Highly efficient gaseous fuel synthesis via co-electrolysis process Toshiaki Yamaguchi 1 , Genki Horiguchi 1 , Hajime Toriumi 1 , Katherine Bagarinao 2 , Takehisa Mochizuki 1 and Haruo Kishimoto 2 1 Energy Process Research Institute, National Institute of Advanced Industrial Science and Technology, Japan, 2 Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology, Japan Introduction As a result of global warming due to the increase in the concentration of greenhouse gases such as CO 2 , urgent problems such as abnormal weather are occurring worldwide. Against this background, the development of materials and processes for reducing CO 2 emissions, as well as technology for storing and using CO 2 , is being vigorously pursued. An electrochemical cell with the same components as SOFC has also been used as a solid oxide electrolysis cell (SOEC) for Power-to-Gas technology. The use of alternative high-performance electrolytes and electrode materials lead to a drastic reduction of the input power for electrolysis. Moreover, co-electrolysis of CO 2 and H 2 O with SOEC is also considered to be one of the most efficient technologies to convert CO 2 and H 2 O into CO and H 2 gases. Typically, the SOEC is operated above 700 ºC, which prevents the methanation reaction of CO and H 2 , whereas CO and H 2 gases (syngas) can be useful raw materials for CH 4 fabrication catalyst at lower reaction temperatures below 400 ºC.In this study, we present the results of high-performance co-electrolysis cell development and gaseous fuel synthesis. Aim The aim of this study is (1) to develop fabrication technologies of electrochemical cell with a reliable dense electrolyte layer on fuel-electrode support with excellent gas permeation, conductivity, and mechanical strength, and (2) to investigate effects of cell components and operation conditions, such as temperature and applied voltage, on the direct methanation efficiency using co-electrolysis reaction of CO 2 and H 2 O at around 400 ºC. In this presentation, we will report SOEC reactor fabrication technologies and the methanation properties. Experimental and Results The SOEC single cell was fabricated using a fuel-electrode support, prepared using the extrusion technique, and subsequently coated with YSZ electrolyte, GDC intermediate layer and LSCF air electrode layer. The microstructure of the coin cell was observed using a field-emission scanning electron microscope operated in secondary electron and back-scattered electron modes. The completed coin cell was electrochemically measured using a frequency response analyzer with an electrochemical interface under a mixture of H 2 O-CO 2 -H 2 fuel gas and air, respectively. Improvement of the performance of the co-electrolysis cell was investigated by reducing the gas diffusion resistance of the fuel-electrode support by making it more porous and by applying a dense GDC intermediate layer prepared using pulsed laser deposition technique. Fuel gases with various H 2 O-CO 2 -H 2 compositions were supplied, and the relationships between porosity of the support, cell temperature, applied voltage and co- electrolysis performance were investigated. Finally, we report on the power to gas performance of co-electrolytic reaction followed by methanation reaction. Acknowledgement This study is partially based on results obtained from a project, JPNP21014, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
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© The Author(s), 2023
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