The International Council on Clean Transportation (ICCT) has issued a publication which highlights the need to revise the IMO’s NOx Technical Code 2008 (NTC 2008).
According to ICCT, the International Maritime Organization’s (IMO) NOx Technical Code 2008 (NTC 2008) is an important tool for certifying marine engines’ compliance with nitrogen oxides (NOx) emission limits. However, this code may not accurately reflect the operational realities of modern shipping.
The analysis shows that existing IMO NOx weighting factors are not representative of real-world engine operations, as estimated using AIS-derived main engine load factors, and the certified emission factors likely differ from actual emission rates. Revising the NTC 2008 to add a low-load test point of 10% for main engines, replacing the 100% engine load test point with 90%, and adjusting the weighting factors to approximate real-world engine operations has two main benefits. First, it regulates emissions at low engine loads, which is important for protecting near-shore air quality.
Second, it would more closely align certified emission factors with actual values, not only for NOX but also for other pollutants such as methane and nitrous oxide, which will be important as ships comply with upcoming IMO climate regulations.
By amending the NTC 2008 so that it more closely aligns with current operational realities, the IMO can ensure that its regulations effectively address NOx emissions and pave the way for more comprehensive environmental protections if the NTC is used to certify engines for methane (CH4) and nitrous oxide (N2O) emissions from LNG-fueled and ammonia-fueled engines, respectively.
Key findings
- The NTC 2008 test cycle is not representative of real-world engine operations
- Low engine load operations are more frequent than previously recognized
Policy recommendations
- Introduce a new low-load test point at 10% engine load.
- Adjust the maximum engine load test point from 100% to 90%.
- Revise the weighting factors to better align with real-world engine operations:
- 10% load: 0.15
- 25% load: 0.30
- 50% load: 0.40
- 75% load: 0.10
- 90% load: 0.05
