Mass culture of microalgae for lipid production

A method to produce high density microalgae having high lipid concentration in mass culture comprising the steps of:

• inoculating and covering a vessel with an inoculant comprising microalgae at mid-log phase to a depth greater than 25 centimeters;
• providing a heat exchanger submerged in the vessel to control temperature;
• providing a plurality of directional air lift pumps inside of the vessel whereby the directional air lift pumps are oriented to simultaneously create an uplift current from the bottom of the vessel to the top of the vessel and a rotational current defined by the perimeter of the vessel as the outer boundary;
• culturing the microalgae to a preselected target density threshold;
• bringing the microalgae to stationary phase;
• manipulating growth parameters selected from the group consisting of temperature, light, pH, nutrients, and salinity during stationary phase to maximize lipid concentration;
• and
• harvesting the microalgal culture from the vessel.