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Unique grid-connected "Wave Rotor" in Denmark

Innovative technology

Principles of wind energy are ingeniously combined to arrive at a very simple solution. Rather than looking at the up and down movements of waves there is also considerable energy to be captured from the circulating water particles in the waves creating local currents. The developers discovered that these circular currents can directly drive a rotor. All other systems developed for harnessing wave energy use inefficient intermediate conversion steps, e.g. compressing air, converting linear motion into rotation motion, using hydraulic pumps etc. In order to tap energy directly from both the up and down and back and forward currents, two types of rotors were combined on the same axis of rotation: a Darrieus rotor and a Wells rotor. These are respectively omni- and bi-directional rotors, which can operate in currents of changing directions. Another advantage of this simple, light but strong structure is that it is expected to better withstand storm conditions than other systems, because of the minimal exposed surface area.   Most other devices need a large surface area to harness the impact force of waves.

Prototype test

The 1:10 scale prototype has been developed by Ecofys   in the Netherlands together with Danish partner Eric Rossen. The tests will take place this summer in the Nissum Bredning fjord on the north-west coast of Denmark, where the Folkecenter for Renewable Energy manages a dedicated wave energy test site. The Wave Rotor will be mounted to a platform and tested for performance, foundation loads and electricity production. The rotor can be grid connected via an inverter and supply energy to the grid. Several parameters can be modified such as the number of blades (2, 3 or 4) and pitch angle.

If the results are promising a pre-commercial 50 kW demonstration unit will be built. Meanwhile the ideas have been patented. In the future 0.5 MW mono-pile units are envisioned which are mounted in arrays on the seabed.  

Ecofys

Ecofys (www.ecofys.com) is a leading company with the mission " a sustainable energy upply for everyone". More than 150 employees in 6 countries deliver expert services, products and projects in all areas of sustainable energy and energy efficiency. Ecofys is part of the Econcern group (www.e-concern.com).

For more information please contact:

Prof Dr. K. Blok

telephone: + 31 (0)30 - 2808 399

e-mail: k.blok@ecofys.nl

D. Berkhout

Telephone: + 31 (0)30 -2808 475

e-mail: d.berkhout@ecofys.nl

Appendix: Visual of the Wave Rotor