Monitoring compliance with fuel sulfur content regulations of sailing ships by unmanned aerial vehicle (UAV) measurements of ship emissions in open water

Abstract

Abstract. Due to technical and cost limitations, the monitoring of emissions from ships sailing in open water within the ship emission control areas (ECAs) is relatively rare. The present study adopts a monitoring method that uses an unmanned aerial vehicle (UAV) that takes off from a patrol boat to measure the sulfur dioxide and carbon dioxide emissions from sailing ships. Our method aims to provide a low-cost, remote approach for estimating the fuel sulfur content (FSC) of sailing ships in open water, which overcomes the limitations of ground-based and small aircraft methods. The selected monitoring area was the Yangtze River estuary, a domestic ECA with an FSC limit of 0.5 % (m/m) implemented by the Chinese government. A total of 27 sailing ships were monitored, 14 of which were found to have an FSC of > 0.5 % (m/m). Moreover, the FSCs of the sailing ships were found to be higher than those of berthing ships in the study area. According to the monitoring results, four of the monitored ships were intercepted by the maritime law enforcement, and fuel samples were collected and analyzed in a laboratory; the results confirmed that all four FSCs were > 0.5 % (m/m). Among them, one offending ship was tracked down on July 15, 2019, which was the first time that a sailing ship had been caught for having failed the FSC regulations in China. Overall, the present study provides scientific support for evaluating the effectiveness of ECA policies, and recommends that emissions from sailing ships should be monitored more often in the open water in the future.

Tracking and measuring plumes from sailing ships using an unmanned aerial vehicle

“…We designed and developed a UAV monitoring system to estimate the FSC based on ship exhaust measurements. This system uses the monitoring process (Section 2) to track and measure the plumes of sailing ships and accurately measures the FSC based on the principle of the 'sniffing' method [23,24]. The following subsections introduce the experimental process and results.…”

“…Of these, 27 measurements produced valid data. Based on the measured SO 2 and CO 2 concentrations, the FSC of each ship was estimated using the principle of the 'sniffing' method [23,24]. The unsuccessful measurements (n > 10) were mainly due to excessive wind speed or low ship emissions.…”

“…Some scholars have proposed estimating FSC by measuring ship plumes. The measuring methods for ship plumes can be divided according to the following platforms: (i) land-based [12][13][14], (ii) airborne [15,16], (iii) ship-based [17,18], (iv) patrol boat-based [19], (v) satellite-based [20,21], and (vi) unmanned aerial vehicle (UAV)-based [22][23][24]. Each plume measurement method has its own merits and scope of application based on the associated cost, specific environment, and various other requirements.…”