The Naval Architect: June 2018
Within the last decade, wind propulsion technologies intended for maritime applications have undergone a period of development and testing that has culminated in a handful of installations on board commercial vessels. Whilst most innovations in shipping follow this path, such progress is unexpected in the case of wind propulsion given the long- standing (and somewhat ironic) tendency to see modern maritime wind propulsion technologies as futurist imaginings: interesting to engineers but with little practical or economic benefit.
Wind’s change in fortune has been spurred primarily by the growing pressure on the shipping industry to reduce emissions, which has become a regulatory issue following the IMO’s agreement of its initial GHG strategy, requiring a 50% reduction of CO2 emissions (compared to 2008 levels) by 2050. As interest in hybrid solutions to meet the emissions challenge has grown, wind has continued to gain legitimacy, particularly as a primary renewable that is free at the point of use, faces no bunkering issues, and does not need to be ‘generated’ as electricity, hydrogen, and biogas do.
The shape of wind propulsion
The most visible symbol in recent years of wind’s tentative return to commercial shipping is the towering Flettner rotors (also known as rotor sails) that have appeared on a number of newbuild vessels and as retrofits. The technology was first deployed in 1924 on German engineer Anton Flettner’s schooner Buckau, but was never developed. However, Flettner rotors have been re-evaluated, aided by CAD design tools and advanced CFD software that allows for a high level of optimisation.
The rotors take the shape of a large cylinder, which is spun using an electric motor in order to capitalise on the Magnus effect, whereby the air passing faster around one side of the spinning rotor produces a force perpendicular to the direction of the airstream, resulting in propulsion. When installed as an auxiliary power source on vessels propelled primarily by fuel, the propulsive effect of the rotors helps to reduce fuel usage and therefore cost and emissions.
The first contemporary installation took place on Enercon’s 2010-launched ro-lo vessel E-Ship1, which features four Flettner rotors and was constructed to transport wind turbine components. It took until 2014 and 2015 for Bore’s ro-ro cargo vessel M/V Estraden to be retrofitted with the next rotors. This year has seen two vessels utilise rotors: Blue Planet Shipping’s bulker M/V Afros, which features four, plus Viking Line’s 2013-built cruiseferry Viking Grace, which was retrofitted with a rotor sail in April.
While Flettner performance is highly dependent on conditions and vessel type, Bore and rotor supplier Norsepower have quoted average fuel savings of just over 5% when M/V Estraden’s rotors are in use, with the potential to achieve 20% using multiple, larger rotors. At present, the rotors can deliver 2MW of engine-equivalent power.
A number of new projects are currently underway. Fehn Ship Management’s 4250dwt general cargo ship Fehn-Pollux is in the process of installing two ‘Eco-Flettners’ developed as part of the ‘Wind Hybrid Coaster’ section of the ‘MariTIM’ project co-ordinated by MariGreen, a German -Dutch consortium promoting green shipping in the countries’ border area. The rotors are optimised to operate across a range of wind speeds and will have the possibility of meeting 100% of propulsion demand if conditions allow. Maersk is also planning to install two 30m Norsepower rotors on a 109,000dwt tanker chartered by Shell, which are expected to save up to 10% in fuel and emissions.
Once these new projects are completed, MariGreen observes that ‘Flettner vessels will be in operation in most of the major vessels segments from general cargo, ro-ro, bulker, tanker, and cruise/ferry’, demonstrating the widespread viability of the technology. Also notable is the pedigree of the companies, such as Maersk, Shell and Cargill, that are choosing to adopt this technology. Wind propulsion may be in its early stages, but with such big players involved and the considerable fuel savings it can deliver, it can no longer be dismissed outright.
At least, that is the message of the International Windship Association, founded in 2015, which according to secretary Gavin Allwright is committed to “the overriding idea that wind is a credible propulsion solution.” The Association’s stated goal is to ‘facilitate and promote wind propulsion for commercial shipping worldwide and bring together all parties in the development of a wind-ship sector to shape industry and government attitudes and policies.’
The Naval Architect recently spoke with Allwright, unsurprisingly a keen advocate of wind propulsion, to gain a sense of the technology’s prospects and understand the role of the IWSA. As for the former, whilst Allwright noted that Flettner rotors are currently “the forerunner of the tech breaking into the market,” he advised they are just one solution out of roughly seven technology groups, comprising hard sails (also known as wingsails), soft sails (including DynaRigs), kites, turbines, hydrofoils and suction wings – a “toolbox of solutions.”
These technologies are at varying stages of development and have so far seen limited commercial application. Despite this, ambitious projects abound, such as SkySail’s towing-kite, installed on two Wessels Reederei vessels – MV Michael A. and MV Theseus – with another in production for a Cargill/Anbros Maritime Ship. Wing sail technology (propulsion- assisting aerofoil rigs similar in concept to aeroplane wings) has also seen much interest and competition, with a number of companies racing to develop solutions including London-based Windship Technology and their competitor Oceanfoil, whose wingsails achieved an average of 14% fuel and emissions savings on a 50,000dwt Panamax operating in the north Atlantic according to a report publishing by BMT (reported in January’s Naval Architect). Bound4Blue is another player, and is set to test its wingsail on an ORPAGU fishing vessel following an agreement signed in April.
As of yet, there isn’t a clear precedent for which solutions work best for particular vessel segments. However, practical considerations of deck layout, visibility, and loading issues play a part in determining which technologies might be most viable in each case. For instance, on containerships where deck space must be preserved, kites offer an unobtrusive choice, whilst for vessels that undergo regular loading and unloading, rigs that can be retracted or moved will have the advantage. Some vessels with large superstructures such as ferries may pose challenges to the installation of large rigs or rotors.
