Cargo Ships Return To Wind Power, Again

Wind power is attracting more heavy hitters in the global shipping industry, including Sea-Cargo and Sumitomo.

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Leading players in the global shipping industry are under enormous pressure to decarbonize, and the quest for solutions has been leading them into some strange areas. The millennia-old technology of wind power is in the mix, but it's not what you think. Instead of canvas sails flapping in the breeze, the cargo-carrying sailing ship of the future is, well, different.

The ocean-going wind power firm Norsepower launched its different-looking Rotor Sails back in 2014, and now it looks like all that hard work is about to pay off.

At first glance, Rotor Sails look nothing like sails. They look that way at second glance, too. No canvas, no ropes, no nothing. Instead, they look like extra-tall smokestacks. Unlike ordinary smokestacks, though, these sails can tilt to navigate under bridges.

By 2019 Norsepower was on a roll, having hooked up with Finland's Wärtsilä to nudge commercial seagoing operations in the direction of wind power.

The idea gained another shot of adrenaline in 2021, when the shipping giant Vale decided to give wind power a whirl on a Very Large Ore Carrier. It was only one ship, but it set of a firestorm of attention in the maritime press (see our complete coverage here).

Rotor Sails deploy a decades-old invention called Flettner rotors, which deploy an effect observed by Isaac Newton in the 17th century while watching tennis games at Cambridge. He observed that the ball can carve a curved path when spinning, a phenomenon he attributed to air resistance. The tricky part is explaining why that happens.

As pointed out by researcher James MacDonald, the roots of the Magnus effect are more commonly attributed to the 18th century British mathematician Benjamin Robins, who took a somewhat more dramatic tack.

"Robins wanted to know why musket and cannon balls tended to drift from their targets, and predicted that air resistance was responsible," MacDonald explained.

To demonstrate the effect, Robins would shoot a bent musket, from which balls would fly in the opposite direction of the bend, to the amazement of onlookers.

The 19th-century German physicist Heinrich Gustav Magnus developed some additional insights into the air resistance phenomenon, having recognized the relation to fluid dynamics, and that's where the name stuck.

For that matter, the invention of the underlying technology for Flettner rotor sails is attributed to a Finnish engineer named Sigurd Savonius, who figured out how to deploy the Magnus effect in a spinning tube. The Flettner name came about after the German aviation engineer Anton Flettner took a ship with rotor sails across the Atlantic Ocean in 1926.

The big question is whether or not Flettner sails make any difference in the fuel consumption of a modern cargo ship.

The answer is that fuel savings is not the only benefit, as experienced by Captain Artur Sylwestrzak of the global shipping firm Sea-Cargo. Sea-Cargo adopted Norsepower's wind power-in-a-tube solution in 2021 and claimed the title of "Norway's largest sailing vessel" for its SC Connector cargo ship, helmed by Captain Sylwstrzak. The retrofit provided an opportunity for him to observe how the same ship behaved before and after wind power.

"The rotor sails have improved the ship's seakeeping behaviour very much — it is a completely different vessel now!" Captain Sylwestrzak told Hellenic Shipping News last month. "The centre of gravity has been raised by one and a half metres, and the rotor sails dampen the roll motion so the ship hardly rolls at all, which the crew are very happy about."

In the context of a labor shortage for the maritime industry, Sylwestrzak also offered some additional insights into the benefits of re-introducing wind power to cargo ships.

"It is a huge benefit when the crew have an interest in this technology and are motivated to learn," he said. "I always try to create an environment that will motivate new people and make them curious. I invite them to get involved, saying ‘let's play with the system and see what we can learn in the process. This approach is much more enjoyable to newcomers."

The whole-of-ship experience on SC Connector has provided Norsepower with key insights into the seaworthiness of its Rotor Sails. The next step is to prove that the technology is investor-worthy on a broad scale. For that, Norsepower joined up with the maritime software and data services firm NAPA and the leading ship builder Sumitomo Heavy Industries Marine & Engineering Co., Ltd. (SHI-ME) for a fuel-saving simulation exercise, which took place from December 2022 to March 2023.

The exercise deployed NAPA's fuel-saving Voyage Optimization software, which incorporates weather conditions into route planning to maximize fuel consumption. In a simulated crossing between New York and Amsterdam, the combo of wind power and route planning reduced emissions by an average of 28%.

"Of these average CO2 emissions savings, the contribution of NAPA Voyage Optimization can be estimated at 12%," NAPA explained.

The simulation involved six different routes in all, with the Rotor Sails plus Voyage Optimization yielding an average cut in carbon emissions of 19%.

That's just for starters. To date, the Norsepower Rotor Sails have only been installed on existing ships originally built to run exclusively on liquid fuel. Incorporating wind power into ship-building from the beginning, at the design phase, could yield even more impressive results. SHI-ME is already aiming at that target.

"The project is part of SHI-ME's plan to develop a new proof of concept for wind-assisted ships, which will be equipped with Norsepower Rotor Sails," NAPA explains. "The project and its findings will help strengthen the business case for investing in wind-assist technology at a time when the industry is under increasing pressure to decarbonize."

NAPA also cites Norsepower CSO Jukka Kuuskoski, who noted that the months-long data collection exercise provides solid ground for investors.

"…this performance data on the benefits of adopting clean technologies will give the industry the necessary confidence to invest in decarbonization," Kuuskoski said.

That could be just the tip of the decarbonization iceberg. Keep an eye out for Rotor Sails popping up in various configurations with other decarbonization options, including other hard sail configurations, solar power, and alternative fuels for new opportunities to make bank in a low carbon economy.

Find me on Spoutible: @TinaMCasey or LinkedIn @TinaMCasey or Mastodon @Casey or Post: @tinamcasey

Photo (cropped): Wind power returns to cargo ships, courtesy of Sea-Cargo via Norsepower.

Tina specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Views expressed are her own. Follow her on Twitter @TinaMCasey and Spoutible.

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