2.3 Marine Vessels

    Category ID Description EIC
    1769 Commercial Harbor Crafts - Crew & Supply - Aux. Engine 83585112109971
    1770 Commercial Harbor Crafts - Crew & Supply - Main Engine 83585112109981
    1771 Commercial Harbor Crafts - Excursion Ves. - Aux Engine 83585312109971
    1772 Commercial Harbor Crafts - Excursion Ves. - Main Engine 83585312109981
    1773 Commercial Harbor Crafts - Fishing Ves. Charter - Aux. Engine 83585712109971
    1774 Commercial Harbor Crafts - Fishing Ves. Charter - Main Engine 83585712109981
    1775 Commercial Harbor Crafts - Fishing Ves. Com. - Aux. Engine 83585912109971
    1776 Commercial Harbor Crafts - Fishing Ves. Com. - Main Engine 83585912109981
    1777 Commercial Harbor Crafts - Other Ves. Aux. Engine 83586212109971
    1778 Commercial Harbor Crafts - Other Ves. - Main Engine 83586212109981
    1779 Commercial Harbor Crafts - Pilot Ves. - Aux Engine 83586312109971
    1780 Commercial Harbor Crafts - Pilot Ves. - Main Engine 83586312109981
    1781 Commercial Harbor Crafts - Tow Boat-Auxiliary Engine 83586512109971
    1782 Commercial Harbor Crafts - Tow Boat - Main Engine 83586512109981
    1783 Commercial Harbor Crafts - Tug Boat - Aux. Engine 83586612109972
    1784 Commercial Harbor Crafts - Tug Boat - Main Engine 83586612109983
    1785 Commercial Harbor Crafts - Work Boat - Aux. Engine 83586712109971
    1786 Commercial Harbor Crafts - Work Boat - Main Engine 83586712109981
    2041 Ships Anchorage - Auto Carrier - Aux. Engine - SFAB - distillate fuel 83383112109974
    2042 Ships Anchorage - Auto Carrier - Boiler - SFAB - distillate fuel 83383112109994
    2043 Ships Anchorage - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 83383312109974
    2044 Ships Anchorage - Bulk Cargo - Boiler - SFAB - distillate fuel 83383312109994
    2045 Ships Anchorage - Container Ship - Aux. Engine - SFAB - distillate fuel 83383512109974
    2046 Ships Anchorage - Container Ship - Boiler - SFAB - distillate fuel 83383512109994
    2047 Ships Anchorage - General Cargo - Aux. Engine - SFAB - distillate fuel 83383712109974
    2048 Ships Anchorage - General Cargo - Boiler - SFAB - distillate fuel 83383712109994
    2049 Ships Anchorage - Passenger Ship - Aux. Engine - SFAB - distillate fuel 83384112109974
    2050 Ships Anchorage - Passenger Ship - Boiler - SFAB - distillate fuel 83384112109994
    2053 Ships Anchorage - Tanker - Aux. Engine - SFAB - distillate fuel 83384712109974
    2054 Ships Anchorage - Tanker - Boiler - SFAB - distillate fuel 83384712109994
    2057 Ships Anchorage - Auto Carrier - Aux. Engine - SFAB - residual fuel 83383115009974
    2058 Ships Anchorage - Auto Carrier - Boiler - SFAB - residual fuel 83383115009994
    2059 Ships Anchorage - Bulk Cargo - Aux. Engine - SFAB - residual fuel 83383315009974
    2060 Ships Anchorage - Bulk Cargo - Boiler - SFAB - residual fuel 83383315009994
    2061 Ships Anchorage - Container Ship - Aux. Engine - SFAB - residual fuel 83383515009974
    2062 Ships Anchorage - Container Ship - Boiler - SFAB - residual fuel 83383515009994
    2063 Ships Anchorage - General Cargo - Aux. Engine - SFAB - residual fuel 83383715009974
    2064 Ships Anchorage - General Cargo - Boiler - SFAB - residual fuel 83383715009994
    2065 Ships Anchorage - Passenger Ship - Aux. Engine - SFAB - residual fuel 83384115009974
    2066 Ships Anchorage - Passenger Ship - Boiler - SFAB - residual fuel 83384115009994
    2067 Ships Anchorage - Tanker - Aux. Engine - SFAB - residual fuel 83384715009974
    2068 Ships Anchorage - Tanker - Boiler - SFAB - residual fuel 83384715009994
    2073 Ships Hotelling - Auto Carrier - Aux. Engine - SFAB - distillate fuel 83383112109972
    2074 Ships Hotelling - Auto Carrier - Boiler - SFAB - distillate fuel 83383112109992
    2075 Ships Hotelling - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 83383312109972
    2076 Ships Hotelling - Bulk Cargo - Boiler - SFAB - distillate fuel 83383312109992
    2077 Ships Hotelling - Container Ship - Aux. Engine - SFAB - distillate fuel 83383512109972
    2078 Ships Hotelling - Container Ship - Boiler - SFAB - distillate fuel 83383512109992
    2079 Ships Hotelling - General Cargo - Aux. Engine - SFAB - distillate fuel 83383712109972
    2080 Ships Hotelling - General Cargo - Boiler - SFAB - distillate fuel 83383712109992
    2081 Ships Hotelling - Passenger Ship - Aux. Engine - SFAB - distillate fuel 83384112109972
    2082 Ships Hotelling - Passenger Ship - Boiler - SFAB - distillate fuel 83384112109992
    2083 Ships Hotelling - Ro/Ro - Aux. Engine - SFAB - distillate fuel 83384512109972
    2084 Ships Hotelling - Ro/Ro - Boiler - SFAB - distillate fuel 83384512109992
    2085 Ships Hotelling - Tanker - Aux. Engine - SFAB - distillate fuel 83384712109972
    2086 Ships Hotelling - Tanker - Boiler - SFAB - distillate fuel 83384712109992
    2087 Ships Hotelling - Misc. Vessel - Aux. Engine - SFAB - distillate fuel 83384912109972
    2088 Ships Hotelling - Misc. Vessel - Boiler - SFAB - distillate fuel 83384912109992
    2089 Ships Hotelling - Auto Carrier - Aux. Engine - SFAB - residual fuel 83383115009972
    2090 Ships Hotelling - Auto Carrier - Boiler - SFAB - residual fuel 83383115009992
    2091 Ships Hotelling - Bulk Cargo - Aux. Engine - SFAB - residual fuel 83383315009972
    2092 Ships Hotelling - Bulk Cargo - Boiler - SFAB - residual fuel 83383315009992
    2093 Ships Hotelling - Container Ship - Aux. Engine - SFAB - residual fuel 83383515009972
    2094 Ships Hotelling - Container Ship - Boiler - SFAB - residual fuel 83383515009992
    2095 Ships Hotelling - General Cargo - Aux. Engine - SFAB - residual fuel 83383715009972
    2096 Ships Hotelling - General Cargo - Boiler - SFAB - residual fuel 83383715009992
    2097 Ships Hotelling - Passenger Ship - Aux. Engine - SFAB - residual fuel 83384115009972
    2098 Ships Hotelling - Passenger Ship - Boiler - SFAB - residual fuel 83384115009992
    2099 Ships Hotelling - Ro/Ro - Aux. Engine - SFAB - residual fuel 83384515009972
    2100 Ships Hotelling - Ro/Ro - Boiler - SFAB - residual fuel 83384515009992
    2101 Ships Hotelling - Tanker - Aux. Engine - SFAB - residual fuel 83384715009972
    2102 Ships Hotelling - Tanker - Boiler - SFAB - residual fuel 83384715009992
    2103 Ships Hotelling - Misc. Vessel - Aux. Engine - SFAB - residual fuel 83384915009972
    2104 Ships Hotelling - Misc. Vessel - Boiler - SFAB - residual fuel 83384915009992
    2105 Ships Maneuvering - Auto Carrier - Aux. Engine - SFAB - distillate fuel 83383112109973
    2106 Ships Maneuvering - Auto Carrier - Main Engine - SFAB - distillate fuel 83383112109983
    2107 Ships Maneuvering - Auto Carrier - Boiler - SFAB - distillate fuel 83383112109993
    2108 Ships Maneuvering - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 83383312109973
    2109 Ships Maneuvering - Bulk Cargo - Main Engine - SFAB - distillate fuel 83383312109983
    2110 Ships Maneuvering - Bulk Cargo - Boiler - SFAB - distillate fuel 83383312109993
    2111 Ships Maneuvering - Container Ship - Aux. Engine - SFAB - distillate fuel 83383512109973
    2112 Ships Maneuvering - Container Ship - Main Engine - SFAB - distillate fuel 83383512109983
    2113 Ships Maneuvering - Container Ship - Boiler - SFAB - distillate fuel 83383512109993
    2114 Ships Maneuvering - General Cargo - Aux. Engine - SFAB - distillate fuel 83383712109973
    2115 Ships Maneuvering - General Cargo - Main Engine - SFAB - distillate fuel 83383712109983
    2116 Ships Maneuvering - General Cargo - Boiler - SFAB - distillate fuel 83383712109993
    2117 Ships Maneuvering - Passenger Ship - Aux. Engine - SFAB - distillate fuel 83384112109973
    2118 Ships Maneuvering - Passenger Ship - Main Engine - SFAB - distillate fuel 83384112109983
    2119 Ships Maneuvering - Passenger Ship - Boiler - SFAB - distillate fuel 83384112109993
    2120 Ships Maneuvering - Ro/Ro - Aux. Engine - SFAB - distillate fuel 83384512109973
    2121 Ships Maneuvering - Ro/Ro - Main Engine - SFAB - distillate fuel 83384512109983
    2122 Ships Maneuvering - Ro/Ro - Boiler - SFAB - distillate fuel 83384512109993
    2123 Ships Maneuvering - Tanker - Aux. Engine - SFAB - distillate fuel 83384712109973
