Wind-Assisted Propulsion on the Rise – Implications for Your GHG Performance

Clean Shipping Index (CSI) welcomes the increasing adoption of wind-assisted propulsion technologies across the shipping sector. A growing number of shipowners are investing in solutions such as rotor sails, wing sails, and other wind-assisted systems to complement conventional propulsion.

This development represents a meaningful step toward reducing greenhouse gas (GHG) emissions, emissions of air pollutants and even underwater noise. By harnessing wind energy, vessels can lower fuel consumption and associated GHG emissions. Reported savings vary depending on vessel type, trade patterns, and technology choice, but operational experience and studies indicate that reductions in the range of 5–20% are achievable.

What this means for your CSI GHG score

Within the CSI framework, GHG performance is assessed based on verified fuel consumption and resulting emissions. The use of wind-assisted propulsion therefore directly positively influences your score by:

• Reducing overall fuel consumption, directly lowering GHG emissions per transport work

• Improving energy efficiency, which is reflected in stronger GHG performance ratings

It is important to note that CSI evaluates actual, verified performance. The impact of wind-assisted technologies will therefore directly be reflected in your score based on measured operational outcomes, rather than projected savings.

Positioning your vessel for the transition

Wind-assisted propulsion is not a standalone solution, but it is a valuable complement to other measures such as fuel switching, energy efficiency improvements, and operational optimization. For shipowners, it offers an opportunity to achieve near-term emissions reductions also for existing vessels, while maintaining flexibility in fuel choices.

CSI encourages continued investment in solutions that deliver real, measurable emission reductions, as well as transparent reporting of performance data. Together, these efforts support a credible and science-based transition toward lower-emission shipping.

Besides wind-assisted propulsion, there are also vessels fully powered by wind. This leads to the highest scores for air pollution in CSI, as it fully replaces the use of fossil fuels. Read through the Methodology and Reporting Guidelines for more information.