Reducing air emissions with the Environmental Ship Index (ESI)

Sabrina Peters

Environmental responsibility is growing in importance. The Vessel General Permit and Ballast Water Management are just a few of the current hot topics. For ship owners these legislative and regulatory changes may mean some changes to their vessels. As well as the changes that will have to be carried out, some of the new rules will also give several benefits, like the Environmental Ship Index (ESI). What do the rules involve? And what are their benefits?

The situation: reducing greenhouse gas emissions

Increased greenhouse gas in the air may cause climate change. Ships and ports are among the main causes for this, so stricter measures by port authorities could help to improve air quality.


The world’s main ports are working to reduce greenhouse gas (GHG) while continuing their roles as transport and business centres. This is called the World Ports Climate Initiative (WPCI). This is to influence the future of distribution and transport, taking into account local conditions and different port arrangements. It also offers support for reducing gas emissions from ships.

The ESI: identifying greener vessels

One of the WPCI projects is the Environmental Ship Index (ESI). This index looks at seagoing vessels that perform better in reducing gas emissions than the current emission standards the International Maritime Organisation asks for. The ESI evaluates the quantity of nitrogen oxide (NOX) and sulphur oxide (SOX) released by a ship, and has a reporting scheme for the ship’s gas emissions. This index is a good indication of the environmental (and maybe greener) performance of ocean-going vessels. It also helps in identifying greener vessels more generally.

The benefit: a fixed bonus!

Ports will use the ESI to reward ship owners with a fixed bonus when they take part in this and promote greener vessels. Ship owners can also use this in their own marketing and promotions. ESI will give a total score, but the rewards can either be based on that total or on each of its separate parts. Everyone in maritime transport can use the ESI to improve and show their environmental performance.

The future: improving maritime and port environment?

The programme is completely voluntary at the moment, and the WPCI hopes that all ports will join in the project to improve the maritime and port environment.



To see the formulas showing how the ESI calculates your NOx, SOx and CO2, please go to:

Lagersmit & green solutions

A shared responsibility for the environment is growing in importance. For example, seals do not contribute directly to decreasing greenhouse gasses, but they can ensure that there are fewer leaks of oil into the marine environment. Lagersmit has designed zero-leak sealing solutions to meet changing legislation and regulations.


The Supreme Ventus® and the Supreme Athmos® are designed to give you peace of mind by guaranteeing zero oil leaks. Their air and drain systems prevent oil leakage into the environment, or water leakage into the stern tube.

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