Powering marine decarbonization with wind-assisted propulsion

Both stakeholders and regulatory bodies worldwide see decarbonizing the maritime industry as a growing priority. The International Maritime Organization (IMO) has already set ambitious target dates for reducing ship emissions by 2030 and 2050, with many local and national organizations following suit. For shipowners, this means finding new, cleaner ways to power their ships, in order to reduce their vessels’ environmental footprints.

In addition to turning to low- and zero-carbon fuels, many owners are researching alternative propulsion methods as a way to limit their impact. Among developing options, wind-assisted propulsion is considered a strong contender for achieving significant emissions reduction. As a free, clean energy source available worldwide, wind can power ships renewably through the use of sails – both advancing the shipping industry and returning it to its roots.

However, much of the technology needed to support wind-assisted propulsion systems is still in the early stages of development. While a handful of pilot projects are underway, several environmental, technical, design and financial challenges remain before widespread adoption of wind-assisted systems is possible.

Meeting early challenges for wind propulsion

Developing wind propulsion systems for onboard installation presents a range of challenges for shipowners, shipyards, ship designers, equipment manufacturers and technology providers.

1. Availability

Wind is a renewable energy source – but it is also a variable, changeable element. Wind availability is highly dependent on weather conditions, geographical area and vessel direction, meaning that it is not a constant energy source. Because of this, wind propulsion alone might not be enough to meet ships’ power needs. For ship owners and designers, this may mean having more than one type of propulsion system available onboard.

2. Space

The masts that support the rigid and rotating sails installed onboard ships can measure up to 80 meters high, taking up significant space on deck. The space required varies with the number of masts, which may reach up to four per ship, based on current prototypes. For ship designers and shipyards this represents a challenge, particularly for smaller vessels (e.g., fishing vessels, inland navigation vessels) that cannot accommodate such large masts.

3. Design

Both newbuilds and retrofitted in-service vessels face design and technical obstacles when integrating wind-assisted propulsion systems onboard.

Retrofitting requires structural modifications for reinforcement, including the ship’s anchor and chains, stabilizing elements, and steering and maneuverability equipment. Bridge visibility may also need to be addressed.

Newbuilds must include several new design features onboard that differ from classic vessel design to prepare the ship to use wind propulsion. These include optimizing deck space, adapting hull shape, and positioning the bridge platform near the front of the ship.

4. Cost

While wind propulsion systems are likely to become more affordable in the future, they remain costly investments for the time being. With no streamlined approach to wind-assisted propulsion systems’ design, construction and onboard integration, it is difficult to achieve the economies of scale or uniform production needed to lower costs.

5. Regulations

Regulatory bodies such as the IMO have yet to produce official rules or guidelines for wind-assisted propulsion systems. Specific criteria have not yet been developed for commercial vessels, and compliance is carried out on a case-by-case basis. The shipping industry will need to adapt current regulatory frameworks to these new technologies, offering designers guidance on important aspects such as stability and visibility requirements.

Shaping the next age of wind propulsion

As a leading classification society, Bureau Veritas is helping develop safe, sustainable wind propulsion methods and technologies. BV NR206 classification rules address safety and reliability from design review through to installation and operations, including maintenance and surveys. These rules help verify that clients have undertaken the necessary risk analysis, ship strength measurement, definition of load cases, etc., before adopting wind propulsion systems.

Bureau Veritas has also developed two new notations for wind-assisted propulsion, which provide load cases and coefficients for freestanding rigs, wing sails, kite sails and wind turbines. The WPS-1 notation is for wind-powered ships with standing rigging, and the WPS-2 notation concerns vessels with both standing and running rigging.

Bureau Veritas is also collaborating on a number of wind propulsion projects in addition to the CANOPÉE. Bureau Veritas experts are involved with the Ville de Bordeaux, a 20,000 DWT ro-ro cargo vessel with a kite system fitted onboard, owned by Louis Dreyfus Armateurs. Bureau Veritas is also working on Solid Sail, spearheaded by Chantiers de l'Atlantique. This project aims to develop a rigid sail made of glass-polyester panels that can be installed onboard large cruise ships.

Finally, as a member of the International Windship Association, Bureau Veritas is helping promote the development of wind propulsion solutions for commercial shipping worldwide.

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