How wind tech hopes to help decarbonize cargo shipping

Though hyperlocal, Kelen’s work is part of a global project from the International Maritime Organization to reduce emissions associated with cargo shipping to net zero by 2050. Beyond these tiny islands, much of the effort to meet the IMO’s goals focuses on replacing gasoline with alternatives such as ammonia, methane, nuclear power, and hydrogen. And there’s also what the Marshallese people have long relied on: wind power. It’s just one option on the table, but the industry cannot decarbonize quickly enough to meet the IMO’s goals without a role for wind propulsion, says Christiaan De Beukelaer, a political anthropologist and author of Trade Winds: A Voyage to a Sustainable Future for Shipping. “If you take time into consideration, wind is indispensable,” he says. Studies show that deploying wind power on vessels could lower the shipping industry’s carbon dioxide emissions by 20%.     

“What wind does is it effectively cuts out a few uncertainties,” says De Beukelaer—variables such as the fluctuation of fuel prices and the costs from any carbon pricing scheme the industry may adopt. The IMO is technology agnostic, meaning it sets the goals and safety standards but lets the market find the best ways to attain them. A spokesperson from the organization says wind propulsion is one of many avenues being explored.      

Sails can be used either to fully power a vessel or to supplement the motors as a way of reducing fuel consumption for large bulk carriers, oil tankers, and the roll-on/roll-off vessels used to transport airplanes and cars worldwide. Modern cargo sails come in several shapes, sizes, and styles, including wings, rotors, suction sails, and kites.

“If we’ve got five and a half thousand years of experience, isn’t this just a no-brainer?” says Gavin Allwright, secretary-general of the International Windship Association.

Older cargo boats with new sails can use propulsive energy from the wind for up to 30% of their power, while cargo vessels designed specifically for wind could rely on it for up to 80% of their needs, says Allwright, who is still working on standardized measurement criteria to figure out which combination of ship and sail model is most efficient.

“There are so many variables involved,” he says—from the size of the ship to the captain steering it. The 50th large vessel fitted with wind-harnessing tech set sail in October 2024, and he predicts that maritime wind power is set to boom by the beginning of 2026. 

COURTESY OF OCEANBIRD

Hard wings

One of the more popular designs for cargo ships is a rigid sail—a hard, winglike structure that is placed vertically on top of the vessel. 

“It’s very much like an airplane wing,” says Niclas Dahl, managing director of Oceanbird, a Swedish company that develops these sails. Each one has a main and a flap, which creates a chamber where the wind speed is faster on the outside than the inside. In an aircraft, that discrepancy generates lift force, but in this case, says Dahl, it propels the ship forward. The wings are rigid, but they can be swiveled around and adjusted to capture the wind depending on where it’s coming from, and they can be folded and retracted close to the deck of the ship when it is nearing a dock.