    2124 Ships Maneuvering - Tanker - Main Engine - SFAB - distillate fuel 83384712109983
    2125 Ships Maneuvering - Tanker - Boiler - SFAB - distillate fuel 83384712109993
    2126 Ships Maneuvering - Misc. Vessel - Aux. Engine - SFAB - distillate fuel 83384912109973
    2127 Ships Maneuvering - Misc. Vessel - Main Engine - SFAB - distillate fuel 83384912109983
    2128 Ships Maneuvering - Misc. Vessel - Boiler - SFAB - distillate fuel 83384912109993
    2129 Ships Maneuvering - Auto Carrier - Aux. Engine - SFAB - residual fuel 83383115009973
    2130 Ships Maneuvering - Auto Carrier - Main Engine - SFAB - residual fuel 83383115009983
    2131 Ships Maneuvering - Auto Carrier - Boiler - SFAB - residual fuel 83383115009993
    2132 Ships Maneuvering - Bulk Cargo - Aux. Engine - SFAB - residual fuel 83383315009973
    2133 Ships Maneuvering - Bulk Cargo - Main Engine - SFAB - residual fuel 83383315009983
    2134 Ships Maneuvering - Bulk Cargo - Boiler - SFAB - residual fuel 83383315009993
    2135 Ships Maneuvering - Container Ship - Aux. Engine - SFAB - residual fuel 83383515009973
    2136 Ships Maneuvering - Container Ship - Main Engine - SFAB - residual fuel 83383515009983
    2137 Ships Maneuvering - Container Ship - Boiler - SFAB - residual fuel 83383515009993
    2138 Ships Maneuvering - General Cargo - Aux. Engine - SFAB - residual fuel 83383715009973
    2139 Ships Maneuvering - General Cargo - Main Engine - SFAB - residual fuel 83383715009983
    2140 Ships Maneuvering - General Cargo - Boiler - SFAB - residual fuel 83383715009993
    2141 Ships Maneuvering - Passenger Ship - Aux. Engine - SFAB - residual fuel 83384115009973
    2143 Ships Maneuvering - Passenger Ship - Boiler - SFAB - residual fuel 83384115009993
    2144 Ships Maneuvering - Ro/Ro - Aux. Engine - SFAB - residual fuel 83384515009973
    2145 Ships Maneuvering - Ro/Ro - Main Engine - SFAB - residual fuel 83384515009983
    2146 Ships Maneuvering - Ro/Ro - Boiler - SFAB - residual fuel 83384515009993
    2147 Ships Maneuvering - Tanker - Aux. Engine - SFAB - residual fuel 83384715009973
    2148 Ships Maneuvering - Tanker - Main Engine - SFAB - residual fuel 83384715009983
    2149 Ships Maneuvering - Tanker - Boiler - SFAB - residual fuel 83384715009993
    2150 Ships Maneuvering - Misc. Vessel - Aux. Engine - SFAB - residual fuel 83384915009973
    2151 Ships Maneuvering - Misc. Vessel - Main Engine - SFAB - residual fuel 83384915009983
    2152 Ships Maneuvering - Misc. Vessel - Boiler - SFAB - residual fuel 83384915009993
    2195 Ships in Transit - Refrig. Cargo - Aux. Engine - OC1, OC2 - distillate fuel 83384312109975
    2196 Ships in Transit - Refrig. Cargo - Main Engine - OC1, OC2 - distillate fuel 83384312109985
    2213 Ships in Transit - Refrig. Cargo - Aux. Engine - OC1, OC2 - residual fuel 83384315009975
    2214 Ships in Transit - Refrig. Cargo - Main Engine - OC1, OC2 - residual fuel 83384315009985
    2633 Ships in Transit - Auto Carrier - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83383112109975
    2634 Ships in Transit - Auto Carrier - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83383115009975
    2635 Ships in Transit - Auto Carrier - Main Engine - SFAB, OC1, OC2 - distillate fuel 83383112109985
    2636 Ships in Transit - Auto Carrier - Main Engine - SFAB, OC1, OC2 - residual fuel 83383115009985
    2637 Ships in Transit - Bulk Cargo - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83383312109975
    2638 Ships in Transit - Bulk Cargo - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83383315009975
    2639 Ships in Transit - Bulk Cargo - Main Engine - SFAB, OC1, OC2 - distillate fuel 83383312109985
    2640 Ships in Transit - Bulk Cargo - Main Engine - SFAB, OC1, OC2 - residual fuel 83383315009985
    2641 Ships in Transit - Container Ship - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83383512109975
    2642 Ships in Transit - Container Ship - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83383515009975
    2643 Ships in Transit - Container Ship - Main Engine - SFAB, OC1, OC2 - distillate fuel 83383512109985
    2644 Ships in Transit - Container Ship - Main Engine - SFAB, OC1, OC2 - residual fuel 83383515009985
    2645 Ships in Transit - General Cargo - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83383712109975
    2646 Ships in Transit - General Cargo - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83383715009975
    2647 Ships in Transit - General Cargo - Main Engine - SFAB, OC1, OC2 - distillate fuel 83383712109985
    2648 Ships in Transit - General Cargo - Main Engine - SFAB, OC1, OC2 - residual fuel 83383715009985
    2649 Ships in Transit - Misc. Vessel - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83383912109975
    2650 Ships in Transit - Misc. Vessel - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83384915009975
    2651 Ships in Transit - Misc. Vessel - Main Engine - SFAB, OC1, OC2 - distillate fuel 83384912109985
    2652 Ships in Transit - Misc. Vessel - Main Engine - SFAB, OC1, OC2 - residual fuel 83384915009985
    2653 Ships in Transit - Passenger Ship - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83384112109975
    2654 Ships in Transit - Passenger Ship - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83384115009975
    2655 Ships in Transit - Passenger Ship - Main Engine - SFAB, OC1, OC2 - distillate fuel 83384112109985
    2656 Ships in Transit - Passenger Ship - Main Engine - SFAB, OC1, OC2 - residual fuel 83384115009985
    2657 Ships in Transit - Ro/Ro - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83384512109975
    2658 Ships in Transit - Ro/Ro - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83384515009975
    2659 Ships in Transit - Ro/Ro - Main Engine - SFAB, OC1, OC2 - distillate fuel 83384512109985
    2660 Ships in Transit - Ro/Ro - Main Engine - SFAB, OC1, OC2 - residual fuel 83384515009985
    2661 Ships in Transit - Tanker - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 83384712109975
    2662 Ships in Transit - Tanker - Aux. Engine - SFAB, OC1, OC2 - residual fuel 83384715009975
    2663 Ships in Transit - Tanker - Main Engine - SFAB, OC1, OC2 - distillate fuel 83384712109985
    2664 Ships in Transit - Tanker - Main Engine - SFAB, OC1, OC2 - residual fuel 83384715009985
    2766 Commercial Harbor Crafts - Barge/Dredge - Aux. Engine 83586812109971
    2767 Commercial Harbor Crafts - Barge/Dredge - Main Engine 83586812109981
    2768 Commercial Harbor Crafts - Ferry - Aux. Engine 83585512109971
    2769 Commercial Harbor Crafts - Ferry - Main Engine 83585512109981
    2770 Ships in Transit - Auto Carrier - Boiler - SFAB, OC1, OC2 - distillate fuel 83383112109995
    2771 Ships in Transit - Auto Carrier - Boiler - SFAB, OC1, OC2 - residual fuel 83383115009995
    2772 Ships in Transit - Bulk Cargo - Boiler - SFAB, OC1, OC2 - distillate fuel 83383312109995
    2773 Ships in Transit - Bulk Cargo - Boiler - SFAB, OC1, OC2 - residual fuel 83383315009995
    2774 Ships in Transit - Container Ship - Boiler - SFAB, OC1, OC2 - distillate fuel 83383512109995
    2775 Ships in Transit - Container Ship - Boiler - SFAB, OC1, OC2 - residual fuel 83383515009995
    2776 Ships in Transit - General Cargo - Boiler - SFAB, OC1, OC2 - distillate fuel 83383712109995
    2777 Ships in Transit - General Cargo - Boiler - SFAB, OC1, OC2 - residual fuel 83383715009995
    2778 Ships in Transit - Misc. Vessel - Boiler - SFAB, OC1, OC2 - distillate fuel 83384912109995
    2779 Ships in Transit - Misc. Vessel - Boiler - SFAB, OC1, OC2 - residual fuel 83384915009995
    2780 Ships in Transit - Passenger Ship - Boiler - SFAB, OC1, OC2 - distillate fuel 83384112109995
    2781 Ships in Transit - Passenger Ship - Boiler - SFAB, OC1, OC2 - residual fuel 83384115009995
    2782 Ships in Transit - Ro/Ro - Boiler - SFAB, OC1, OC2 - distillate fuel 83384512109995
    2783 Ships in Transit - Ro/Ro - Boiler - SFAB, OC1, OC2 - residual fuel 83384515009995
    2784 Ships in Transit - Tanker - Boiler - SFAB, OC1, OC2 - distillate fuel 83384712109995
    2785 Ships in Transit - Tanker - Boiler - SFAB, OC1, OC2 - residual fuel 83384715009995

