Sustainable decommissioning of an offshore wind farm

Abstract

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

Recycling offshore wind farms at decommissioning stage

“…This analysis could not be performed for other types of foundations due to the lack of available data. Moreover, taking into account the figures from a previous study which estimated the total decommissioning costs in around £200,000/MW [7], Table 7 is achieved, where nearly 9% of the decommissioning costs could be paid just by recycling offshore wind turbines materials. If monopile foundations are also included, then the value rises to 13%.…”

“…Refurbishment (or partial repowering), involves the replacement of minor elements of the project such as the drivetrain or the rotor and keeping if possible, the tower, foundations and cables. This would allow the existing projects to increase efficiency and consequently, energy production [7], but in the end, certain decommissioning is required as elements are removed.…”

“…It has been estimated that a total amount of around 2Mt of steel has already been deployed in the European sea, but this will not be the total amount to be recycled. For the removal and dismantling of these embedded foundations, these are cut a minimum of a meter into the seabed to minimise environmental impacts and avoid extreme costs [7]. In consequence, the removed length and weight of the monopiles need to be calculated, being the removed length of the monopile equal to the water depth plus the 2 meters required by excavation, and the weight, a proportion of these lengths.…”

“…These result in decommissioning programmes that are exclusive and unique for each wind farm, complicating the creation of a general methodology. Additionally, recent studies are suggesting that these decommissioning programmes are underestimating costs as well as being performed vaguely[7].End of life decisions previously described have an enormous potential in becoming sustainable by means of reusing or recycling the dismantled components, which has been the focus of this study, and where the contributions of this research can be summarised as follows: 1. As decommissioning will always be the final stage of an offshore wind energy project, efforts must be attempted on making it as sustainable as possible by means of enhancing the recycling of the removed components, 2.…”

Resource Recovery from Waste: Restoring the Balance between Resource Scarcity and Waste Overload

“…Another large potential environmental threat comes from materials that have been relatively recently introduced in large quantities to the technosphere, such as the cocktail of elements used in IT and communications technologies, the rare earth metals used in high-performance electrical motors and generators, the lithium and cobalt compounds used in electrical storage systems, or the various high-performance composite materials introduced into the transport and power generation sectors [41,42]. Since such products-e.g., electric vehicles, wind turbines, computers and 'internet of things'-enabled products, and the ubiquitous cellphone-are not designed with any significant regard for the recovery of these critical and/or difficult to recycle materials at the end-of-life stage, they will, without careful management, eventually enter the biosphere.…”