In order to reduce air pollution in the maritime atmosphere, ships must use low-sulphur fuels or exhaust gas cleaning systems (Scrubber) when sailing on the North Sea and Baltic Sea (ship emissions). This is associated with higher operating costs. Some of the ships calling at German ports are inspected by the Water Police and Port State Control (PSC). However, on board inspections of ships are labour intensive and therefore costly. As a result, the number of ships inspected in German ports is limited. In order to increase the hit rate in ship inspections, information on the chemical composition of ship exhaust gases can be used to draw conclusions on the sulphur content of the currently burned fuel. Appropriate measurements of ship plumes are carried out at selected measurement sites near shipping lanes, analysed online and made available to local authorities promptly.
How does this work? The exhaust plume of a ship is transported with the wind to a measurement station on the shore. At the measurement station the plume is measured with highly sensitive air quality monitoring instruments with a temporal resolution of less than one minute. The fuel sulphur content is estimated from the concentrations of the gases sulphur dioxide (SO2), carbon dioxide (CO2) and nitrogen monoxide (NO). For the assignment of a measured plume to a passing ship the additionally recorded wind direction and speed, as well as the ship identity and position is used. Ships have to transmit their identity and current position, the so-called AIS signal (Automatic Identification System), approximately every 30 seconds. If a ship shows a conspicuous exhaust gas composition, an e-mail is automatically sent to the responsible authorities, depending on the ship's destination. The time between a ship passing at a measurement site and the sending of an e-mail is usually less than 2 hours. The measurement and analysis algorithm works completely automatically at a 24/7 basis. In the event of conspicuous but ambiguous measurement situations (e.g. simultaneous passage of several ships), a BSH employee checks the measurements before informing the responsible authorities. This operational method was developed by the University of Bremen as part of the BSH-funded research project MeSMarT (Measurements of shipping emissions in the marine troposphere; www.mesmart.de) and is published here.
The BSH currently operates monitoring stations in the approaches to the ports of Hamburg, Bremerhaven and Kiel. Further stations are planned at the Warnow as well as on authority ships. The BSH cooperates closely with other European countries such as Belgium, the Netherlands, Denmark, Sweden and Finland, which carry out comparable measurements. The aim of the cooperation is to establish a European monitoring network in order to support each other in tracking the use of non-compliant marine fuels.