    Introduction

    This document outlines the methodology for estimating greenhouse gas (GHG) emissions from commercial ocean-going vessels (OGVs) and commercial harbor crafts (CHCs). The emissions inventory encompasses GHG emissions resulting from fuel combustion in the engines of OGVs and CHCs. These vessels utilize various fuel types—OGVs typically use marine distillate or heavy fuel oil, while CHCs primarily use diesel fuel. Combustion of these fuels produces GHGs, including carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Emissions from other waterborne craft, such as pleasure crafts and recreational boats, are addressed in the Off-Road Mobile Sources section.

    The scope and classifications covered in this document are described below:

    • Consistent with California Air Resources Board (CARB) methodology in the 2021 OGV Emission Inventory (CARB OGV, 2022) and 2021 CHC Emission Inventory (CARB CHC, 2021), emissions for OGVs are estimated for operations within 100 nautical miles (nm) of the San Francisco Bay Area (SFBA) coastline, while emissions for CHCs are estimated or operations within 24 nm of the SFBA coastline.
    • Ocean-Going Vessels (OGVs): As defined by CARB, OGVs are commercial marine vessels that meet any of the following criteria: exceed 400 feet in length, have a carrying capacity of 10,000 gross tons or more, or are propelled by a marine compression ignition engine with a displacement of at least 30 liters per cylinder.
    • OGVs include various vessel categories such as auto carriers, bulk cargo carriers, container ships, cruise ships, general cargo ships, reefers, roll-on/roll-off (Ro-Ro) vessels, tankers, and others. Emissions are estimated based on their specific operational modes as defined by CARB in the 2021 OGV Emissions Inventory (CARB OGV, 2022):
      • Berth Hoteling: This is when vessels docked at port. This mode is designated to be within a 4 km grid of port, not in the anchorage zone, and speed of 0 knots.
      • Anchorage Hoteling: This is when vessels are anchored outside port areas awaiting berth. This mode is designated to be within anchorage zones with speeds less than 1 knot.
      • Maneuvering: This mode consists of slow-speed operations within port areas. This mode is designated within 3 nm of shore or anchorage areas at speeds less than 3 knots.
      • In-Transit: This mode is for vessel operations at sea, in between destinations. This mode is designated at all speeds greater than 3 knots within the 3 nm boundary, or all operations outside anchorage areas past the 3 nm boundary.
    • Commercial Harbor Crafts (CHCs): According to CARB, CHCs encompass a diverse range of commercial marine vessels, including, but not limited to, commercial fishing vessels, commercial passenger fishing vessels, ferries, excursion vessels, tugboats, pilot vessels, crew and supply vessels, and workboats.
    • Emissions from OGVs and CHCs are produced by the propulsion engines (or main engines) and auxiliary engines that provide electric power or directly drive other onboard components. In addition to main and auxiliary engines, OGV emissions are also generated from boilers used for supplying steam and hot water for non-propulsion purposes, such as fuel heating, space heating, and driving steam turbines on tankers that offload petroleum crude oil in ports.

