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Air Quality and Vehicle Emission
Standards: An Overview of the National Low Emission Vehicle Program and Related Issues II
CONTENTS FOR THIS SECTION
Fleet Average
Standards
Trading Program
EPA's Estimates of Air
Quality Benefits and Costs
Related Regulatory Issues
Sulfur Levels in Gasoline
Relative Stringency
of Emission Standards for Light Trucks
Conclusion
Fleet
Average Standards
While certified vehicles are
subject to emission standards for a total of five pollutants, manufacturers will
demonstrate compliance by averaging only the NMOG emissions of their vehicle fleets, which
represent the most significant reductions under the program. Similar to the certification
standards, passenger automobiles and smaller light trucks weighing up to 3,750 pounds are
subject to stricter fleet averages than larger light trucks weighing between 3,751 and
5,750 pounds. Vehicles sold in the Northeast in MY1999 and MY2OOO will be subject to less
stringent averages than those that will become effective nationwide in MY2OO1. At this
time, the fleet average standards will become as stringent as the LEV certification
standards for NMOG at 5 years or 50,000 miles. (Refer to table.) To preserve
regional air quality benefits, manufacturers must calculate separate fleet emission
averages for vehicles sold in the Northeast and for those sold in other states.
Trading
Program
To provide additional flexibility
in demonstrating compliance, manufacturers can trade NMOG credits to meet the fleet
average standards. A manufacturer will generate credits in a model year if its fleet
average is lower than the standard, and will generate debits if its fleet average exceeds
the standard. Manufacturers with debits can purchase credits from others to achieve
compliance. However, trading will be conducted in two separate regions (the Northeast and
the remaining states) to prevent manufacturers from using credits generated in states with
relatively clean air to achieve compliance in the more heavily polluted Northeastern
states. Manufacturers also can save credits for use or sale in future model years.
However, these credits will lose a portion of their value each year and will no longer be
valid after the third year held. As an incentive to introduce cleaner vehicles nationwide
sooner than the program requires, manufacturers will be eligible for early reduction
credits if they meet the fleet average standards in states outside of the Northeast prior
to MY2001.
EPA's Estimates of Air Quality Benefits and Costs
The main air quality benefit of
the National LEV program would be reductions in the ozone precursors, NMOG and NOx, which
also could help to reduce fine particulates. Other benefits would be reductions in two
carcinogens, formaldehyde and benzene. 15 Based on the stringency of the
certification standards, EPA estimates that by 2005 the National LEV program would reduce
NOx emissions by 400 tons per day nationwide, NMOG by 279 tons, PM by 29 tons, benzene by
7 tons, and formaldehyde by 4 tons. 16 While such reductions would help
to reduce pollution from new vehicles, they are relatively small (less than 1%) compared
to total emissions of these pollutants from all sources combined. In 1996, nationwide
emissions of NOx were roughly 64,000 tons per day, emissions of VOCs (including NMOG) were
over 52,000 tons per day, and emissions of PM were approximately 9,000 tons per day. 17 Actual emission reductions will depend to a large extent on whether
certified vehicles operate as cleanly in actual use as they do under test conditions.
