Dredging as an Integrated Part of Monopile Decommissioning by Hydraulic Extraction
Type:
Presented during:
WODCON XXIII - Dredging is changing - The Practice. The Science. The Business.
Authors:
J.M. van Wijk, R.G. van de Wetering, J.B.L. Hoebe, C.F. Hofstra, W. Coumans, J. van Dijk
Abstract
"Driven by climate change and the call for an energy transition, offshore wind energy has rapidly developed from a marginal business into one of the main renewable energy sources worldwide. Offshore wind farms (OWFs) increase in number, in size, and individual turbines are increasing in size as well. Most offshore wind turbines have a monopole (MP) foundation or jacket foundation, with monopiles being the dominant support structure, and the number of MP's per OWF is typically in the range of 50-100. With this development, decommissioning of offshore support structures will become a necessity and substantial business in a few decades time when the wind farms have reached the end of their lifecycle. Typical monopiles are steel tubular structures with a diameter of 5-10 m and embedded lengths of tens of meters. Decommissioning by simply lifting the monopile is not an option due to the extreme loads that need to be overcome. Decommissioning strategies need to incorporate different tools and technologies. In this paper the application and possible limitations of a novel decommissioning method, hydraulic pile extraction, will be discussed. This technology is shown to be complementary to the role of specialized dredging methods, and a general overview of different decommissioning strategies will be presented. In this way this paper contributes to the development of monopile decommissioning as a mature and professional activity on the interface of dredging and offshore installation works."
Keywords: offshore monopile foundations, decommissioning, specialized dredging, hydraulic pile extraction