Entropy Analysis of Solar Two-Step Thermochemical Cycles for Water and Carbon Dioxide Splitting

Entropy

Matthias Lange¹  Martin Roeb²  Christian Sattler²  Robert Pitz-Paal²  Michel Feidt²  Daniel Tondeur²  Jean-Noël Jaubert² 

[1]German Aerospace Center (DLR), Institute of Solar Research, Linder Höhe, 51170 Köln, Germany

关键词: solar;    thermochemical cycle;    CSP;    water splitting;    CO₂ splitting;    T-S diagram;    efficiency;    entropy;   

DOI  :  10.3390/e18010024

来源: mdpi

【 摘 要 】

The present study provides a thermodynamic analysis of solar thermochemical cycles for splitting of H₂O or CO₂. Such cycles, powered by concentrated solar energy, have the potential to produce fuels in a sustainable way. We extend a previous study on the thermodynamics of water splitting by also taking into account CO₂ splitting and the influence of the solar absorption efficiency. Based on this purely thermodynamic approach, efficiency trends are discussed. The comprehensive and vivid representation in T-S diagrams provides researchers in this field with the required theoretical background to improve process development. Furthermore, results about the required entropy change in the used redox materials can be used as a guideline for material developers. The results show that CO₂ splitting is advantageous at higher temperature levels, while water splitting is more feasible at lower temperature levels, as it benefits from a great entropy change during the splitting step.

【 授权许可】

CC BY   
© 2016 by the authors; licensee MDPI, Basel, Switzerland.