DOSSIER

 

  Applying Wind Assisted Propulsion to ships report (II)

 

4 Market forecast

 

 

Overall demand

Only two significant attempts have been made to size the future WAPS market. As part of the UK government’s Clean Maritime Plan in July 2019, a study was commissioned to assess the annual global market for wind propulsion systems alongside other technologies and fuels. This was estimated to grow from a conservative £300 million a year in the 2020s to around £2 billion a year by the 2050s.

In this analysis, wind technologies – which here include both WAPS and primary wind propulsion vessels, is rated as the second most important propulsion technology field behind alternative fuels (at £8-11 billion per year in the 2050s), representing around 15% of the market potential for propulsion systems.

Another study, undertaken by CE Delft for the European Commission in 2017, predates both the post-2018 surge in uptake and the commercial maturation of some leading technologies, notably suction sails. The report concludes that, ‘should some wind propulsion technologies for ships reach marketability in 2020’, the maximum market for bulk carriers, tankers and container vessels is estimated at around 3,700–10,700 installed systems by 2030, including both retrofits and newbuild installations depending on the bunker fuel price, the speed of the vessels, and the discount rate applied.

Although some WAPS technologies did reach maturity before 2020, and while greater clarity on emissions legislation has emerged since 2017, the early years of uptake forecasted by the CE Delft study do not match with the observed reality: by the end of 2023, there were just 29 WAPS installations rather than the several hundred projected in the report.

The discrepancy could be the result of pricing assumptions – for example, a significant and permanent fuel cost increase after the introduction of IMO’s 2020 sulphur cap, which never emerged.

However, the dynamics of the model remain interesting and could yet prove correct: “By the time 100+ installations have been completed, the learning effect is large enough to have brought the costs down such that all [suitable] newbuilds and retrofits make financial sense, given our cost data and the oil prices and discount rates that have been assumed.”

Standing at 101 planned installations today, perhaps the short, sharp increase projected by the CE Delft model is on the verge of being realised. This ‘S’ shaped curve would see the majority of installations occurring in the next few years, both retrofits and newbuilds, before demand flattens out and is limited to suitable newbuilds as they are added to the fleet.

 

Retrofit demand
The study also indicates that retrofits will continue for some years to represent between 33% and 50% of all installations. This contrasts with the shift towards newbuild projects observed in the market today. But according to IWSA, this observation is a result of shortening lead times for the announcement of retrofit projects . This leaves the prospect that, beyond the 72 planned installations for 2024 and beyond, more retrofit projects may be announced and even completed over the coming year.

IWSA has compiled a more recent, albeit less rigorous, forecast based on a 2022/23 survey of its membership of WAPS suppliers and users, combined with public project announcements. Even though that projection seems to lag behind the current status of projects, the doubling of installations beyond the 100-project milestone tallies with the earlier CE Delft analysis.

The IWSA forecast does not separate newbuild from retrofit projects but gives its assessment that retrofit projects may not be adequately represented in long-term orderbook numbers: “The market for retrofitting could expand far quicker as the installation time is relatively short , depending on the amount of deck reinforcement and foundation work that is required. The actual installation of the [WAPS] unit onto its foundation can be completed in a matter of hours or a number of days for more complex systems.”

LR’s own experience based on the number of pre-feasibility studies it is conducting for owners considering WAPS projects aligns with the sense from the CE Delft and IWSA analyses that the uptake of WAPS technologies is reaching, if not already at, a tipping point beyond which installation numbers will increase dramatically in the next two years.

