Algae are naturally growing organisms and are very diverse in nature. Different algal strains have different properties. Since the major concern is to choose such an algae strain which is easily available in the location, can multiply easily at the prescribed location and has maximum quantity of lipid/oil content in it so that it can be used to produce biodiesel. Algae absorb carbon dioxide and nutrients from the water and make oil out of their biomass, while producing oxygen. Algae reproduce themselves non-sexually; they divide themselves into two cells, grow bigger and divide again.

There are a large number of strains available and some of them are:

Dunaliela tertiolecta haetoceros muelleri sochrysis galbana Phaeodactylum tricornutum Tetraselamis suecica Navicula saprophila Haematococcus pluvialis Neochloris oleoabundans Chlorella

The algal strains to be cultivated would be selected based on many criteria, of which oil content, productivity, and harvest ability would be primary, but also resistance to contamination, tolerance of high oxygen levels and temperature extremes, and adaptation to the local water chemistry and other local conditions experienced by the algal cells in the growth ponds. For harvesting, further concentration and oil extraction is required, for which various processes are proposed, including cell breakage and solvent extraction, possibly using a three phase centrifugation. The residual biomass could be either sold as animal feed or, more plausibly at present, converted to biogas, for use in on-site power production, with the residual nutrients (and carbon) recycled back to the growth ponds.

Chlorella vulgaris	Haematococcus pluvialis	Dunaliella salina	Spirulina (Arthrospira platensis)

Theoretical maximum yields of few microalgae in open ponds:

The successful growth of algae is more or less an art and a daily tightrope act with the aim of keeping the necessary prerequisites and various unpredictable events involved in algal mass cultivation in a sort of balance. Microalgae cultivation using sunlight energy can be carried out in open or covered ponds or closed photobioreactors, based on tubular, flat plate or other designs.