EPA Publishes Notice of Data Availability on 2018 Emissions Inventory Modeling Platform

EPA published on January 14, 2014, a Notice of Data Availability (NODA) regarding its 2018 emissions inventory modeling platform (79 FR 2437). The platform consists of emission inventory data, supporting data used to develop the 2018 emission inventories, and methods and data that are used to process emission inventories representing the year 2018 into a form that can be used for air quality modeling. In its announcement, EPA said that “the platform, or portions of the data that make up the platform, may be used by the Office of Air and Radiation in several contexts, including the development of rules related to the transport of air pollution and the National Ambient Air Quality Standards.”

The 2018 platform includes emission inventories representing projected emissions of both criteria and some hazardous air pollutants in the year 2018. It also includes ancillary data files that are used to convert the National Emissions Inventory (NEI) emissions into a form that can be used for air quality modeling, and methods used to prepare model inputs and for the development of projections of emissions in the year 2018. Emission inventories for source categories including fire events, county-level emissions of onroad mobile sources, nonroad mobile sources, and other nonpoint sources are in the inventory.

For inventory modeling projections, point source emissions are categorized by modeling sectors that include  peaking electric generating units (EGUs), other EGUs, oil and gas point sources, and other point sources. Nonpoint emission sources are separated into agricultural ammonia, residential wood, oil and gas, and other nonpoint source categories.

The 2018 emissions modeling platform is named for the year of the data that it represents. The inventories in the platform were developed using projection methods specific to the type of emission source. Emission projections for EGUs for 2018 are developed using the Integrated Planning Model (IPM). Most non-EGU source emissions projections are based on EPA’s 2011 emissions modeling platform. The relevant 2011 data is available in docket number EPA-HQ-OAR-2013-0743.

Future emissions are projected from this base case either by running models to estimate emissions in the future year (i.e., EGUs, and onroad and nonroad mobile sources), or by adjusting the base year emissions. Documentation of the methods used for each sector is provided in the Technical Support Document Preparation of Emissions Inventories for the Version 6.0, 2011 Emissions Modeling Platform, available in the docket.

EPA states that the 2018 platform, or portions of the platform data, may be used by the Office of Air and Radiation in many projects, including the development of rules related to the transport of air pollution and the National Ambient Air Quality Standards. Air quality modeling results that are based on the outputs of the emissions modeling platform are typically used in support of Regulatory Impact Analyses (RIAs) and sometimes support other aspects of rulemaking efforts.

EPA requests comment on a number of aspects of the data including:

  • Emissions values and supporting data for EGUs.
  • Emission values for non-EGU sources
  • Model inputs and activity data used to develop mobile source emission inventories.
  • Projection data and methods.
  • Existing control techniques.
  • Emissions modeling methods.
  • Temporal allocation of annual inventories
  • Spatial surrogates used to allocate county-level emissions
  • Chemical speciation of the pollutants in the inventories, specifically speciation of oil and gas information, along with VOC to TOG adjustment factors that are used to compute methane emissions for each distinct process at oil and gas drilling/production facilities (e.g., glycol dehydrators)

EPA is requesting comments no later than June 30, 2014, regarding the emission inventories, the supporting data, and the methods used to develop and process the 2018 emission inventories. Comments may be submitted referencing Docket Number EPA-HQ-OAR-2013-0809.

Edward L. "Skipp" Kropp focuses his practice in the area of environmental law and is resident in Indianapolis, Indiana. He is a former Chief of the West Virginia Division of Environmental Protection Office of Air Quality and former Deputy Director of the West Virginia Division of Environmental Protection.
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