Wind propulsion in shipping: Where we stand

Why wind propulsion

#1 Environmental benefits

As global climate policies are becoming increasingly stringent, shipping is examining all the possible options to decarbonize. According to IWSA, 5-20% of the propulsive energy delivered to a vessel can bring up to 30% carbon emissions reduction. However, optimized newbuilds can bring 50-80% with operational changes on particular windy routes.

In addition, a study on three bulk carriers by the International Council on Clean Transportation (ICCT) earlier in 2022 found benefits from the rotor sails and several port-to-port energy savings of 0.1% to 7.2% per rotor.

Recently, Danish ferry operator Scandlines reported a 4% reduction in CO2 emissions from a hybrid ferry with a wind propulsion system installed. On good days with optimal wind conditions, this decrease was as much as 20%.

#2 OPEX reduction

Being less dependent on oil, wind sounds like an attractive energy source as operating expenses are getting more and more uncertain amid an energy crisis that recently brought a spike in fuel prices.

#3 Reliability

Wind works very well for smaller vessels and is a constant energy source, available for everyone, and free. It can also be combined with other fuel options for the power needs of bigger vessels. The wind solution is also future-proof as it does not require additional infrastructure.

What are the key types of wind propulsion?

According to IWSA, there are 7 different types of wind propulsion:

• Soft Sail – Soft sails mostly resemble traditional sails. They are light, cheap and relatively easy to make, flexible and can be stowed when needed. VPLP is a new technology of soft sails.
• Hard Sail – This system uses air pressure to push the vessel forward. Hard sails can be covered with photovoltaic coatings to produce solar power but can take up a lot of space on the deck.
• Flettner Rotor or Rotor Sails – These are rotating cylinders operated by low power motors that use the Magnus effect to generate thrust. They can add significantly to the vessel’s efficiency. The cruise ferry Viking Grace is the first passenger vessel with a rotor installed.
• Suction Wings – Suction wing is a non-rotating wing with vents and internal fan (or other device) that use boundary layer suction to provide as maximum effect as possible.
• Kites – Dynamic or passive kites are installed off the bow of a ship to assist propulsion or generate a mixture of thrust and electrical energy.
• Turbines – Marine adapted wind turbines are installed to produce electrical energy or a combination of electrical energy and thrust.
• Hull Form – This refers to redesigning the upper part of ship hulls to capture the force of the wind and generate thrust.

Wind propulsion in shipping: Key barriers

Talking to the Oceanbird, Mr. Gavin Allwright, co-founder and Secretary general of the International Windship Association (IWSA), shared what he thinks are the main barriers to the integration of wind propulsion in shipping at the moment:

• The current perception of a sailing ship: With shipping having an ancient presence, the public perception of wind propulsion includes Jack Sparrow-like ships rather than the industrial solution of modern wind turbines.
• The conservative nature of shipping: Despite the current energy crisis, shipping finance remains disproportionately focused on a fuel transition rather than a more generic renewable energy discussion, that would include wind.
•  Lack of global sea traffic control: As there currently is limited wind infrastructure, a unified monitoring system could enable the planning for ports in connection to wind corridors.

Wind-powered ships: Current landscape and the way forward

Attention to wind propulsion as a supporter of decarbonization has been growing in 2021 and into early 2022. Last June, the Dutch maritime research institute MARIN initiated the project Optiwise, an EU-funded research and innovation project aiming to improve and demonstrate energy savings using wind propulsion and hydrodynamic improvements in propulsion.

In early October, the SHOFU MARU, the world’s first coal carrier powered by wind propulsion, started operation in Japan. The ship will be transporting coal mainly from Australia, Indonesia, and North America as a dedicated vessel for Tohoku Electric Power Co.

Currently, 21 large commercial vessels have wind propulsion systems installed onboard, representing over 1 million DWT of cargo carrying capacity. By the end of this year, IWSA estimates that wind propulsion technology will be installed on around 25 large commercial vessels, representing 1.2 million DWT.

However, wind propulsion seems to be currently lacking an adequate presence in the international regulatory frameworks and subsidies, which impedes a level playing field for all energy sources, said Mr. Allwright during the latest 2022 GREEN4SEA Forum. Current wind technology cannot be the only option to power vessels, but it can assist and increasingly take up a larger percentage of the needed propulsion in combination with green fuels, solar, or nuclear.

In the current landscape of fuel price uncertainty, shipping leaders that wish to comply or go beyond environmental legislation should examine all the potential options considering their budget, flexibility and timeline.