    Methodology

    CHCs and OGVs are area source categories where emissions by category are obtained from CARB, largely through the Off-Road Web Platform (Off-Road Inventory version 1.0.7; CARB EMFAC, 2024). The general methodology used by CARB (and modified as needed by the Air District) to calculate emissions for the base year(s) of the area source CHC and OGV categories is as follows:

    Emissionsstate;national,pollutant = Activity Data × Emission Factorpollutant

    Base Year(s) Emissions county,pollutant =

    Emissionsstate;national,pollutant × Control Factorpollutant × Fractioncounty × GWPpollutant

    Where:

    • Base Year: is a year for which emissions data is directly reported by CARB and available.
    • Activity Data: is the total statewide (or regional) throughput or activity data for applicable base year(s).
    • Emissionsstate;national,pollutant: is the amount of emissions from a larger area (e.g. state or national level) to be allocated to a smaller regional area based on a proportional measure, such as allocating based on the ratio of county to state population.
    • Emission Factorpollutant: is a factor that allocates an amount of emissions, in mass, of a particular pollutant by unit of activity data.
    • Control Factorpollutant : is a fractional ratio (between 0 and 1) that captures the estimated reduction in emissions as a result of Air District rules and regulations.
    • Fractioncounty : is the fraction of total regional emissions (between 0 and 1) estimated to be allocated to a particular county.
    • GWPpollutant is the Global Warming Potential of a particular GHG pollutant. The current version of the GHG emissions inventory incorporates the global warming potential (GWP) reported in the Fifth Assessment report of the Intergovernmental Panel for Climate Change (IPCC, 2014). The GWPs for the three principal GHGs are 1 for carbon dioxide (CO2), 34 for methane (CH4), and 298 for nitrous oxide (N2O), when calculated on a 100-year basis with climate-carbon feedback included. The CARB emissions are given in MMTCO2eq using IPCC Assessment Report 4 (AR4; IPCC, 2007) and the Air District uses the values in IPCC Assessment Report 5 (AR5; IPCC, 2014). Since the GWPs for both species reported in this chapter, CO2 and N2O (including climate feedback), for both Assessment Reports, are the same, no correction is applied.

    CARB CHC and OGV inventories rely on vessel registries containing engine and vessel characteristics for all vessels operating out to 100nm from the California coastline. The CHC population is obtained from data reported to CARB by vessel operators (CARB CHC, 2019), U.S. Coast Guard registry (USCG, 2019), and population data from the Ports of Los Angeles, Long Beach, and Oakland. The OGV population is obtained from the Automatic Identification System (AIS) database (AIS, 2020). Emission factors are estimated for each vessel based on the engine age, engine type, and type of fuel burned and are obtained from EPA (EPA, 2020). Transit, maneuvering, and anchorage activity for each vessel is obtained from the AIS database, which provides vessel speed, bearing, and location with frequency up to every second. Berthing activity is obtained from CARB At-Berth Compliance Reporting, which requires all vessels to report total time at berth. Vessel fuel consumption is estimated from AIS and berthing activity data, which is multiplied by the vessel emission factor to estimate emissions for each vessel in the entire fleet population.

    Once base year emissions are determined, historical backcasting and forecasting of emissions relative to the base year emissions are estimated using growth profiles as follows:

    Current Year Emissionscounty = Base Year(s) Emissioncounty x Growth Factor

    Where:

    • Growth Factor: is a scaling factor that is used to derive historical emissions estimates for years for which activity data and/or emissions are not available, and to forecast emissions for future years, using surrogates that are assumed to be representative of activity and/or emissions trends.

    Forecasted future year populations and emissions are estimated by accounting for the rate that older engines are retired or replaced, along with the overall population or activity growth needed to meet projected demands for goods. Port and future vessel capacities are also used in future year forecasts to constrain growth.

    Emissions

    For OGVs, the CARB Off-Road Web Platform derives emissions from the 2021 OGV Emission Inventory (CARB OGV, 2022). It does not provide an option to report emissions by operating mode, but a more detailed inventory with an additional breakdown by operating mode was obtained via personal communication with CARB staff. Emissions are reported for all GHGs by year (2020-2050), county, vessel type, operating mode, engine type, and type of fuel consumed.

    For CHCs, the CARB Off-Road Web Platform derives emissions from the 2021 CHC Emission Inventory (CARB CHC, 2021). Emissions are reported by the year (2018-2050), county, vessel type, engine type, and type of fuel consumed. The inventory does not report methane (CH4) or nitrous oxide (N2O) emissions and requires surrogate methods to estimate CH4 and N2O emissions for CHC categories which is described below.

    CH4 and N2O Emissions

    Since the CARB Off-Road inventory does not include CH4 or N2O emissions for CHC categories, the CARB Statewide Greenhouse Gas Inventory Tool (CARB, 2023) is used to calculate representative CH4/CO2 and N2O/CO2 ratios for CHCs. These ratios are applied to the CO2 emissions for all CHC categories to derive county-level CH4 and N2O emissions. The ratios are shown in the table below and are consistent across all CHC categories.

    Ratio

    Value

    CH4/CO2

    4.66 × 10-6

    N2O/CO2

    2.33 × 10-6

    The Air District applies these ratios to the CO₂ emissions from OFFROAD2021 to estimate CH₄ and N₂O as follows:

    • CH₄ = CO₂, OFFROAD2021 × (CH₄ / CO₂)
    • N₂O = CO₂, OFFROAD2021 × (N₂O / CO₂)

    Once CH4 and N2O emissions are determined, the Global Warming Potential (GWP) of a particular GHG pollutant is used to derive emissions on a CO2-equivalent (CO2eq) basis. The current version of the GHG emissions inventory incorporates the GWPs reported in the Fifth Assessment report of the Intergovernmental Panel for Climate Change (IPCC, 2014). The GWPs for the three principal GHGs are 1 for carbon dioxide (CO2), 34 for methane (CH4), and 298 for nitrous oxide (N2O), when calculated on a 100-year basis with climate-carbon feedback included.

    County Fractions

    County fractions are presented in the following table. For both CHCs and OGVs, county fractions are based on GHG emissions assigned to each county in the CARB Off-Road inventory. Since CARB defines the geographic scope of OGV emissions out to 100nm and CHC emissions out to 24nm from the coastline, vessel emissions are allocated to the county closest to where the activity and emissions occur.

    Emission Factors and Local Controls

    Because emissions are derived directly from CARB datasets, no emission factors are derived or used.

    OGVs and CHCs are regulated at the federal and state level and are not subject to any additional rules adopted by the Air District. CARB has implemented two key regulations to reduce emissions from ocean-going vessels (OGVs). The OGV Fuel Regulation (CARB OGV, 2008) requires OGVs operating within 24 nautical miles of California's coastline to use low-sulfur marine fuels. The OGV at Berth Regulation (CARB OGV, 2020) was originally enacted in 2007 and requires that certain categories of vessels—specifically container ships, passenger vessels, and refrigerated cargo ships—must reduce emissions while docked at California ports. This is typically achieved by connecting to shore power, which allows ships to shut down auxiliary engines and eliminate fuel combustion during berthing. The regulation was amended in 2020 to expand its scope, including additional vessel types such as roll-on/roll-off vessels, tankers, and other reefers. It also extended coverage to more ports across the state.

    CARB originally passed the CHC Regulation (CARB CHC, 2022) in 2008 and amended the regulation in 2010 and 2022. The initial 2008 CHC Regulation required most CHC owners to replace older, high-emitting diesel engines with cleaner Tier 2 engines and transition to ultra-low sulfur diesel fuel. In 2010, amendments expanded the regulation’s scope to include additional vessel types, such as fishing vessels, ferries, and tugboats, and introduced requirements for upgrades to Tier 3 engines as well as idling limits to minimize emissions during vessel downtime. In 2022, CARB adopted significant updates to the CHC regulation to further reduce emissions and promote the use of zero-emission technologies. Key changes included mandating the replacement of older engines with Tier 4 engines, requiring short-run ferries (those operating less than three nautical miles per trip) to be fully zero-emission by the end of 2025, and requiring new excursion vessels to be capable of operating with at least 30% of their power from a zero-emission source. The 2022 amendment also applies existing requirements to additional vessel categories such as tank barges over 400 feet, workboats, pilot vessels, research vessels, and commercial passenger fishing vessels that were previously exempt from cleaner engine standards.

