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2020 National Emissions Inventory Technical
Support Document: Portable Fuel Containers


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EP A-454/R-23 -001 n
March 2023

2020 National Emissions Inventory Technical Support Document: Portable Fuel Containers

U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Air Quality Assessment Division
Research Triangle Park, NC


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Contents

List of Tables	i

14	Portable Fuel Containers	14-1

14.1	Sector Descriptions and Overview	14-1

14.2	EPA-developed estimates	14-1

14.2.1	VOC allocation	14-2

14.2.2	VOC emissions	14-2

14.2.3	Hazardous air pollutants	14-3

14.2.4	Changes in the 2020 NEI and looking forward to the 2023 NEI	14-4

14.3	References	14-4

List of Tables

Table 14-1: Portable Fuel Container SCCs in the 2020 NEI, with nonpoint flagged	14-1

Table 14-2: Toxic to VOC ratios for benzene and naphthalene from PFCs	14-4

Table 14-3: Toxic to VOC ratios for Other HAPs (Vapor Displacement, Permeation, and Evaporation). 14-4

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14 Portable Fuel Containers

14.1 Sector Descriptions and Overview

There are several sources of emissions associated with portable fuel containers (PFC) used for storage of
gasoline. These sources include vapor displacement and spillage while refueling the gas can at the
pump, spillage during transport, permeation and evaporation from the gas can during transport and
storage, and vapor displacement and spillage while refueling equipment. Vapor displacement and
spillage while refueling nonroad equipment from PFCs, and spillage during transport and at the pump
are included in the nonroad inventory. This section describes how the nonpoint data category PFC
emissions (permeation, evaporation, and vapor displacement at the pump) are accounted for in the NEI.
This source category is one of many components in the Miscellaneous Non-industrial sector.

Table 14-1 shows the SCCs covered by this source category, and those for which we generate nonpoint
estimates. EPA will likely retire the PFC SCCs that are included in the MOVES model [ref 1], and hence
nonroad data category, prior to the 2023 NEI. The SCC level 3 and 4 descriptions are also provided. The
leading SCC description is "Storage and Transport; Petroleum Product Storage" for all SCCs.

Table 14-1: Portable Fuel Container SCCs in the 2020 NEI, with nonpoint flagged

Estimated for the





Nonpoint NEI?

SCC

Description

Yes

2501011011

Residential Portable Gas Cans; Permeation

Yes



Residential Portable Gas Cans; Evaporation (includes Diurnal



2501011012

losses)

No

2501011013

Residential Portable Gas Cans; Spillage During Transport

Yes



Residential Portable Gas Cans; Refilling at the Pump - Vapor



2501011014

Displacement

No

2501011015

Residential Portable Gas Cans; Refilling at the Pump - Spillage

Yes

2501012011

Commercial Portable Gas Cans; Permeation

Yes



Commercial Portable Gas Cans; Evaporation (includes Diurnal



2501012012

losses)

No

2501012013

Commercial Portable Gas Cans; Spillage During Transport

Yes



Commercial Portable Gas Cans; Refilling at the Pump - Vapor



2501012014

Displacement

No

2501012015

Commercial Portable Gas Cans; Refilling at the Pump - Spillage

14.2 EPA-developed estimates

For the 2020 NEI, where states did not submit their own data, we relied on an inventory developed for
the Tier 3 motor vehicle and fuel standards rule [ref 2], This inventory assumed all fuel dispensed from
PFCs was E10, with an average RVP of 8.7 psi. Use of ethanol in gasoline fuels can increase evaporative
emissions from PFCs, relative to E0, for several reasons. First, if E10 fuels have higher volatility than
corresponding E0 fuels, that can increase evaporation and vapor displacement. Second, ethanol in
gasoline increases permeation of fuel through gas can materials. Finally, the lower energy content of

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ethanol fuels leads to more frequent refueling, and, thus, greater emissions from spillage and
displacement while filling the gas can at the pump.

The use of ethanol also changes the mix of hydrocarbons in the evaporated fuel. In particular, it can
change the fraction of several hazardous air pollutants as well as ethanol.