EPA analyzed the costs of the
National LEV program based on cost estimates of vehicles sold in California. The
California Air Resources Board estimates that the cost of an LEV in the state is on
average $96 higher than a Tier I vehicle. EPA estimates a somewhat lower cost of $76 under
the National LEV program due to the following reasons: advances in technology could reduce
costs; economies of scale also could lower costs since manufacturers will be able to
produce a single fleet of vehicles subject to the same standards nationwide; past cost
estimates from the California Air Resources Board have proven higher than actual price
differences; and industry historically has lowered vehicle prices in successive model
years after the introduction of new technologies. Based on projections of vehicle sales
nationwide, EPA estimates that the total cost of the National LEV program would be $950
million annually. 18
Comparison of Tier 1 and National
LEV Standards
| Vehicle Type / Weight |
5 Years / 5O,000 miles (grams/mile) |
10 Years / 100,000 miles (grams/mile) |
|
NMHC/ NMOG a |
Co |
NOx |
PM b |
HCHO |
NMHC/ NMOG a |
CO |
NOx |
PM b |
HCHO |
| Tier 1 Certification Standards |
LDVs/LDTs
(0-3750 lbs.) |
.250 |
3.4 |
.4 |
.08 |
-- |
.310 |
4.2 |
.60 |
.10 |
-- |
| LDTs (3751-5750 lbs.) |
.320 |
4.4 |
.7 |
.08 |
--- |
.400 |
5.5 |
.97 |
.10 |
-- |
| National LEV Certification Standards |
LDVs/LDTs
(0-3750 lbs.) |
|
|
|
|
|
|
|
|
|
|
| TLEV |
.125 |
3.4 |
.4 |
-- |
.015 |
.156 |
4.2 |
.60 |
.08 |
.018 |
| LEV |
.075 |
3.4 |
.2 |
-- |
.015 |
.090 |
4.2 |
.30 |
.08 |
.018 |
| ULEV |
.050 |
1.7 |
.2 |
-- |
.008 |
.055 |
2.1 |
.30 |
.04 |
.011 |
|
|
|
|
|
|
|
|
|
|
|
| LDTs (3751-5750 lbs.) |
|
|
|
|
|
|
|
|
|
|
| TLEV |
.160 |
4.4 |
.7 |
-- |
.018 |
.200 |
5.5 |
.90 |
.10 |
.023 |
| LEV |
.100 |
4.4 |
.4 |
-- |
.018 |
.130 |
5.5 |
.50 |
.10 |
.023 |
| ULEV |
.050 |
2.2 |
.4 |
-- |
.009 |
.070 |
2.8 |
.50 |
.05 |
.013 |
|
|
|
|
|
|
|
|
|
|
|
| National LEV NMOG Fleet Averages |
LDVsILDTs
(0-3750 lbs.) |
|
|
|
|
|
|
|
|
|
|
| MY1999(Northeast) |
.148 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| MY2000
(Northeast) |
.095 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| MY2001
(Nationwide) |
.075 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
|
|
|
|
|
|
|
|
|
|
|
| LDTs
(3751-5750 lbs.) |
|
|
|
|
|
|
|
|
|
|
| MY1999
(Northeast) |
.190 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| MY2OOO
(Northeast) |
.124 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| MY2001
(Nationwide) |
.100 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
a Tier 1 vehicles are subject to the testing
procedure for NMH C, whereas vehicles certified under the National LEV program are subject
to the testing pmcedure for NMOG. Both pollutants are closely related hydrocarbon
compounds that can combine with NOx in the presence of sunlight to fonn ozone. The
National LEV pmgram adopted California's use of the testing procedure for NMOG because it
more accurately measures the level of hydrocarbons in a vehicle's exhanst.
b The National LEV standards for PM apply
only to diesel-fueled vehicles at 10 years or 100,000 miles.
c The National LEV program requires manufacturers
to meet fleet a,'erage standards only for NMOG at 5 years or 50,000 miles.
Prepared by the Congressional Research Service
with data from the Environmental Protection Agency.
LDV = light duty (passenger) vehicle
LDT = light duty truck
TLEV = Transitional low emission vehicle
LEV = low emission vehicle
ULEV = ultra low emission vehicle
NMHC = non-methane hydrocarbons
NMOG = non-methane organic gases
CO = carbon monoxide
NOx = nitrogen oxides
PM = particulate matter
HCHO = formaldehyde
Related Regulatory Issues
Two regulatory issues could play
significant roles in determining the extent to which the National LEV program is able to
reduce actual emissions and help states improve air quality. First, certified vehicles may
not operate as cleanly in actual use as the program's low emission standards suggest
because high sulfur levels in commercial gasoline could diminish the effectiveness of low
emission technologies. Second, light trucks are not regulated as strictly as passenger
automobiles. As a result, the increasing market share of light trucks could alter the
composition of the vehicle fleet significantly enough to increase total emissions and
offset the sharper reductions from passenger automobiles. Each of these issues is
discussed below.
Sulfur Levels in Gasoline
Sulfur occurs naturally in crude
oil, and the amount remaining in gasoline varies widely among refineries. Nationwide, the
sulfur level in commercial gasoline averages 330 parts per million (ppm) and can reach as
high as 1,000 ppm in some areas. 19 Levels are lowest in California
where a cap is currently in place that limits sulfur to a maximum of 80 ppm with a
statewide average of 30 ppm. To meet emission standards, conventional gasoline-powered
vehicles primarily depend on catalytic converters to reduce levels of CO, NOX, and VOCs
from the exhaust. However, the sulfur present in gasoline can chemically react with the
surface of the catalyst and inhibit the removal of other pollutants. The extent to which
sulfur increases emissions depends on numerous factors such as the design of the catalyst,
materials used, air to fuel mixture of the engine, and range of exhaust temperatures.
