Is it possible to measure whether an individual ship is emitting too many pollutants into the atmosphere? The Netherlands Human Environment and Transport Inspectorate (ILT) is conducting research to answer this question. In it, a satellite is used to assess emissions and the first results are promising.

ILT is conducting the research together with the Royal Netherlands Meteorological Institute (KNMI) and the universities of Leiden and Wageningen. The researchers have been able to pinpoint the emissions of individual ships; a heavier plume was measured from bigger and faster ships. Being able to assess these differences is necessary for determining whether a ship is adhering to international regulations.

Global monitoring and enforcement

From 2020, seafaring vessels – including those far out at sea – have to meet much lower emission standards for sulphur dioxide. And as of 2021, stricter emission norms for nitrogen oxides take effect for newbuild ships on the North and Baltic Seas.

ILT oversees compliance to these international rules for the Netherlands, but has limited means to monitor a ship once it has left port. If satellites are able to play a part, this will be a massive step forward in global monitoring and enforcement. It will lead to better compliance to air quality regulations, as well as encouraging fairer competition in merchant shipping.

Weather conditions

In the first research study, individual ships’ nitrogen dioxide emissions were monitored under ideal conditions. Daily and global measuring of all vessels’ emissions, and whether they comply with standards, is a massive challenge. Weather conditions or measuring from vessels that sail close to each other is difficult. Moreover, measuring sulphur dioxide is a lot harder than the nitrogen dioxide measured during the research. These are some of the challenges further research will focus on.

In early 2020, ILT started a project aimed at using satellite imagery to monitor the tens of thousands of sea vessels worldwide sailing far out of view from regulators. Ships are required to use cleaner but more expensive fuels, and newbuild vessels have to be equipped with very clean engines.

Picture: Satellite images of measurement results in the Central Mediterranean. The more red the color, the higher the concentrations of nitrogen dioxide. In the middle of the image thin colored (yellow / red) lines are visible; ships on maritime routes. To see further: the coastlines of Italy and Sicily, Greece (top) and North Africa (bottom) with urban and industrial areas such as (from left to right) Tunis, Tripoli, Benghazi and Athens.