As part of the 2007 regulation controlling emissions of hazardous pollutants from mobile sources
(MSAT2 rule), EPA promulgated requirements to control VOC emissions from gas cans. The methodology
we used to develop emission inventories for gas cans was developed for that regulation and is described
in the regulatory impact analysis for the rule and in an accompanying technical support document [ref 3,
ref 4], However, while that regulation included estimates for spillage emissions occur when refueling
equipment, most of these emissions is already included in the nonroad equipment inventory. Thus, we
did not include these emissions in the PFC inventory for the NEI. Vapor displacement for nonroad
equipment container refueling was also subtracted from vapor displacement in the PFC inventory to
avoid double counting these emissions.

14.2.1 VOC allocation

For the NEI, emissions were separated into commercial and residential fuel container emissions. Total
state level PFC emissions were allocated to the categories by using national level residential and
commercial emission splits from the MSAT2 rule for each of the categories using the following
equations:

F	= Fx

residentiaLXXXX ,YY

F	= Fx

commerciaLXXXX JY

r Re ^ ^
VR Qs + Com J

( Com \

vRes + Com j

(l)

(2)

where E was the emissions of the category being split, XXXX was year, YY was state, and Res and Com
were the national residential and commercial PFC emissions.

Permeation and evaporation were also separated as follows:

EAAA,XXXX,YY, perm ~ E'AAA,XXXX,YY,perm&evap X 0.3387	(3)

EAAA,XXXX,YY,evap ~ E'AAA,XXXX,YY,perm&evap X (1 — 0.3387)	(4)

The fraction 0.3387 represents the fraction of combined permeation and evaporative emissions
attributable to permeation, based on data from the California Air Resources Board.

14.2.2 VOC emissions

VOC emissions estimates are based on gasoline volumes for calendar year 2018, calculated with
NONROAD2005 for the Tier 3 rule. Nonroad gasoline consumption estimates from the newer MOVES3
model are used to update the NONROAD2005 gasoline volume estimates; these updated values are then

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adjusted to calendar year 2020. PFC emissions from permeation and evaporation are developed
separately from PFC emissions from vapor displacement.

Permeation and evaporation estimated for year 2018 from Tier 3 rule

These emissions are represented by the following SCCs:

•	2501011011 - Residential Portable Fuel Containers: Permeation

•	2501011012 - Residential Portable Fuel Containers: Evaporation

•	2501012011 - Commercial Portable Fuel Containers: Permeation

•	2501012012 - Commercial Portable Fuel Containers: Evaporation

Emissions from these SCCs are impacted by 2007 MSAT rule standards limiting evaporation and
permeation emissions from these containers to 0.3 grams of hydrocarbons per day [ref 5], Inventory
estimates developed for calendar year 2018 in EPA's Tier 3 vehicle rule modeling platform [ref 6] reflect
the impact of these standards, as well as impacts of RVP and oxygenate use. These Tier 3 inventories
were interpolated from earlier 2015 and 2020 MSAT2 rule inventories and assumed 100% E10.

Vapor Displacement estimated for year 2018 from Tier 3 rule

Vapor displacement emissions occur while refueling containers at the pump. These emissions are
represented by the following SCCs:

•	2501011014 - Residential Portable Fuel Containers: Refilling at the Pump: Vapor Displacement

•	2501012014 - Commercial Portable Fuel Containers: Refilling at the Pump: Vapor Displacement

These emissions are not impacted by MSAT2 rule standards but are impacted by RVP and oxygenate use.
Inventory estimates were developed for calendar year 2018 in EPA's Tier 3 vehicle rule modeling
platform.

14.2.3 Hazardous air pollutants

Hazardous air pollutants found in liquid gasoline will be present as a component of VOC emissions.

These MSATs include benzene, ethyl benzene, toluene, hexane, xylenes, 2,2,4-trimethylpentane, and
naphthalene. For vapor displacement emissions of benzene and naphthalene, toxic to VOC ratios were
obtained from headspace vapor profiles from EPAct test fuels [ref 7], For permeation emissions of these
pollutants, vehicle permeation speciation data from Coordinating Research Council (CRC) technical
reports E-77-2b and E-77-2c were used [ref 8, ref 9], We relied on three-day diurnal profiles from the
CRC data. For evaporative emissions resulting from changes in ambient temperatures, speciation data
from the Auto/Oil program were used for E0 and E10 [ref 10], Table -2 lists the toxic to VOC ratios for
each type of PFC emission.

