Maersk is testing a giant spinning cylinder to cut fuel use on cargo ships

On a cargo ship packed with 8,700 shipping containers, there isn’t much room for anything else. But in a new test aboard one of its vessels, Maersk is making an exception for a giant rotor sail—a spinning cylinder 10 to 12 stories tall that harnesses wind to help reduce fuel use. The test comes as shipping fuel costs continue to soar. In some areas, the price has risen as much as 76% since the Iran war started. The tech, made by a U.K.-based company called Anemoi, is one way to help blunt future price spikes while also cutting carbon emissions for one of the world’s most polluting industries. It’s also an example of how the industry is increasingly making use of wind power. [Photo: Anemoi/Maersk] The 115-foot-tall rotor sail works much like an aircraft wing, which generates lift as air moves faster over the top of a wing than underneath. “Our rotor sails work on the same basic principle of creating a pressure difference, but instead of a wing, we use a tall spinning cylinder,” says Anemoi CEO Clare Urmston. “As the cylinder spins, it speeds the airflow on one side and slows it down on the other. This creates low pressure on one side and high pressure on the other, producing the fo…