Three major methods of extracting oil from algae are: (1) solvent extraction with hexane, (2) expeller/press, and (3) supercritical fluid extraction (SFE). The extracted oil can then either be used as SVO or processed by a transester­ification reaction to produce biodiesel. Algal oil is considered a "balanced" carbon neutral fuel, because any CO2 taken out of the atmosphere by the algae is returned when the algae biofuels are burned. It has been estimated

by Weyer et al. [31] that the theoretical maximum limit of unrefined oil that could be produced from algae is 354,000 L • ha-1 • yr-1 or 38,000 gal • ac-1 • yr-1, and limits for the practical cases examined in their study range from 46,300 to 60,500 L • ha-1 • yr-1.