    ID Description ALA CC MAR NAP SF SM SNC SOL SON
    1769 Commercial Harbor Crafts - Crew & Supply - Aux. Engine 0.17 0.00 0.00 0.00 0.83 0.00 0.00 0.00 0.0
    1770 Commercial Harbor Crafts - Crew & Supply - Main Engine 0.16 0.00 0.00 0.00 0.84 0.00 0.00 0.00 0.0
    1771 Commercial Harbor Crafts - Excursion Ves. - Aux Engine 0.34 0.00 0.02 0.00 0.57 0.07 0.00 0.00 0.0
    1772 Commercial Harbor Crafts - Excursion Ves. - Main Engine 0.29 0.00 0.06 0.00 0.60 0.05 0.00 0.00 0.0
    1773 Commercial Harbor Crafts - Fishing Ves. Charter - Aux. Engine 0.20 0.10 0.12 0.00 0.59 0.00 0.00 0.00 0.0
    1774 Commercial Harbor Crafts - Fishing Ves. Charter - Main Engine 0.33 0.03 0.13 0.00 0.45 0.05 0.00 0.00 0.0
    1775 Commercial Harbor Crafts - Fishing Ves. Com. - Aux. Engine 0.10 0.00 0.00 0.00 0.50 0.40 0.00 0.00 0.0
    1776 Commercial Harbor Crafts - Fishing Ves. Com. - Main Engine 0.07 0.04 0.06 0.02 0.52 0.28 0.01 0.00 0.0
    1777 Commercial Harbor Crafts - Other Ves. Aux. Engine 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    1778 Commercial Harbor Crafts - Other Ves. - Main Engine 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    1779 Commercial Harbor Crafts - Pilot Ves. - Aux Engine 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    1780 Commercial Harbor Crafts - Pilot Ves. - Main Engine 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    1781 Commercial Harbor Crafts - Tow Boat-Auxiliary Engine 0.09 0.24 0.00 0.00 0.67 0.00 0.00 0.00 0.0
    1782 Commercial Harbor Crafts - Tow Boat - Main Engine 0.07 0.28 0.00 0.00 0.65 0.00 0.00 0.00 0.0
    1783 Commercial Harbor Crafts - Tug Boat - Aux. Engine 0.26 0.09 0.00 0.00 0.65 0.00 0.00 0.00 0.0
    1784 Commercial Harbor Crafts - Tug Boat - Main Engine 0.35 0.10 0.00 0.00 0.55 0.00 0.00 0.00 0.0
    1785 Commercial Harbor Crafts - Work Boat - Aux. Engine 0.36 0.27 0.00 0.00 0.37 0.00 0.00 0.00 0.0
    1786 Commercial Harbor Crafts - Work Boat - Main Engine 0.22 0.35 0.03 0.00 0.37 0.00 0.03 0.00 0.0
    2041 Ships Anchorage - Auto Carrier - Aux. Engine - SFAB - distillate fuel 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    2042 Ships Anchorage - Auto Carrier - Boiler - SFAB - distillate fuel 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    2043 Ships Anchorage - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 0.00 0.00 0.00 0.00 0.97 0.03 0.00 0.00 0.0
    2044 Ships Anchorage - Bulk Cargo - Boiler - SFAB - distillate fuel 0.00 0.00 0.00 0.00 0.96 0.04 0.00 0.00 0.0
    2045 Ships Anchorage - Container Ship - Aux. Engine - SFAB - distillate fuel 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    2046 Ships Anchorage - Container Ship - Boiler - SFAB - distillate fuel 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    2047 Ships Anchorage - General Cargo - Aux. Engine - SFAB - distillate fuel 0.00 0.00 0.00 0.00 0.89 0.11 0.00 0.00 0.0
    2048 Ships Anchorage - General Cargo - Boiler - SFAB - distillate fuel 0.00 0.00 0.00 0.00 0.90 0.10 0.00 0.00 0.0
    2049 Ships Anchorage - Passenger Ship - Aux. Engine - SFAB - distillate fuel 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    2050 Ships Anchorage - Passenger Ship - Boiler - SFAB - distillate fuel 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.0
    2053 Ships Anchorage - Tanker - Aux. Engine - SFAB - distillate fuel 0.00 0.00 0.00 0.00 0.99 0.01 0.00 0.00 0.0
    2054 Ships Anchorage - Tanker - Boiler - SFAB - distillate fuel 0.00 0.00 0.00 0.00 0.99 0.01 0.00 0.00 0.0
    2073 Ships Hotelling - Auto Carrier - Aux. Engine - SFAB - distillate fuel 0.00 0.09 0.00 0.00 0.03 0.00 0.00 0.88 0.0
    2074 Ships Hotelling - Auto Carrier - Boiler - SFAB - distillate fuel 0.00 0.09 0.00 0.00 0.03 0.00 0.00 0.87 0.0
    2075 Ships Hotelling - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 0.18 0.82 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2076 Ships Hotelling - Bulk Cargo - Boiler - SFAB - distillate fuel 0.12 0.88 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2077 Ships Hotelling - Container Ship - Aux. Engine - SFAB - distillate fuel 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2078 Ships Hotelling - Container Ship - Boiler - SFAB - distillate fuel 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2079 Ships Hotelling - General Cargo - Aux. Engine - SFAB - distillate fuel 0.30 0.70 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2080 Ships Hotelling - General Cargo - Boiler - SFAB - distillate fuel 0.39 0.61 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2081 Ships Hotelling - Passenger Ship - Aux. Engine - SFAB - distillate fuel 0.95 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.0
    2082 Ships Hotelling - Passenger Ship - Boiler - SFAB - distillate fuel 0.95 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.0
    2083 Ships Hotelling - Ro/Ro - Aux. Engine - SFAB - distillate fuel 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2084 Ships Hotelling - Ro/Ro - Boiler - SFAB - distillate fuel 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2085 Ships Hotelling - Tanker - Aux. Engine - SFAB - distillate fuel 0.00 0.93 0.00 0.00 0.00 0.00 0.00 0.07 0.0
    2086 Ships Hotelling - Tanker - Boiler - SFAB - distillate fuel 0.00 0.84 0.00 0.00 0.00 0.00 0.00 0.16 0.0
    2087 Ships Hotelling - Misc. Vessel - Aux. Engine - SFAB - distillate fuel 0.00 0.00 0.00 0.00 0.86 0.14 0.00 0.00 0.0
    2105 Ships Maneuvering - Auto Carrier - Aux. Engine - SFAB - distillate fuel 0.00 0.14 0.00 0.00 0.01 0.00 0.00 0.85 0.0
    2106 Ships Maneuvering - Auto Carrier - Main Engine - SFAB - distillate fuel 0.00 0.14 0.00 0.00 0.03 0.00 0.00 0.83 0.0
    2107 Ships Maneuvering - Auto Carrier - Boiler - SFAB - distillate fuel 0.00 0.13 0.00 0.00 0.01 0.00 0.00 0.86 0.0
    2108 Ships Maneuvering - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 0.00 0.59 0.00 0.00 0.01 0.40 0.00 0.01 0.0
    2109 Ships Maneuvering - Bulk Cargo - Main Engine - SFAB - distillate fuel 0.01 0.58 0.00 0.00 0.30 0.09 0.00 0.03 0.0
    2110 Ships Maneuvering - Bulk Cargo - Boiler - SFAB - distillate fuel 0.00 0.54 0.00 0.00 0.01 0.44 0.00 0.01 0.0
    2111 Ships Maneuvering - Container Ship - Aux. Engine - SFAB - distillate fuel 0.95 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.0
    2112 Ships Maneuvering - Container Ship - Main Engine - SFAB - distillate fuel 0.81 0.00 0.00 0.00 0.19 0.00 0.00 0.00 0.0
    2113 Ships Maneuvering - Container Ship - Boiler - SFAB - distillate fuel 0.96 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.0
    2114 Ships Maneuvering - General Cargo - Aux. Engine - SFAB - distillate fuel 0.26 0.22 0.00 0.00 0.28 0.23 0.00 0.00 0.0
    2115 Ships Maneuvering - General Cargo - Main Engine - SFAB - distillate fuel 0.02 0.06 0.00 0.00 0.90 0.03 0.00 0.01 0.0
    2116 Ships Maneuvering - General Cargo - Boiler - SFAB - distillate fuel 0.32 0.27 0.00 0.00 0.23 0.19 0.00 0.00 0.0
    2117 Ships Maneuvering - Passenger Ship - Aux. Engine - SFAB - distillate fuel 0.96 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.0
    2118 Ships Maneuvering - Passenger Ship - Main Engine - SFAB - distillate fuel 0.62 0.00 0.00 0.00 0.38 0.00 0.00 0.00 0.0
    2119 Ships Maneuvering - Passenger Ship - Boiler - SFAB - distillate fuel 0.96 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.0
    2120 Ships Maneuvering - Ro/Ro - Aux. Engine - SFAB - distillate fuel 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2121 Ships Maneuvering - Ro/Ro - Main Engine - SFAB - distillate fuel 0.98 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.0
    2122 Ships Maneuvering - Ro/Ro - Boiler - SFAB - distillate fuel 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0
    2123 Ships Maneuvering - Tanker - Aux. Engine - SFAB - distillate fuel 0.00 0.48 0.00 0.00 0.26 0.00 0.00 0.26 0.0
    2124 Ships Maneuvering - Tanker - Main Engine - SFAB - distillate fuel 0.00 0.04 0.00 0.00 0.82 0.00 0.00 0.14 0.0
    2125 Ships Maneuvering - Tanker - Boiler - SFAB - distillate fuel 0.00 0.45 0.00 0.00 0.23 0.00 0.00 0.32 0.0
    2633 Ships in Transit - Auto Carrier - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.13 0.22 0.00 0.46 0.19 0.00 0.01 0.0
    2635 Ships in Transit - Auto Carrier - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.05 0.26 0.00 0.53 0.15 0.00 0.01 0.0
    2637 Ships in Transit - Bulk Cargo - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.10 0.36 0.00 0.28 0.20 0.00 0.06 0.0
    2639 Ships in Transit - Bulk Cargo - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.07 0.39 0.00 0.29 0.21 0.00 0.04 0.0
    2641 Ships in Transit - Container Ship - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.01 0.00 0.19 0.00 0.62 0.18 0.00 0.00 0.0
    2643 Ships in Transit - Container Ship - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.00 0.21 0.00 0.64 0.15 0.00 0.00 0.0
    2645 Ships in Transit - General Cargo - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.10 0.12 0.00 0.56 0.13 0.00 0.09 0.0
    2647 Ships in Transit - General Cargo - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.07 0.12 0.00 0.65 0.11 0.00 0.04 0.0
    2649 Ships in Transit - Misc. Vessel - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.00 0.37 0.00 0.16 0.47 0.00 0.00 0.0
    2651 Ships in Transit - Misc. Vessel - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.00 0.42 0.00 0.15 0.43 0.00 0.00 0.0
    2653 Ships in Transit - Passenger Ship - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.01 0.00 0.01 0.00 0.51 0.48 0.00 0.00 0.0
    2655 Ships in Transit - Passenger Ship - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.00 0.00 0.00 0.49 0.50 0.00 0.00 0.0
    2657 Ships in Transit - Ro/Ro - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.01 0.00 0.35 0.00 0.41 0.23 0.00 0.00 0.0
    2659 Ships in Transit - Ro/Ro - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.00 0.39 0.00 0.33 0.28 0.00 0.00 0.0
    2661 Ships in Transit - Tanker - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.04 0.25 0.00 0.44 0.24 0.00 0.04 0.0
    2663 Ships in Transit - Tanker - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.00 0.03 0.25 0.00 0.48 0.21 0.00 0.03 0.0

