In April 2018, cruise ferry M/S Viking Grace became the world’s first passenger ship equipped with a rotor sail, a vertical spinning cylinder that harnessed wind power to propel a ship.

As the commercial maritime industry is collectively pressed by international and regional regulation to cut emissions, Viking Line's Viking Grace -- which is already fueled by liquefied natural gas (LNG) -- is now using its rotor sail for wind-assisted voyages between Turku, Finland and Stockholm, Sweden.

Developed by Finnish engineering company Norsepower Oy Ltd. as a modernized version of the Flettner rotor, Viking Grace's 24-meters-tall rotor sail is fully automated and senses whenever the wind is strong enough to deliver fuel savings, at which point the rotor start automatically. The system will shut down in response to any disadvantageous changes in the direction or force of the wind.

The  rotor installed on board Viking Grace is expected to slash the vessel’s fuel consumption and reduce carbon emissions by up to 900 metric tons annually.