In the port of Rotterdam, sustainable seagoing vessels are rewarded. Vessels that score high on the Environmental Ship Index (ESI) receive a discount on seaport dues already paid. The ESI is an international benchmark for emissions from seagoing vessels.
Vessels that perform better than the legal norm will be rewarded a 10% discount on the gross tonnage part of the port dues. Since 01-01-2015, the discount is doubled when vessels also have low NOx emissions. Low NOx emissions are achieved by using LNG as fuel or large catalysts. The discount for clean vessels is in line with the policy of the Port of Rotterdam Authority on sustainable port development.