Rotor Sails: Putting a New Spin on Shipping?
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Feature 3 Rotor sails: putting a new spin on shipping? In early March, an interview study with shipowners, technology providers and the crew of a rotor ship was performed to investigate the impact of wind propulsion on operations and crew and uncover clues to unlocking the full potential of this technology. David Newman reports on the findings number of wind devices have Figure 1: Viking seen renewed interest in recent Grace was years due to their potential to retrofitted with a Afuture-proof vessels by considerably rotor sail in 2018 reducing fuel consumption, such as hard and soft sails, turbosails and kites. Rotor sails have been the most widespread solution so far, being now operational on seven vessels worldwide, with up to four rotors per vessel. From the small cargo coaster, Fehn Pollux, to large vessels such as the 110,000dwt LR tanker, Maersk Pelican and 64,000dwt geared bulk carrier MV Afros, the rotor sail is establishing a reputation as a proven technology, offering Rotor sails saw a brief and limited centred around the creation and sharing of reliable, simple, efficient and low-maintenance deployment at sea when first invented technical knowledge, a cyclical interaction wind propulsion tailored to specific vessel but were swiftly made obsolete by cheap was identified: (1) full-scale installations needs. As one interviewee put it: “they are not oil, seemingly dooming the device to the acquire funding, (2) creating valuable rocket science”. dustbin of failed maritime contraptions. operational experience and learning by Despite these advantages, the However, we live in fast-changing doing, (3) in-turn increasing the general promising technology is held back by a and challenging times and Anton’s awareness of rotor sails and raising policy landscape that continues to favour long-forgotten device has re-emerged shipowner expectations which, finally, traditional fossil fuel propulsion and revamped for the digital age, to alleviate (4) validates interest groups who lobby design choices which fail to recognise the both the environmental impact of for more funding, and so on. The cyclical human element in operation. international shipping and the financial innovation loop is shown in Figure 2. A master’s student project was recently woes of unpredictable oil prices. This cycle has been instrumental in the completed at the maritime consultancy SSPA With proven fuel savings ranging early uptake of the rotor sail but illustrates Sweden AB as part of the Interreg North between 300 and 920tonnes annually, the sector’s reliance on outside funding. Sea Europe’s project Wind-Assisted Ship rotor sails offer shipowners hundreds To date, every rotor sail installation Propulsion (WASP), investigating the state of of thousands of dollars in savings each has received government subsidy in the art in this sector’s innovation and to gain year and considerable reductions in some form, confining the technology insight into the human factors influencing carbon emissions and air pollutants. The in a pre-commercial snare. Rotor sail their operation and performance. technology is a potential co-solution for manufacturers struggle to offer affordable shipowners to meet coming regulations payback times, or returns of investment, to What are rotor sails? such as EEDI (and possibly EEXI) operators of large vessels. Attractive returns Developed in Germany by Anton Flettner energy efficiency requirements while on large vessels remain elusive because in 1922, rotor sails are electrically powered simultaneously lowering fuel spending. of the large overall fuel costs despite rotating columns which exploit renewable As stand-alone systems, rotor sails can be substantial absolute fuel savings. wind energy using the Magnus Effect to retrofitted easily onto existing vessels or Even hundreds of tonnes of fuel saved provide forward propulsion to a vessel. integrated into the design of new builds. per year may only translate to a few The same effect used by a tennis player percent of overall costs. For ro-pax, ro-ro who ‘slices’ or ‘curves’ the ball by spinning Achieving self- and tankers, the payback period has not it to change its trajectory can be applied sustaining innovation yet quite reached a ‘sweet spot’ of under to the sail which, when spinning, transfers Interviews with key shipowners and five years. Anything under this and the perpendicular wind force into forward rotor sail manufacturers revealed an short leases and high insurance fees on propulsion. The resulting auxiliary thrust innovation trend in this blossoming sector. vessels make rotor sail capex unviable for reduces main engine fuel consumption. By analysing key innovation indicators shipowners. One solution to drive down The Naval Architect November 2020 31 Feature 3 | ECO SHIP TECHNOLOGY payback times is to increase the fuel saving Figure 2: The performance of rotor sails. cyclical innovation loop Ramping up performance with human factors On a Monday morning, I arrived