Offshore green hydrogen production and transportation to shore via pipelines in the North Sea with parallel natural gas transport

Abstract

The North Sea has significant potential in becoming a green energy hub, due to its remarkable offshore wind potential, and could therefore facilitate the energy transition to a net-zero energy system in Europe in the coming decades. In this transition, hydrogen is also predicted to play a key role, due to its ability to transport and store substantial amounts of energy. Previous studies have shown that for large offshore wind capacities and substantial distances from the shore, transporting the produced energy in the form of molecules (converting the electricity to hydrogen) via dedicated pipelines would be a more cost-effective option than using electricity cables and converting electricity to hydrogen. This transport could be achieved by developing new hydrogen-dedicated infrastructure or reusing existing natural gas pipelines, which is a cost-effective alternative.

This research study aims to determine the potential for repurposing existing gas infrastructure in the North Sea for hydrogen transport, taking into consideration that this infrastructure will still have to transport natural gas to the shore over the coming years. Redirecting an amount of this natural gas to other, neighboring pipelines creates the possibility for existing pipelines to be freed up for hydrogen transportation, and therefore achieve parallel transmission of green hydrogen and natural gas from the Dutch North Sea to the shore. Consequently, the purpose of this thesis project is to examine the geographical, technical, and economic feasibility of large-scale green hydrogen transportation (produced offshore with green energy from wind turbines), with parallel natural gas transport, via new and already existing gas infrastructure in the North Sea, by 2030.

The first aspect to be analyzed was the geographical configuration of such a system. For that purpose, different possible configurations for parallel transport of hydrogen and natural gas via existing North Sea infrastructure were examined. This analysis indicated that the most suitable scenario, considering the projected timeline and current circumstances, would be repurposing the NGT pipeline for 100% hydrogen transportation (produced from offshore wind search areas 7 and 3), and rerouting the natural gas to the NOGAT pipeline. Both NGT and NOGAT pipelines are parts of the North Sea offshore pipeline system, currently transporting natural gas to the Dutch shore. The next part of the study concerned the physical configuration of the hydrogen transportation system. A component analysis was done, highlighting the most suitable components across the entire system configuration, including the offshore hydrogen production by water electrolysis, its compression, and its transportation via the NGT pipeline among others.

Furthermore, a more elaborate analysis was done to determine the project’s technical feasibility, with emphasis being placed on the key aspects of hydrogen compression and transportation, evaluating its flow characteristics and compression requirements. The analysis results showed that transporting hydrogen via the NGT pipeline to the Dutch shore is technically feasible. Based on the analyzed scenario, the maximum hydrogen transport capacity was found to be 7.9 GW, and the total compression capacity 103 MW. During its transportation along the length of the pipeline (253 km), hydrogen experiences a pressure drop of 10.4 bar (65 bar to 55 bar). An economic evaluation of the system was also performed, indicating that the project is feasible from a financial standpoint as well. The LCOH transport for the proposed system, including hydrogen compression and NGT pipeline repurposing costs, was found to be 0.17 €/kg/1000km. The overall conclusion of this study is that reusing existing infrastructure in the North Sea for hydrogen transportation is a physically and technically feasible option, which can be achieved at a competitive cost.