Model-based optimization of electrochemical systems for the use of electricity from renewable energy sources

  • Modellbasierte Optimierung elektrochemischer Systeme für die Nutzung von Strom aus erneuerbaren Energiequellen

Brée, Luisa Carola; Mitsos, Alexander (Thesis advisor); Wessling, Matthias (Thesis advisor)

Aachen (2020)
Book, Dissertation / PhD Thesis

In: Aachener Verfahrenstechnik series - AVT.SVT - Process systems engineering 9 (2020)
Page(s)/Article-Nr.: 1 Online-Ressource (XVI, 178 Seiten) : Illustrationen, Diagramme

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2020

Abstract

Means are required to integrate energy from renewable sources ecologically and economically into current electricity use. In this context, we present Power-to-X processes and categorize them along three modes of purpose and operation: e-storage, e-production and load management. For selected electrochemical processes we illustrate via model-based analysis and optimization how prevailing challenges may be overcome and thus how the presented processes may be turned economically competitive on an industrial scale. An important challenge that must be overcome for e-storage processes is increasing the efficiency. We analyze the conditions under which the efficiency can be increased by proposed design and operational changes for a vanadium redox flow battery. Furthermore, we show the effect of these changes on total costs. For e-production, we present a technological evaluation at system level at an early stage of development using the example of electrochemical reduction of H2O and CO2. We develop a modular model for such reactors to investigate overpotentials and to compare different reactor setups. We determine unknown reaction parameters by estimation and achieve good agreement of the simulation with data from literature in the case of water electrolysis and for most of the data in the case of CO2 reduction. We show that the typically collected experimental data is not sufficient to fully identify the parameters. The modular models allow the analysis and detailed comparison of the overpotentials. We investigate the benefits of demand side management for the energy-intensive chlor-alkali electrolysis. We show and analyze the economic benefit of flexible operation realized with a new type of switchable electrode. Furthermore, additional strategies for flexibility provision are then compared by considering six more process options.

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