Currently, a substantial
discrepancy exists between sulfur levels in commercial gasoline and the amount in fuels
used to certiiy that vehicles meet emission standards. Under the National LEV program,
manufacturers can certify their vehicles with the test fuel for California's LEV program
or the federal test fuel for Tier 1 vehicles. Sulfur levels in California's test fuel are
frequently below 30 ppm, and the amount present in federal test fuel is typically much
less than 100 ppm, both of which are lower than the average of 330 ppm in commercial
gasoline available nationwide. Even in areas where the second phase of reformulated
gasoline will be sold in 2000, sulfur levels will average as much as 150 ppm and continue
to exceed test fuel amounts by a significant margin. 20 In effect,
vehicles certified under the National LEV program may emit greater quantities of
pollutants in actual use than the stringency of the low emission standards alone would
suggest, and therefore, make less of an impact on improving air quality. However, the
extent to which the air quality benefits of the program might be compromised is difificult
to determine since different makes and models of vehicles can respond quite differently to
high sulfur gasoline.
The automobile and oil industries
have conducted studies to examine the effects of gasoline sulfur levels on emissions
performance. They generally conclude that actual emissions depend on the amount of sulfur
in gasoline, and NOx emissions seem to be affected by sulfur more dramatically than other
pollutants. However, some vehicles are not as sensitive to high sulfur levels as others.
EPA has combined the test results from two recent industry studies that indicate a wide
range of effects among LEVs and ULEVs when operated on high sulfur gasoline. For example,
emissions of NOx from the 9 most sensitive vehicles increased by 251% when operated on
gasoline with a national sulfur average of 330 ppm, whereas NOx emissions from the 9 least
sensitive vehicles increased by only 61% when operated on the same gasoline. These studies
also tested the effects of sulfur on Tier I vehicles and observed a much lower increase in
NOx emissions of 13.6% relative to the national sulfur average of 330 ppm, which indicates
that the technologies used to achieve the LEV and ULEV standards are significantly more
sensitive than those typically used in Tier 1 vehicles. 21
The effects of gasoline sulfur
levels on emissions could possibly be addressed in two major ways. First, manufacturers
might be able to redesign vehicle engines and exhaust systems so that they are less
sensitive to sulfur. Second, the amount of sulfur in gasoline might be limited either
nationally or on a regional basis in areas with serious air quality problems. While the
technology is currently available to lower sulfur levels at least to that already achieved
in California, such reductions would require refineries to invest in new equipment and
lead to increases in operating costs of 5 to 8 cents per gallon, which in turn could raise
gasoline prices. 22 However, recent developments in refinery technology
could lower the costs of reducing gasoline sulfur levels to 1 or 2 cents per gallon
nationwide. If EPA proposes more stringent Tier 2 standards, it also may consider
regulatory controls on gasoline sulfur levels to insure that the low emission technologies
necessary to achieve further reductions in emissions from new vehicles are not
compromised.
Relative Stringency of Emission Standards for Light Trucks
The discrepancy between the
standards for passenger automobiles and light trucks is a rising issue in the regulation
of vehicle emissions. While smaller light trucks weighing up to 3,750 pounds are subject
to the same emission standards as passenger automobiles, larger light trucks weighing in
excess of this amount are allowed to meet less stringent standards. Congress initially
established more lenient standards for larger light trucks because their capacity for
carrying heavy loads compromised emissions performance and they composed a smaller portion
of the vehicle fleet, which made less of an impact on air quality. However, the
composition of the vehicle fleet has changed over the years in favor of light trucks, and
their market share has increased from 16.5% in 1980 to 40.4% of total vehicle sales in
1996. 23 The sharp rise in sales is mostly due to the heightened
popularity of sport-utility vehicles and minivans. Such vehicles accounted for only 13.6%
of total light truck sales in 1975, but by 1996, their market share had more than tripled
to nearly 50% of all light trucks sold nationwide. 24 Many of these
vehicles weigh in excess of 3,750 pounds and are therefore allowed to meet less stringent
emission standards even though they are used primarily for personal transportation rather
than for carrying heavy loads, which the more lenient standards were initially designed to
accommodate. As a result, the larger market share of light trucks and increased mileage of
these vehicles from passenger use has expanded the total emissions inventory of the
on-road vehicle fleet and raised the issue of whether light trucks should be regulated
more strictly.