    

 

                                         5         Technologies

 

At present WAPS technologies installed and on order can be classed into four distinct types, as described in the sections below. While the mechanisms for all four are different, each generates thrust and lift, reducing the additional propulsion power needed to move ships. Crossover technologies are also emerging as technology evolves, for example suction sails incorporating rigid sail elements. Some common observations can be made about factors affecting WAPS technologies:

  • Manoeuvrability: All WAPS technologies can have a significant impact on vessel manoeuvrability due to both their impact on vessel weight, size and shape, as well as the conditions that need to be maintained for them to achieve the intended power savings. Size and location of installations, wind conditions, ship speed and several other factors can influence manoeuvrability and must be carefully considered before a project.
  • Deck and air space: All technologies demand free deck space. Rigid sails potentially occupy the most deck space, followed by Flettner rotors and suction wings. While kites require less space, deck installation is still required for deployment and retrieval, and obstructions to air-space on deck during these processes needs consideration. Installations must also take account of space needed for deck operations such as loading and un-loading. Manufacturers are deploying several solutions to minimise the required deck space, including elevated, foldable or retractable designs as well as units mounted on containers or rails.

Air draught limitations: As all technologies can significantly alter the height of the vessel, operational height limitations need to be taken into account. As well as avoiding interaction with operations-related structures on the vessel, the available air draught should be calculated based on routes used and ports of call to avoid interfering infrastructural barriers including cranes and bridges. WAPS providers offer tiltable bases to minimise these limitations, although these bring additional cost and complexities to installation and operation.

Intermittence: The effect of all technologies will vary with the prevailing wind conditions and therefore will not be fully effective all of the time, with some conditions in which they cannot be operated.

Power demand: Unlike conventional sails, WAPS devices all require some element of power to rotate, manoeuvre or deploy/retrieve – or, in the case of suction wings – to generate a boundary layer of air around the sail. This power demand needs to be accounted for in the installation and operational plan, as well as accommodated when calculating power savings.

Hidden costs: Beyond the unit cost and the expense of installing the unit, all WAPS projects contain further costs associated to, for example, steelwork for foundations and engineering for compliance that need to be carefully considered before the project.


Suction sails

Suction sails are non-rotating wing-shaped sails with vents and an internal fan that creates suction, pulling in a boundary layer of air around the wing for enhanced effect. The system was originally designed and deployed in the 1980s.

The vertical structures are mounted onto the deck like rigid sails and rotor sails. In contrast to rotor sails, their outer parts do not rotate to generate thrust. The orientation of the wings is adjusted automatically to the direction of the wind.

The sails deliver optimal thrust at beam winds, while their thrust is practically zero at head and tail winds. The current height of suction wings ranges from 10-36 m. Two or four wings per ship is common but, in some instances, only one wing is installed.

Installations to date have been deployed on the bow and stern, as well as in deck containers or on flat racks. Suction wings can cost between US$200,000 and US$900,000 per unit depending on size.

 

Installations

Including planned installations to the end of 2024, nine vessels have been equipped with suction sails since 2020.


Flettner rotors
Rotor sails, or Flettner rotors, named after the German innovator who was the first to install them on a ship in the early 1920s, are vertical cylinders which spin and cause lift as the wind blows across them as a result of a phenomenon known as the Magnus effect. They are mechanically driven to develop lift and propulsion power, with the rotors reducing the energy consumption of a ship by providing lift and thrust.

The rotating cylinders generate thrust with force resulting in the horizontal plane, forward and sideways. To make sure the seagoing properties of the vessel remain good, it must be prepared and planned because the healing moment influencing the stability and the strength of the cylinder foot must be properly supported as it is subject to high stresses.

The range of cost for a Flettner rotor (excluding installation) is between US$500,000 and US$1 millionviii depending on the size of the rotor. A typical delivery with multiple rotor sails ranges between US$1 million and US$3 million, although could be higher depending on the types of bases used.

        

 

Rigid sails

Rigid sails can make use of wind to replace some or all of the propulsion power needed for a vessel.

Rigid sails designs to date can provide up to 1,200 kW of power per installed mast, with forward thrust reducing the power needed from the main engine. The effect will vary with the prevailing wind and therefore will not be effective all of the time. The effect and general applicability are also dependent on operating speed, with sails being most effective at lower speeds.

