Caterpillar prepares for EPA Tier 4 with SCR

EPA Tier 4 has applied to all US-flagged vessels since January 2014, while IMO Tier NOx limits will apply to all vessels within NOx Emission Control Areas from January 2016.

Nathan Kelly, production definition engineer, Caterpillar Marine, said: “We have more than 160,000 Tier 4 Final and Interim engines in land-based operations using various NOx-reduction technologies. In marine applications, we specifically chose the best technology to fit the needs of our industry. We view SCR as the preferred option for the commercial marine industry.”

Caterpillar noted that reducing lifecycle costs was a key focus of the upgrade. It said the Tier 4 engines can run at optimal fuel efficiency because the SCR system is in place to reduce the higher NOx output. Any concerns about the cost of diesel exhaust fluid (DEF) – used to process NOx into nitrogen and water – are more than offset by the improved fuel efficiency achieved with SCR technology, the company added.

Kelly added: “Unlike some other NOx reduction technologies, our engines operate without interruption even in the event of SCR failure or running out of DEF. There is no effect on engine operation.”

The engines are available in eight, twelve and sixteen-cylinder models ranging from 2,300-5,060kW. They can be used either as main engines or as auxiliary generator sets.