Marine emission legislation
As is the case for all fossil fuel-powered machines, emissions legislation is applicable. For the marine industry this legislation is slowly moving towards more stringent demands for deep sea, coastal and inland vessels. Read more about this legislation in the section below.
The IMO (International Maritime Organization) rules for pollution can be found in the “International Convention on the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978”, also known as MARPOL 73/78 or just MARPOL. The convention was designed to minimize the pollution of the oceans and seas, including dumping, oil and exhaust pollution.
The original convention was designed in 1973, but did never come into force due to a lack of ratification. The current convention is a combination of the original convention from 1973 and the 1978 Protocol and has been in effect since 1983. As of May 2013, 152 states, representing 99.2 per cent of the world's shipping tonnage, are parties to the convention.
The convention has multiple annexes, which all were signed on different dates. Not all participating countries have signed all annexes. Annex VI is titled ‘Regulations for the Prevention of Air Pollution from Ships’ and sets limits on nitrogen oxide (NOₓ) and sulphur oxide (SOₓ) emission from ships.
The IMO emission standards are commonly referred to as Tier standards. The Tier I standards were defined in the 1997 version of Annex VI. Tier I applies retroactively to new engines greater than 130 kW installed on vessels constructed on or after January 1, 2000, or which undergo a major conversion after that date. The regulation also applies to fixed and floating rigs and to drilling platforms (except for emissions associated directly with exploration and/or handling of sea-bed minerals). In anticipation of the Annex VI ratification, most marine engine manufacturers have been building engines compliant with the above standards since 2000.
Tier II and Tier III
The Tier II and Tier III standards were introduced by Annex VI amendments in 2008. The amendments introduced new fuel quality requirements starting from July 2010, Tier II and III NOₓ emission standards for new engines and Tier I NOₓ requirements for engines existing before 2000.
Tier II standards are expected to be met by combustion process optimization. The parameters examined by engine manufacturers include fuel injection timing, pressure, and rate (rate shaping), fuel nozzle flow area, exhaust valve timing, and cylinder compression volume.
Tier III standards are expected to require dedicated NOₓ emission control technologies such as various forms of water induction into the combustion process (with fuel, scavenging air, or in-cylinder), exhaust gas recirculation, or selective catalytic reduction.
ECA - Emission Control Areas
Emission Control Areas (ECA) are areas in certain seas where stricter rules apply to minimise the emission from ships. An Emission Control Area can be designated for SOₓ and PM, NOₓ or all three types of emission.
Current Emission Control Areas are:
- Baltic Sea (SOₓ)
- North Sea (SOₓ)
- North American ECA, including most of the coasts of the United States and Canada (NOₓ and SOₓ)
- US Caribbean ECA, including Puerto Rico and the US Virgin Islands (NOₓ and SOₓ)