Flettner rotors are placed on ships to allow them to use wind energy for their propulsion. This was first demonstrated by the Buckau, a ship that had 2 Flettner rotors, which sailed across the North Sea and the Atlantic in the 1920’s. The reduced fuel consumption was large enough to lead to the construction of another vessel with Flettner Rotors. However, due to the low oil prices and the high investment costs, the use of Flettner rotors has declined.
In the past few years this technology has been rediscovered. Two commercial cargo ships are currently equipped with Flettner rotors. The E-Ship 1 has 4 rotors and is being used by ENERCON for the transport of wind turbine components and she can save up to 15% fuel. The roro-vessel M/V Estraden uses one Flettner rotor. During sea trials, it was independently verified that her fuel consumption was reduced by up to 2.6%.
Flettner rotors help to use wind power for the propulsion of vessels using the Magnus effect to create lift. The so-called Magnus effect lets a spinning body, in liquid or air, creates a force perpendicular to the direction of that flow. In other words: the difference in the pressure at either sides of the spinning body creates lift. This effect can be seen in sports like football and tennis, where a spinning ball makes a curved trajectory. In the case of ships, the rotor is a tall round mast that is driven by a motor.
Equipping a commercial vessel with Flettner rotors is not easy. Even with specialist knowledge and determination, the financial side of such an investment can determine whether the implementation will be successful. For example, Wärtsilä and Viking Lines designed a ship with Flettner rotors in 2009, but the ship was eventually built without the rotors. Even though this attempt to implement Flettner rotors was unsuccessful, Wärtsilä still believes in the concept and sees it as a viable option for sustainable ships.
An important element to help introduce Flettner rotors into the market is clarity on the building guidelines (specification standards) for ships. Recently Lloyds Register published a guide on the installation of Flettner Rotors, making it easier for future projects to work on the construction of these wind power devices.
The long-term reliability of operational Flettner rotors is still uncertain, and only time will tell how much maintenance and repairs these installations will require. However, since the majority of the components used to create Flettner rotors are not ‘new’, no major reliability problems are expected.
Flettner rotors can reduce the fuel consumption of commercial ships leading to CO2 and emission reductions and decreased operational expenses. While the effectiveness of Flettner rotors depends on the operational profile of the ship and the geographic area in which it operates (more wind = more savings), experiences from the real-life examples and computer simulations show that considerable
Many commercial vessels could potentially use Flettner rotors. However, not all ships are suitable as the operational and practical context of the ships determine, to a large extent, how suitable a ship is for Flettner rotors. The deck-space requirements for these rotors, for example, make them suitable for implementation on cargo vessels rather than on container vessels. Ships with long constant speeds are also more suitable than ships that maneuver a lot, such as tugs or supply vessels.
Flettner rotor technology details, Ian Pickard, November 2015
Global, freight, international shipping, technology, innovation, adaptation
Norsepower Ey Ltd, ENERCON, Wärtsilä
Sara Consuegra firstname.lastname@example.org