Industry joins forces to study the sustainable decommissioning of offshore wind turbine foundations

Published: 26 March 2019

The limited lifetime of offshore wind farms requires an efficient and safe decommissioning. The project Hydraulic Pile Extraction Scale Tests (HyPE-ST) studies the option of removal of offshore wind turbine foundations (monopiles) in a sustainable way. This experimental research will take place in the Deltares’ Water-Soil Flume facility in Delft and aims at a proof of concept by the end of 2019.

Offshore wind farms are being built in large numbers to meet the ever-increasing demand for renewable energy. However, wind farms have a limited lifetime. Wind farm owners, such as energy companies, therefore have the responsibility to decommission the wind turbines from the sea when needed. For instance, current offshore turbines were designed with a technical lifetime of 25 years.

This photo of monopiles for a offshore wind park is taken by an unknown author, licensed under CC BY-NC-ND

The HyPE-ST project is part of the GROW program and a joint industry initiative of innogy, Deltares, DOT BV, IHC IQIP, Jan De Nul Group and ECN part of TNO. The project receives also financial support from the Topsector Energy of the the Dutch Ministry of Economic Affairs and Climate.

Monopile foundations

This research project primarily focuses on monopile foundations. Monopiles are open-ended steel piles that can be up to 80 metres long and weigh up to 1,300 tonnes and are the most commonly used foundation type for offshore wind turbines. Currently, offshore (mono)piles are removed by cutting them off several metres below the seabed, which leaves behind tonnes of steel buried in the seabed. The HyPE-ST project aims at developing innovative and smart technology to remove the entire monopile in order to make it possible to recycle the steel.

Hydraulic extraction

In the Deltares’ Water-Soil Flume facility, scaled monopiles will be tested on the possible use of water-pressure to fully retrieve them from the seabed. The tests will take place in different (engineered) soil conditions such as sands with varying densities, clay, and layered soils. The project is scheduled to be concluded by the end of 2019.

David de Jager director of GROW: “The time has come to get more insight in the end of life phase of wind farms. To bring the cost down we have to investigate the possibilities of re-use of materials. This project brings offshore wind energy generation one step closer to circularity.”

About HyPE-ST

The Hydraulic Pile Extraction Scale Tests research project (HyPE-ST) is a Joint Industry Project and supported by the TKI Wind op Zee. The subsidy scheme, which is covered by the Topsector Energie, is managed by the Dutch Ministry of Economic Affairs and Climate. Project partners are Deltares, DOT BV, IHC IQIP, Jan De Nul Group, innogy and ECN part of TNO. HyPE-ST is a GROW project. GROW is a joint research program that initiates research and accelerates innovations in offshore wind.