Green hydrogen production for high-temperature heat decarbonization: a case study from the ceramic sector

Nowadays the reduction of CO2 emissions in many sectors is a primary need: the goal of the decarbonization of the industrial sector and the attempt to find sustainable alternatives to natural gas is leading to the implementation of the Renewable Energy Resources (RES). The production of hydrogen by means of water electrolysis is one of the most studied technologies and it could play an important role in decarbonization, in particular if RES are exploited to feed the electrolysis process. In fact hydrogen is an optimal solution because it guarantees a long term storability and the possibility to decarbonize final sectors in which is technically not possible or not convenient, such as the high-temperature heat sector. The present study aims at analyzing the techno-economic performance of an electrolysis plant for the production of green hydrogen in the Italian industrial scenario, in particular in the high-temperature heat sector. The electrolyzer is coupled with a photovoltaic plant for the renewable energy production; the performances of both PEM and alkaline electrolyzers are investigated. A case study coming from the ceramic sector is analyzed and two main scenarios are considered: the plant with a tank for the hydrogen storage and the plant with a battery for the electricity storage. The technical analysis provides the performances of alkaline and PEM electrolyzers (e.g., load factor, specific consumption curves, hydrogen production) in the two scenarios, considering a natural gas-hydrogen mixture with a mixing rate that goes from 5% to 50% vol. of hydrogen. The model is based on a given hourly profile of natural gas consumption. The economic feasibility of the study includes the calculation of the Payback Time (PBT), Net Present Value (NPV) and Levelised Cost Of Hydrogen (LCOH). The results reveal that there is a significant difference in the amount of working hours and the size of the electrolyzer in the two cases; furthermore the results show a good flexibility of the electrolyzer in guaranteeing blending mixtures different from the one it is sized for. On the other side, the economic analysis shows the need of public incentives to enhance the integration of green hydrogen in the industrial sector.