When I first started working at the editorial department of Schiff&Hafen and Ship&Offshore, the delivery of the LoRo vessel E-Ship 1 was a big topic. The vessel, ordered in 2006 by wind turbine manufacturer Enercon at the Lindenau shipyard in Kiel, was completed in 2010 at the Cassens shipyard in Emden. It is not the first ship incorporating Flettner rotors for extra power, but it brought the concept into the new century.
The idea of harnessing the Magnus effect for shipping goes back to the year 1924, when Anton Flettner had the three-masted schooner, Buckau, converted into a rotor ship with “roller sails” at the Germania shipyard in Kiel.
The experiment was technically successful but the results indicated that these rotors were not suitable as a principal source of power, especially for larger ships. However, the Flettner rotor has remained a household name in the industry.
Almost one hundred years later, no form of wind propulsion has yet been able to establish itself in commercial shipping, for a variety of reasons. However, interestingly, the past few months have seen various promising concepts and approaches for windassisted propulsion systems all over the world. Big names, such as Wallenius Wilhelmsen and Oldendorff Carriers, are now assessing wind power as a supplementary source of energy for their vessels.
The French start-up Neoline is even planning two pilot vessels that rely on wind as a main power source. The first one is scheduled to start on a transatlantic line in 2023. With other projects on the horizon and the pressing need to work towards the industry’s climate goals, there is also rising acceptance from customers to transport their cargo on vessels with this alternative power supply. The Michelin Group, for example, recently signed a transport commitment with Neoline, to transport at least 50% of the group’s containers on the shipping company’s transatlantic line by 2024.
So does wind have the potential to serve as a main source of propulsion for shipping after all? Probably not.
Among many others, two different shipping companies, Maersk and Viking Line, are currently working on low-emission and zeroemission ship types, respectively, and have not incorporated any wind power technology. Both have experience with rotor sails.
In 2018, Maersk Tankers installed a Norsepower Rotor Sail on board the products tanker Maersk Pelican and recorded a reduction of more than 8% in fuel consumption and related emissions over a twelve-month period of analysis. Now, the group’s container line has announced plans for a carbon-neutral liner vessel using methanol as fuel by 2023. However, the company is not considering wind-assisted propulsion systems for this vessel.
Viking Line’s RoPax ferry Viking Grace was retrofitted with a rotor sail in 2018. The operator had expected great savings in fuel and emissions, which apparently have not been met. The newbuilding Viking Glory, which is currently being finalised at China’s Xiamen Shipbuilding Industry Co Ltd, will not receive the rotor sails yet, contrary to what was initially planned. Despite the decision not to use this additional propulsion for the Viking Glory, the shipping company nonetheless expects a 10% improvement in efficiency from its new larger flagship compared with the first vessel. So far, this is the only RoPax ship in service with LNG/wind propulsion.
So, what are the main shortcomings of wind power? Is the installation or retrofit of these rotors too costly for the comparatively small emission saving effect? Experts also point out that payback times are uncertain and depend on a variety of factors including the operating profile of a ship and the availability of wind.
Alternative (e-) fuels such as methanol and ammonia seem more promising and feasible in many respects on the road to decarbonised shipping. The necessary technologies are available and flexible enough to burn LNG today and methanol tomorrow. On major routes, therefore, a significant uptake of wind and sail propulsion in the near future is not likely; for niche markets and special routes, however, there is still potential.