Unit and installation costs combined can range from US$438,000 to US$876,000ix. However, it should be noted that LR has observed higher costs than the range provided by EMSA. Fuel consumption reduction depends on vessel size, segment, operation profile and trading areas.


Installations

Including planned installations to the end of 2024, rigid sails have been installed on 7 vessels since 2018 as seen in the chart below.


Kite sails
Kite sails can be attached to the bow of a ship to generate thrust. They need to be launched and retracted depending on the wind conditions, for which automated systems have been developed. Kites make use of the higher wind speeds found at higher altitudes available to sails positioned on the deck.

The largest kite currently operating is 1,000m2, with larger kite sizes under development. These can meet the requirements of larger vessels, especially when multiple kites are deployed.

Unlike other WAPS technologie s, kites can be suitable for vessels with limited deck space. However, they could be less efficient than other technologies due to the impact of the altitude and angle to the deck affecting on drive force.

The deployment and recovery of the kites also adds complexity compared to deck-mounted systems.
Kite sails can cost between US$340,000 and US$2.3 millionx depending on the size of kite used.


Installations
There have been two performed installations of kite sails since 2018, both on bulk carriers, with a further installation planned by the end of the year.

 

 

6         Project planning

                    

 

Planning a WAPS retrofit project entails several challenges that may be beyond the experience of a shipowner. The multiple technology options and specialist suppliers are likely to be unfamiliar to companies that have previously relied on conventional propulsion configurations. The potential fuel, saving, capital and operating costs, project timeframes and regulatory requirements will also be new. This section delivers a brief overview of the main considerations to be undertaken before embarking on a WAPS retrofit project.


Regulatory and classification issues

In December 2023, LR released Guidance Notes on Wind Assisted Propulsion Systems., replacing earlier dedicated guidance on Flettner rotors. The guidance covers class requirements for WAPS vessels, statutory regulations, safety and operational considerations and intact stability requirements. For vessels that are primarily wind-powered, LR rules related to its RIGGING notation lay out the structural requirements, and these rules can be optionally used for WAPS projects.

However, the European Maritime Safety Agency (EMSA) has identified several gaps in the statutory regime that complicate the deployment of wind technologies . These mainly relate to stability, with current criteria for assessing intact stability not necessarily applicable to modern sail installations. There are further issues with regulations on bridge visibility and manoeuvrability.

While these gaps exist, it is essential that class societies support shipowners in working closely with the chosen flag state in order to deal with potential non-compliance due to a WAPS installation. At present, these issues are identified by LR and resolved during dedicated Hazard identification (HAZI D) workshops specific to each project.

The table below highlights the classification requirements for vessels deploying WAPS versus primary wind propulsion solutions.

 

Technical issues
Alongside regulatory requirements, there are other technical issues that need to be considered. These include the impact on cargo handling operations, which can be compromised by deck installations for some vessel types. Air draught is another crucial consideration, as infrastructure in ports and harbours – bridges and cranes, for example – could impede vessels with tall, fixed sails. Other factors include:

  • Auxiliary loads and their balance
  • Structural strength
  • General operational obstructions of WAPS
  • Equipment number, anchoring, and mooring

Many of these factors can have a significant impact on the safety of operating the vessel, yet are not fully accounted for in existing class rules and IMO regulations.

For example the vessel's equipment number calculation, which determines the type, strength and length of anchors, chains and moorings needed to secure the vessel, does not include WAPS units under IACS Unified Requirement A1. But depending on the front and side projected area, these technologies can dramatically affect the strength of equipment needed to assure safe anchoring and mooring.

LR's guidance provides full descriptions of safety and operational factors - including how to factor WAPS into equipment number calculations - that will be of value to shipowners planning a WAPS project.


