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.

Irmão is a beach restaurant located in the region of Lisbon in Portugal and has been taken over by the new owners one year ago. Since the takeover, the owners of Irmão have been trying to work in a sustainable way, but there is always room for improvement. In addition, Irmão may have to move 100 metres inland due to a possible change in local regulations. Because of the uncertainty in the course of events, this report is written as guideline in order to make the current restaurant more sustainable and as a guideline during the design of the new beach restaurant, should the restaurant have to be relocated.

The aim of the report is therefore to provide beach restaurant Irmão with a consult on how to establish and operate a more sustainable beach restaurant, in present or future times. The study, executed at Irmão, focused on three main themes; the water system, waste management and the energy system. The level of sustainability in these areas is quantified in three ways, namely: the use of resources such as fossil fuels and groundwater; the emission of greenhouse gases CO2, NOx and CH4; the pollution of the direct environment, for example waste that ends up in nature or polluted waste water that flows into the soil. The present and future times refer to the two different scenarios used to implement sustainable solutions. If the restaurant is allowed to stay at its current location, it is referred to as the Improved Irmão Scenario. If the location has to be changed, it is referred to as the Future Irmão Scenario. For the Improved Irmão Scenario, the boundaries and limits of the current restaurant are taken into account and the design is carried out within these limits. For the Future Irmão Scenario on the other hand, these limits are loosened and the design is carried out from scratch.

To provide Irmão with a consult how to establish and operate a more sustainable beach restaurant, three steps were taken. First, the current situation of the three subjects is analysed to get a clear understanding of the current situation. This is done to have a baseline against which the final improvements can be compared. Secondly, different solutions to make Irmão more sustainable, within the three main topics, are compared using a multi¬criteria analysis to determine the most promising solutions. Thirdly, the final solutions are elaborated for the Improved Irmão Scenario and for the Future Irmão Scenario.

Regarding the Water system, the analysis showed that the water consumed at Irmão partly originates from the water grid and partly from the borehole in the dunes. The water use is estimated to cause an emission of 182 kg CO2 annually, leaving little room for improvement in emission reduction as this is a relative low amount. However, the water system is currently not water-efficient because it does not contain any water circularity and the water system does not contain any water saving equipment. Improvements regarding water usage are therefore possible. Regarding waste management, the analysis showed that currently, only residual waste is not recycled. Therefore, the section on waste management focused on making residual waste more sustainable. Regarding the energy system of Irmão, it became clear from the analysis that Irmão currently consumes propane gas and electricity from the local electricity grid. Both the consumption of propane gas and electricity from the local grid contribute to an emission of 26.8 tonnes of CO2 annually. From all processes carried out during the operation of Irmão, only the consumption of propane gas leads to an emission of NOx, namely 382 kg NOx annually…