The hybrid system is a cultivation method comprising of two stages and utilizes both open ponds and PBR for different growth phases. The first stage of cultivation is completed in a photobioreactor where uninterrupted cell growth occurs in a pollution-free environment under controlled conditions. The second stage of cultivation occurs in open ponds and is intended to expose the culture to ecological and nutrient stresses. This enhances the production of desired lipid product.

The methods, which are presently being profitably used for algae cultivation, are raceway ponds and tubular PBR. Open ponds are a much cheaper method for algal cultivation. Setup and maintenance are also easier. Open ponds require less energy as compared to PBR. Open ponds are, however, less efficient as compared to PBR. Contamination, losses due to evaporation, temperature vacillation, inept mixing, and light limitations are some of the malfunctions associated with open pond systems.