The tens of thousands of cargo ships that travel the world’s oceans—carrying everything from jeans and smartphones to cars and bananas—collectively emit more CO2 than most countries. A new ship called the Oceanbird, in development now, is designed to help: With huge, wing-like sails, it runs on wind power, but will be able to cross the Atlantic in less than two weeks, only a few days longer than a ship running on fossil fuels.
For the shipping industry, which is racing to figure out how to cut emissions in line with the goals of the Paris climate agreement, the design has advantages compared to other potential solutions. Unlike cars, ships can’t easily shift to electric power, since the massive size of a cargo ship means that it would need to be filled with batteries to run, leaving little room for cargo. Ships can run on liquified natural gas, but that would only partially reduce emissions. Ammonia fuel doesn’t pollute as it burns but is polluting to produce. Wind energy can avoid all those challenges.
“Wind is there—we don’t need to produce anything,” says Ulysse Dhomé, a researcher at Sweden’s KTH Royal Institute of Technology and part of a team collaborating with the shipbuilding company Wallenius Marine and the Swedish research institute SSPA on the project. “With most alternative fuels, you need to either produce the fuel or transform the energy, whereas the wind is just there, and there’s a lot of it.”
The design uses 260-foot-tall rigs made of steel and composite—more like airplane wings than traditional cloth sails—that can rise up and turn to optimally catch the wind. The huge size of the ship, at more than 650 feet long, meant that the sails also had to be large so that it could keep moving even in light winds. The hull of the ship is also different than a typical cargo ship and may use fins, like a smaller sailboat, to compensate for the sideways movement from the sails. When it comes into a harbor, the ship will revert to fuel. But the overall design can reduce emissions by 90%.
It’s technically challenging to design, since the approach is new. “No one has ever really studied from an aerodynamic point of view how this actually works,” Dhomé says. It will also have to operate differently than any traditional sailboat. “We can’t have sailors on the ship constantly be looking at the wings and trimming them, like we would do on a normal sailboat,” he says. “So we have to find ways to have the right sensors that enable algorithms that do the control. Again, that’s not something that has been done before.”
After several years of development, the team has constructed a small model of the ship and will begin testing it in the open water in the coming weeks. By 2021, Wallenius Marine will begin taking orders; by late 2024, it expects to begin selling the vessels. The first ship design is a “ro-ro,” short for “roll-on, roll-off,” made to carry wheeled cargo like cars. But the basic approach could be adapted to other types of ships as well, Dhomé says, including container ships, though it would require some changes to how shipping containers are typically handled. As shipping companies face increasing pressure to cut emissions, more of the industry could begin to move in this direction. “I think more and more companies are actually going this way,” he says. “Once we prove that it’s feasible, I think that we will manage to convince other shipping companies to make this change as well.”