Semi-centralised hydrogen production

Abstract

The escalating demand for green hydrogen as a sustainable energy carrier has sparked significant interest in offshore wind-to-hydrogen systems, which hold the promise of expediting the transition towards renewable energy sources. The objective of this research is to provide insight in the techno-economic feasibility of semi-centralised electrolysis in an offshore wind farm. The semi-centralised offshore wind-to-hydrogen configuration will be compared with centralised and decentralised offshore wind-to-hydrogen to potentially reduce the levelised cost of hydrogen (LCOH) in future wind-to-hydrogen production designs.

This research was conducted in collaboration with Vattenfall, a leading player in offshore wind energy within Europe, who recognizes the potential of green hydrogen as a key driver in the ongoing energy transition. Vattenfall provided access to an in-house wind farm layout optimisation model to create optimised wind farm layouts as well as site specific data for the case study. This model and data allowed a narrowed focus on the hydrogen aspects of the wind-to-hydrogen configurations.

The technical examination explores crucial elements such as the conversion of wind energy into hydrogen through electrolysis, hydrogen transmission and variances in offshore substations and hydrogen wind turbines, to understand the technical differences between the different offshore wind-to-hydrogen configurations. Additionally, by analysing the hydrogen production process and comparing the scale of hydrogen production in offshore substations or hydrogen wind turbines, the study exhibits the technical feasibility of a wind-to-hydrogen farm with numerous semi-centralised monopile hydrogen substations in comparison with wind-to-hydrogen farms consisting of a single centralised jacket hydrogen substation or decentralised hydrogen wind turbines.

To enable a quantitative comparison of the different offshore wind-to-hydrogen setups in the economic analysis, the LCOH for each configuration was modelled. This process involved creating wind farm layouts and calculating the associated cost for a variety of offshore substations using Vattenfall's optimisation model. Moreover, aspects such as hydrogen production, the dimensions and cost of hydrogen pipelines, and the weight and expense of offshore hydrogen facilities were modelled to estimate the costs associated with hydrogen production and transmission for each configuration.

In the economic analysis, a detailed case study is conducted. The research investigates cost drivers, including wind farm expenses, hydrogen substation investments, and energy transmission infrastructure costs. The results reveal the economic viability of the semi-centralised configuration. The findings highlight the importance of considering monopile load capacity and substructure costs in determining the optimal number of hydrogen substations for semi-centralised configurations. However, the decentralised configuration exhibits a 5\% lower LCOH compared to the centralised and semi-centralised configurations due to the lack of additional substructures and high voltage electrical equipment.

In conclusion, this research contributes comprehensive insights into the techno-economic feasibility of semi-centralised offshore wind-to-hydrogen configurations. The findings highlight the potential of semi-centralised configurations and call for further research and optimisations. Unlocking the potential of semi-centralised offshore wind-to-hydrogen configurations can drive the transition toward sustainable and renewable energy sources.