11 August 1999
Caterpillar announced that all marine CAT engines offered as of 1 January 2000 will meet IMO certification requirements for NOx emissions limits. While complying with the emission standar, Caterpillar said it will make sure that all popular CAT marine engine ratings will continue to be offered and the potential performance impacts incurred to bring engines into compliance will be minimized.
IMO developed an international agreement, MARPOL 73/78, which regulates all types of ship generated pollution. Annex VI of this agreement regulates NOx emissions from ships. The IMO regulation will go into effect on 1 January 2000. The regulation, which applies to both commercial boats and pleasure craft with engines over 174 bhp (130 bkW), requires that nitrogen oxide (NOx) emissions be kept under a specified level on propulsion engines, auxiliary engines and marine generator sets.
The regulation comes from the International Maritime Organization (IMO). IMO is a United Nations agency responsible for maritime safety and pollution prevention. It consists of 156 member states representing over 95% of the world’s shipping tonnage.
Although compliance with the IMO Annex VI NOx standard is formally not required, engine manufacturers and ship operators anticipate that it will be eventually ratified and enforced in the USA and other countries. The IMO NOx regulations will not "enter into force" until ratified by at least 15 countries representing 50% of the world’s merchant shipping tonnage. Upon ratification the regulations will be enforced retroactive to 1 January 2000. The IMO goal is to have protocol ratified by 31 December 2002. Enforcement agencies will vary from country to country. In the USA, the Environmental Protection Agency (EPA) and US Coast Guard will be the enforcing agencies. In other countries, the local government's regulatory agency, or in some cases, marine classification societies, will enforce the regulations.