Researchers from the University of Almería, including Enrique Rodríguez-Miranda, Pablo Otálora, José González-Hernández, José Luis Guzmán, and Manuel Berenguel, have developed a comprehensive benchmarking framework to evaluate process control strategies for outdoor microalgae raceway reactors. Their work, published in the journal Computers & Chemical Engineering, aims to bridge the gap between control methodology and outdoor algal bioprocess engineering.
Microalgae cultivation is gaining attention in the energy sector for its potential to produce biofuels, capture carbon dioxide, and generate high-value bioproducts. However, controlling the complex processes involved in outdoor raceway reactors has been a significant challenge. The researchers’ benchmark platform addresses this by integrating four key control regulation tasks: pH, dissolved oxygen (DO), culture volume through coordinated harvest-dilution actions, and temperature via a sump-mounted spiral heat exchanger.
The benchmark is built upon a high-fidelity, experimentally calibrated dynamic model that captures the strongly coupled thermal, physicochemical, and biological processes governing industrial-scale open raceway ponds. This model forms the basis of a closed-loop simulation environment, which includes realistic actuator constraints, gas transport delays, stiff integration, and a fully specified scenario based on multi-day outdoor disturbances such as irradiance, temperature, wind, and humidity.
The platform allows users to replace and test different controllers for manipulating CO2 injection, air bubbling, harvest/dilution sequencing, and heat-exchanger operation. It computes a unified global performance index, along with individual metrics for each control problem, combining tracking error, gas and energy usage, and biomass productivity. This enables consistent and quantitative comparison of alternative control strategies.
The researchers have included baseline regulatory architectures such as On/Off, PI/PID, and Economic Model Predictive Control (EMPC) to illustrate the benchmark’s use for both classical and advanced control methods. By providing an openly specified, reproducible, and computationally tractable benchmark with well-defined function interfaces, this work supports the development of multivariable control strategies for disturbance-rich environmental systems.
Practical applications for the energy sector include optimizing microalgae cultivation processes for biofuel production, improving carbon capture efficiency, and enhancing the overall productivity of algal bioprocesses. The benchmark platform can help researchers and industry professionals develop and compare control strategies that maximize energy output while minimizing resource consumption.
Source: Rodríguez-Miranda, E., Otálora, P., González-Hernández, J., Guzmán, J. L., & Berenguel, M. (2023). A comprehensive benchmark platform for process control research of outdoor microalgae raceway reactors. Computers & Chemical Engineering, 174, 108215.
This article is based on research available at arXiv.