Algae - Members of the genera Chlorella, Scenedesmus and Spirulina are generally grown in ponds/tanks. They use CO₂ and sunlight as substrate, which are without any cost. Generally, the limiting factor in their large scale production is illumination.

Algal SCP has about 60% crude protein, which is generally good in amino acid composition except for some deficiency in sulphur containing amino acids. They are suitable for animal feed as protein rich supplement. The disadvantages of algal SCP are:

(i) rich chlorophyll content, which is not suitable for human use,