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Table -2: Toxic to VOC ratios for benzene and naphthalene from PFCs

Pollutant

Process

Speciation Surrogate

E10

Benzene

Vapor Displacement

Vehicle Headspace

0.0087

Permeation

Vehicle Permeation

0.0227

Evaporation

Vehicle Evap

0.0340

Naphthalene

Vapor Displacement

Vehicle Headspace

0.0000

Permeation

Vehicle Permeation

0.0004

Evaporation

Vehicle Evap

0.0004

Emissions of other air toxics for permeation, evaporation, and vapor displacement were all estimated
from the EPAct headspace vapor displacement profile for E10 (SPECIATE profile 8870). Toxic to VOC
ratios are provided in Table -3.

Table -3: Toxic to VOC ratios for Other HAPs (Vapor Displacement, Permeation, and Evaporation)

Pollutant

Toxic to VOC Ratio

Ethylbenzene

0.0068

Hexane

0.0616

Toluene

0.0521

Xylenes (o,m,p)

0.0300

2,2,4-Trimethylpentane

0.0540

14.2.4 Changes in the 2020 NEI and looking forward to the 2023 NEI

Inventories for the 2017 NEI were based on gasoline volumes for year 2018 using the NONROAD2005
estimates. These 2018 estimates were then adjusted to account for the differences in gasoline volumes
used for PFCs in MOVES3 versus NONROAD2005. Next, MOVES3 was run to estimate nonroad fuel
consumption for year 2020, and these adjustments were applied between year 2018 and 2020 MOVES3
consumption estimates.

It is important to note that this PFC methodology does not account for current levels of non-compliance;
this will be an improvement sought for the 2023 NEI PFC estimates.

14.3 References

1.	MOVES-Nonroad, its documentation and technical reports can be found here: Nonroad
Technical Reports.

2.	U. S. EPA. 2014. "Development of Air Quality Reference Case Upstream and Portable Fuel
Container Inventories for the Tier 3 Final Rule." Memorandum from Rich Cook, Margaret
Zawacki and Zoltan Jung to Docket, February 25, 2014, Docket No. EPA-HQ-OAR-2011-0135.

3.	U. S. EPA. 2007. Final Regulatory Impact Analysis: Control of Hazardous Air Pollutants from
Mobile Sources: EPA420-R-07-002; Office of Transportation and Air Quality, Ann Arbor, Ml.

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4.	Landman, L. C. (2007) Estimating Emissions Associated with Portable Fuel Containers (PFCs). U.
S. EPA, Assessment and Standards Division, National Vehicle and Fuel Emissions Laboratory, Ann
Arbor, Ml, Report No. EPA420-R-07-001.

5.	Federal Register. 2007. Control of Hazardous Air Pollutants from Mobile Sources. 72 (37): 8428-
8570.

6.	U.S. EPA. 2014. Emissions Modeling Technical Support Document: Tier 3 Motor Vehicle and
Emission and Fuel Standards. Office of Air Quality Planning and Standards, Research Triangle
Park, NC, Report No. EPA-454/R-13-003, February 2014.

7.	U. S. EPA. 2011. Hydrocarbon Composition of Gasoline Vapor Emissions from Enclosed Fuel
Tanks. Office of Research and Development and Office of Transportation and Air Quality. Report
No. EPA-420-R-11-018. EPA Docket EPA-HQ-OAR-2011-0135.

8.	U. S. EPA. 2010. Evaporative Emissions from In-Use Vehicles: Test Fleet Expansi	: E-77~2bi.
Prepared by Harold Haskew and Associates for Assessment and Standards Division, Office of
Transportation and Air Quality, October, 2010.

9.	Coordinating Research Council. 2010. Study to Determine Evaporative Emission Breakdown,
Including Permeation Effects and Diurnal Emissions, Using E20 Fuels on Aging Enhanced
Evaporative Emissions Certified Vehicles. Report No. E-77-2c.

10.	Auto/Oil Air Quality Improvement Research Program. 1996. Phase I and II Test Data. Prepared
by Systems Applications International, Inc.

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United States	Office of Air Quality Planning and Standards	Publication No. EPA-454/R-23-001n

Environmental Protection	Air Quality Assessment Division	March 2023

Agency	Research Triangle Park, NC


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