Web Alert: California - Auxiliary diesel engine enforcement (1 January 2017)

News & Insights 23 December 2016


The California Air Resources Board (CARB) issued an advisory on enforcement of the Airborne Toxic Control Measure for Auxiliary Diesel Engines Operated on Ocean – Going Vessels at Berth in a California Port from 1 January 2017.

The California Air Resources Board (CARB) issued an advisory on enforcement of the Airborne Toxic Control Measure for Auxiliary Diesel Engines Operated on Ocean – Going Vessels at Berth in a California Port from 1 January 2017.

ARB’s At-Berth Regulation is intended to reduce emissions of diesel particulate matter (PM) and oxides of nitrogen (NOx) from auxiliary engines on ocean-going vessels while at-berth at California ports.

Fleets can comply through one of two paths: the Reduced Onboard Power Generation Option (that relies on use of shore-based electrical power), or the alternative Equivalent Emissions Reduction Option.

The Regulation requires fleets complying under the Reduced Onboard Power Generation Option to satisfy the following two criteria beginning on January 1, 2017:

  • Visits: At least 70 percent of a fleet’s visits to a port must satisfy the following limit on engine operation: for each visit, the auxiliary engines on the vessel cannot operate for more than three hours during the entire time the vessel is at-berth (e.g., a shore power visit); and
  • Power Reductions: The fleet’s total onboard auxiliary engine power generation must be reduced by at least 70 percent from the fleet’s baseline power generation.


Fleets that comply under the Equivalent Emission Reduction Option pathway must reduce NOx and PM by 70% or more through use of an ARB-approved technology.

On January 1, 2020, the requirements under the existing regulation increase to 80 percent for the visit, power reduction, and equivalent emission reduction requirements.

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