TANDEM: Towards an Advanced Design of Large Monopiles

Monopile foundation structures also represent a cost-effective solution for future generations of offshore multi-megawatt wind turbines for water depths of more than 30 metres. The monopile for a 7.5 MW offshore wind turbine would have a diameter of up to 10 metres and weigh up to 1,000 tonnes. Monopiles’ properties are strongly related to their dimensions. Therefore, a large monopile is not the upscaled version of a largely understood, normal-sized monopile, but a system which has not yet been extensively investigated and, as such, is still fraught with risks.

When designing monopiles, uncertainties are encountered in the calculation of hydrodynamic loads, in the area of installation methods and in the field of geotechnical dimensions in particular. The absence of well-founded knowledge is currently compensated for by a conservative design with safety reserves factored in. Reduction of the safety factors – without affecting the structural integrity – is possible and would open up considerable potential for saving costs.

The aim of the TANDEM research project is to collect findings and develop methods for lowering the number of uncertainties when designing larger monopiles. Material savings are not the only source of cost advantages – savings are also possible in transport and installation, which in turn contribute to the reduction of energy production costs.