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Open Access Publications from the University of California

Spatial Disaggregation of CO2 Emissions for the State of California


This report allocates California's 2004 statewide carbon dioxide (CO2) emissions from fuel combustion to the 58 counties in the state. The total emissions are allocated to counties using several different methods, based on the availability of data for each sector. Data on natural gas use in all sectors are available by county. Fuel consumption by power and combined heat and power generation plants is available for individual plants. Bottom-up models were used to distribute statewide fuel sales-based CO2 emissions by county for on-road vehicles, aircraft, and watercraft. All other sources of CO2 emissions were allocated to counties based on surrogates for activity. CO2 emissions by sector were estimated for each county, as well as for the South Coast Air Basin. It is important to note that emissions from some sources, notably electricity generation, were allocated to counties based on where the emissions were generated, rather than where the electricity was actually consumed. In addition, several sources of CO2 emissions, such as electricity generated in and imported from other states and international marine bunker fuels, were not included in the analysis. California Air Resource Board (CARB) does not include CO2 emissions from interstate and international air travel, in the official California greenhouse gas (GHG) inventory, so those emissions were allocated to counties for informational purposes only. Los Angeles County is responsible for by far the largest CO2 emissions from combustion in the state: 83 Million metric tonnes (Mt), or 24percent of total CO2 emissions in California, more than twice that of the next county (Kern, with 38 Mt, or 11percent of statewide emissions). The South Coast Air Basin accounts for 122 MtCO2, or 35percent of all emissions from fuel combustion in the state. The distribution of emissions by sector varies considerably by county, with on-road motor vehicles dominating most counties, but large stationary sources and rail travel dominating in other counties. The CO2 emissions data by county and source are available upon request.

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