It is called Oceanbird and it is the world's largest wind-powered cargo ship. It was designed by Swedish shipbuilder Wallenius Marine with the support of the Swedish government and the Royal Institute of Technology in Stockholm, along with other research institutes. Still in the design phase, Oceanbird is 198 metres long and its majestic hull is topped by five telescopic "wing sails" that will be made from steel and composite materials, each 80 metres tall and capable of reducing their height in poor weather conditions and rotating 360 degrees.

The good news? Powered primarily by wind, Oceanbird will be able to cut CO2 emissions by 90 per cent compared to a conventional cargo ship. "Solutions like these could help Sweden say goodbye to fossil fuels by 2045," explained finance minister Per Bolund during a recent visit to the shipyard.

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Swedish minister Per @Bolund think that wind powered ships will help Sweden to become fossil-free by 2045, after testing an Oceanbird model at @KTHuniversity
walleniusmarine.com/blog/sustainab…

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The bad news? With a projected top speed of around 10 knots (compared to a current average of 17), Oceanbird risks being much slower — and therefore less economically competitive — than motor vessels, meaning that an Atlantic crossing could take around 12 days rather than the current 7.

Sails like steel wings, the tallest ever built

The sails need to be so imposingly large to allow Oceanbird to move using the force of the wind alone, and for this to happen the sail area must be able to generate enough propulsive power to move a displacement of 35,000 tonnes. Designing these sails was a genuine challenge, and although "the general principles of solid wing sails are not new," Mikael Razola, naval architect and head of the Oceanbird project, told CNN, "these are the tallest sails that have ever been built."

"The top of the mast will be more than 100 metres above the water's surface," Razola explained, noting that at that height the direction and speed of the wind change considerably, which is why many preliminary studies were needed before arriving at the final design — ultimately resulting in the choice of wing-shaped metal sails, "capable," according to the naval architect, "of harnessing the power of the wind to the fullest." Oceanbird currently exists as a scale prototype, 7 metres long, on which the designers are carrying out calculations on performance and aerodynamics under realistic sailing conditions. In practice, this ship will be able to move almost entirely on wind power, using its engines only for manoeuvring in ports or in emergencies. According to the shipbuilder, Oceanbird could enter service as early as 2024.

The United Nations to shipbuilders: cut emissions by 50 per cent by 2050

Oceanbird is a ship designed to transport cars — it can carry up to 7,000 — a category of maritime transport that has attracted considerable attention for its significant environmental impact. Known as RoRo — Roll on, Roll off — these are ferry vessels designed and built to carry wheeled vehicles, and are therefore used by car manufacturers to ship their new models around the world; manufacturers who could see their environmental impact greatly reduced if they adopted ships like these.

To understand where the problem lies today, it is enough to consider that current ferry vessels use an average of 40 tonnes of fuel per day, generating emissions of 120 tonnes of CO2, equivalent to 400,000 kilometres travelled by a car. This is why the shipping industry has been under pressure for years to try to reduce its impact. According to the International Maritime Organization (Imo), the United Nations regulatory body, this type of transport accounted for 2.89 per cent of global greenhouse gas emissions produced by humans in 2018, the same year in which the organisation introduced the requirement for the shipping industry to cut emissions by 50 per cent by 2050, with the aim of reaching zero emissions "as soon as possible this century."