Determination of NO_x emission rates of inland ships from onshore measurements

Abstract

Abstract. Inland ships are an important source of NOx, especially for cities along busy waterways. The amount and effect of such emissions depend on the traffic density and NOx emission rates of individual vessels. Ship emission rates are typically derived using in situ land measurements in relation to NOx emission factors (e.g. the number of pollutants emitted by ships per unit of burnt fuel). In this study, a different approach is taken, and NOx emission rates are obtained (in g s−1). Within the EU LIFE project, CLean INland SHipping (CLINSH), a new approach to calculating the NOx emission rates from data of in situ measurement stations has been developed and is presented in this study. Peaks (i.e. elevated concentrations) of NOx were assigned to the corresponding source ships, using the AIS (automated identification system) signals they transmit. Each ship passage was simulated, using a Gaussian puff model, in order to derive the emission rate of the respective source ship. In total, over 32 900 ship passages have been monitored over the course of 4 years. The emission rates of NOx were investigated with respect to ship speed, ship size, and direction of travel. Comparisons of the onshore-derived emission rates and those on board for selected CLINSH ships show good agreement. The derived emission rates are of a similar magnitude to emission factors from previous studies. Most ships comply with existing limits due to grandfathering. The emission rates (in g s−1) can be directly used to investigate the effect of ship traffic on air quality, as the absolute emitted number of pollutants per unit of time is known. In contrast, for relative emission factors (in g kg−1 fuel), further knowledge about the fuel consumption of the individual ships is needed to calculate the number of pollutants emitted per unit of time.

Identification and detection of high NO x emitting inland ships using multi-source shore-based monitoring data

“…where, C measured represents the area under the peak concentration measured at the monitoring site, and C simulated represents the area under the peak concentration simulated by the dispersion model. Utilizing the peak area proves to be a more dependable metric than the peak maximum, as it considers the overall quantity of pollutants reaching the measurement site (Krause et al 2023). Furthermore, the ship emission rates, measured in g s −1 , are converted to ship EFs (EF) in g kWh −1…”

“…Similarly, this method can also be applied to the identification of high-emission ships. There are various methods for testing ship EFs, including bench testing (Geng et al 2016), on-board testing (Yang et al 2022, Fan et al 2023, and plume testing (Zhao et al 2013, Ekmekçioglu et al 2020, Krause et al 2023. Bench testing is conducted in controlled environments using high-precision instruments, yielding accurate results but struggling to reflect the emission characteristics of marine engines under actual navigation conditions (Fan et al 2023).…”

“…However, they require expensive instruments and intricate manual operations, and can only measure individual ships, limiting the potential for screening conventional high-emission ships under real-world conditions. Shore-based plume testing is an indirect method that involves capturing ship plumes diffusing in the atmosphere using sensors (Contini et al 2011, Krause et al 2023. Compared to bench testing and on-board testing, shore-based monitoring methods offer the advantage of automated snapshot measurements, enabling data collection over a broader range and improving screening efficiency.…”

Assessment of the Effect of International Maritime Regulations on Air Quality in the Southern North Sea

“…To determine these factors three special gas mixtures, containing SO2 and CO2 in different levels were used to imitate exhaust plume of different FSC levels (Figure 1). The NOx emission factor (EFNOx) in g NOx/kg fuel are calculated similarly to the FSC using the background and plume NOx and CO2 concentrations [51,53,56,58].…”

Measurement report: Inland ship emissions and their contribution to NOx and ultrafine particle concentrations at the Rhine

“…Shipping is a potential contributor to air pollution in coastal regions, harbors and along inland waterways with high traffic density (Eyring et al, 2010;Viana et al, 2014;Karl et al, 2019;Tang et al, 2020;Fink et al, 2023). In western Europe, where a large number of goods are transported on rivers and canals, inland ships can increase nitrogen oxides (NO x = NO + NO 2 ), particulate matter (PM), aerosol black carbon (BC) and ultrafine particle (UFP) concentrations on a local scale (Uherek et al, 2010;Van der Gon and Hulskotte, 2010;Keuken et al, 2014;Kurtenbach et al, 2016;Pohl et al, 2017;Krause et al, 2023). In particular the Rhine as Europe's most important waterway in terms of transport volume is of major significance as it connects densely populated cities where people are often exposed to air pollution from road transport, industry and residential heating (Uherek et al, 2010;WHO, 2021).…”