Challenges and constraints in offshore wind: an end-of-life perspective

Abstract

The offshore industry faces a challenge regarding the number of offshore wind turbines approaching the end of their design life due to the substantial growth experienced in the last two decades. The sector currently lacks the necessary guidance to manage these assets sustainably, potentially leading to developers considering financially less risky but environmentally unsustainable options like decommissioning. This project aimed to develop the groundwork for a decision support framework to assist repowering of offshore wind turbines. The framework focused on identifying constraints within the offshore wind supply chain that would affect end-of-life options and on developing an accurate method to estimate a turbine's remaining useful life.

Constraints within the availability of fabricators and installation vessels was highlighted as having a substantial impact on both greenfield sites and full repowering. Instead, partial repowering and life extension were identified as having lower financial risk due to their limited supply chain engagement.

The study also highlighted the potential for structural reserves within operating turbines due to conservatism within design standards used during their development. Offshore structural monitoring was discussed, and the lack of open-access structural data was highlighted as a key barrier in tool development for structural assessment of offshore wind turbines. A methodology to artificially age a 5 MW offshore wind turbine utilising a monopile foundation was developed using OpenFAST, whereby the stiffness of the monopile was decreased in steps and the response recorded across different environmental conditions. The aged models’ tower top deflection saw a small increase compared to the intact model, but further analysis is recommended before a comprehensive conclusion is drawn.

Finally, the study evaluated the identified offshore supply chain constraints and structural health assessments by discussing their influence on different end-of-life options and recommendations were proposed to encourage a more sustainable offshore wind industry.

Date of Award	Jul 2024
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Gavin & Doherty Geosolutions Ltd
Supervisor	Madjid Karimirad (Supervisor), Vinayagamoothy Sivakumar (Supervisor) & Soroosh Jalilvand (Supervisor)