Outlook of industrial-scale green hydrogen production via a hybrid system of alkaline water electrolysis and energy storage system based on seasonal solar radiation

Hydrogen has been considered as a clean energy carrier by generating electricity via fuel cells without carbon dioxide emissions; however, in the current stage, most hydrogen is produced by a steam methane reforming, emitting carbon dioxide as a by product, together. In this context, a green hydrogen production system, which is consisted of water electrolysis and a renewable energy plant, should be expanded to prepare for the upcoming hydrogen society in the future. A techno-economic analysis is carried out for green hydrogen production based on seasonal solar radiation data in the case of the single and the hybrid system, which is designed as only alkaline water electrolyzer and a combination of alkaline water electrolyzer and energy storage system. In addition, a carbon footprint analysis is performed to quantify the carbon dioxide emissions for the proposed systems. And the optimal scale of alkaline water electrolyzer and energy storage system is figured out via a genetic algorithm considering a carbon tax on emitted carbon dioxide. Based on itemized cost estimation results, 6.55 and 6.88 USD kgH(2)(-1) of unit hydrogen production costs were obtained for the case of a hybrid and a single system, respectively. Further, the results present that the hybrid system is preferred when Li-ion battery costs decrease to under 79.67 USD kWh(-1). In addition, the capital cost is a crucial factor to figure out the optimized alkaline water electrolyzer scale and energy storage system capacity that set the optimized size is important to minimize the unit hydrogen production cost. Finally, the effort to reduce the capital cost to produce the green hydrogen is necessary when increasing trend of carbon dioxide tax is considered.