Session: 17-06: Symposium Steinfeld - Radiative and materials characterization and solar technology development

Paper Number: 138550

138550 - Electrochemical Pump Assisted Solar Driven High Temperature Fuel Production 

Abstract: 

Solar thermochemical cycle based on metal oxide-based redox couples is a promising pathway to convert intermittent solar energy into storable fuels. The solar-to-fuel efficiency of a thermochemical reactor is dictated by an efficiency reduction step requiring high temperature and low partial pressure of oxygen. The efficiency of oxygen removal during the reduction step is one of the keys to improving solar-to-fuel efficiency. The conventional inert gas sweeping method requires a high heating load and additional gas separation work, which limits the reactor's efficiency. In this study, we propose the integration of a high-temperature electrochemical oxygen pump (EOP) for in-situ oxygen removal to minimize the heating load and allow for effective oxygen pumping. A transient model was developed to quantify the reactor performance using EOP or NS schemes. The model predicted that the ceria nonstoichiometric coefficient at the end of the reduction was enhanced by 56.8% when using the EOP scheme compared to the NS scheme. Correspondingly, the solar-to-fuel efficiency enhancement factor was 1.64 at reference conditions. In addition, the EOP scheme showed more uniform temperature and species concentration distributions, leading to a more favorable thermo-mechanical stability. Subsequently, the development of a 40 kWe high flux solar simulator at the Southern University of Science and Technology (SUSTech) used for the reactor performance testing will be introduced. The design and the calibration method for both highly concentrated operation modes, using the direct method, and uniform flux operation modes, using the indirect method, will be compared. Operating at a highly concentrated mode leads to a peak flux of over 40 MW/m². The uniform flux mode can produce flux maps of 500 kW/m2 within 1 cm* 1cm with a non-uniformity smaller than 2%. Finally, the performance testing of the EOP-assisted solar reactor for proof-of-concept operated using the HFSS at SUSTech will be discussed. The design of an environmental chamber that can be used for various materials testing and reactor performance testing will be introduced with 3 oxygen sensors to simultaneously measure the local temperature and oxygen partial pressure. Ceria fabricated with the templated method was used for thermochemical reaction, and an LSM/YZS/LSM-based solid oxide cell was used as the high-temperature EOP. The active cooling strategy enhances oxygen mass transfer from the ceria via induced natural convection to the EOP and protects the EOP from overheating. This study presents our recent progress in EOP-assisted solar thermochemical fuel production from theoretical analysis to experimental demonstration.

Presenting Author: Meng Lin Southern University of Science and Technology

Presenting Author Biography: Meng Lin is an assistant professor heading the Solar Energy Conversion and Utilization Laboratory (SECUL) at the Southern University of Science and Technology (SECUL), Shenzhen. He received his PhD (2018) in the mechanical engineering from EPFL, Switzerland. Between 2018 and 2019, he was a postdoctoral researcher at the Joint Center of Artificial Photosynthesis (JCAP) and the Chemistry and Chemical Engineering Division of California Institute of Technology (Caltech). In 2019, he joined the department of mechanical and energy engineering at SUSTech with research focus on the engineering of high-performance solar conversion materials, devices, and systems to fulfill industrial-scale needs for electricity, heat, fuels, or a combination thereof.

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