Rotor sail technology applied to VLCCs

The rotor sail has been applied successfully to a product tanker, and is now being scaled up for application to a VLCC

Lloyd’s Register (LR) has presented Hyundai Heavy Industries Co (HHI) with approval in principle (AiP) for a very large crude carrier (VLCC) ‘eco-tanker’ design, capable of using a combination of volatile organic compounds (VOC) mixed with LNG as fuel and Norsepower’s rotor sail solution for wind-assisted propulsion.

This was the result of a joint development project collaboration between HHI, LR and Norsepower*.

The VOC recovery system was developed by HHI and will allow the VLCC to use fuel produced from naturally occurring vapour from the cargo tank during operation.

The AiP has been verified for interface and control logic stability with other systems, resulting in reduced emissions and stably improved efficiency.

The impact of installing Norsepower’s rotor sail solution, such as structural reinforcement and visibility calculation, was reviewed using computational fluid dynamics during the project. It was confirmed that it has the potential to provide 5-7% fuel savings, dependent on operating routes.

LR facilitated a high-level hazard and operability (HAZOP) workshop for the LNG fuel-supply system and associated technology in accordance with LR’s ShipRight procedure for risk-based designs. The concept design has been examined in conjunction with the result of the HAZOP.

This AiP demonstrates the potential for reducing emissions in ship designs, by combining VOC recovery and LNG in a dual-fuel system with the addition of rotor sails, to help the shipping industry address the challenge of reducing greenhouse gas (GHG) emissions by 2050.

HHI vice president in the initial design office Hong-Ryeul Ryu said: “We have focused on developing clean and smart ships that are technically reliable and commercially feasible. We are doing our best to design advanced ships that will benefit shipowners and lead to eco-friendly shipping. We believe that these efforts will bring us a step closer to the future.”

Norsepower’s Jukka Kuuskoski said: “We are excited to be collaborating with HHI and Lloyd’s Register on this project. We are optimistic that support from these industry-leading organisations will open up the market for our rotor sail technology to a larger number of VLCCs – propelling towards a modern era of auxiliary wind propulsion for the global maritime industry, while supporting shipping’s transition to decarbonisation and achieving greater ship fuel efficiencies. Wind is one of the most freely available energy sources, making wind-assisted propulsion viable in supporting the shipping industry to reduce its fuel consumption and meet impending carbon-reduction targets.”

LR marine and offshore director Nick Brown, presenting the AiP certificate, commented: “Lloyd’s Register is proud to award this AiP to HHI, with collaboration from Norsepower. LR has a unique expertise in the LNG field and alternative fuels, which is widely recognised by the market. This LNG-fuelled VLCC is a clear step towards meeting IMO’s 2050 GHG goal.”

The Norsepower rotor sails were first tested on a tanker by Maersk. The rotor sails were installed on board the product tanker Maersk Pelican, and it is expected that the rotors will produce a 7–10% reduction in fuel costs and associated emissions on typical shipping routes. When wind conditions are favourable the main engines can be throttled back, saving fuel and reducing emissions, while maintaining speed and voyage time.

As well as the physical structure, Norsepower has updated the control mechanism to include automatic software-driven functions. The rotor sails require a small amount of energy to spin, but the payoff is the additional forward energy. The speed of the spin and the direction of the rotor sails is controlled by a variable-speed electric motor requiring 15 to 35 kW, depending on the size of the rotor. The whole operation is fully automatic and requires no input from the crew.

*The Finnish company was only founded in 2012. In 2019 it concluded its equity financing round, raising €3.6M (US$4.1M) in funding to drive the company’s expansion and growth plans.

The equity financing round was conducted in partnership with Korkia, a leading investment firm in Finland that partners with disruptive technology growth companies.

While the financing round saw Norsepower’s existing investors subscribe to shares, new investors formed the majority – signalling the growing interest in rotor sail technology.