While interacting with the wind rotating columns fixed to ship’s deck cold save up to 10 percent of fuel now even as they were invented a century ago.

In a step that could lead to more environmentally friendly tankers worldwide, an ocean-going tanker is to be fitted with a type of “spinning sail” invented almost a century ago.

The interaction with the wind provides forward thrust by the unusual sails that are rotating columns fixed to the deck of the ship. Shell’s shipping arm and one of the world’s biggest shipping companies, Maersk is backing the trial.

The industry is coming under increasing pressure to play its part in tackling climate change by reducing emissions and international shipping runs largely on highly polluting “bunker” fuel. Kites, batteries or using biofuels are among the technologies being explored to cut pollution.

Put it into practice on two ships, one of which crossed the Atlantic in 1926, the spinning, or rotor sail, was invented by the German engineer Anton Flettner. A thrust force perpendicular to the wind direction is created as the air flow accelerates on one side and decelerates on the opposite side since it propels the ship because when wind passes the spinning rotor sail.

Modern lightweight versions of the rotor sails, produced by the Finnish company Norepower, are being installed on a 240 metre-long Maersk tanker. The largest rotor sails ever deployed and the first to be used on a tanker, they will be 30 metres tall and 5 metres in diameter.

Norsepower’s CEO, Tuomas Riski said that much more than the 50kW of electricity needed to turn it will be produced by the rotor sails, each of which can produce the equivalent of 3MW of power in favourable wind conditions. The rotation of the sail can be also be reversed if the wind direction reverses.

Equivalent to about 1,000 tonnes of fuel a year, overall fuel savings of 7-10% were expected, Riski said. “We are pretty confident we are in this kind of range.” The company has already seen a saving of 6% by deploying its rotor sails on a roll-on/roll-off ferry.

Having failed to compete with diesel power in the 1920s, the rotor sail could take off now due to echnology improvements and the rise of environmental regulations, Riski said. “Wind is the only renewable energy available at large scale in the ocean,” said Riski.

“This is one of the few fuel-saving technologies that could offer double-digit percentage improvements,” said Andrew Scott at the UK’s Energy Technologies Institute, an industry-government partnership that is helping fund the trial.

Shipping is a significant source of air pollution and carbon emissions but it also moves much of the world’s goods.

While being heavily criticised for postponing any action on greenhouse gases,  a deal agreed by the UN’s International Maritime Organization in 2016 will cut sulphur emissions from 2020.

“The IMO was first charged with acting by the Kyoto Protocol in 1997 and now, two decades later, the IMO’s latest greenhouse gas emissions reduction plan envisages a further seven-year period to collect data and navel gaze with no commitment to act at the end of all this,” said Bill Hemmings at the NGO Transport & Environment.

Riski said: “Flettner sailed across the Atlantic and proved they worked. Now the world might be ready to make this real product. I think it will be a no-brainer.”

(Adapted from The Guardian)

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