Integrated Hybrid Solar Energy for Efficient Green Hydrogen Production via Alkaline Water Electrolysis: A Research Framework

Alkaline water electrolysis (AWE) is one of the promising processes that could be used to produce green hydrogen using intermittent solar power. However, the study of the PV supply, heat recovery, dynamic operation and the durability of the PV stack are generally studied separately. In this paper, experimental and modelling studies are reviewed to create a research framework to integrate the use of useful solar heat with PV electricity in hot high irradiance conditions for AWE. Various evidence from modelling electrolyzer, direct PV coupling, PV/T heat recovery, part load and physics guided machine learning was taken into account. The results indicate that recovered heat could decrease the electricity load on the stack and alkaline system could be flexible enough to handle variable renewable energy. It is not clear how a controller is to respond to faster electrical responses and slower thermal/gas responses without accelerating deterioration of the components. The suggested scheme is based on irradiance and ambient temperature for the scheduling of current density and heat input, electrolyte flow, and operating mode. Feedback mechanisms between performance and condition monitoring are provided by the stack voltage, temperature, pressure, gas purity, hydrogen yield, and specific energy consumption, as well as by the voltage rise. A set of five test case hypotheses is provided to (partially) differentiate one electrical-only control and coordinated hybrid and health-aware controls. This paper is not intended to provide final performance results and serves only to provide the foundation for the experiments planned.