower (p < 0.05) lipid yield and fatty acid concentration than that of lower temperature but of the same pressure (24.1 MPa/40 °C). Concentrations of docosapentaenoic acid and docosahexaenoic acid were significantly higher (p < 0.05) at 37.9 MPa/40 °C than at 37.9 MPa/50 °C.

Freeze-dried samples of the microalga Chlorella vulgaris were submitted to supercritical CO2 at temperatures of 40 and 55 °C and pressures up to 35.0 MPa. This study was carried out on whole and crushed algae. The extraction yields of carotenoids and other lipids were low in the former case and improved significantly in the latter one. Extraction yields of carotenoids and other lipids increased with pressure. The fraction of carotenoids in the oil was also greater at higher pressures. On the other hand, supercritical CO2 extraction of carotenoids compared favourably with hexane and acetone extractions.

Algal cells of Dunaliella tertiolecta with a moisture content of 78.4 wt% were converted directly into oil by thermochemical liquefaction at around 300°C and 10 MPa. The oil yield was about 37% on an organic basis. The oil obtained at a reaction temperature of 340°C and holding time of 60 min had a viscosity of 150–330 mPas and a calorific value of 36 kJ g−1, comparable to those of fuel oil.