Algae are a group of plants that are usually found in water. Like all plants, algae have a pigment called chlorophyll that they use to turn sunlight into food. Algae can be found in all types of waters, including salt water, fresh water, and brackish water.  Algae absorbs atmospheric Carbon dioxide for its growth and produce oxygen via photosynthesis.

There are four main types of Algae, Chlorophyta (Green algae), Rhodophyta (Red algae),  Paeophyta (Brownalgae) and Xanthophyta (Yellow-green algae).

A photo bioreactor is a device used to cultivate microorganisms using light as an energy source and produce biofuels, such as algae or cyanobacteria. Biofuels produced in this way have the potential to be more sustainable and environmentally friendly than fossil fuels. Some microorganisms grown in photo bioreactors can absorb and fix atmospheric CO2, potentially reducing greenhouse gas emissions.