Hurdles and challenges for modelling and control of microalgae for CO2 mitigation and biofuel production

Oleaginous microalgae are seen as a potential major biofuel producer in the future since, under conditions of nitrogen deprivation, they can contain high amounts of lipids, while they consume CO2 from power plants. These photosynthetic microorganisms are however rather different from the microorganisms usually used in biotechnology. In particular, predicting the behaviour of microalgal based processes is delicate because of the strong interaction between biology (microalgal development and respiration), and physics (light attenuation and hydrodynamics). This paper reviews existing models, and in particular Droop Model which has been widely used to predict microalgal behaviour under nutrient limitation. It details a model for photobioreactors or raceways, when both light and nutrients are limiting. The challenges and hurdles to improve photobioreactor modelling and control in order to optimise biomass or biofuel production are then discussed.