A novel V-shaped photobioreactor design for microalgae cultivation at low latitudes: Modelling biomass productivities of Chlorella sorokiniana on Bonaire

Microalgae are a promising renewable feedstock for a wide range of biobased products, such as food, feed, chemicals, and biofuels. To commercialize bulk products from microalgae, the production costs need to be reduced, for example, by improving biomass productivities in outdoor photobioreactors. Geographical locations near the equator are considered ideal for outdoor cultivation, due to the abundance of sunlight throughout the entire year. However, at high light intensities the photosystems of microalgae become oversaturated, which limits photosynthetic efficiencies and biomass productivities. Therefore, we propose a novel V-shaped photobioreactor to capture and dilute available sunlight at low latitudes. For different V-shaped designs, we modelled the sunlight entering the photobioreactor during several days of the year and theoretically estimated the maximal biomass productivity of Chlorella sorokiniana on the island Bonaire (12°N, 68°W) assuming clear-sky conditions and light-limited growth. Our results show that theoretical biomass productivities of 38.3–50.5 g m−2 day−1 can be achieved in V-shaped photobioreactors, corresponding to photosynthetic efficiencies of 2.5–3.3%. These productivities are up to 1.4 times higher than those estimated for a flat horizontal photobioreactor, primarily due to improved light dilution in V-shaped photobioreactors. Thus, V-shaped photobioreactors present opportunities for more efficient microalgae production.