Rotor Sail Efficiency:
Fuel & Emission Savings

Increasing awareness of the environmental implications of shipping has led to new and enhanced regulatory targets. Rotor Sails are a cost-effective, proven technology that can help comply with International Maritime Organisation emission reduction targets and regulations.

If Anemoi Rotor Sails were installed on every suitable vessel in the world fleet, the average savings per year would be:

Tonnes of fuel


Tonnes of carbon

This equates to…

Km driven by an average car
Tonnes of waste to landfill
Tonnes of coal burned

To generate these savings traditionally, it would take…

Acres of forests in one year
Tree seedlings grown for 10 years

The shipping industry accounts for approximately 90% of world trade and contributes around 3% of global CO2 emissions. Although this is a relatively low figure, global trade volumes are expected to rise which could lead to an increase in emissions unless new ships entering the market are of much greater efficiency and old ships are made ‘cleaner’ through the use of novel technologies. The International Maritime Organisation (IMO) estimated that in 2012, the shipping industry emitted 796 million tonnes of CO2 and consequently decided to introduce emission targets to align the shipping industry with the Paris Agreement, of which it is currently exempt.

The two stage targets are initially to reduce Greenhouse Gas emissions by 40% (compared to 2008) by 2030 and then to pursue a 50% reduction by 2050. To help achieve these targets, the IMO has put in place measures such as the Energy Efficiency Design Index (EEDI). Other initiatives such as Rightship’s GHG rating and Poseidon Principles have been introduced by other industry bodies to drive decarbonisation within shipping.

Read on to find out more about how Anemoi Rotor Sails can help achieve these targets.

Energy Efficiency
Design Index (EEDI)

The IMO introduced the Energy Efficiency Design Index (EEDI) in 2013. It requires new ships to comply with minimum mandatory energy efficiency performance levels, becoming increasingly stringent over time through different phases. Vessels delivered after 2020 must now start in phase 2 (20% below baseline for most vessel types).

The EEDI aims to promote the use of more energy efficient equipment and engines and requires a minimum score (carbon emissions per tonne nautical mile) for different ship types and size segments. With traditional hull and engine efficiency gains now reaching their maximum potential, innovative solutions will have to be utilised to reach the next phases. Although there is no “one size fits all” solution, installing Anemoi Rotor Sails could reduce a vessel’s EEDI rating by an estimated 3-13%, moving vessels towards the next EEDI phase and helping to meet the necessary requirements.

A key benefit of Anemoi Rotor Sails is that they can be used in combination with many other energy efficient technologies such as Air Lubrication, LNG/dual-fuel engines, waste heat recovery, low friction hull coatings and propulsion efficiency technologies.

Efficiency Existing Ship
Index (EEXI)

At the 75th Marine Environment Protection Committee (MEPC) in November 2020, the IMO approved a technical approach for existing ships to sit alongside Energy Efficiency Design Index (EEDI). Set to come into force in 2023, the Energy Efficiency Existing Ship Index (EEXI) requires ships to meet set energy efficiency requirements.

The calculation of required EEXI is expected to utilise the existing EEDI reference lines, which would suggest that Rotor Sails will enable vessels to move towards or into the next phase of compliance. However, the guidelines on the method of calculation won’t be announced until MEPC 76, which is planned for June 2021.

Wind-assisted propulsion is a more mature technology when compared to some other technologies and could be one of the possible solutions to help satisfy anticipated EEXI requirements and reduce operational carbon intensity. In this sense EEXI (and possibly additional operational measures) could be a driving factor in accelerating uptake of wind-assisted propulsion systems. Attention will need to be paid to the overall regulatory framework to foster further development and implementation of this technology.  
Jan Otto de Kat
Director, Innovation - Global Sustainability Center, American Bureau of Shipping

Greenhouse Gas Rating and Port Incentive Programs

Although EEXI is not currently in force, there are other measures in use to encourage the efficiency of existing ships. For example, RightShip’s GHG Emissions Rating offers a “systematic and transparent means of comparing the relative efficiency of the world’s shipping fleet … using an easy to interpret A – G scale.” Charterers are now focusing more time and effort on selecting efficient ships. 1 in 5 charterers use RightShip’s GHG rating in order to do so.

Benefits are both environmental and economical as new programs such as port incentives are put in place. Anemoi Rotor Sails are classed as a Category B energy saving technology and therefore can help charterers and owners reap these benefits:

“Category (B): Technologies that reduce the propulsion power, PP, at Vref, but not generate electricity. The saved energy is counted as Peff”

Carbon Credits and Poseidon Principles

The economic impact of owning and chartering more efficient ships extends far beyond port incentive programs. In 2019, the Poseidon Principles framework was introduced. This framework integrates climate considerations into lending decisions to promote international shipping’s decarbonization. The four principles include assessments of climate alignment, accountability, enforcement and transparency.

Use of carbon credits has also become more prevalent in recent years. The goal of carbon credits and trading is to reduce the emission of Greenhouse Gases into the atmosphere by assigning a cost to each tonne of CO2 a company emits. By selecting an energy efficient technology such as Rotor Sails for your fleet, charterers can benefit from the economic incentives and ship owners may be able to charge more for the use of their vessel.

Fuel & Emission Saving Assessments

See how much you could save

The first step in understanding the potential of Anemoi Rotor Sails for your vessel is for us to undertake a fuel and emission saving assessment. By sending us some specific information about your vessel(s), we can provide a bespoke Rotor Sail arrangement and estimate of your potential savings.

Learn more