    Historical Emissions / Backcast

    Historical GHG emissions are obtained from the CARB Off-Road inventory back to 2018 for CHCs and 2020 for OGVs. Linear regression is used to project emissions back to 1990 based on the trends from 2018-2022 for CHCs and 2020-2022 for OGVs.

    Future Projections / Growth Factor

    Future projections are obtained from the CARB Off-Road inventory for emissions from 2023 to 2050. For both OGVs and CHCs, CARB future year projections are based on activity projections extrapolated from historical AIS data, economic growth and industry projections, capacity of vessel populations at certain ports, continued impact of adopted regulations, and fleet turnover and technological advancements such as alternative fuels, shore power use, and zero-emission technologies.

    Sample Calculation

    The table below presents a sample calculation for estimating base year 2022 CHC emissions for San Francisco County in units of metric tons of CO2 equivalents (MTCO2eq).

    CO2

    CH4

    N2O

    Step 1

    Obtain statewide CHC GHG emissions from CARB 2021 statewide GHG Inventory (tons/day)

    2310

    0.011

    0.005

    Step 2

    Proportion the emissions relative to that of CO2

    1

    0.011

    ÷ 2310

    = 4.66 × 10-6

    0.005

    ÷ 2310

    = 2.33 × 10-6

    Step 3

    Obtain/derive San Francisco county GHG emissions from CARB 2021 Off-Road Inventory (tons/day)

    462.2

    4.66 × 10-6

    × 462.2

    = 0.0022

    2.33 × 10-6

    × 462.2

    = 0.0011

    Step 4

    Global Warming Potential

    1

    34

    298

    Step 5

    Calculate emissions using IPCC AR5 GWP and sum up all GHG emissions (tons CO2eq/day)

    462.2

    × 1

    = 462.2

    0.0022

    × 34

    = 0.073

    0.011

    × 298

    = 0.33

    462.2 + 0.073 + 0.33

    = 462.6 tons CO2eq/day

    Step 6

    Convert emissions to MTCO2eq/year

    462.6 tons CO2eq/day

    × 365 day/year

    × 0.907 MT/tons

    = 153,146 MTCO2eq/year

    Assessment of Methodology

    The methodology for estimating the emissions for CHCs and OGVs remains consistent as it relies heavily on the inventory available from CARB. As each inventory is updated, the county fractions change depending on the activity level estimated for each county. In previous inventories, a surrogate method was used to estimate GHG emissions from CHCs and OGVs since GHG emissions were not included in the CARB Off-Road inventory.

    Base Year

    Revision

    Reference

    2022

    1. CARB Off-Road Inventory (v1.0.7) for county-level base year 2022 CHC emissions
    2. Custom query from CARB Off-Road Inventory (v1.0.7) for county-level base year 2022 OGV emissions split by activity type
    3. Added CHC categories for barge/dredge and ferries
    4. Added OGV categories for transiting emissions from boilers
    5. Used CARB GHG inventory Tool to derive ratios for CH4 and N2O to CO2 for estimating CHC GHG emissions
    6. Used linear regression for available years prior to and including 2022 for developing backcast profiles
    7. Global Warming Potential (GWP) taken from the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC, 2014)
    1. CARB EMFAC, 2024
      CARB CHC, 2021
    2. CARB EMFAC, 2024
      CARB OGV, 2022
      Personal communication with CARB
    3. CARB CHC, 2021
    4. CARB OGV, 2022
    5. CARB GHG, 2023
    6. CARB EMFAC, 2024
    7. IPCC, 2014

    2015

    1. Criteria Pollutant Emission Inventory (CEPAM) Database for base year emissions
    2. County fractions based on emissions split in base year inventory
    3. Used NOx as surrogate pollutant to derive CO2 emissions for all CHC and OGV categories
    4. Global Warming Potential (GWP) taken from the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC, 2014)
    1. CARB CEPAM database v1.03
    2. CARB CEPAM database v1.03
    3. CARB GHG, 2014
    4. IPCC, 2014

    2007

    1. CEPAM Database for base year emissions
    2. County fractions based on emissions split in base year inventory
    3. Used NOx as surrogate pollutant to derive CO2 emissions for all CHC and OGV categories
    4. Global Warming Potential (GWP) taken from the Intergovernmental Panel on Climate Change Second Assessment Report (IPCC, 1995)
    1. CARB CEPAM database, accessed in 2008
    2. CARB CEPAM database, accessed in 2008
    3. CARB GHG, 2004
    4. IPCC, 1995

    Emissions

    The table below shows the total greenhouse gas emissions by pollutant in MTCO2eq for marine vessel categories.

