Optimal design and operation strategies for renewable-electrolysis-based green hydrogen hubs

This thesis investigates the role of green hydrogen in energy systems, focusing on the integration of hydrogen production with renewable energy sources like wind and solar power. The research spans several case studies, analyzing the technical and economic implications of different hydrogen production configurations, particularly within offshore energy hubs and national energy systems. The growing need for decarbonization in sectors like heavy industry, maritime transport, and shipping has spurred interest in renewable hydrogen production and Power-to-X (PtX) technologies.

First, the basic modeling principles of electrolyzers are outlined. In a case study of an offshore wind-electrolyzer systems, the modeling principles are tested. The case presents a Power-to-Hydrogen application possibility in the context of an offshore energy hub, where the performance of the hub is evaluated in decentralized and centralized formats. According to this study, localizing the electrolyzers at centralized substations achieves a lower levelized cost of hydrogen compared to decentralizing them within the wind turbines. Another case study illustrates a Hydrogen-to-X application within a PtX system, integrating solar power with e-methanol production from hydrogen. The system provides ancillary services in the grid balancing market and its profitability from a producer’s perspective is investigated. This dual role of PtX systems — fuel production and grid balancing — offers a cost-effective pathway to scaling PtX technology. Second, a comparative analysis of Power-to-Hydrogen systems in Denmark, the U.S., and China highlights how local conditions, design choices, and operational strategies drive the economic viability of these systems. The results underscore the importance of customizing system configurations to regional characteristics to maximize technical eciency and cost-effectiveness. Third, this thesis draws the focus to a systems perspective for validating and testing some of the initially investigated concepts. The potential of integrating offshore wind and hydrogen production, with further conversion to ammonia, in small, isolated energy systems is analyzed, using the Faroe Islands as a case study. Different electrolyzer technologies and placement options are evaluated, with the findings showing that green hydrogen can reduce reliance on fossil fuel, both on land and in the maritime sector.

The thesis contributes to the understanding of how hydrogen production can be optimally integrated with renewable energy sources to support decarbonization efforts across various sectors and geographies. It offers insights into systems design, operational strategies, and market participation, helping to shape the future of green hydrogen and PtX technologies in the global energy transition.