Marcel Janssen

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

Abstract

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.

 

Date
2022
Data type
Scientific article
Geographic location
Bonaire

Growth parameter estimation and model simulation for three industrially relevant microalgae:Picochlorum, Nannochloropsis,and Neochloris

Abstract

Multiple models have been developed in the field to simulate growth and product accumulation of microalgal cultures. These models heavily depend on the accurate estimation of growth parameters. In this paper growth parameters are presented for three industrially relevant microalgae species: Nannochloropsis sp., Neochloris oleoabundans, and Picochlorum sp. (BPE23). Dedicated growth experiments were done in photobioreactors to determine the maximal biomass yield on light and maintenance rate, while oxygen evolution experiments were performed to estimate the maximal specific growth rate. Picochlorum sp. exhibited the highest specific growth rate of 4.98 ± 0.24 day−1 and the lowest specific maintenance rate of 0.079 day−1, whereas N. oleoabundans showed the highest biomass yield on light of 1.78 gx·molph−1. The measured growth parameters were used in a simple kinetic growth model for verification. When simulating growth under light conditions as found at Bonaire (12 °N, 68° W), Picochlorum sp. displayed the highest areal biomass productivity of 32.2 g.m−2·day−1 and photosynthetic efficiency of 2.8%. The presented growth parameters show to be accurate compared to experimental data and can be used for model calibration by scientists and industrial communities in the field.

Date
2022
Data type
Scientific article
Theme
Research and monitoring
Geographic location
Bonaire