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.

The experimental Flettner rotor craft Cloudia, developed at Edinburgh University as part of Stephen Salter's geoengineering project
The experimental Flettner rotor craft Cloudia, developed at Edinburgh University as part of Stephen Salter’s geoengineering project

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.

Enercon’s supply vessel E-Ship 1

Another notable proponent of Flettner ships is marine energy pioneer Stephen Salter, who in The Engineer has proposed that a fleet of 1500 autonomous Flettner yachts could travel the seas spraying a seawater mist into the air to increase the reflectivity of clouds and thereby combating climate change by preventing some of the sun’s heat from reaching the ground.

However, according to the manager of the ETI Flettner Rotor Supply, Install and Commission Project, Andrew Scott, “there has been insufficient full scale demonstration on a suitable marine vessel to prove the technology benefits. Successfully demonstrating this would make the technology more attractive to shipping companies and investors.”

The project aims to provide Flettner technology for a large, internationally traded ship; with partners asked to demonstrate how their technology can provide the 10 per cent efficiency improvement and also to explain how they would design, supply, install, commission and then test and support the rotors. The project also calls for at least a year of at-sea testing of the resulting vessel.

“The technology, if proved successful, could also be retrofitted to existing shipping fleets and play a significant role in reducing the fuel costs, so improving environmental impact,” said Scott, whose organisation seeks to demonstrate new energy-saving technologies to reduce the risk of investing in them.

The deadline for notification of intention to submit a proposal is 31 March 2016, while submissions will close on 16 April.