Transition in the wind as shipping warms to alternative propulsion

804-foot tanker Maersk
Wallenius Wilhelmsen is developing Orcelle Wind, a roll-on/roll-off ship
Wallenius Wilhelmsen is developing Orcelle Wind, a roll-on/roll-off ship that will have the capacity to carry 7,000 vehicles at 10 to 12 knots under sail, a speed that can be increased with a supplemental power system. The operator predicts a 90 percent reduction in emissions, with delivery in 2025.

In the light of the current scramble for alternative, low-carbon fuels that will take until the 2030s to substantially penetrate the maritime fuel mix, wind propulsion is gaining more attention from vessel owners and operators. Gavin Allwright, the secretary-general of the International Windship Association (IWSA), discusses the uptake of this technology and what is behind a spate of recent public announcements.

With a lot of attention and investment going into alternative, low-emission fuel development, how does the return of wind propulsion avoid becoming an “also-ran” technology segment? 

Allwright: To answer this question, I have to start with the fact that IWSA and its members welcome the developments in alternative fuels as they are vital to carbon-neutral and ultimately zero-emissions vessels. The term “also-ran” is actually perfect, but in a positive sense. Wind propulsion systems are compatible with all other energy sources, and all retrofit installations and newbuilds are “hybrid” systems by their very nature. As retrofits, they can deliver 5 to 20 percent of the propulsive energy to a ship with the potential to reach 30 percent (derived on a motorship operation profile without operational changes), and in newbuilds they can deliver 50 percent or more. While it is obvious wind can’t do the job alone, the same can be said about these new fuels that we are asking to do some very heavy lifting in decarbonizing the fleet.

Whether you are paying $350 a ton for heavy fuel oil or $1,000 for the equivalent in a “green” alternative fuel, you are still paying for fuel. With a wind propulsion component it is possible to decouple a portion of your energy requirement from the fuel markets, with that zero-emissions energy delivered to the point of use at zero cost, with zero need for storage on board and zero infrastructure required on shore, and that energy predictably remains at zero cost for the lifetime of the vessel.

Your association has this year declared the “Decade of Wind Propulsion.” Is that just a marketing ploy or is there real substance behind it?

Allwright: There is of course an element of informing the market in any announcement, and the message there is that wind propulsion is a credible, robust and increasingly economically attractive solution. However, the “Decade of Wind Propulsion” announcement is far more than that. It is a renewed commitment from our 130-plus members to deliver on the potential of wind propulsion in this decade. We already have wind propulsion units in the market, with 11 large vessels with systems installed, from ferries to bulkers and a couple of tankers including a VLCC, and over 20 rigs in operation. There is another large “wind-ready” bulker and three more installations pending in the second quarter this year, along with two newbuilds underway. These are alongside 20-plus smaller cargo and cruise vessels. 

However, it is scaling these installations that is the challenge. More demonstrator vessels, mass production facilities and preparations for fleet installations will be vital to deliver significant numbers by 2030. The foundations for these are being laid now and we predict the number of demonstrators will double year-on-year up to 2024 without any further commercial orders. We are also seeing large industry players engaging with wind. The past few months have seen announcements from Oldendorff Carriers, Mitsui O.S.K. Lines, Wallenius Wilhelmsen and Cargill, among others.

There is also the need to optimize the systems that will be increasingly common in the fleet over the next few years. This involves better integration into excursion monitoring systems along with improved support systems, such as weather routing for wind, satellite forecasting and sensors on rigs to monitor performance — and even lidar to identify wind patterns as they affect the ship in real time. All of these technical solutions will feed into the third-party validation and fleet evaluation that is also under development to assist shipowners identifying the best solutions for their fleets. 

Facilitation is the third key area and this is a wide one, covering everything from working with class to continually improve and adapt wind-assist guidelines to the setup of an accelerator program to cluster together expertise to help deliver wind propulsion systems from concept to market. This also extends to assisting with the rollout of low- and zero-emission fuels as mentioned before and integrating those in the design of new vessels.

On that final point, you recently penned a piece suggesting that wind propulsion could actually fund not only the IMO 2050 decarbonization target, but also full decarbonization. Can the industry really accept that as a credible assertion? 

Allwright: Yes, I think the industry can. That thought piece adopted some conservative assumptions on fuel price: no increase this decade and then a 35 percent increase each decade after that as carbon levies are introduced and higher-cost alternatives enter the mix. It assumed that wind propulsion would be rolled out substantially this decade, securing 20 percent reductions in fuel use and emissions across the fleet in the 2030s with some adjustments in speed and routing.  Even using these conservative assumptions, this calculation would yield about $1 trillion in savings by 2050 with a price tag of roughly $300 billion, and also decrease the total cost of rollout by a margin of 10 to 20 percent. The total cost for decarbonization has been estimated by University Maritime Advisory Services and the Energy Transitions Commission at roughly $1 trillion to reach IMO 2050 and $1.4 trillion to $1.9 trillion for full decarbonization, taking a fuel-heavy approach — thus wind could in theory pick up the tab. This scenario is of course predicated on a decision to adopt wind propulsion systems at scale this decade, involving extensive retrofitting of the existing fleet and newbuilds being wind-optimized as they enter the fleet.

That brings us to the most recent development, an open letter released by the IWSA. The letter calls on industry decision-makers to adopt a level playing field for all energy sources and go beyond the current narrow “fuel-centric” approach. Why now and how do you propose to make this happen?

Allwright: Firstly, I would like to make the point that the open letter is signed by 97 maritime companies, from large shipowners to small technology developers. Admittedly this is a big ask, but our industry is embarking on an unprecedented transition far greater in scale than the first wind to fossil fuel transition — and in a far shorter period — meaning at least 50 percent decarbonization within the life span of a vessel launched today.

That means we need to use all of the tools in the energy toolbox and they need to be assessed side by side in a transparent way, taking in the full life cycle and all external impacts and costs. Currently wind propulsion is under-represented in those assessments and thus we are calling for wind to be fully integrated into all industry reports and decarbonization pathways going forward. We are calling for a multi-stakeholder working group to be established to ensure we fully understand the potential of wind propulsion and ensure that all policies and regulations recognize wind as a direct energy source.

The challenges facing the industry mean we need to make sure decision-making is based on clear definitions, credible data and standardized assessment criteria, and that is currently not the case. Thus, the letter goes on to call for a strategic review of our decarbonization efforts so we are all pulling in the same direction. A review of this kind doesn’t need to slow down the market development but run parallel. It will ensure that we fully appreciate what a hybrid approach to decarbonization means, and hopefully we can avoid any dead ends or stranded assets in the future.

We stand ready to work with all stakeholders across the shipping spectrum to put these initiatives into action. They will be able to draw on a lot of fantastic work already underway in silos across the industry — just in a more collective, transparent and urgent manner.

Gavin Allwright is secretary-general of the International Windship Association, a nonprofit group that facilitates and promotes wind propulsion solutions for commercial shipping worldwide. IWSA is made up of wind propulsion technology suppliers and designers, naval architects, engineers, academics, NGOs and seafarers. To learn more, visit

By Professional Mariner Staff