Algae can be cultivated in open ponds, photobioreactors, or in closed and hybrid systems. Open pond systems for cultivation of algae are cheap and economical, but suffer from the obvious disadvantages. In that, they require a large expanse of land and water and are susceptible to contamination by other microorganisms, and to climatic changes.

Photobioreactors are closed tank systems, where most of the disadvantages stated under open pond systems can be obviated. These systems, though they involve higher infrastructure costs, are more efficient and offer higher biomass concentrations, high surface-to-volume ratios, and shorter harvest times. A major advantage with these reactors is that along with cultivation of algae, they can be used for simultaneous scrubbing of power plant flue gases and removing nutrients from wastewater. A variety of designs is available to give higher productivity and reproducibility as better control of cultivation conditions is possible. Demirbas et al. [30] have described the different types of systems available for cultivation of algae and the comparative costs involved for each system.

Harvesting of algae can be done by a number of different methods such as centrifugation, foam fractionation, flocculation, membrane filtration, and ultra­sonic separation. The harvesting costs may contribute to about 20-30% of the total cost of cultivation.