Offshore wind and green hydrogen have the potential to help address the energy trilemma
of sustainability, security, and affordability. However, their high cost remains one of the
main barriers to their rapid development. Using DC collection systems in offshore
wind farms has the potential to make the transfer of electrical energy to shore more
cost-effective by reducing the size of offshore platforms or by removing them entirely.
Similarly, co-locating electrolysers and wind turbines without a grid connection can
make the transfer of chemical energy more cost-effective by removing the need for the
offshore platform, export cables, and collector cables.
The first part of this thesis identifies the most promising DC wind farm configurations
and carries out a cost-benefit analysis. The results show that all-DC wind farms can
lower the levelised cost of electricity, depending on factors such as the DC/DC converter
costs, platform costs, and collector voltage. A multi-objective optimisation is then
carried out for four promising DC/DC converter topologies, and their performance is
compared in terms of reliability, volume, weight, and losses. The optimal operating
frequency for each of the selected topologies is also determined. The results show that
the single-phase single active bridge operating at 2.5 kHz or the three-phase dual active
bridge operating at 1 kHz are optimal.
The second part of the thesis investigates the technical challenges associated with a standalone wind turbine and electrolyser system. A complete control system is developed to
allow off-grid operation, and three strategies are proposed to balance the power between
the wind turbine and electrolyser. The levelised cost of hydrogen is then investigated
for each power balancing strategy, as well as for three alternative DC-based drivetrains
to improve the system efficiency. The results show that using supercapacitor energy
storage and the standard AC-based drivetrain is the most realistic and cost-effective
option.
| Date of Award | 14 Jan 2025 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Sponsors | University of Strathclyde |
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| Supervisor | Agusti Egea Alvarez (Supervisor) & Lie Xu (Supervisor) |
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