Optimization of the capacity factor of energy ships for far-offshore wind energy conversion using weather-routing

• Main Author: Binti Abd Jamil, Roshamida
• Other Authors: Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), Centre National de la Recherche Scientifique (CNRS)-NANTES UNIVERSITÉ - École Centrale de Nantes (Nantes Univ - ECN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), École centrale de Nantes, Aurélien Babarit, Jean-Christophe Gilloteaux
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Offshore wind energy; Energy ship; Capacity factor; Weather-routing; Optimization; Énergie éolienne en mer; Voilier hydro-éolien; Facteur de capacité; Routage météorologique; Optimisation; [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]; North Atlantic
• Online Access: https://theses.hal.science/tel-03901190; https://theses.hal.science/tel-03901190/document; https://theses.hal.science/tel-03901190/file/R_BINTI_ABD_JAMIL.pdf

The energy ship is a relatively new concept for offshore wind energy harvesting. It consists of a windpropelled ship that generates electricity using water turbines attached underneath its hull. Since the energy ship is not grid-connected, the generated energy is stored aboard (for instance, using batteries or through conversion to hydrogen using an electrolyzer). A key advantage of the energy ship is that it is mobile. Therefore, its trajectory can be optimized using weatherrouting in order to maximize energy production, which is the focus of this thesis. The analysis in the thesis is based on numerical simulations. The weather-routing software is a modified version of QtVlm in which the optimization objective has been replaced by the maximization of the energy production. The energy ship is modelled in the software by a velocity polar and a power production polar. The wind data is based on the ECMWF ERA-5 wind dataset. The energy ship concept is particularly well-suited for the harvesting of the wind energy conversion in the faroffshore. Therefore, the capacity factor of energy ships deployed in the North-Atlantic Ocean is investigated first. Results show that a capacity factor of 70% can be (annual average). It is similar to that of floating offshore wind farms which would be deployed in the same area. Energy ships may also be used for the power supply of islands and coastal communities. Therefore, the capacity factor of energy ships deployed nearshore is also investigated. Two case studies are considered: the island of “Ile de Sein” and the “Saint-Pierre-et-Miquelon” archipelagos. Results show that the capacity factor is in the order of 50%. In this case, it would be 10 to 20% smaller than that of offshore wind farms. The weather-routing optimization depends on physical (e.g. storage capacity, rated power) and numerical parameters. Sensitivity analyses are performed in order to understand their effect on energy production. Results show that the optimization algorithm in QtVlm tends to converge to local ...