Kevin Keane<\/span>Environment, energy and rural affairs correspondent, BBC Scotland<\/span><\/p>\n <\/span><\/div>\n<\/div>\n It must have been a bizarre sight when a freight ship, equipped with two large rotating towers, made its way under the Forth Bridge a century ago.<\/p>\n The experimental sail technology, on the rotor ship Buckau, was first demonstrated in 1925 on a journey carrying timber from Danzig – now Gdansk, in Poland – to the Scottish port of Grangemouth.<\/p>\n The spinning towers were designed to harness the wind as a way of saving fuel but it didn’t catch on for about 90 years.<\/p>\n Now the pioneering Flettner rotors are being used on at least 35 commercial freight ships to improve fuel efficiency and reduce their impact on the climate.<\/p>\n<\/div>\n The original ship was modified to incorporate the tall spinning towers, which were powered by motors, as a way of saving money on fuel costs.<\/p>\n Experts say the relatively low cost of fossil fuels, like diesel, meant it was unlikely the shipping lines of the 1920s would make back the investment required to install them.<\/p>\n The Great Depression of 1929 was the final nail in the coffin for the design, with orders being cancelled by ship owners.<\/p>\n But modern-day decarbonisation targets mean technologies which can improve fuel efficiency, like this one, are becoming more highly prized in the maritime sector.<\/p>\n<\/div>\n The technology, known as Flettner rotors, were designed by aeronautical engineers led by the German inventor Anton Flettner.<\/p>\n The towers are powered by motors which effectively redirect the wind to generate forward thrust.<\/p>\n It’s called the Magnus effect and is the same principle which causes a spinning football to bend through the air – especially when kicked by David Beckham.<\/p>\n Operators say it can cut fuel bills by up to 20% as well as reducing planet warming greenhouse gas emissions from burning diesel.<\/p>\n<\/div>\n Modern rotors are even more efficient than the ones on Buckau in 1925 because they are made with lighter composite materials such as carbon fibre.<\/p>\n Prof Mehmet Atlar, an expert in hydrodynamics at Strathclyde University, believes there was a lot of initial interest in the design with an order book starting to grow.<\/p>\n A larger ship was launched, called the Barbara, with a further six waiting to be built.<\/p>\n But by the end of the 1920s, those orders were being cancelled and the design concept was shelved.<\/p>\n He said: “In my opinion, nothing is new. <\/p>\n “The need is the most important thing. The need now is there, therefore the Flettner rotor came back.”<\/p>\n He said that the lighter materials, combined with more effective motors to drive the rotors, mean it’s much more effective than a century ago.<\/p>\n<\/div>\n The Finnish company Norsepower revived the design when it began exploring fuel efficiency systems for ships more than a decade ago.<\/p>\n It has since built 35 sails, mostly retrofitted, with orders for a further 48.<\/p>\n The company said some ships were even being built “rotor ready”.<\/p>\n Chief executive Heikki P\u00f6ntynen said: “I would say that this will become a very common sight. <\/p>\n “We can see the market booming and developing very fast.” <\/p>\n He added the lighter materials were important.<\/p>\n But Mr P\u00f6ntynen said the use of artificial intelligence, to drive the positioning of the “sails” against the direction of the wind, made it most effective.<\/p>\n He also said the Flettner rotor was a “really sustainable solution” for decarbonising shipping.<\/p>\n The technology can be added to any ship so long as there is sufficient deck space.<\/p>\n That makes it ideal for freight carriers and tankers.<\/p>\n However, Mr P\u00f6ntynen added that it would be difficult fitting the rotors to container ships which use every available space.<\/p>\n<\/div>\n<\/div>\n![\"Pathe](\"https:\/\/ichef.bbci.co.uk\/news\/480\/cpsprodpb\/b152\/live\/65b36cb0-a389-11f0-a56f-0b1b78ebdf89.jpg.webp\")
Pathe News<\/span><\/div>\n<\/div>\n![](\"https:\/\/static.files.bbci.co.uk\/bbcdotcom\/web\/20251010-110820-1cf8d3aa45-web-2.31.3-2\/grey-placeholder.png\")
![\"Hulton](\"https:\/\/ichef.bbci.co.uk\/news\/480\/cpsprodpb\/f633\/live\/60dda880-9953-11f0-9789-e38e7689efaf.jpg.webp\")
Hulton Deutsch\/Getty Images<\/span><\/div>\n<\/div>\n![\"Norsepower](\"https:\/\/ichef.bbci.co.uk\/news\/480\/cpsprodpb\/107e\/live\/c6ab0fe0-9de0-11f0-9108-f9efa9785693.jpg.webp\")
Norsepower<\/span><\/div>\n<\/div>\n![\"BBC](\"https:\/\/ichef.bbci.co.uk\/news\/480\/cpsprodpb\/9f9b\/live\/4a25e800-9e17-11f0-a5c6-afce0def12b6.jpg.webp\")
BBC News<\/span><\/div>\n<\/div>\n‘Sustainable solution’<\/h2>\n<\/p>\n