    ID Description CH4 CO2 N2O Total
    2643 Ships in Transit - Container Ship - Main Engine - SFAB, OC1, OC2 - distillate fuel 185.3 303639.7 3924.9 307749.9
    2663 Ships in Transit - Tanker - Main Engine - SFAB, OC1, OC2 - distillate fuel 66.1 98933.7 1406.6 100406.4
    2641 Ships in Transit - Container Ship - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 30.8 79077.0 982.2 80090.0
    1784 Commercial Harbor Crafts - Tug Boat - Main Engine 8.5 53733.9 37.4 53779.8
    2086 Ships Hotelling - Tanker - Boiler - SFAB - distillate fuel 3.0 42061.5 977.4 43041.9
    2635 Ships in Transit - Auto Carrier - Main Engine - SFAB, OC1, OC2 - distillate fuel 17.3 26318.0 366.9 26702.2
    2661 Ships in Transit - Tanker - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 8.0 20414.0 253.6 20675.6
    2078 Ships Hotelling - Container Ship - Boiler - SFAB - distillate fuel 1.3 18047.5 419.4 18468.2
    2659 Ships in Transit - Ro/Ro - Main Engine - SFAB, OC1, OC2 - distillate fuel 11.4 17217.7 241.6 17470.7
    1782 Commercial Harbor Crafts - Tow Boat - Main Engine 2.6 16426.7 11.4 16440.7
    2077 Ships Hotelling - Container Ship - Aux. Engine - SFAB - distillate fuel 4.5 11540.8 143.3 11688.6
    2085 Ships Hotelling - Tanker - Aux. Engine - SFAB - distillate fuel 4.2 10712.1 133.0 10849.3
    2639 Ships in Transit - Bulk Cargo - Main Engine - SFAB, OC1, OC2 - distillate fuel 6.7 9708.8 139.8 9855.3
    1783 Commercial Harbor Crafts - Tug Boat - Aux. Engine 1.5 9765.4 6.8 9773.7
    1774 Commercial Harbor Crafts - Fishing Ves. Charter - Main Engine 1.5 9311.9 6.4 9319.8
    1770 Commercial Harbor Crafts - Crew & Supply - Main Engine 1.3 8638.3 6.0 8645.6
    1772 Commercial Harbor Crafts - Excursion Ves. - Main Engine 1.4 8025.1 5.6 8032.1
    1776 Commercial Harbor Crafts - Fishing Ves. Com. - Main Engine 1.2 7588.4 5.2 7594.8
    2111 Ships Maneuvering - Container Ship - Aux. Engine - SFAB - distillate fuel 2.8 7162.2 89.1 7254.1
    2647 Ships in Transit - General Cargo - Main Engine - SFAB, OC1, OC2 - distillate fuel 4.6 6784.9 98.1 6887.6
    1786 Commercial Harbor Crafts - Work Boat - Main Engine 0.9 6290.2 4.3 6295.4
    2045 Ships Anchorage - Container Ship - Aux. Engine - SFAB - distillate fuel 2.2 5568.3 69.2 5639.7
    2633 Ships in Transit - Auto Carrier - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 2.0 5184.9 64.4 5251.3
    1780 Commercial Harbor Crafts - Pilot Ves. - Main Engine 0.7 4182.8 2.9 4186.4
    2046 Ships Anchorage - Container Ship - Boiler - SFAB - distillate fuel 0.3 3642.1 84.6 3727.0
    2053 Ships Anchorage - Tanker - Aux. Engine - SFAB - distillate fuel 1.3 3241.1 40.3 3282.7
    2054 Ships Anchorage - Tanker - Boiler - SFAB - distillate fuel 0.2 2999.3 69.7 3069.2
    1771 Commercial Harbor Crafts - Excursion Ves. - Aux Engine 0.3 2436.6 1.7 2438.6
    2081 Ships Hotelling - Passenger Ship - Aux. Engine - SFAB - distillate fuel 0.9 2404.6 29.9 2435.4
    2082 Ships Hotelling - Passenger Ship - Boiler - SFAB - distillate fuel 0.1 2142.1 49.8 2192.0
    1781 Commercial Harbor Crafts - Tow Boat-Auxiliary Engine 0.3 2143.5 1.5 2145.3
    2655 Ships in Transit - Passenger Ship - Main Engine - SFAB, OC1, OC2 - distillate fuel 1.0 1978.8 23.2 2003.0
    2123 Ships Maneuvering - Tanker - Aux. Engine - SFAB - distillate fuel 0.8 1924.9 23.8 1949.5
    2113 Ships Maneuvering - Container Ship - Boiler - SFAB - distillate fuel 0.1 1889.6 43.9 1933.6
    1785 Commercial Harbor Crafts - Work Boat - Aux. Engine 0.3 1474.1 1.1 1475.5
    2073 Ships Hotelling - Auto Carrier - Aux. Engine - SFAB - distillate fuel 0.4 1239.4 15.4 1255.2
    2645 Ships in Transit - General Cargo - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.5 1205.1 14.9 1220.5
    2657 Ships in Transit - Ro/Ro - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.5 1176.2 14.6 1191.3
    2637 Ships in Transit - Bulk Cargo - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.3 973.2 12.0 985.5
    2653 Ships in Transit - Passenger Ship - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.4 900.4 11.2 912.0
    2125 Ships Maneuvering - Tanker - Boiler - SFAB - distillate fuel 0.0 657.5 15.2 672.7
    2043 Ships Anchorage - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 0.2 658.2 8.2 666.6
    2044 Ships Anchorage - Bulk Cargo - Boiler - SFAB - distillate fuel 0.0 639.1 14.9 654.0
    2074 Ships Hotelling - Auto Carrier - Boiler - SFAB - distillate fuel 0.0 557.3 12.9 570.2
    2108 Ships Maneuvering - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 0.2 523.2 6.4 529.8
    1769 Commercial Harbor Crafts - Crew & Supply - Aux. Engine 0.1 455.4 0.4 455.9
    1775 Commercial Harbor Crafts - Fishing Ves. Com. - Aux. Engine 0.0 415.9 0.2 416.1
    2117 Ships Maneuvering - Passenger Ship - Aux. Engine - SFAB - distillate fuel 0.2 402.3 5.0 407.5
    2083 Ships Hotelling - Ro/Ro - Aux. Engine - SFAB - distillate fuel 0.1 379.3 4.7 384.1
    2075 Ships Hotelling - Bulk Cargo - Aux. Engine - SFAB - distillate fuel 0.1 344.2 4.3 348.6
    1773 Commercial Harbor Crafts - Fishing Ves. Charter - Aux. Engine 0.0 329.5 0.1 329.6
    2048 Ships Anchorage - General Cargo - Boiler - SFAB - distillate fuel 0.0 270.1 6.3 276.4
    1779 Commercial Harbor Crafts - Pilot Ves. - Aux Engine 0.0 246.9 0.2 247.1
    1778 Commercial Harbor Crafts - Other Ves. - Main Engine 0.0 238.3 0.2 238.5
    2105 Ships Maneuvering - Auto Carrier - Aux. Engine - SFAB - distillate fuel 0.1 212.2 2.6 214.9
    2047 Ships Anchorage - General Cargo - Aux. Engine - SFAB - distillate fuel 0.1 209.0 2.6 211.7
    2110 Ships Maneuvering - Bulk Cargo - Boiler - SFAB - distillate fuel 0.0 206.1 4.7 210.8
    2076 Ships Hotelling - Bulk Cargo - Boiler - SFAB - distillate fuel 0.0 205.0 4.8 209.8
    2084 Ships Hotelling - Ro/Ro - Boiler - SFAB - distillate fuel 0.0 184.2 4.3 188.5
    2079 Ships Hotelling - General Cargo - Aux. Engine - SFAB - distillate fuel 0.0 125.4 1.6 127.0
    2124 Ships Maneuvering - Tanker - Main Engine - SFAB - distillate fuel 0.0 115.8 0.5 116.3
    2050 Ships Anchorage - Passenger Ship - Boiler - SFAB - distillate fuel 0.0 102.1 2.4 104.5
    2119 Ships Maneuvering - Passenger Ship - Boiler - SFAB - distillate fuel 0.0 96.8 2.3 99.1
    2114 Ships Maneuvering - General Cargo - Aux. Engine - SFAB - distillate fuel 0.0 77.7 1.0 78.7
    2087 Ships Hotelling - Misc. Vessel - Aux. Engine - SFAB - distillate fuel 0.0 73.2 0.0 73.2
    2651 Ships in Transit - Misc. Vessel - Main Engine - SFAB, OC1, OC2 - distillate fuel 0.0 53.8 1.1 54.9
    2107 Ships Maneuvering - Auto Carrier - Boiler - SFAB - distillate fuel 0.0 41.7 0.9 42.6
    2080 Ships Hotelling - General Cargo - Boiler - SFAB - distillate fuel 0.0 39.3 1.0 40.3
    2041 Ships Anchorage - Auto Carrier - Aux. Engine - SFAB - distillate fuel 0.0 38.0 0.5 38.5
    2120 Ships Maneuvering - Ro/Ro - Aux. Engine - SFAB - distillate fuel 0.0 32.6 0.4 33.0
    2112 Ships Maneuvering - Container Ship - Main Engine - SFAB - distillate fuel 0.0 30.5 0.1 30.6
    2042 Ships Anchorage - Auto Carrier - Boiler - SFAB - distillate fuel 0.0 23.5 0.5 24.0
    2116 Ships Maneuvering - General Cargo - Boiler - SFAB - distillate fuel 0.0 20.3 0.5 20.8
    2049 Ships Anchorage - Passenger Ship - Aux. Engine - SFAB - distillate fuel 0.0 15.9 0.2 16.1
    2649 Ships in Transit - Misc. Vessel - Aux. Engine - SFAB, OC1, OC2 - distillate fuel 0.0 7.5 0.0 7.5
    2122 Ships Maneuvering - Ro/Ro - Boiler - SFAB - distillate fuel 0.0 5.2 0.1 5.3
    1777 Commercial Harbor Crafts - Other Ves. Aux. Engine 0.0 4.5 0.0 4.5
    2109 Ships Maneuvering - Bulk Cargo - Main Engine - SFAB - distillate fuel 0.0 1.3 0.0 1.3
    2106 Ships Maneuvering - Auto Carrier - Main Engine - SFAB - distillate fuel 0.0 0.5 0.0 0.5
    2121 Ships Maneuvering - Ro/Ro - Main Engine - SFAB - distillate fuel 0.0 0.4 0.0 0.4
    2115 Ships Maneuvering - General Cargo - Main Engine - SFAB - distillate fuel 0.0 0.4 0.0 0.4
    2118 Ships Maneuvering - Passenger Ship - Main Engine - SFAB - distillate fuel 0.0 0.2 0.0 0.2

