^ FP/\          Office of Transportation                           EPA420-F-04-033
 ^Cr*^         and Air quality                                May 2004
   United States                                                   '
   Environmental Protector
   Agency
                  Technical
                  Highlights
                  Frequently Asked Questions on the
                  Draft NONROAD2004 Emission
                  Inventory Model
                 What is the draft NONROAD2004 model?
                 The draft nonroad model calculates past, present, and future emission
                 inventories (i.e., tons of pollutant) for all nonroad equipment categories
                 except commercial marine, locomotives, and aircraft. Fuel types included
                 in the model are: gasoline, diesel, compressed natural gas, and liquefied
                 petroleum. The model estimates exhaust and evaporative hydrocarbons
                 (HC), carbon monoxide (CO), oxides of nitrogen (NOx), particulate
                 matter (PM), sulfur dioxide (SO2), and carbon dioxide (CO2). The user
                 may select a specific geographic area (i.e., national, state, or county) and
                 time period (i.e., annual, monthly, seasonal, or daily) for analysis.
                 What are the differences between draft
                 NONROAD2002a and draft NONROAD2004?
                 Draft NONROAD2004 has several changes and enhancements:
                   • The most notable change is that draft NONROAD2004 accounts for
                     the final Tier 4 nonroad diesel engine standards (also known as the
                     Clean Air Nonroad Diesel Rule).
                   • Draft NONROAD2004 contains more horsepower (hp) bins in order
                     to model the final Tier 4 diesel engine standards. Specifically, the
                     50-100 hp bin was split into 50-75 hp and 75-100 hp bins. Also, the
                     1500 hp point was moved to 1200 hp, giving bins of 1000-1200 hp
                     and 1200-2000 hp.

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    Draft NONROAD2004 eliminates the Tier 3 NOx and PM transient
    adjustment factors (TAFs) for steady-state applications.
    The base year diesel populations in draft NONROAD2004 were
    updated from 1998 to 2000, based on newer sales data.
    The PM25 fraction of PM10 for diesel engines was revised from 0.92
    to 0.97, based on an updated analysis of size distribution data for
    diesel engines.
    The recreational marine populations, median life, and deterioration
    factors for HC and NO were revised to match what was used in the
                        X
    2002 final rulemaking that covers large spark ignition engines (>25
    hp), recreational equipment, and recreational marine diesel engines
    (>50 hp).1 The exhaust emission factors for these three categories
    were also revised in draft NONROAD2004 to reflect the final
    standards.
    The output label in the core model and Reporting Utility was
    changed from "SOx" to "SO2" to avoid confusion, since SO2 emis-
    sions are calculated by the model.
    Reporting Utility Enhancements:
    -  Reports have been updated to reflect the new hp ranges, PM2.5
       fraction, and SO2 label, as mentioned above.
    -  County level reports now include the Federal Information Pro-
       cessing Standard (FIPS) code as well as the county name.
    -  For users who have their own copy of Microsoft Access 2000 or
       later, a new reporting utility version is also being provided for
       testing purposes that includes National Emissions Inventory
       Input Format (NIF) 3.0 output, as well as two new reporting
       options: "Emission Totals by HP and Source Classification" and
       "Emission Totals by HP and SCC."
What are the differences between draft
NONROAD2002b and draft NONROAD2004?
Draft NONROAD2002b incorporates the Tier 4 diesel standards con-
tained in the April 2003 Notice of Proposed Rulemaking, whereas draft
NONROAD2004 incorporates the Tier 4 diesel standards in the Final
Rulemaking. Draft NONROAD2004 supercedes draft
NONROAD2002b.

