CARB Low NO _X Stage 3 Program - Aftertreatment Evaluation and Down Selection

With the conclusion of the California Air Resources Board (CARB) Stage 1 Ultra-Low NO_X program, there continues to be a commitment for identifying potential pathways to demonstrate 0.02 g/hp-hr NO_X emissions. The Stage 1 program focused on achieving the Ultra-Low NO_X (ULN) levels utilizing a turbo-compound (TC) engine, which required the integration of novel catalyst technologies and a supplemental heat source. While the aftertreatment configuration provided a potential solution to meet the ULN target, a complicated approach was required to overcome challenges from low temperature exhaust. The Stage 3 program leverages a different engine architecture more representative of the broader heavy-duty industry to meet the Phase 2 Greenhouse Gas (GHG) targets and to simplify the ULN aftertreatment solution. The following work will discuss the aftertreatment technology evaluation, down selection criteria, and the emission results for the candidate ULN systems