    Summary of Base Year 2022 Emissions

    A breakdown of the year 2022 marine vessel GHG emissions contribution to the transportation sector and regional total is provided in the table below. OGVs account for 82% of the total regional marine vessel emissions, and CHCs account for the remaining 18%.

    In 2022, container ships accounted for 61% of regional OGV GHG emissions, followed by tanker ships at 27%. This is consistent with the Marine Exchange data on Golden Gate Ship traffic (Marine Exchange, 2023), which shows that container ships and tankers account for 58% of all OGV vessel calls in the Bay Area in year 2022. Emissions per vessel are much larger for container and tanker ships as they are generally carry heavier loads than other vessel types such as passenger and general cargo ships. For CHCs, tug boats are the highest emitting vessel type at 50%, followed by ferries at 23% of regional CHC GHG emissions.

    Contribution of Marine Vessels Emissions by Sector
    Subsector Sector Subsector GHG Emissions (MMTCO2eq) Sector GHG Emissions (MMTCO2eq) % of Sector
    Marine Vessels Transportation 0.84 22.60 3.70%

    Contribution of Marine Vessels Emissions to Regional Total
    Subsector Subsector GHG Emissions (MMTCO2eq) Regional Total GHG Emissions (MMTCO2eq) % of Regional Total
    Marine Vessels 0.84 65.68 1.27%

    Trends

    OGV and CHC emission trends from 1990 to 2050 are presented in the figure below.

    Summary of Trends

    In general, emissions from marine vessels increase over time due to increasing demand for maritime goods movement. This is evident in the emissions trend for container ships, which account for about half of all marine vessel emissions in the Bay Area. Although other vessel types such as tankers and most CHCs show a slight decreasing trend in future years, the decrease in emissions is offset by the increase in emissions from container ships. Forecasts show that the increasing trend for container ships will likely remain without future regulations to limit OGV emissions. The current CARB forecasting methods incorporate impacts from both regulations for OGVs (OGV Fuel Regulation and OGV At-Berth Regulation) and the CHC Regulation, all of which are summarized in the Emissions Controls subsection. However, impacts from the 2022 Amendments to the CHC Regulation are not currently incorporated into the projections.

    Uncertainties

    CARB is in the process of updating the OGV emission inventory to incorporate more recent AIS activity data, vessel registries, emission factors, and forecasting. The updated inventory is under review and will supersede the current CARB Off-Road v1.0.7 inventory. Other methodology changes in the updated inventory include using 5-year average AIS data (2019-2023) to estimate baseline activity and emissions, redefining the delineation between maneuvering and transiting modes, incorporating actual time on shore power for vessels at berth, and incorporating updated growth forecasts for the Ports of Los Angeles, Long Beach, and Oakland. The draft inventory shows a significant decrease in GHG emissions (~37%) compared to the current CARB Off-Road inventory and will be incorporated into the next regional base year inventory once finalized.

    Contact

    Author: Tan Dinh

    Reviewer: Abhinav Guha

    Last Update: 07/16/2025

    References

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    CARB CHC. 2021. Appendix H: 2021 Update to the Emission Inventory for Commercial Harbor Craft: Methodology and Results, California Air Resources Board. https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2021/chc2021/apph.pdf

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    IPCC. 1995. Climate Change 1995 The Science of Climate Change Report, Intergovernmental Panel on Climate Change (IPCC). https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_sar_wg_I_full_report.pdf

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