Tier III air pollution regulations require the reduction of NOx emissions by 80 percent from existing Tier I limits during operation in ECAs such as North American coastal waters and the U.S. Caribbean Sea and will apply to marine diesel engines of over 130 kW output power and installed from 1 January 2016 onwards (except for the engines of certain recreational vessels). Whilst many see the widespread installation of liquefied natural gas (LNG) powered units as a cure all, for many the development costs and other factors may make the technology impractical.

A solution to the problem of reducing noxious emissions is currently being tested aboard the two A.P. Moller-Maersk vessels the Alexander Maersk and the Maersk Cardiff and involves the use of Exhaust Gas Recirculation (EGR) technology developed by MAN Diesel & Turbo with the support of the Marine Division at Alfa Laval. EGR, which involves the recirculation of exhaust gas, is one of two technologies being developed to meet Tier III NOx limits without resorting to liquefied natural gas. Unlike Selective Catalytic Reduction, which is an after-treatment technology that removes NOx with the help of a catalyst, EGR is integrated into the engine and prevents the formation of NOx during combustion.

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