Modelled Behaviour of a High Temperature Electrolyser System Coupled with a Solar Farm

A system model was developed in Simulink (R) in order to describe the dynamic behaviour of HTE (High Temperature Electrolysis) systems fed with variable power. This model is composed of three coupled submodels focusing on the electrolyser, on the Balance of Plant and on the control strategies, respectively. The implemented control strategies ensure optimised operation in terms of both electrolysis material restrictions, such as thermal gradients, and system efficiency. The presented results were simulated for a standalone system composed of a four-unit electrolyser fed with electrical power from a virtual 1.35 MW solar farm in Marignane (France) and producing compressed hydrogen (3 MPa). A thermal insulation of 30 cm around each unit limits thermal losses, so the temperature drops by only 10 K overnight. Over the simulated year, the solar farm produced 2.76 GWh which were converted into 64.5 t of compressed hydrogen. The results show that HTE intermittent operation is technically feasible without an external heat source. Moreover, the system efficiency remains as high as 92 % based on the hydrogen Higher Heating Value (HHV) if suitable control strategies are employed.