Microalgae are microscopic aquatic plants that are being investigated principally as potential sources of oils for biodiesel production although other fuels (e.g., ethanol) and bioproducts could also be produced. Because of their high photosynthetic efficiency, microalgae are capable of producing substantially higher quantities of oil per unit area of land compared to terrestrial oilseed crops. Efforts are underway to identify and develop microalgae species that can not only produce high levels of oil, but which can also grow under a wide range of environmental conditions. Scaling up the size of the production facilities is a significant technical challenge to the use of microalgae.