Economic issues

As detailed in Section 4, the economics around wind technologies are far from straightforward. The fuel savings that can be generated from each solution vary widely depending on wind conditions, vessel type, speed, route and the number and positioning of WAPS units. There is as yet no single standard for comparing fuel saving claims or validating that those claims are upheld at commissioning or while the vessel is in service.
LR uses ISO Standard 19030 to validate and verify the fuel savings of WAPS installations during long-term trials. Although not a statutory procedure, this framework allows for a robust analysis of the ship performance with the WAPS, and other EETs, across time.

As WAPS systems are relatively novel, the impact on other operating costs is also unclear. This can include auxiliary power requirements for some technologies, and new demands on crew in terms of maintenance.

De-risking WAPS investments

To counter the uncertainties mentioned above and many others, LR proposes a step-by-step framework for removing the risk from WAPS installations. The process starts with a feasibility study of the fleet to assess suitable options for reducing emissions and fuel consumption, concluding with verification of actual, in-service performance.

 

7 Voyage optimisation

 

Voyage optimisation
Aside from operating considerations discussed in previous sections, the role of voyage optimisation in effective WAPS deployment cannot be understated. In LR’s experience, while most technology providers offer optimisation solutions (and crew familiarisation with them), this is not universal. Shipowners preparing to introduce WAPS technologies should take as much care over optimisation as they do over the technology itself.
As a second thought, the complementarity of WAPS and voyage should be quite clear: technologies that depend on weather can improve their performance when vessels adapt their route to find the best weather. The scale of the impact, though, is more surprising, and is confirmed in multiple academic research papers:

  • An Improved Ship Weather Routing Framework for CII Reduction Accounting for Wind-Assisted Rotors: Weather routing, speed optimisation and wind-assisted rotors produced 4.61%, 10.61% and 4.41% reductions in total fuel consumption respectively on a single route from China to the Middle East, with a similar reduction in the attained Carbon Intensity Indicator (CI I).
  • A New Routing Optimization Tool - Influence of Wind and Waves on Fuel Consumption of Ships with and without Wind Assisted Propulsion Systems: A new software tool showed around 4% savings on its own, but 50% when combined with WAPS.
  • Minimal Time Route for Wind-Assisted Ships: A
    76,000DWT wind-assisted cargo ship achieved a shorter crossing time, with lower fuel consumption and emissions, despite the longer optimised route planned by a weather algorithm.
  • Weather Routing Benefit for Different Wind Propulsion Systems: Higher benefits from weather routing were found first for rotor sails, then for suction wings, and finally for wing sails.

8 Conclusion

 

Wind assisted propulsion systems is in its late childhood and due to a significant growth spurt. The associated growing pains are inevitable. Lack of familiarity with the technology – not necessarily helped by multiple suppliers promoting many different systems – is one obstacle, both for shipowners hoping to retrofit WAPS technology and for the majority of shipyards that will be needed to perform those installations. Lack of standardisation of fuel-saving claims and methodologies for verifying them is another. Both are in hand but will remain a challenge for early adopters.

Despite those challenges, the significant impact of harnessing the wind – on fuel cost, carbon cost exposure and environmental compliance – should not be ignored. And the indications are that it will not be. Projections are hard to ascertain but based on the best available analyses and the volume of feasibility studies being requested from LR, uptake of both retrofit and newbuild installations is poised for a sharp upward tick within the next two years.

For retrofit projects, the scaling up of technology supply will be a particularly acute consideration. Taking ships out of service to find components not waiting for installation adds to the already extra expense of such conversions. Choosing the right supplier and the right yard will be vital. So too will navigating the potential pitfalls of new technologies – costs not predicted, operational constraints unanticipated and regulatory regimes unknown or incomplete.

LR has undertaken expert services for shipowners, shipyards and technology suppliers preparing to capitalise on wind technology. From approvals in principle of new technologies and feasibility studies to complex computational fluid dynamics (CFD) calculations and in-service performance verifications, LR has the breadth of experience and expertise to support stakeholders through adopting new technologies, securing confidence that WAPS retrofits can be safely and optimally deployed.

 

 

 

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