Multiphysics Modelling and experimental analysis of low temperature electrolysis

The main cause of climate change is the combustion of fossil fuels such as coal and natural gas, which emit greenhouse gases into the atmosphere. To counteract this phenomenon, there is a need for a green transition, in which renewable energies and related energy storage systems play the leading role. In this perspective, green hydrogen, i.e. hydrogen produced through electrolysis, using electricity from renewable sources, is certainly an important resource. Electrolysis can be done in an electrolyser which consists of an electrochemical cell capable of producing hydrogen through feeding of current, and water, from which the hydrogen is drawn. Among the electrolysers, one of the most interesting from the point of view of research is Proton Exchange Membrane Electrolysers Cell (PEMEC), which has a membrane capable of conducting ions. In this work, after a deep review of the electrolysis reaction and the major electrolysers on the market, the production of hydrogen is studied through two approaches, experimental and modelling. The experimental approach involves a series of experiments carried out during my internship at Environment Park on a PEMEC electrolyser which consist of preliminary tests on the polarization of the cell and degradation tests. The modelling approach concerns the development and validation of a model of the cell used in the experiments in COMSOL Multiphysics, where 2D and 3D models are developed. The results achieved in the experiments consist in the polarization curves of the cell, with different configurations of temperature, pressure, mass flows and comparison of open and closed cathode configurations, and for what regards the degradation tests, in the monitoring of voltage, pressure and temperature with focus on the production of hydrogen throughout all duration of the experiment. The outcomes obtained in COMSOL Multiphysics concern the validation of the results accomplished in the polarization tests and the application of turbulent and multiphase models at both 2D and 3D configurations. Possible future developments of this work, with regard to improvements in the experimental side, are building an automatic refilling system, to avoid having manual refills during long degradation tests as well as having a system to control and monitor the pressure in the connection between mass spectrometer and the rig, to avoid high pressures that cause an interruption of the scan with relative loss of data until a new scan is manually performed. Regarding the modelling side, a possible improvement is the deepening of the turbulent motion applied to 2D and 3D models, in order to have a better understanding of the multiphase processes that are present in the cell.