Winds of change: Reinventing sails for the modern age

At Isahaya Shrine in Japan, dozens of pinwheels spin in the wind as a beautiful reminder of the power of this elemental force and the divine spirit it embodies. Scientifically, wind is created by the sun heating the Earth unevenly, causing the air to move around the world as everything from a light breeze to a stormy tempest. For millennia, humans have harnessed wind energy, building sailing ships to cross the oceans and windmills to grind grains. The emergence of fossil fuel powered engines superseded wind power, but now wind is making a resurgence.

In recent decades, we have begun to harness the wind’s energy to power our lives. Megastructures like these wind turbines at Hachiryu Wind Farm in Mitane, Japan have become a familiar sight as the world shifts towards cleaner renewable energies. The wind drives three scientifically engineered blades, each as much as 200 feet (60 meters) long. These turn a drive shaft through a series of gears so that it spins fast enough for a generator to convert the kinetic energy into electricity. It’s an evolution of the windmill for modern times, and now technology is transforming sail power for shipping.

Having taken in the immense size of the MOL cargo ship Shofu Maru, what attracts attention is the immense structure on its foredeck. At first glance it may appear an unconventional addition to an otherwise streamlined vessel, but every inch of this structure is scientifically engineered to improve fuel efficiency by harnessing the wind. Ships like the Shofu Maru carry cargo around the world, with 14.3 billion tons of goods transported by sea every year. And for many essential resources, such as grain and iron ore, their sheer volume makes shipping the only viable option. The challenge is to do this cleanly.

The Shofu Maru is a ship around 100,000 tons in size; responsibility for its safe and efficient running lie squarely with its captain. Supported by advanced technology, the captain must constantly factor in numerous shifting variables such as cargo and crew, weather and sea conditions, and engine and fuel status. In planning and executing every voyage, safety is paramount, but shipping schedules and operating costs remain a crucial factor, making maximizing fuel efficiency a constant concern.

Since the 1800s, the maritime world has shifted from sail power to steam power—and even nuclear power. And over the generations, ships’ engines have evolved from relatively simple coal-powered boilers to huge and immensely complex engines driven by diesel, like this one aboard the Shofu Maru. Standing an impressive 35 feet high and 25 feet wide, the engine is capable of producing more than 12,000 horsepower, providing the Shofu Maru with the reliable propulsion needed for its long ocean voyages.

Engines like these are painstakingly designed and built to be powerful and efficient, capable of driving ever larger ships ever more quickly across the seas. Modern bulk carriers like the Shofu Maru can sail from Japan to Australia in under a month—a fraction of the time taken by even the fastest sailing ships, while carrying many times the cargo. But this comes at a cost: Despite all its efficiencies, the global shipping industry burns more than 220 million tons of oil each year.

The vast structure on the foredeck of the Shofu Maru is helping to shrink the carbon footprint of cargo ships: The Wind Challenger is a sail for the modern age. Since 2009, MOL has been exploring the potential of wind power as a clean, unlimited source of propulsion. In 2022, the Shofu Maru became the world’s first Wind Challenger ship, and over the past three years its sail cut its fuel consumption by as much as 17 percent per day—averaging around 5 to 8 percent fuel savings. It’s a significant reduction of the ship’s carbon footprint, made possible by applying modern technology to wind power.

In the Koyagi shipyard of Oshima Shipbuilding, a Wind Challenger sail is under construction. The Wind Challenger system attaches multiple sails to a telescopic mast that is deployed through a fully automated system. Each sail is more than 7,000 square feet in size but, by using a lightweight composite of glass fiber reinforced plastic, it doesn’t upset the balance of the vessel or reduce its cargo capacity—both essential factors in its success. With precision engineering paramount across the project, fine tuning the shape of the sail’s cross section enables Wind Challenger to catch even more wind, even more effectively.

Assembly of the Wind Challenger is a meticulous process with each component precisely designed, manufactured, and fitted using the latest technologies. And technology is key to its operational success, helping Wind Challenger maximize the available wind. At sea, the sails are automatically deployed, being raised and rotated according to the weather conditions, including the wind speed and direction as analyzed by shipboard sensors. Wind Challenger also incorporates a high-tech weather routing system that optimizes the ship’s course to make the most of the winds and currents, further reducing fuel consumption.

Once assembled, the Wind Challenger system is installed and tested using specialist equipment. A key benefit of Wind Challenger is that it can be retrofitted to existing ships, making it a truly scalable option for reducing the carbon footprint of the global shipping industry. Already, two ships in the MOL fleet have had Wind Challenger installed and a further nine installations have been confirmed. MOL’s plan is to roll out Wind Challenger on 25 vessels by 2030 and on 80 vessels by 2035—a significant step towards the company’s goal of zero emissions by 2050.

It’s also a technology that continues to evolve. Building on the Shofu Maru’s success, in 2026 MOL is set to launch a carrier fitted with two sails and is progressing its designs for a carrier concept that incorporates four sails—all further decreasing the carbon footprint of the vessels. It’s a technology that is set to make a difference. While Wind Challenger isn’t yet a complete solution, the fuel savings it brings are an important step towards a more fuel-efficient future for the logistics that drive our lives.

Find more megastructure innovations here.