BLUE Piling Offshore Test Project

Publieke samenvatting

The monopile has proven to be the most efficient, cost effective and simple foundation technology for offshore wind. With the growth of production facilities and installation vessels, as well as improvements in the design envelope, it has become increasingly popular.
Conventional monopile installation uses hydraulic impact hammers. This has detrimental effects on the foundation and the environment. Due to the high acceleration levels, caused by the steel-on-steel impact from pile driving, monopiles cannot be outfitted with preplaced secondary steel. Thus, additional offshore activities are needed to assemble the foundation. Significant fatigue damage can be inflicted during installation, which results in conservative design margins and heavier foundations than necessary. To prevent damage to marine wildlife, some countries have introduced regulatory thresholds for underwater noise. This creates a need for costly noise mitigation measures. Lastly, current installation technology does not allow full decommissioning of the entire monopile which would result in tens of thousands of tons of steel lost in the seabed.
These aspects have triggered the invention of the BLUE Piling.

Based on previous work, the project aims to reduce the cost in offshore wind by lowering the CAPEX for wind turbine substructures, the installation and decommissioning cost, and the offshore wind farm (OWF) related OPEX.
The overall objective is the acquisition of new knowledge and skills for a new pile driver – the BLUE 25M hammer. The following aspects are investigated, modelled and validated: blow profile of the new hammer and correlation with soil resistance, induced fatigue loads on primary and preplaced secondary steel, underwater noise emissions from piling, and an innovative decommissioning strategy.
The ultimate goal is to enable cost savings by simplifying the installation process, developing ‘transition piece free’ monopile designs, making secondary noise mitigation measures obsolete, and establishing a decommissioning method that allows the full recovery of monopiles.

Korte omschrijving
Blue Piling is a new technology to hammer monopiles for offshore wind turbines with considerable less noise and less stress on the monopile. It uses a falling water mass in stead off a steel hammer to drive the monopile into the seabed

The direct results of the project will be the development of validated underwater noise prediction models, which will allow the BLUE 25M to be used as an alternative for conventional hammers, resulting in direct savings on secondary noise mitigation measures. Switching to a BLUE 25M Hammer will reduce the fatigue of conventional designed foundations, therefore increasing their allowable life span or reducing steel and cost for a similar life time.
After the successful completion of the project, the knowledge gained will enable OWF developers to use monopiles without a transition piece, thereby simplifying them - allowing all secondary steel to be positioned on the pile and resulting in a leaner and safer installation process.
Following the project, OWF operators and installation contractors will be able to use the knowledge gained during the BLUE PILOT project to utilise an integrated decommissioning solution allowing complete removal of the wind turbine substructures.
It is anticipated that the project will enable cost over lifetime savings for a 720 MW OWF in the order of magnitude of €33-40m, which is equal to a LCoE reduction of 0.9-1.2 €/MWh.