Despite new legislation that requires ships to burn low sulphur marine oil in EU and US coastal waters, the economic benefits of continuing to use inexpensive, high-sulphur fuels, combined with the relatively small risk of getting caught, means that many ships are flouting the rules. However, this could be about to change as a real-time, airborne pollution detection system based around a pair of Andor UV spectrographs has been shown to be capable of checking up to 20 ships per hour.
The optical module at the heart of the airborne, remote absorption spectroscopy system was developed by a team from the Department of Earth and Space Sciences at Chalmers University of Technology in Gothenburg, Sweden, led by Professor Johan Mellqvist. From an altitude of 300-400 meters, a pair of Andor Newton cooled CCD cameras and Shamrock UV spectrographs measure reflected solar light from the water surface underneath the ship’s exhaust plume to simultaneously measure SO2 and NO2. The data is paired with information from an Automatic Identification System (AIS) which provides the name and speed of the target ship and can be passed to harbour inspection authorities for follow-up inspection.
“Our compact, experimental instrument pack was designed to be carried in a Piper Navajo light aircraft and could be adapted for most small and inexpensive-to-operate aircraft and helicopters,” says Johan Mellqvist. “This offers the possibility of routine, international, compliance monitoring of ships at sea, which is vital if significant reductions in sulphur and NOx from shipping are to be achieved over the next 10 years.
“The small form factors and low weight of the Andor Newton DU920 camera and Shamrock 303i spectrograph were huge assets for our airborne application but the choice was mainly due to Andor’s high performance levels combined with the comprehensive range of complementary equipment and software. Performance was important to us as we have also used our detection technology from a stationary platform and for remote measurements of industrial emissions,” concludes Mellqvist.
“Ships are one of biggest sources of sulphur dioxide (SO2) emissions in the EU and contribute significantly to ‘acid rain’ in many parts of Europe. Indeed, because of tighter regulations on the use of low sulphur fuels for heating oil and automotive petrol and diesel fuels, ship emissions of SO2 are now equivalent to all land-based emissions from all sources,” according to Antoine Varagnat, Product specialist at Andor. “Combining the Newton camera and Shamrock spectrograph, Johan’s team were able to successfully demonstrate a very sensitive and accurate setup for the rapid identification of gross polluting ships. This powerful technique is enabling his team to implement international surveillance of ships, together with a data repository in Gothenburg, and shows the way for the international community to tackle one more source of global pollution.”