Sails were once the primary driving force for humans to conquer the ocean. Today, in the urgent context of carbon reduction in the global shipping industry, this ancient technology is being revitalized in the new form as a “wind-assisted propulsion” system (WAPS).

According to the statistics of the International Wind Ship Association (IWSA), 33 large ships worldwide were installed with wind-assisted propulsion systems in 2023. The wind-assisted propulsion fleet was expected to exceed 100 ships by 2024, covering various types of ships including bulk carriers, oil tankers, roll-on/roll-off ships, general cargo carriers, ore carriers, large cruise ships, etc. Nowadays, industry giants such as Maersk, CMA CGM, COSCO Shipping, and CNOOC have taken the lead in promoting and applying this technology in their own fleets, and have received significant environmental and economic benefits. This has played a huge demonstration role in the application of this technology in the industry. 

From the current situation, the rapid growth of marine wind-assisted propulsion technology is driven by the triple “rigid demands”. Firstly, regulatory pressure. The CII energy efficiency rating of the International Maritime Organization (IMO), the EU ETS carbon trading and FuelEU Maritime carbon intensity targets have forced shipowners to seek low-cost emissions reduction solutions. The actual test data shows that the CII rating of ships can be improved by 1-2 levels by installing rotor sails. Under the FuelEU framework, a 10% energy-saving effect will be sufficient to meet the compliance requirements by 2025. Taking a 100,000t bulk carrier as an example, if WAPS was not installed in 2030, an annual carbon quota of 3 million euros needs to be purchased, but the retrofitting cost is only 1.5 to 3 million euros. Secondly, cost advantage. Compared to forward-looking technologies such as hydrogen fuel and ammonia fuel, the cost of retrofitting the wind-assisted propulsion system only accounts for 5%～15% of the ship price, and the fuel costs can be saved by 10%～30% throughout the full lifecycle. According to the analysis by the international shipping consulting firm AHTI, when the price of heavy oil exceeds $600/ton, the investment payback period for WAPS will be shortened to 3～5 years. Thirdly, resource endowment. Wind energy is available on 70% of the global shipping routes, with vessels operating over 10 hours daily within the effective wind speed range of 6～8m/s. Taking the coastal areas of China and the “21^st Century Maritime Silk Road” route as examples, the annual effective wind energy density reaches 300～500W/m², which is equivalent to that each ship can receive free power of 20～50 tons of oil equivalent per day (according to data from the China Meteorological Administration in 2023). 

It can be foreseen that with increasing stringent global environmental requirements and growing pressure on the shipping industry to reduce emissions, more and more shipping companies will realize the importance and advantages of wind-assisted propulsion technology, thus increasing investment in and application of this technology. The IWSA predicted that by 2030, there will be thousands of ships equipped with wind-assisted propulsion systems, and the market size will reach billions of dollars. In some European countries, such as Norway and Denmark, the governments have introduced a series of incentive policies to support the shipping companies in adopting wind-assisted propulsion technology, which will further promote the market development.？

In recent years, as an important technological support force to promote the sustainable development of the global shipping, shipbuilding, and related industries, China Classification Society (CCS) has continuously increased its R&D efforts in marine wind-assisted propulsion technology. In 2020 and 2023, CCS successively released the “Guidelines for Evaluation and Inspection of Marine Hard Wing Sails” and the “Guidelines for Survey of Marine Wind-Rotor Assisted Propulsion System”, and also achieved the corresponding calculation and survey capabilities, and developed relevant calculation software. This move has not only provided clear technical guidance for shipyards, shipowners, design units, etc., but also laid a solid foundation for the safe and high-quality development of the industry. For example, the successful delivery and operation of the world’s first new-generation energy-saving and environmental-friendly VLCC “New Aden” equipped with two pairs of wing sails device, the world’s first 308,000t wing sail-assisted VLCC “New Vitality”, the first domestic oil tanker newbuilding “Jun Bai 56” equipped with a rotor sail assisted propulsion system, the first domestic bulk carrier “Changhang Shenghai” installed with wind-rotor assisted propulsion, have set a benchmark for the industry. These practical cases are like sparks that ignite the enthusiasm for green transformation in the shipping industry. 

The interaction between human beings and marine wind energy has spanned thousands of years, but today it has found a new resonance in the era of carbon neutrality. For this reason, CCS is willing to work together with the industry to further move forward, as wind-assisted propulsion technology is not only a revolution in ship technology, but also represents a reinterpretation of human wisdom in the new era.