Developing and testing of co electrolysis with metal supported solid oxide cells

Climate changes is a looming shadow, getting every year closer, and institutions are finally starting to get the picture of the terrible consequences we are about to face. Investments into green energy solutions have never been that massive. European Union is towing the wagon of research, development and innovation in this field. Many projects are carried out in order to achieve a more sustainable society before it’s too late. One of them is E-TANDEM, where the goal is to perform a co-electrolysis of CO2 and steam to produce sustainable fuels. This work aims to study the first part of this production chain, in particular the Solid Oxide Electrolyser Cells (SOEC) responsible for the co-electrolysis of steam and CO2 into a hydrogen and CO syngas. This kind of cell provides many advantages when compared to other typologies, like the extremely high efficiency, the ability to easily reverse their operational mode from electrolysis to fuel cell and vice versa and the great fuel flexibility, allowing to convert directly and at the same time water and inorganic carbon compounds. Two technologies are studied and compared: a state-of-the-art ceramic supported cell and a newly developed metal supported cell. This latest type is very promising, since it strives to improve the global performance of the already great ceramic supported cells, allowing greater robustness and flexibility, with the immediate consequences of lower losses and handier operation, easing the way to renewable energy coupling. Both cells have been characterised by performing fingerprint tests at different temperatures and gas compositions and with a 500 hours durability tests in 0.5 A/cm^2 galvanostatic conditions at 650°C, which is the main focus of the analysis. Metal supported cell test was also combined with a mass spectroscopy evaluation, to fully characterise its performance in this first of a kind procedure. To complete the analysis, both cells were then analysed at microscopic level to fully assess their conditions under load. The ceramic supported cell showed an average degradation rate of 26.75% voltage increase in 1000 hours, displaying a linear increment throughout the whole test. The metal supported cell showed an average degradation rate of 17.69 % voltage increase in 1000 hours, with a high growing rate in the first hours that then quickly flattened out into a linear behaviour. Mass spectroscopy results make visible how the chemical reaction gets very close to the thermodynamic equilibrium, with discrepancies among the two always smaller than 5%. The most severe degradation phenomenon for both cells turned out to be the nickel migration from the electrode to the support, triggering a steep resistance increase. The accomplished results are very promising, suggesting an ever-growing role of MSC in the future’s market. Starting from here, further tests are crucial to obtain a more comprehensive knowledge regarding the behaviour of this still quite new cell’s typology.