Sail cargo may once again take to the seas, with ships trying to reduce their fuel consumption with wind power.

It’s estimated that maritime shipping is responsible for about 2.1% of global carbon dioxide emissions. The fuel that ships use is especially dirty, mostly what’s left over when other fuel is refined. A cargo ship burns between 2 and 4 million gallons of fuel oil in a journey from China to US ports.

In an effort to cut back on fuel costs, and incidentally emissions, the shipping firm Cargill is trial-running sail assist. The Pyxis Ocean, a ship chartered by Cargill, has been fitted with two immense rigid sails. Called WindWings, each one stands taller than a ten-story building. They’re made of the same material as wind turbines. The technology was developed for the America’s Cup team, racing sailboats. The hope is that sail cargo will reduce fuel use by as much as 30% over the course of an ocean-crossing.

Jan Dieleman, president of Cargill Ocean Transportation, said the industry was on a “journey to decarbonise”. He admitted there was “no silver bullet” – but said this technology demonstrated how fast things were changing.

“Five, six years ago, if you would ask people in shipping about decarbonisng, they would say ‘well, it’s going to be very difficult, I don’t see this happening any time soon’,” he told the BBC.

“Five years later, I think the narrative has changed completely and everybody is really convinced that they need to do their part – everybody is just struggling a little on how we’re going to do this.

“That’s why we’ve taken the role as one of the larger players to underwrite some of the risk, and try things, and take the industry forward.”

Cargill is the largest privately held company in the U.S, almost 140 years old. They ship approximately 225 million tons of commodities, mostly agricultural products, every year.