Convincing the industry
The maritime industry would be forgiven for being skeptical towards the idea that wind propulsion is the shining hope for emissions reduction, given the tiny percentage of vessels using the technology. Allwright is certainly not blinkered in this regard, but is keen to add context: “If you look at LNG ten years ago, they had a handful of ships. Wind will be the same. Yes, it needs development. We need more ships out there using wind – we need demonstrator vessels doing sea trials with all of the technologies.”
Should the majority of wind propulsion technologies currently being developed reach the market, a study on market potentials and barriers to wind propulsion in maritime – carried out by CE Delft, the Tyndall Centre for Climate Change Research, Fraunhofer ISI and Chalmers University of Technology – suggests that they will see an uptake of between 3,700 and 10,700 installations (taking into account retrofits and newbuilds) by 2030. The number, the study suggests, will depend on the ability of the windship sector and governments to provide or facilitate:• ‘(Trusted) information on the performance, operability, safety, durability, and economic implications of the wind propulsion technologies.’
- ‘Access to capital for the development of wind propulsion technologies, especially for building and testing of full scale demonstrators.’
- ‘Incentives to improve energy efficiency/reduce CO2 emissions of ships.’
To make progress on these requirements, the IWSA is involved in the creation of a collection of regional hubs around the world, which will allow technology companies to engage with local industry clusters and court the support of regional and national institutions and government to secure funding. Already well established in Nantes, with dealings with over 40 companies, is Europe Atlantique de l’IWSA; although currently unofficial, clusters in the south Pacific and in northern Europe have also seen significant activity, and there are further plans to establish hubs in North America and Asia.
Once these hubs are up and running, the IWSA intends to act as a kind of umbrella organisation, sharing best practice and organising events. Allwright says that there is even discussion about developing a ‘Wind Code’, akin to the Polar Code, which will establish standards to smooth the adoption of the technology. Fortunately, wind technologies do not face the classification challenge currently looming over other innovations such as autonomous shipping; as Allwright notes, “almost every technology development we have on the books is class-certified,” avoiding the lengthy delays that can often slow the uptake of technological innovations.
Allwright agrees that the IMO’s recent GHG strategy has certainly given wind propulsion a boost. Wind has the advantage of being a primary renewable, which can have considerable impact as an auxiliary energy source when coupled with more common secondary renewables such as hydrogen or biogas:
“To reach the IMO target, everyone is looking at secondary renewables. If you look at 100% fleet switchover to secondary renewables, that’s a big nut to crack, a lot of fuel. If you put wind assist of primary wind into the mix, suddenly that nut becomes a much smaller one to crack. With wind-assist, you can get 10%-30% savings. Something like a Flettner rotor, you’re looking at 5-20%. A big rig, you may be looking at 15-30%. If you go with an optimised newbuild, you could be getting anywhere up to 50%. Even with retrofits, the middle number is 20%. That means you only have to find 80% secondary renewables, which becomes far more manageable.”
A new market approach
As the above suggests, the driving force behind wind uptake will ultimately be the cost savings it delivers against expensive secondary renewables, as well as conventional fuels, which are expected to increase in price with the sulphur cap and possible future carbon pricing. As engine manufacturers achieve ever-smaller efficiency gains, the possibility of 10% savings are a huge incentive.
However, the problem faced by the IWSA until regulation kicks in, which struck concurrently with their founding in 2015 as bunker prices dropped, is the cheapness of fuel compared with renewables. Cheap fuel stretches the ROI of any wind technologies, putting off shipowners cautious of fledgling technology: “At current prices, all of the wind systems have an ROI of around 3-4 years. Shipping companies, from my experience, won’t go for anything above 3 years unless a political decision is made,” Allwright says.
One route that the IWSA is keen to explore to alleviate the pricing issue is leasing. As Allwright explains: “You go to a customer and say you don’t have to pay a penny – we’ll come in and fit it, monitor it, maintain it. You can take it off anytime. The way you pay for it is we assess over a 3-month period what saving it is giving, and we split it in half. That changes the dynamic completely – there is no ROI anymore. And that’s always been a sticking point. If you completely switch that model around and say it’s all leased, of course it’ll cost a little down the road, but it’s maybe paid for completely by fuel savings.”
Whether such a scheme would prove popular is ultimately dependent on shipowners, but if so would represent a significant market shift, aligning shipping with the aviation industry, for instance, where 40 percent of all newbuild aeroplanes are delivered to leasing companies. For wind propulsion developers, leasing allows them to validate their technology at sea, but in a commercial context that may deliver a profit. For the shipowner, leasing removes the anxiety of taking a gamble on new equipment, but allows them to benefit from the possible efficiency gains, as well as demonstrate their commitment to greener shipping. Further ahead, Allwright even foresees – and hopes for – a switch from time charters to fuel charters, which would provide huge impetus behind wind propulsion as fuel usage becomes an even more carefully scutinised cost factor.
Allwright is confident that, given a little encouragement, canny shipowners will come to recognise the benefits of wind as they begin the task of converting their fleets to alternative energy sources. As for the shape of this encouragement, Allwright admits that playing on shipowners’ commercial anxieties may prove most effective: “The message that we put out is that you’ve got a problem. If you don’t check [primary renewables] out, you’re going to be left behind. And there’s nothing people hate more in shipping than the feeling they are being left behind.”
Some opponents, however, seem put off by aesthetics alone: “Because [the technology] is so visible, many captains have said ‘I don’t like the look of it’,” Allwright says. “I should remind them that they don’t actually get to choose – if it’s safe and saving money, it’s your duty to your shareholders. But I usually answer that you can have it in any colour you like.