Nov 4, 2011

Energy saving and the wind powered rotor ships


Energy saving and the wind powered rotor ships

In March 1925, Popular Mechanics featured an innovation called the “rotor ship,” invented by German engineer Anton Flettner. The vessel was hailed as “the first new development in sailing ships since the earliest navigators discovered they could utilize the wind’s power.” Buckau, the first of the rotor ships, featured two hollow towers of steel, 10 ft. in diameter and 65 ft. tall, mounted on pivots powered by 9-hp motors. The towers utilized the Magnus effect—wind currents striking a rotating cylinder exert a force approximately at right angles to the direction of the wind. After an initial jumpstart from the motors, the cylinder’s motion caused the ship to advance, PM reported. Its designers claimed the vessel outran other sailing ships as well as freight steamers. The basic idea was to use the Magnus effect.

Following completion of its trials, the Buckau set out on her first voyage in February 1925, from Danzig to Scotland across the North Sea. The rotors managed to withstand even the stormiest weather, and the rotor ship could tack, i.e. sail into the wind at 20-30 degrees, while the vessel with its original sail rig could not tack closer than 45 degrees to the wind. More than 80 years after the rotor ship’s birth and demise—engines proved most practical at the time—engineers are searching for modern methods of harnessing the winds to propel cargo ships.




Most rotor ships have a system with an electric engine which allows the stopping or initial starting of the rotor by the sailor. This allows the sailor to control the rotor's RPM and direction of spin. However, Buckau which was renamed as Baden Baden got destroyed in a Caribbean storm in the year 1930. Later, he built much advanced Rotor Ship which is used even today.


E-Ship 1 from ‘Enercon’, one of the world’s leading companies in the wind energy sector from Germany. E-Ship 1 uses wind energy to cut down fuel costs and also helps to reduce emissions. Unlike Beluga Skysail which uses a huge parasail, E-Ship 1 uses four giant 25 metre high, 4 metre in diameter, rotating, vertical metal sailing rotors positioned two fore and two aft to harness wind energy. E-Ship 1 has been designed to cut down fuel costs by 30 percent. 

Technical data of E-Ship 1:
Length: 130 metres
Width: 22.5 metres
Draught: 6-9 metres
Tonnage: 10.500 tdw / 9.700 tdw
Speed: 17.5 knots
Engine power: 2 x 3,500 kW

The hull vibratea when the tower rotates at several hundred rpm, and bolting in a brace would stop the vibration. Now, with oil prices up, the Magnus Effect ship is back. Its design has been worked out for ships of all classes, and instrumented tests have proved the device’s effectiveness. The day of the rotor-assisted windship may at last be at hand.

Then came Enter Bergeson, a naval architect with a degree from MIT, who had spent his life in the shipbuilding industry, supervising the production of nuclear submarines for General Dynamics and functioning as general manager of two major shipyards. In 1979 he formed Wind Ship to promote the idea and, as his first major project, undertook a study of sail power for the US Maritime Administration. 

Bergeson noticed that despite the fact that Flettner’s rotor ship worked and at least one other rotor ship went into commercial service, the idea gradually died. “The shipping industry didn’t care about saving energy”, said Bergeson. “Oil was a dime a barrel and was replacing coal. And about that time Flettner turned to designing planes .

Bergeson put his theory to the test in 1981. He designed a 3000 square foot sail for the 3100-ton dead weight ship Mini Lace, a freighter operating in the Caribean out of New Orleans. His calculations showed that fuel savings would average about 20 percent. After 18 months of operation, the ship’s owner published the actual results. Savings had been a satisfying 24 percent.

Sources:
flettnerpat
en.wikipedia
PopularMech..
freearticles..
marinebuzz.co
enercon.de

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