Improving energy efficiency of magnetic CO$_{2}$ methanation by modifying coil design, heating agents, and by using eddy currents as the complementary heating source

The Sabatier reaction activated by high-frequency magnetic fields is a promising approach for the power-to-gas process because of expected high energy efficiencies and fast switch-on times. Recent progresses have been achieved by combining nanoparticles displaying both a high heating power and a good catalytic activity. Here, we alternatively use iron microparticles associated with our own-designed Ni/CeO$_{2}$ catalyst. The heating agent is cheap and abundant, and we demonstrate that the presence of eddy currents in the system improves its heating performance. The contribution of eddy currents to global heating is successfully determined by an original protocol consisting in comparing a calorimetric and a high-frequency hysteresis loop-based method to measure heating power. In addition, the optimization of the catalyst bed using SiC-spacers limits sintering and thus improves the durability of the catalyst. The energy efficiency of the catalysis process, calculated as a function of coil consumption and gas flow, is clearly improved by the use of an air-cooled Litz wire coil. These improvements are a step forward toward the development of a cheap and efficient process for chemical energy storage.