Offshore wind turbines are getting bigger and more powerful. In the coming decade they are going to be installed in harsh marine environments in increasingly deep waters. This will pose significant challenges to the design and installation of support structures.
Currently, monopiles support about 80% of all offshore wind turbines in Europe and are expected to remain a very popular foundation solution in the coming decade. The design of monopiles does not only depend on the characteristics of the wind turbine, but also on soil conditions and severity of repeated (‘cyclic’) loading from wind and waves. Current design practice relies on large safety margins, which results in using more steel than strictly needed. Because support structures make up around 20% of the total investments, optimisation of monopile design can certainly lead to significant cost reduction.
The project title, MIDAS – Monopile Improved Design through Advanced cyclic Soil modelling, defines its mission. MIDAS targets deeper fundamental understanding of monopile-soil interaction under cyclic loading. We will focus on sandy soils, especially relevant to the North Sea.
In the project, we will combine advanced experimental and computational work to improve foundation design in relation to cyclic loading conditions. The resulting new knowledge on cyclic monopile-sand interaction will be translated into a cyclic p-y model. This model will link local lateral soil reactions (p) to lateral displacement (y) along the monopile.
The new cyclic p-y model will be directly usable in design software to engineer new-generation monopiles. Industry project partners will test and incorporate the novel design method into their in-house practice.
We expect that MIDAS will produce a proven methodology for the analysis and design of monopiles under environmental cyclic loading. The primary benefit brought by MIDAS to end-users will be the opportunity to offer foundation solutions at lower manufacturing costs. In particular, the improved design methodology will allow to optimise monopile diameter, length and wall thickness. This will directly lead to reduced use of steel, and therefore significantly lower costs.
MIDAS’ partners will gain front-runner positions in the monopile business. They will increase their success rate in future tenders, create more job opportunities, and enable lower cost of offshore wind energy. Ultimately, the whole offshore wind sector will benefit from MIDAS results shortly after their public dissemination.
This project is supported by the Netherlands Enterprise Agency and TKI Wind op Zee.