Royal Dutch Shell and Maersk shipping group are about to find out, as they team up to fit a tanker with two “rotor sails” to see if the futuristic devices can make a serious dent in fuel bills.
Reducing emissions:
International shipping runs largely on highly polluting “bunker” fuel and the industry is coming under increasing pressure to play its part in tackling climate change by reducing emissions. Technologies being explored to cut pollution include kites, batteries or using biofuels.
An ocean-going tanker is to be fitted with a type of “spinning sail” invented almost a century ago in a step that could lead to more environmentally friendly tankers worldwide.
The unusual sails are rotating columns fixed to the deck of the ship, whose interaction with the wind provides forward thrust.
The tall, spinning cylinders have been used on smaller craft in the past but this is the first time anyone has tried to put them on a vessel as large as a 245-metre tanker, said Tommy Thomassen, Maersk Tankers’ chief technical officer. “It’s quite ground breaking,” he said, adding that if the devices save as much fuel as expected — up to 10 per cent on average on a typical global route — Maersk Tankers could use them on its larger vessels.
Switch over to sails:
The vessel to be fitted with the sails will carry refined products, such as diesel, and will be smaller than a crude tanker. But it should still offer insights into whether sail power has a role in modern shipping.
Groups such as Maersk have eyed several ideas to cut marine fuel use over the years, from solar-powered sails to kites that tow a vessel. However, interest in such developments has grown as companies prepare for pollution rules coming into force in 2020 requiring them to use fuel with a much lower sulphur content that is expected to be more expensive than current fuel oils.
Modernised version:
The 30-metre cylinders will be a modernised version of the rotor developed nearly a century ago by Anton Flettner, the German engineer. They harness the wind by using the Magnus effect, the physical force that makes a tennis ball swerve when hit with topspin. A motor sets the cylinders spinning and when the wind blows, the airflow speeds up on one side of the sail and slows down on the opposite to create a pressure difference that generates lift, propelling the vessel through the water. The sails were first fitted on a ship in the 1920s but were too heavy to be effective, said Mr. Riski. Those he is building for Maersk are made of lightweight carbon-composite materials, typically costing between €1m and €2m to install.
Funded research:
The UK Energy Technologies Institute, a government-funded research group, is footing most of the £3.5m bill for the project in the belief that rotor sails are one of the few fuel-saving technologies to offer double-digit percentage improvements. Cutting fossil fuel use might not seem an attractive option for an oil company such as Royal Dutch Shell. However, its shipping and maritime business, which is co-ordinating the project, has 10 oil tankers and about 40 liquefied natural gas carriers. The rotor sails are due to be installed in the first half of 2018 and tested until the end of 2019.
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Reference: Financial Times, The Guardian
