Into the deep

Floating 20 MW offshore wind turbines

Wind Energy
November 9, 2010

Floating offshore wind turbines with a rating of 20 MW could be possible, according to the DeepWind project lead by Risø DTU.

The DeepWind consortium consisting of 12 international numbers is supported by a €3 million grant under the European FP7 programme for future emerging technologies.

“Our objective is to develop more cost-effective MW wind turbines through dedicated technology rather than advancing existing concepts that are based on onshore technology being transported to the sea environment,” says DeppWind Project Manager Uwe Schmidt Paulsen at Risø DTU.

“Offshore wind energy today is twice as expensive as onshore technologies. That means that there is plenty of room for improvement.”

At depths of 30-60 m, floating offshore wind turbine foundations are more feasible than piled, jack-up of gravity foundations.

Furthermore, floating offshore wind turbines could enable the placement of offshore wind farms near large cities with a deep-water coastline.

DeepWind technology

The DeepWind project combines a vertical-axis wind turbine, new wind turbine blade technology, a full power transmission and control system, and a rotating, floating offshore substructure.

The vertical-axis wind turbine is based on the Darrieus design, and includes a direct drive generator with its electronic control system at the bottom of the subsea shaft together with the electrical power transmission cables.

“The technology behind the proposed concept gives significant challenges and requires technological breakthroughs. We need explicit research in a wide area of different technology fields and materials. For example we foresee research in the dynamics of the system, pultruded blades with adequate material properties, subsea power generators and converters, turbine control and safety systems, wave and current loading on the rotating and floating shaft, and also the mooring and torque absorption system,” says Schmidt Paulsen.

Reaching 20 MW

A kW-sized demonstration turbine is planned in open waters of Roskilde Fjord next to Risø DTU. Data from this will be used to design a 5 MW version, and eventually be up-scaled to 20 MW.

“DeepWind is a challenging and sound project. This project goes beyond a technology transfer from onshore vertical wind turbine generation and constitutes a radical upgrade of existing technologies and would constitute a real breakthrough in the energy sector,” adds Risø DTU Director Henrik Bindslev.