ETI seeks partners for Flettner rotor ship trials

The Energy Technologies Institute (ETI) is looking for partners to develop a type of mechanical sail for large ships that, it claims, could improve their fuel efficiency by 10 per cent. Called Flettner rotors, the sail devices were originally invented in the 1920s.

Flettner rotors are vertical cylindrical structures that are installed on the deck of a ship, often with horizontal disc-shaped blades at the top and sometimes down their length. As the name implies, they are free to rotate around a mast, and do so under the influence of the wind. This rotation creates a thrust due to a phenomenon called the Magnus effect, in which a spinning body in a moving airstream generates a force perpendicular to the direction of the airstream.

There have been a few applications of Flettner ships over the years, since German engineer Anton Flettner launched the first experimental ship in 1924. Scuba diving pioneer Jacques Cousteau built a hybrid diesel-Flettner ship called the Alcyone in the 1980s; it remains the primary research vessel for the Cousteau Foundation. German wind-turbine manufacturer Enercon operates a hybrid cargo vessel called E-Ship 1 with four Flettner rotors to transport turbine components, and claimed in 2013 that since its launch in 2008 it had used 25 per cent less fuel than comparable ships during 170,000 sea-miles of voyages.