The decarbonization of a floating glass production plant: a cost comparison of alkaline and PEM electrolyzers

The decarbonization of the industrial sectors is crucial to reach the ambitious climate goals and the carbon neutrality. Heavy industries such as refining, iron and steel, chemicals and glass manufacturing are responsible of significant CO2 emissions due to the utilization of fossil-based energy sources and feedstock. Electrifying these energy-intensive processes is currently challenging due to both technical and economic barriers. In this context, a growing interest for green hydrogen is emerging in the recent years. Green hydrogen can effectively replace fossil fuels and fossil-based hydrogen in multiple industrial processes and its role is thus becoming pivotal in transforming hard-to-abate industries. This study aims to investigate the decarbonization of a float glass industry by installing a power-to-hydrogen (PtH) system. In the float glass manufacturing, hydrogen is already used to create an inert atmosphere (90% N2 and 10% H2) in the tin bath chamber and prevent the formation of defects. Thus, green hydrogen can be easily adopted without modifying the production process. In this work, a real production facility located in Larbaa (Algeria) was considered as case study. The PtH system was sized to continuously meet the hydrogen demand, which exhibits seasonal variation and results in 102 ton/y. In the design procedure, a techno-economic optimization based on minimizing the levelized cost of hydrogen (LCOH) was carried out by using the particle swarm optimization (PSO) algorithm. The optimal design tool implemented in MATLAB provided as outcome the size of the PV, the electrolyzer, the hydrogen tank and the hydrogen compressor. The main low temperature electrolyzer technologies were considered: the proton exchange membrane (PEM) and the alkaline (ALK). The techno-economic performances of these electrolyzers were assessed and compared in order to identify the most cost-effective solution. Furthermore, the effects of the lifetime of PEM electrolyzer, the modulation range of ALK electrolyzer, the interest rate and the annual operational expenditure (OPEX) were investigated to determine their impact on the LCOH. Finally, a further comparison with a grid-based scenario was performed. In this case, the electrolyzer was fed by electricity withdrawn from the national grid and a sensitivity analysis on the electricity price was conducted.