Measurements of NOx emissions and in-service duty cycle from a towboat operating on the inland river system.
This paper describes measurements of NOx emissions from one engine on a commercial towboat operating on the Upper Ohio River system around the Port of Pittsburgh. Continuous measurements were made over a one-week period to characterize emissions during normal operations. The average NOx emission factor is 70 +/- 4.2 kg of NOx per t of fuel, similar to that of larger marine engines. A vessel-specific duty cycle is derived to characterize the towboat's operations; more than 50% of the time the vessel engines are at idle. Although recently promulgated EPA regulations apply only to new marine engines, these data provide insight into inland-river operations, which can be used to evaluate these regulations within the inland river context. This vessel operates as a courier service, scheduling pickups and deliveries of single- or multiple-barge loads per customers' requests; as many as 30% of the 277 towboats in the Pittsburgh region operate in this fashion. The EPA-prescribed ISO E3 duty cycle does not accurately describe inland-river operations of this towboat: its application overestimates actual NOx emissions by 14%. Only 41% of this vessel's operations fall within the Not-To-Exceed Zone defined by the EPA regulations, which limits the effectiveness of this component of the regulations to limit emissions from vessels that operate in a similar fashion.
Corbett
J J
JJ
Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Robinson
A L
AL
D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000517:prevention & control; D004784:Environmental Monitoring; D009569:Nitric Oxide / Q000032:analysis*; D011640:Public Policy; D012016:Reference Values; D012767:Ships; D001335:Vehicle Emissions / Q000032:analysis*
D000393:Air Pollutants; D001335:Vehicle Emissions; D009569:Nitric Oxide