Measurement of SO2 and NO2 in ship plumes using rotary unmanned aerial system

Abstract

A key research problem in the field of ship emissions is how to perform efficient, accurate, and timely measurements of pollutant gases in a ship's plume. To address this, we have designed and implemented an unmanned aerial system (UAS) that consists of a rotary unmanned aerial vehicle (UAV), a lightweight pod for exhaust monitoring, and a mobile control terminal. The UAV carries the pod and a camera and can fly into a plume at close range. The pod is equipped with a gas acquisition module, SO2 and NO2 sensors, and communication modules to measure the gases in real time. The mobile control terminal is convenient for operators and receives real-time video and measured gas concentrations. We measured SO2 and NO2 in six ship plumes in 2018 to verify the effectiveness and accuracy of the UAS. The SO2/NO2 ratios in high-sulfur fuel were significantly higher than of those in low-sulfur fuel and can thus be used for distinguishing the sulfur content of ship fuel. In comparison to land-based and airborne-based measurements, we conclude that the UAS provides an active, close-range, low-cost, and accurate measurement approach for monitoring ship emissions in real time.