CH4 and N2O Emissions | California Sustainability Alliance

Join Our Mailing List Introduction Overview The Manual LGOP Tool Buildings Vehicles CO2 Combustion Emissions CO2 Emissions From Biofuels CH4 and N2O Emissions Non-Highway Vehicles Alternative Fuel/Electric Vehicles Air Conditioning Emissions Power Generation Facilities Solid Waste Facilities Wastewater Treatment Facilities Other Process & Fugitive Emissions Scope 3 Emissions	CH4 and N2O Emissions Mobile Combustion CH₄ and N₂O Emissions Unlike CO₂ emissions, CH₄ and N₂O emissions from mobile combustion sources depend more on the emission control techniques employed in the vehicle rather than fuel type. Calculating emissions of CH₄ and N₂O requires data on vehicle characteristics (which takes into account emission control technologies) and vehicle miles traveled. Because of this distinction, guidance on calculating CO₄ and N₂O is provided separately from guidance on calculating CO_2. The recommended and alternate activity data and emission factors for calculating Scope 1 CH₄ and N₂O emissions from mobile combustion are found below: Recommended Approach: Annual Mileage by Vehicle Type, Model Year and Fuel Type: Identify the vehicle type (e.g. passenger car, heavy-duty truck), the fuel type, and the model year of each vehicle the local government owns and operates. Identify the annual mileage by vehicle type. Select the appropriate emission factor for each vehicle type using Table G.10 for highway/on-road vehicles, Table G.11. for alternative fuel and Table G.12 for non-highway/off-road vehicles. Calculate CH₄ and N₂O emissions for each vehicle type, and use Equations 7.6 and 7.7 to obtain total CH₄ and N₂O emissions. Convert CH₄ and N₂O emissions to units of CO₂ equivalent and sum to determine total emissions using Equation 7.8. Alternate Approach 1: Fuel use by vehicle type, model year, and fuel type If mileage data is not available, but fuel data by vehicle type is, you can estimate the vehicle miles traveled using fuel economy factors by vehicle type. Obtain fuel economy factors on EPA’s website www.fueleconomy.gov. Then use Equation 9 to estimate annual mileage. Alternate Approach 2: Annual mileage by vehicle type and fuel type Identify the vehicle type (e.g. passenger car, heavy-duty truck), the fuel type, and the model year of each vehicle the local government owns and operates. Identify the annual mileage by vehicle type. Select the appropriate emission factor for each highway vehicle type using Table G.13. Calculate CH₄ and N₂O emissions for each vehicle type and use Equations 7.6 and 7.7 in the recommended approach to obtain total CH₄ and N₂O emissions. Convert CH₄ and N₂O emissions to units of CO₂ equivalent and sum to determine total emissions using Equation 7.8 in the recommended approach. Alternate Approach 3: Proxy year data Identify the vehicle type (e.g. passenger car, heavy-duty truck), the fuel type, and the model year of each vehicle the local government owns and operates. Identify the annual mileage by vehicle type in the proxy year, and adjust the mileage based on any changes in fleet size and composition between the proxy year and the inventory year. Select the appropriate emission factor for each vehicle type using Table G.13. Calculate CH₄ and N₂O emissions for each vehicle type and use Equations 7.6 and 7.7 in the recommended approach to obtain total CH₄ and N₂O emissions. Convert CH₄ and N₂O emissions to units of CO₂ equivalent and sum to determine total emissions using Equation 7.8 in the recommended approach.
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