Optimization of the design and operation of outdoor microalgae production in industrial-scale tubular photobioreactors

Microalgae are an attractive alternative to face urgent global challenges; their cultivation performances depend on various factors and require a large amount of location-specific productivity data to be evaluated. Mathematical models to simulate and optimize cultivation performance are considered the fastest and most cost-efficient way to verify economic viability. In this work, a Julia modeling framework has been developed that, from weather data of a specific geographical location, can accurately predict light distribution and culture evolution in tubular photobioreactors and link it to biomass productivity. Furthermore, this framework optimizes the design and operation of these reactors simultaneously, employing a two-level mathematical optimization, finding the conditions for the highest biomass productivity and, by adding economic considerations, the conditions for the highest economic profitability. A case study in Chennai, India, is considered to verify the correct operation of the framework. The results of the underlying model are verified for physical relevance, and a sensitivity analysis is performed on the optimization variable space. Results demonstrate the capabilities of the implemented framework to correctly optimize the design and operation of tubular photobioreactors with reasonable computational time and resources.