The offshore wind industry has historically focused on setting up new projects, with the decommissioning phase receiving little attention. This can cause future problems as decommissioning needs to be planned at the beginning to prevent complications that may arise, as it implies important operations and high costs. There are numerous features that make decommissioning a challenge, such as the marine environment, the technical limitations of vessels and the lack of specific regulations that determine what should be done, increasing the uncertainty of the process. Additionally, the unique characteristics of the sites involve exclusive optimal solutions for each project. This article analyses the main operation parameters that affect the decommissioning process, identifying the benefits and drawbacks of the influencing variables. A model is designed to compare different transportation strategies, searching for cost reduction. A decommissioning methodology is been proposed based on this analysis, taking into consideration the technical aspects of the process, and minimising environmental impacts. The model forecasts that the predicted duration and costs of this process are not being adequately captured in site decommissioning plans

Since Vindeby in 1991, more than 100 projects have been installed in Europe, and will need decommissioning one day. Despite the increasing number of projects reaching this phase, decommissioning is still an area that has received relatively little attention. This paper considers the practicalities and economic implications of recycling offshore wind components as part of an end of life strategy. There is no existing source that gathers together materials data for currently operational wind turbines in Europe relevant to recycling. Since this information is necessary for any economic analysis of component recycling, such a dataset was generated. The results illustrate the specific wind turbine materials suitable for recycling, expressed in percentage values of the wind turbine's total mass. An economic analysis is then performed to study how recovering these materials and selling them as scrap metal can impact the decommissioning costs. As concluding remarks, recycling offshore wind components could pay for nearly 20% of the total wind farm decommissioning costs if monopile foundations are considered. Furthermore, the volatility of scrap prices is such that this could even help define when it would be best to decommission an offshore wind farm. COVER LETTERThank you very much for considering our article. It has a lot of effort with diverse expertise from people with different backgrounds. It is a topic that is currently receiving a lot of attention and causing concerns, and is the first outcome of a wider research we are producing.We are proud of submitting it to Energy Policy as we consider this journal is ideal for generating the corresponding concerns and in consequence, enable a transition to a potential improvement and make this end of life stage, more sustainable. Cover LetterTitle page HIGHLIGHTS  Uncertainties in end of life strategies of offshore wind projects make decisions complex and challenging  An inevitable decommissioning era is arriving which must adequate to project's characteristics  Recycling should be included as a target and taken into consideration since the planning  An appropriate recycling could pay part of the decommissioning costs while making the process more sustainable  The volatility of scrap value can help determine when it is best to decommission *Highlights Response to Reviewers1 ABSTRACT Since Vindeby in 1991, more than 100 projects have been installed in Europe, and will need decommissioning one day. Despite the increasing number of projects reaching this phase, decommissioning is still an area that has received relatively little attention.This paper considers the practicalities and economic implications of recycling offshore wind components as part of an end of life strategy. There is no existing source that gathers together materials data for currently operational wind turbines in Europe relevant to recycling. Since this information is necessary for any economic analysis of component recycling, such a dataset was generated.The results illustrate the specific wind turbine...

In the coming years, an important number of offshore wind turbines will reach the end of their initially planned service life. In a wind turbine end-of-life scenario, owners can decide between extending the life of the asset, repowering the site or decommissioning. This decision-making process is affected by important sources of uncertainty, especially in offshore environments. The limited experience makes the decommissioning procedure challenging, as it is still largely unexplored. This work assesses the current state of knowledge about the challenges surrounding the decommissioning process of an offshore wind farm. The four main challenges encountered are identified and analysed in detail, namely the regulatory framework, the overall planning of the process, the logistics and vessels’ availability, and the environmental impacts confronted. Ultimately, this paper aims at stimulating the dialogue among stakeholders and raising the awareness of adequately regulating and preparing the upcoming decommissioning of offshore wind farms in Europe.

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