A control based on a knapsack problem for solar hydrogen production

Abstract

Summary The Hydrosol pilot plant was installed in the small solar power systems solar tower at CIEMAT‐Plataforma Solar de Almería (PSA), Spain, for producing solar hydrogen from water using a ferrite‐based redox technology. It consists of two reactors where hydrogen and oxygen production cycles are alternated for quasi‐continuous hydrogen production. In the first step (water splitting), an exothermic reaction takes place at an operating temperature of 800℃. The second step (thermal reduction) is an endothermic reaction, which requires an operating temperature of 1200℃. Recently, an adaptive control strategy for controlling these operating temperatures in the solar hydrogen reactor has been proposed and implemented, using the number of heliostats focused as the control signal. The algorithm chooses which heliostats have to be focused estimating the concentrated solar power contribution of each heliostat. Then, the heliostats are focused, starting from those which provide lower power. This paper is based on this control strategy, but considering a new algorithm to choose the heliostats. Using the concentrated solar power contributions, a knapsack problem is defined to obtain a local optimal solution, which provides a set of heliostats that minimizes the error between the setpoint and the reactor concentrated solar power. In order to evaluate the performance of this method, simulation and experimental results are shown and discussed. Copyright © 2014 John Wiley & Sons, Ltd.

Controlling a solar receiver with multiple thermochemical reactors for hydrogen production by an LSTM neural network based cascade controller

“…Heliostats within the respective group are focused or defocused if a certain tolarance limit is exceeded. As an improvement to their first study, Roca et al (2016) applied a feed forward Knapsack controller in combination with a PI controller.…”

“…These studies obtained good results: the temperature in the reactors could be controlled well, even when some weather disturbances were present (Roca et al, 2016;Säck et al, 2016). However, even though a two-reactor system was investigated, there was no interdependency between reactors as for each reactor a dedicated portion of the field was reserved and only one reactor was irradiated at once.…”

“…The developed cascade control takes advantage of this fact and couples heliostat field and receiver control. In contrast to Roca et al (2016), Säck et al (2016) and Grobbel et al (2022), the interdependency between multiple reactors is considered by this control for the first time and 19 batch reactors are operated in parallel by a single solar field. While the periods of oxidation and reduction as well as the temperature setpoints are fixed by Roca et al (2016) and Säck et al (2016), they are flexible in this work.…”

Editorial optimal control of solar energy systems

“…Roca et al. provide an application of control approaches for producing solar hydrogen from water using a ferrite‐based redox technology. The Hydrosol pilot plant used for evaluation purposes consists of two reactors where hydrogen and oxygen production cycles are alternated for quasi‐continuous hydrogen production.…”

Balancing the profit and capacity under uncertainties: a target‐based distributionally robust knapsack problem

“…Lust and Teghem (2012) extended the knapsack problem and its multidimensional variant (multidimensional knapsack problem, MKP) to multiobjective versions, for which a new approach was designed to obtain or approximate the solutions. Roca et al (2016) applied the knapsack formulation to find a locally optimal solution for error minimization in solar hydrogen production control. Deplano et al (2021) proposed a mixed-integer linear programming (MILP) model to solve the heterogeneous knapsack problem, which minimizes the wasted space of the bins under realistic container loading constraints.…”