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Horizons article 14 December 2023

Rotor sails taking off

  • Maritime energy transition
  • Wind Assisted Propulsion
Issue 67

Dry bulk charterers, cargo owners and leading ship operators are amongst those driving demand for wind sail propulsion systems developed by Anemoi Marine Technologies Ltd, a rotor sail technology designer and supplier with strong Greek roots.

Brazil-based mining giant Vale, global trading house Cargill, and Berge Bulk are among the leading names which are already supporting Anemoi rotor sail installations supplied by the UK-based company, a spin-off from Greece’s dry bulk owner, Blue Planet Shipping Ltd. Anemoi Chief Executive, Kim Diederichsen, claims that WASP technology – Wind Assisted Ship Propulsion – has now come of age and is likely to be widely adopted as retrofits for existing ships and a standard feature of ship designs in the future.

Anemoi Rotor Sails, known generically as Flettner Rotors, are vertical cylinders which spin and generate thrust through the Magnus effect. Anemoi sails have a lift coefficient of around 12, significantly more than other WASP technologies, and have already been installed on several vessels including Kamsarmax and Ultramax vessels.

Broad appeal

The agreement between Brazilian mining giant, Vale, and Anemoi covers the installation of five 35m by 5m folding rotor sails on board the 400,000dwt ore carrier, Sohar Max, owned by Asyad Shipping of Oman and engaged on a long-term charter to Vale. Installation of the sails is likely to be completed in the second quarter of 2024.   

Singapore-based Berge Bulk is testing different wind-assist technologies in its drive to decarbonise and is installing Anemoi sails on two of its vessels. The 2012-built 388,000dwt Valemax, Berge Neblina, made ‘wind-ready’ during a recent survey, is to have four folding rotor sails installed in the first quarter of 2024 and a second Berge Bulk vessel will be installed in 2025.

In June 2023, Anemoi sails were installed on the 82,048dwt TR Lady, a 2017-built Kamsarmax bulk carrier owned by a company controlled by Tufton Investment Management Ltd and time-chartered to Cargill. Three 24m by 5m sails were fitted at Chengxi Shipyard in China. Installed on Anemoi’s patented transverse rail deployment system and class-approved by LR, the sails can be moved from the centreline to port or starboard during cargo operations.

Anemoi rotor sail being installed on TR Lady

Key alliances

Late in 2022, Anemoi executives sealed an agreement with Cosco Shipping Heavy Industry Co (CHI) to offer Anemoi Rotor Sails to customers at its nine shipyards. CHI has up to 7.5 million dwt of building capacity and the agreement enables CHI customers to have Rotor Sail options on new ships or to retrofit them to existing vessels during dockings. CHI and Anemoi can offer a turnkey package to customers.

But the market is far broader than shipowners and operators. Diederichsen identifies a change in charterers╩╝ behaviour. There are, for example, new clauses in some charterpartys, stipulating a requirement for WASP  technology and offering a premium for suitably equipped vessels.    

He explains that although the company’s sails have been retrofitted so far exclusively to dry bulk carriers, they are also suitable for other ship types including tankers, vehicle carriers, and gas carriers. The company recently signed a Joint Development ProjectAgreement with Hudong-Zhonghua Shipbuilding Group for the design of rotor sails to be installed aboard two LNG newbuildings. The deal, signed at the end of October, could pave the way for widescale sail installations in the booming LNG sector.

Stricter regulations

For the moment, however, about 80-85% of the company’s orderbook, he says, relates to bulk carriers and contracts are dominated by retrofits, a market that he believes will last for at least ten years. He points out that IMO regulations affect all ship types and have far-reaching commercial implications. Many owners are intent on exploring ways of improving their ships’ carbon intensity ratings.

“Owners are constantly looking at ways to make sure their ships stay at least in the C band,” Diederichsen says, referring to the IMO’s carbon intensity indicator (CII) requirements which are set to become steadily stricter over the second half of the decade. And although the company’s Fuel Saving Assessment Model can be used to provide a guide for owners on likely payback periods given certain fuel price scenarios, payback is not the main metric underpinning the drive for WASP technologies.

Aiming higher

“Owners need to do something, not only for their own future benefit, but also to demonstrate proactive strategies to their shareholders, charterers, and financiers. Our systems can provide net fuel savings of 10-20% depending on ship type and route. That’s the driver for existing ships,” he declares.    

Diederichsen reveals that the privately owned company is currently engaged in a capital-raising exercise.  This, he explains, is to fund the expansion of Anemoi including more ‘hands’ and additional production facilities, in line with growing uptake of the technology.

At present, around 50 sails can be produced each year but, with interest in WASP technologies accelerating to an average of about one new enquiry every day, more production capacity is urgently required. So the company has adopted a rapid scaling-up strategy to reach an annual manufacturing target of 200 sails by the end of 2025 rising to 250 thereafter.

RNMB Hydra

Pioneering goal-based assurance for uncrewed assets