Water depth can be converted to the V/S ratio. The daily growth limit divided by the V/S ratio yields biomass productivity (g/Ld) (Fig. 2). With a dilution rate of 0.1, biomass productivity for the flat panel, tubular and raceway is 5.4, 3.8 and 1.3 g/L, respectively. Thus, the annual production of microalgae and energy invested in cultivation are estimated (Table 1).