A recent working paper by the International Council on Clean Transportation has revealed concerning levels of nitrogen oxide (NOx) emissions from ships. The study analyzed real emissions from 545 ships in Danish waters, using helicopter-mounted sniffers to collect data. Surprisingly, the results showed that newer Tier II engines had higher NOx emission rates than older Tier I engines, with no significant difference between unregulated Tier 0 engines and Tier II engines. The highest mean NOx emission rates were observed at main engine loads below 25%, contradicting existing assumptions in NOx test cycles for marine engines.
The study suggests that current NOx regulations may need to be revised to effectively reduce air pollution. The authors call on the International Maritime Organization to consider adopting not-to-exceed (NTE) standards for both new and existing ships, focusing on off-peak operations. Furthermore, the importance of including a test point below 25% load in future regulations is emphasized.
These findings demonstrate the need for stricter measures to combat ship emissions and protect air quality in coastal areas. Addressing the issue of NOx pollution from ships is crucial in the efforts to combat climate change and promote sustainable maritime practices.