Micro-algae productivity optimization using extremum-seeking control

Dewasme, Laurent; Letchindjio, Christian G. Feudjio; Zúñiga, Ixbalank Torres; Wouwer, Alain Vande

doi:10.1109/med.2017.7984195

Cited by 14 publications

(5 citation statements)

References 10 publications

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“…The effect of activation, inhibition, and optimum are clearly evidenced by the ESC tests (which are model‐free). In order to give more insight into this observation, we refer to the results from Dewasme et al, 29 which can be exploited to show that the maximum growth rate is proportional to

\frac{D}{1 - X}

in steady‐state. The values reported in Table 2 show that, with respect to a light intensity reference of 800 (

μ

E m −2 s −1 ), the estimate of the maximum growth rate () decreases for lower and higher light intensities, exhibiting the expected Haldane dynamic behavior.…”

Section: Resultsmentioning

confidence: 99%

An experimental application of extremum seeking control to cultures of the microalgae Scenedesmus obliquus in a continuous photobioreactor

Letchindjio

Dewasme

Wouwer

2020

Adaptive Control & Signal

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Summary The cultivation of microalgae in photobioreactors (PBRs) is important in various sectors such as food, bioenergy, pigments, and cosmetics. Productivity optimization can be achieved without the need for a dynamic process model using model‐free extremum seeking control (ESC). This article explores the use of ESC to drive the productivity of a continuous PBR to optimal or suboptimal setpoints. The latter can be achieved by estimating on‐line the gradient of a measurable performance index using a recursive least squares estimator and by regulating this gradient to a specific value (zero corresponding to the optimum) using the dilution rate as a manipulated variable. Experimental results for the cultivation of the microalgae Scenedesmus obliquus in a lab‐scale flat‐panel PBR are discussed. They show the fast convergence of ESC and its robustness towards environmental perturbations, such as changes in the incident light intensity.

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\frac{D}{1 - X}

in steady‐state. The values reported in Table 2 show that, with respect to a light intensity reference of 800 (

μ

E m −2 s −1 ), the estimate of the maximum growth rate () decreases for lower and higher light intensities, exhibiting the expected Haldane dynamic behavior.…”

Section: Resultsmentioning

confidence: 99%

An experimental application of extremum seeking control to cultures of the microalgae Scenedesmus obliquus in a continuous photobioreactor

Letchindjio

Dewasme

Wouwer

2020

Adaptive Control & Signal

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“…A full model development description can be found in [25,26]. This model has been implemented in several occasions [20,21,24,27,[29][30][31][32], sometimes including simplifications. The mass balance model of a photobioreactor for the main species in liquid and gaseous phases (including, substrates, products, and biomass concentration) is given by the general model representation [33].…”

Section: Model Descriptionmentioning

confidence: 99%

Experimental Study of Substrate Limitation and Light Acclimation in Cultures of the Microalgae Scenedesmus obliquus—Parameter Identification and Model Predictive Control

et al. 2020

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In this study, the parameters of a dynamic model of cultures of the microalgae Scenedesmus obliquus are estimated from datasets collected in batch photobioreactors operated with various initial conditions and light illumination conditions. Measurements of biomass, nitrogen quota, bulk substrate concentration, as well as chlorophyll concentration are achieved, which allow the determination of parameters with satisfactory confidence intervals and model cross-validation against independent data. The dynamic model is then used as a predictor in a nonlinear model predictive control strategy where the dilution rate and the incident light intensity are simultaneously manipulated in order to optimize the cumulated algal biomass production.

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“…Furthermore, bifurcation analysis of a simple microalgae culture model has shown that the wash-out equilibrium is generally very close to the optimum, 37 with a narrow security margin.…”

Section: Application To Microalgaementioning

confidence: 99%

An Extremum Seeking Strategy Based on Block-Oriented Models: Application to Biomass Productivity Maximization in Microalgae Cultures

Letchindjio

Dewasme

Deschênes

et al. 2019

Ind. Eng. Chem. Res.

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This paper proposes an adaptive slope seeking strategy targeting any reachable operating pointincluding extremumon the input/output map of a general dynamic single input single output (SISO) system approximated either by a quadratic Hammerstein, Wiener, or Wiener−Hammerstein model. The proposed control strategy is based on a recursive estimation algorithm which is used to estimate the model parameters, a slope reference generator, and a controller. A new algorithm called auxiliary model-recursive prediction error method (AM-RPEM) is used for the first task, and it is shown that the three model structures are equivalent from an identification point of view. Using the estimated parameters, a slope reference generator is proposed together with a self-governed pole placement controller with integral action, which advantageously replaces the heuristic integrator gain tuning in classical extremum-seeking schemes. Finally, the proposed control strategy is tested in simulation, first with a numerical example and then, using a dynamic model of Isochrysis galbana cultures so as to achieve concurrently extremum-seeking and suboptimal control. Simulation results using a recursive least squares algorithm and the proposed AM-RPEM are discussed.

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Micro-algae productivity optimization using extremum-seeking control

Cited by 14 publications

References 10 publications

An experimental application of extremum seeking control to cultures of the microalgae Scenedesmus obliquus in a continuous photobioreactor

An experimental application of extremum seeking control to cultures of the microalgae Scenedesmus obliquus in a continuous photobioreactor

Experimental Study of Substrate Limitation and Light Acclimation in Cultures of the Microalgae Scenedesmus obliquus—Parameter Identification and Model Predictive Control

An Extremum Seeking Strategy Based on Block-Oriented Models: Application to Biomass Productivity Maximization in Microalgae Cultures

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