Like the Tier 1 standards under
the Clean Air Act and California's current low emission standards, the National LEV
program continues the practice of allowing light trucks weighing in excess of 3,750 pounds
to meet less stringent standards. Consequenily, if the market share of higher-emitting
light trucks continues to rise, the air quality benefits of the National LEV program might
be less promising. If EPA proposes more stringent Tier 2 standards, it might regulate
emissions from all light trucks more strictly due to air quality considerations. Higher
emissions from light trucks could possibly be addressed in at least three different ways.
First, all light trucks might become subject to the same standards as passenger
automobiles regardless of vehicle use. Second, larger light trucks might continue to be
subject to less stringent standards but be required to use the same low emission
technologies as passenger automobiles. Third, separate standards might be established
according to vehicle use rather than vehicle type. While the first option has the greatest
potential for providing the most air quality benefits, reducing emissions from heavier
trucks with larger engines could prove to be problematic as it would require manufacturers
to use more advanced catalytic technologies that could increase production costs and to
improve engine operating efficiencies which might result in diminished performance. As
discussed earlier, California recently finalized revisions to its LEV program (LEV II) and
decided to address the issue of higher emissions from light trucks by requiring all
vehicles weighing up to 8,500 pounds to meet the same emission standards beginning in
MY2004.
Conclusion
The automobile industry has been
complying with low emission standards in California for the past few years. During this
time, manufacturers have demonstrated that the technology to produce cleaner vehicles is
currently available. However, the ability of this technology to reduce emissions in actual
use depends on how sensitive a vehicle is to the amount of sulfur in gasoline. At this
time, low sulfur gasoline is not commercially available outside of California, and plans
under the National LEV program to reduce vehicle emissions with current technologies in
areas where cleaner fuels are not available could prove extremely difficult. In addition,
the rising market share of light trucks could result in expanding the emissions inventory
of the nation's on-road vehicle fleet and offset some of the sharper reductions in
emissions from passenger automobiles. While the National LEV program will regulate
emissions from new vehicles more strictly than the current standards under the Clean Air
Act, it is a partial artempt at introducing cleaner vehicles nationwide because it leaves
the two larger regulatory issues of gasoline sulfur levels and higher emissions from light
trucks open for further debate. EPA may address these issues in the near future if it
decides to propose more stringent Tier 2 emission standards.
Endnotes
15 Although the
National LEV program does not include a standard for benzene, EPA expects that the low
emission technologies used to achieve the certification standards also would reduce
emissions of this pollutant.
16 EPA. Federal
Register. June 6, 1997. p.31195-31196.
17 EPA. Office
of Air Quality Planning and Standards. 1996 National Air Quality and Emissions Trends
Report. January 1998. p.84-85. EPA estimates that in 1996 stationary and mobile
sources in the United States emitted 23.4 million tons of NOx, 19.1 million tons of VOCs,
and 3.3 million tons of PM, yielding adaily emissions average of roughly 64,000 tons for
NOx, over 52,000 tons for VOCs, and approximately 9,000 tons for PM.
18 EPA. Federal Register. June 6, 1997. p. 31197.
19 EPA. Office
of Mobile Sources. StaffPaper on Gasoline Sulfur Issues. May 1998, p.3.
20 Reformulated
gasoline (RFG) burns more cleanly and results in fewer emissions ofozoneforming and toxic
compounds. Under the Clean Air Act, 10 metropolitan areas with serious air quality
problems require the sale of RFG, and 13 additional areas voluntarily require the sale of
RFG. The majority of these areas are located in Northeastern states.
21 EPA. Office
of Mobile Sources. Staff Paper on Gasoline Sulfur Issues. May 1998. p.11. Test
results compiled from two studies conducted by the Coordinating Research Council (CRC),
representing the oil industrv, and by the American Automobile Manufacturers Association
and the Association of International Automobile Manufacturers.
22 Ibid.,
p.32-34. EPA and the Department of Energy have studied the costs of reducing sulfur levels
in gasoline to an average of 40 ppm in the Northeast and Gulf Coast states and have
estimated that costs to refmeries would range between 5.1 and 8 cents per gallon. The
American Petroleum Inntitute sponsored a different study to also include the Midwest,
which estimated an average cost to refineries of no more than 5.1 cents per gallon.
23 Department of
Transportation. Bureau of Transportation Statistics. Transportation Statistics Annual
Report for FYI 997 p.87
24 Ibid., p. 88
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