Marine emissions modelling

Marine emissions modelling

Shipping steers a clear course on emissions

Pollutants and greenhouse gas emissions from shipping form a significant part of the overall air quality picture and are now included in national and international reporting obligations. Surrounded by some of the world’s busiest shipping lanes the UK is a particular focus, and Ricardo has been commissioned to deliver a comprehensive update of the shipping emissions inventory for the UK National Atmospheric Emissions Inventory.

The 2015 Paris Agreement on Climate Change, reinforced a year later at the climate summit in Marrakech, has been the starting point for significant additional moves to help limit international greenhouse gas (GHG) emissions. At the highest strategic level some 200 nations agreed to measure, report and verify their emissions of GHGs: by cataloguing emissions from activities such as industry, agriculture, power generation and transport, countries establish their individual national GHG inventories, the first step towards applying targeted reductions. Ricardo has been involved in such strategic initiatives for many countries.

On a more detailed level, Ricardo’s work also includes running the UK’s National Atmospheric Emissions Inventory (NAEI). Although the inventories that countries have to report under the Paris agreement do not need to include international shipping, for some nations – especially island states such as the UK that are on busy shipping lanes – the reporting  of purely inland sources is insufficient to provide a complete picture of atmospheric pollutants. Such is the intensity of shipping around Britain, through the English Channel and around some UK ports, that emissions that occur at sea are likely to have a significant effect on air quality in coastal communities on land; they can make a sizeable contribution inland too. 
Ricardo’s analysis, in conjunction with project partner University College London Consultants, has addressed several drawbacks to the existing maritime inventories – principally that they were based on estimated rather than actual routes taken by ships, that they did not take account of variation in vessels’ engine loads or speeds, and that they failed to capture certain types of craft, especially fishing vessels, offshore fleet and service vessels.

Reviewing the available options, Ricardo and its partners opted for an entirely new methodology relying on AIS (Automatic Identification System) data from the UK’s Maritime and Coastguard Agency. AIS uses VHF radio signals to report vessels’ positions and identify them. The AIS messages are sent up to every three seconds, and the messages are received directly by other vessels and by the AIS receivers operated by the UK Coastguard. AIS messages also provide additional information on the speed of the vessel among other parameters. This, says Scarbrough, enables very precise plotting of ships’ courses and speeds, pollutants with the high degree of granularity that is essential to understanding the effects of maritime emissions on the air quality of coastal cities such as Southampton. One year’s worth of stored AIS data was used.

The Ricardo maritime air quality work comes in the context of growing international concern over pollution at sea, be it in the atmosphere or in the water. Ricardo’s water practice offers expertise on monitoring port water quality for environmental permit compliance, while on the engineering side of the business Ricardo specialists in large marine engines are working at the forefront of technical developments.