Algae biofuel production often uses petroleum-based NPK (Nitrogen, Phosphorus Potassium) fertilizers to grow algae. Over half of US NPK fertilizer is imported. In addition, algae biofuel facilities are generally based in deserts where the sun is strong and water scarce, yet it uses large amounts of water. It takes over three gallons to produce one gallon of algae fuel.
Thus it is clear that algae biofuel is not environmentally friendly nor does it cut dependence of foreign oil. This from  the president of a non biofuel algae company with 40 years experience and who has no financial interests in biofuel or petroleum.
Nearly every in-depth economic (fiscal and physical) analysis – and especially mass balance analysis of the algae biofuel production process – has shown it to be both economically, environmentally and resource unsustainable and non-renewable at-scales significant enough to impact the U.S.’s energy deficits.
However, some types of algae biofuel doesn’t need NPK fertilizer.
Algae biofuel companies generating algae biofuels and other products from wastes – such as sewage and CAFO (Concentrated Animal Feeding Operations – cattle, dairy, poultry, swine and aquaculture) discharges are largely unaffected directly by the NPK sustainability issues.