Representing Freight in Air Quality and Greenhouse Gas Models (2010) / Chapter Skim
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Pages 141-150
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From page 141... ...
The EPA GHG Inventory methodology uses both top-down and bottom-up approaches simultaneously, in which a top-down calculation of fuel consumption by sector and mode based on fuel statistics is reconciled with a bottom-up modal analysis of fuel consumption by industry activity measures. Although the NEI focuses on regional allocation and the EPA GHG Inventory focuses on modal allocation, the accuracy of both methodologies depends on the quality of regional and activity data and the allocation method used, which vary across modes.
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From page 142... ...
Finally, since the GHG Inventory allocates emissions by mode but not region, the research will analyze potential methods to allocate regional GHG emissions. The research and results should span pollutant types including CAP, HAP, and GHG, as well as transportation modes including on-road, nonroad, locomotive, marine, and aircraft.
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From page 143... ...
It relies primarily on second-by-second vehicle emissions data to develop emissions rates, and better represents the physical processes from vehicles, including the ability to model cold starts and extended idling, which is especially critical for heavy-duty trucks. Although the modal approach taken by MOVES seems appropriate to capture some local impacts, other tools, such as the Comprehensive Modal Emissions Model, developed by UC Riverside under an EPA contract, provide a more direct and transparent way to account for factors such as vehicle aerodynamics, pavement quality, and road grade.
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From page 144... ...
vehicle-specific power. Currently MOBILE6 and EMFAC estimate the effects of congestion on emissions by using speed correction factors that differentiate emission factors by average speed.
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From page 145... ...
. Streamlined, or "top-down," methods determine emissions based on publicly available data on fuel consumption at the national or state level, and apportion emissions to the state or county level using an available activity metric, such as traffic density or mileage of active track.
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From page 146... ...
For example, emissions from OGVs are usually determined at and around ports only, as these are the entrances and clearances of cargo into the regions of modeling interest, using information on number of calls at a particular port, engine power, load factors, emission factors and time in like modes. These data are often incomplete or of insufficient quality.
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From page 147... ...
Several new emissions testing programs funded by the California Air Resources Board, EPA, and Environment Canada, among others, have involved OGVs, H/C, and CHE. These new data need to be reviewed and compared against currently accepted emission factors.
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From page 148... ...
Task 1: Conduct Kick-Off Call Conduct a conference call with the panel within 30 days after contract initiation to discuss the revised work plan developed in response to the panel review of the research plan in the agency's original proposal. Task 2: Conduct Literature Review Conduct a literature review and analysis to determine appropriate emission factors, load factors, duty cycles, and other parameters to represent the current fleet of engines used in CHE, H/C, and main, auxiliary, and boiler engines for OGV, and compare them to currently accepted factors.
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From page 149... ...
This could include both activity data as well as emission indices. Task 4: Provide Interim Report Provide an interim report to panel members summarizing the findings from Task 2 and Task 3.
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From page 150... ...
Identify how these technologies will change aircraft operations such as takeoff weight, glide slope, and emission indices, and the resulting likely change in air freight emissions. Task 9: Prepare Final Report Prepare a final report providing results of the entire research effort.
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