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Does the draft NONROAD2004 model reflect all of
EPA's final nonroad engine emission standards to
date?
No. The model does not fully reflect the evaporative inputs (permeation,
running loss, hot soak, and diurnal) for the new recreational equipment
and large spark-ignition (SI)  engine standards that were published in the
Federal Register in November 20022. These will be incorporated into the
final version.
How do I account for evaporative emission benefits
from the new recreational equipment and large
spark-ignition standards?
Until these benefits are incorporated into the NONROAD model, users
will need to estimate the diurnal, hot soak, running loss, and permeation
emissions and benefits based on the information in the September 2002
Regulatory Support Document for this rule (EPA420-R-02-022). This
document can be downloaded from the EPA Office of Transportation and
Air Quality web site at: www.epa.gov/otaq/recveh.htm.
Does the draft NONROAD2004 model reflect the final
nonroad diesel fuel sulfur standards associated with
the Tier 4 rule?
Annual in-use diesel fuel sulfur levels are provided and account for the
500 parts per million (ppm) standard beginning in 2007, the 15 ppm
standard for land-based nonroad diesel engines only beginning in 2010,
and the 15 ppm standard for marine engines (both recreational and
commercial marine) and locomotives beginning in 2012. Two sets of
diesel  sulfur levels are provided for land-based nonroad diesel engines
and recreational marine diesel engines. To model these two diesel cat-
egories, separate NONROAD runs will be necessary. Since NONROAD
does not include locomotives and commercial marine vessels, the diesel
fuel sulfur benefits for these are not accounted for by draft NON-
ROAD2004.

Can the option files used for previous versions of the
model  be used for draft NONROAD2004?
Only option files created with draft NONROAD2002a are compatible
with draft NONROAD2004, but the diesel fuel sulfur levels will need to
be updated per the Sulfur.txt file being provided with this model release
to accurately model the diesel fuel sulfur requirements.

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Have the technical reports and User's Guide for draft
NONROAD2004 been updated?
The technical reports have been updated to reflect changes incorporated
into draft NONROAD2004. The User's Guide has not been updated for
draft NONROAD2004 but will be for the final version. These documents
can be downloaded from the NONROAD model web site at:
www. epa.gov/otaq/nonrdmdl. htm.


What additional changes are currently underway  or
being considered for the  next version of the
NONROAD model?
There are several additional changes and enhancements being consid-
ered:
  • Revised evaporative emissions (permeation, hot soak, running loss,
    and diurnal) for recreational and large SI engines, to account for the
    provisions of the November 2002 rulemaking.
  • Minor revisions to scrappage algorithm.
  • Updated allocation of national diesel construction emissions to the
    state and county level, accounting for regional cost differences.
  • Revised evaporative HC conversion factors (e.g., total hydrocarbon
    [THC] to volatile organic compound [VOC] or non-methane hydro-
    carbon [NMHC]), to be compatible with those in the National
    Mobile Inventory Model (NMEVI).
  • Revised emission factors and other inputs for SI recreational marine
    engines and other SI engines under 50 hp.
  • Incorporation of ammonia emissions.
  • Enhanced Reporting Utility with NIF v3.0 output.
What is EPA's guidance on the use of the draft
NONROAD2004 model for official submissions?
EPA is allowing the use of the draft NONROAD2004 Model and associ-
ated default inputs in development of inventories supporting State Imple-
mentation Plans (SIPs). Although draft NONROAD2004 or its default
inputs will likely change between the public release of the draft and the
final version, now anticipated for later in 2004, the draft NON-
ROAD2004 Model currently represents EPA=s best tool for estimating
nonroad emissions, as evidenced by the Agency's use in the Clean Air
Nonroad Diesel Engine Final Rule. Therefore, we are allowing state
agencies to use the draft model in SIPs during the period between public
release of the draft and final versions of the model. Given the likely

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additional changes to the model, coupled with the rather short time
period projected between this release and the final version, states may
choose to wait and use the final version of NONROAD for SIPs, if the
final version is available in time to meet their SIP requirements.

EPA will not require that inventories developed using the draft version
be updated following release of the final version. Given the likely
changes, however, states may choose to update SIPs after EPA releases
the final version of NONROAD.

After the release of the final version of NONROAD, states that are just
beginning new SIP development, or are in the early stages of SIP devel-
opment, should use the final version of NONROAD for those new SIPs.
When will the final NONROAD2004 model be
released?
It is anticipated that a final NONROAD model will be released in late
2004.
How can I receive assistance if I have questions
about draft NONROAD2004?
Please send an email with your question to nonroad@epa.gov or write
to:

    U.S. Environmental Protection Agency
    Assessment and Standards Division
    Air Quality and Modeling Center
    2000 Traverwood Drive
    Ann Arbor, MI 48105
  1    U.S. Environmental Protection Agency. Control of Emissions From Nonroad
      Large Spark-Ignition Engines, and Recreational Engines (Marine and Land-
      Based); Final Rule. 67 FR 68241-68290. November 8, 2002. (Docket
      Number A-2001-01, Document V-B-05)

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