While recent research is driving down the costs of constructing foundations for offshore wind farms, the cost of decommissioning the UK’s 37 wind farms that are in operation or under development is up to £3.64bn, according to a new report.
The Cost Estimation and Liabilities in Decommissioning Offshore Wind Installations was prepared by Arup for the Department of Business, Energy and Industrial Strategy (BEIS).
BEIS has said that it may be required to execute the role of decommissioner of last resort for offshore wind farms and the report aims to develop a cost model to quantify the government department’s potential liability.
To support development of the cost model Arup consulted with the offshore wind industry, gathering stakeholder views and considering future scenarios that may influence the decommissioning costs.
The report assumes that foundations will be cut below seabed level and the top section removed from site.
According to Arup, this element of the report benefitted from experience on the Yttre Strengrund decommissioning where 3.5m diameter monopiles were cut and removed. However, the report warns that technology required to cut through large diameter monopiles is not currently available off the shelf and environmental conditions and differing design may affect operations.
The report also warns that any calls for greater or complete removal of foundations could have a significant effect on decommissioning costs. The report states: “If the complete removal of monopiles or jacket foundation piles was required this would mean significant excavation around the foundation, or the development of new removal technologies such as high capacity vibratory hammers. As these options are currently considered technologically and economically challenging for large-diameter piles, there is a high degree of uncertainty as to how complete foundation removal could be achieved in practice.”