Issue 6, 2020

Power-to-gas systems utilizing methanation reaction in solid oxide electrolysis cell cathodes: a model-based study

Abstract

Power-to-gas is an emerging technology to convert electrical energy into chemical energy, and usually consists of two steps. First, hydrogen or syngas is produced in electrolysis cells, and then the hydrogen is used to methanate COx in catalytic reactors. Solid oxide electrolysis cells (SOECs) have the potential to integrate these two steps because methane can be directly synthesized in the SOEC cathodes. However, the advantages and drawbacks of such a direct process have not been discussed quantitatively. In the present work, we established a model using Aspen Plus to simulate the direct process. By analyzing the energy conversion processes in detail, it was clarified that the suppression of SOEC overpotentials at low temperatures is crucial. If the SOEC overpotentials are decreased at 400 °C, the energy conversion efficiency of the direct process will become higher than that of the conventional two-step process especially at small methane production rates. The superior performance can be ascribed to the recuperative heat utilization between the exothermic methanation reaction and the endothermic electrolysis reactions.

Graphical abstract: Power-to-gas systems utilizing methanation reaction in solid oxide electrolysis cell cathodes: a model-based study

Supplementary files

Article information

Article type
Paper
Submitted
22 sept. 2019
Accepted
11 janv. 2020
First published
13 janv. 2020

Sustainable Energy Fuels, 2020,4, 2691-2706

Power-to-gas systems utilizing methanation reaction in solid oxide electrolysis cell cathodes: a model-based study

N. Fujiwara, S. Tada and R. Kikuchi, Sustainable Energy Fuels, 2020, 4, 2691 DOI: 10.1039/C9SE00835G

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