This hybrid arrangement has been shown to curb the fuel consumption of individual ships by around 20 to 30 percent. But results can vary widely depending on the type of ship and the routes and conditions of a particular voyage. That’s why, when spread across an entire fleet, the energy savings can be closer to 5 to 10 percent, said Tristan Smith, a professor of energy and transport at the UCL Energy Institute, who co-authored the recent emissions report.
Still, even those smaller figures represent “a massive potential and contribution to overall targets and objectives” for slashing shipping emissions, Smith said by email.
Sailing ships are scaling up
Meanwhile, more than 20 smaller, more traditional sailing ships are busy hauling batches of cargo by river and sea, including the two owned by Grain de Sail.
The company launched its flagship vessel in 2021, a newly built schooner with an aluminum hull and seven sails. The ship brought strapped-down pallets of organic wine in its foam-insulated hold to a private marina in Brooklyn, New York. From there, the crew carried donated medical supplies down to the Dominican Republic, then loaded up with coffee beans and cacao before sailing home to Saint-Malo.
Today that ship sails on shorter routes within Europe, having been replaced by the larger Grain de Sail II, which has embarked on four trans-Atlantic journeys since its maiden voyage in March. Now the company is developing its third and largest vessel yet — one that will stretch twice as long and hold two times the cargo as the one that just docked in New Jersey. In another change, the 40-million-euro ship will use three Solid Sails, which can automatically hoist, lower, and rotate to more effectively harness the wind and speed up voyages.
Gallard, the chief marketing officer, said the company aims to generate no more than 2 grams of CO2 per metric ton per kilometer of transportation. (The vessels use small diesel engines when navigating in harbors and ports.) By contrast, conventional diesel ships can emit between 10 to 20 grams of CO2, he said.
Those carbon savings come at a significant financial price. Shipping boxes of, say, French cosmetics or leather wares with Grain de Sail can be anywhere from two to five times more expensive than hauling goods on a conventional cargo ship, mainly due to unfavorable economies of scale. The largest ships can hold over 24,000 containers of cargo; Grain de Sail III will hold close to 200 containers if completed as planned in 2027.
For now, the company’s high-end clients are willing to foot the higher bill in the hopes of jumpstarting a wider shift toward cleaner shipping, Gallard said. And the per-ton price of shipping goods with wind power is expected to decline over time as high-tech sail technologies become more mainstream and mass produced, and as firms like Grain de Sail expand their fleets to operate more frequently.
“We hope that makes it more accessible … and allows us to get some more diversity in our client base,” he added.
In the meantime, Grain de Sail II is already making its way back to France. After unloading the cargo in New Jersey on December 1, the crew spent much of the last week bobbing off the waters of New York City, after a paperwork snafu kept them from docking at a private pier in lower Manhattan. The vessel, which is sailing home empty this time, expects to return to New York and New Jersey in early February with a cargo hold full of more coffee, wine, and chocolate.