at Stockholm’s Stadsgårdskajen terminal to interview the crew of the M/S Viking Grace, which has entered into a small but fast-growing group of vessels that hail a promising new trend in international shipping: the return of wind power. Since 2018, the 57,000gt luxury RoPax ferry has operated a single Norsepower rotor sail on its route between the Swedish capital and Turku, Finland via the complex Åland Archipelago. While the engine crew reported very little change in their tasks and no complaints, improvements in communication between with the right collaboration between actors the navigators and Master provided special crew and technology providers is generally and operational improvements in human insight into rotor sail operation. an invaluable measure to improve the usage factors, they can fill a technological niche Many might assume that humans are of any automatic technology. between energy efficiency measures and designed out of rotor sail operation through These relatively simple measures are expensive zero-emissions fuels. Access to such automation, but this was found not to be low-hanging fruit and should be adopted a solution, especially in developing countries, true. Granted, all rotor sails do function before further complex technological small island states and remote areas, will be automatically. Onboard or onshore software solutions are implemented, such as route key to international shipping tackling the controls their speed and rotation direction optimisation. The stacking of ever more climate crisis on a truly global scale. to extract the maximum thrust available disjointed and fragmented systems atop It is hoped that this study will add to the from the existing wind conditions, based on one another risks harming usability and growing effort to facilitate the transition real-time data for wind speed and direction. can result in misuse. A successful Fourth of shipping towards a sustainable future But, decisions by the bridge crew about Industrial Revolution for shipping must rely in line with IMO strategy and Paris when to reduce main engine power are on automated and smart technologies being Agreement commitments. Analysis of entirely manual and can greatly impact fuel transparent and integrated and human factor rotor sail innovation trends showed that saving performance. issues should be addressed first, before ever the length of return-of-investment periods If this is left unacknowledged, bridge more complexity is introduced. prevents widespread uptake. One solution crews will be frustrated by not being able to drive down payback times is to increase to access fuel savings data or calculation Towards zero- fuel saving performance through the methodologies which could help improve emission shipping acknowledgement and understanding of their understanding of the system and their The IMO’s target of 50% GHG emissions human factors. By implementing in-depth navigational decisions. Giving the bridge reduction by 2050 will help ensure that a training for bridge crews, improving the user the best possible information for their catastrophic 2°C of warming is not reached. interface and generally maintaining strong decision making is key to ensuring that rotor Despite the benefits of rotor sails, they alone communication with crews, technology sails are used to their full potential while cannot reach this target or meet the power providers can maximise fuel savings to bring simultaneously reducing the burden of their demands of modern ocean-going vessels. rotor sails closer to commercialisation and already-demanding workload. To develop truly zero-carbon vessels, main widespread uptake. A myriad of quite simple solutions exist propulsion using hydrogen or sustainable which can help to achieve this. Shipowner e-fuels to power fuel cells must be coupled About the author investment in high-quality, in-depth with auxiliary thrust from wind systems David Newman is a graduate of the training ensures the crew’s understanding of and/or batteries. The European Parliament’s MESPOM master’s program, completing his sailing to save fuel. Supporting this, proper recent decision to include shipping in the thesis at Lund University in Environmental design of user interfaces can instruct crew Emission Trading Scheme is an important Science, Policy and Management, in on how much main engine power can be signal that environmental regulation collaboration with SSPA Sweden AB under reduced while maintaining speed. Such anticipated by shipowners will come into the WASP project. He now works for the initiatives increase bridge crew motivation, force. Carbon prices must now rise and Zero Emissions Ship Technology Association as do the introduction of financial or marine fuel tax exemptions scrapped. (ZESTAs) and is compiling a compendium competitive incentives for crews of vessels Rotor sails are already proven to cause of regulations, standards and policies for with low fuel consumption. Finally, immediate carbon emissions reductions and, zero-emission ship technologies. NA 32 The Naval Architect November 2020.