Hydrogen production in the North Sea: Decarbonizing European energy with offshore wind, natural gas and carbon capture and storage

English summary The North Sea has delivered secure and stable energy to Europe for over 50 years in the form of oil and natural gas. In Norway, this industry has long accounted for more than half of Norwegian exports, resulting in an industrious economic development. However, the continued use of oil and gas as today is incompatible with limiting anthropogenic climate change. The European Union has set ambitious targets for reducing their greenhouse gas emissions, including a 55% reduction by 2030, and reaching net-zero by 2050. These targets may put the Norwegian economy at risk. This may also be an opportunity. The North Sea also has excellent conditions for offshore wind development, and large capacities for storing CO2. Additionally, the North Sea may be a central source of hydrogen for Europe, both through its large potential for renewable electricity production (opening for green hydrogen production), but also through the combination of natural gas and CO2 storage (allowing for blue hydrogen production). This thesis thus poses two questions: 1. What is the value of North Sea energy resources in the European energy transition? and 2. How are the North Sea energy resources used together with hydrogen in the European energy transition? These questions are answered in four papers, where each paper adds one of the North Sea resources. The first paper investigates the role of green hydrogen in the European energy system, and how it synergizes with offshore wind in the North Sea. The second paper investigates the relationship between blue and green hydrogen, whereas the third considers the impact of uncertainty in the cost-optimal development of the hydrogen supply chain. Finally, the fourth paper investigates the cost-optimal development of the European energy system following the energy crisis and considers the role of alternative solutions to hydrogen. The results show that the North Sea can play a large role in the European energy transition. Through offshore wind and carbon capture and storage, the North Sea can supply Europe with decarbonized energy in the form of electricity and hydrogen. Its large potential in CO2 storage also allows it to further contribute by reducing emissions in hard-to-abate sectors.