Microalgae are cultivated in liquid medium, such that the cultivated suspensions have a low solid content (0.13–0.54% w/w). Correspondingly, the initial marigold flowers have 20% w/w solid contents. To remove the larger volume of water, the microalgae suspension needs more energy than marigold flowers. The small sizes of microalgae cells, except for parts of such colonies as Spirulina, acquire additional energy/chemicals for the solid–liquid separation stage. Further drying of both biomasses consumes similar amounts of energy.