Transcript Document

Review and Evaluation of
Studies on the Use of E15 in
Light-Duty Vehicles
Iowa RFA Summit
Matthew Ratcliff, Robert L. McCormick,
Janet Yanowitz, Bradley T. Zigler
January 28, 2014
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
E15 Waiver
• EPA has granted a waiver for the use of E15 in
2001 and newer light-duty cars
o October 2010 waiver for 2007 and newer
o January 2011
waiver for 2001-2006
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What’s so special about 2001?
– More sophisticated emission control
systems
– CAP2000 requires actual in-use vehicle
testing over full useful life
NOx Emission Standard, g/mi
• National low emission vehicle
(NLEV) standards (2001) and
Tier 2 emission standards
(2004)
1.2
1.0
Tier 0
1981-1993
0.8
0.6
0.4
0.2
Tier 1
1994-2000
NLEV
2001-2003
Tier 2
2004-Present
0.0
• Improved compensation for
fuel oxygen content
– Prevents high temperature excursions at
full load operation
– Protects engine and catalyst from higher
levels of oxygen in fuel
λ (lambda)
3
Scope of Review
• Objective:
Review and evaluate research on the effects of E15 on 2001 and
newer vehicles
o Draw robust conclusions based on the entire available dataset
o
• Reviewed 43 studies
o
o
o
33 unique research studies
10 studies of methodology, reviews, or same data as other studies
More studies on E20 than E15, E20 studies included
• Primarily conducted by:
o
USDOE
– Oak Ridge National Laboratory
– National Renewable Energy Laboratory
o
o
Minnesota Center for Automotive Research
Coordinating Research Council
– Auto and oil company consortium
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Limitations of the Data
• Studies are not large enough to make quantitative
predictions of potential equipment failure rates
o
o
Including CRC engine durability study
Largest studies of whole vehicles (U. of Minnesota and USDOE)
found no fuel-related issues
• Wide variety of control fluids and unique test protocols
o
Difficult to combine studies into a single analysis
• Test fuels versus test fluids
o
o
Test fuels use commercial ethanol and hydrocarbon, typically
meet ASTM D4814
Test fluids
– Contain “aggressive” components
– Do not meet fuel quality standards
– Not intended for comparison of effects of different fuels because
effects of aggressive test fluids relative to real world fuels are unknown
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Overall Conclusions
• 2001 and newer cars compensate adequately for
higher ethanol content
o
o
No difference in emissions or catalyst durability for E10
compared to E15
Combustion and exhaust temperatures not significantly
changed
• Materials studies show little difference in effects of
E10 and E15
o
Effect of going from E0 to E10 is much larger
• Fuel system, engine, and whole-vehicle durability
studies, taken together, confirm expectations from
emissions and materials studies
• The use of E15 is likely to have little impact on 2001
and newer model year vehicles
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Emissions and Catalyst Durability Studies
• Sophisticated air/fuel ratio control produces little or no change in NOx or NMOG
• Fuel oxygen lowers unburned hydrocarbons and CO (mostly during open loop
operation)
• Full useful life catalyst durability tests showed no difference in catalyst
degradation for E15 vs. E0
o
Strongly implies that engine and exhaust temperatures are not significantly changed
• These results (and other studies) show that engines compensate for fuel ethanol
content
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Materials Compatibility Summary
o
o
Corrosion Rate in Ethanol Fuel Blends
with 1% Water
1.00E+00
1.00E-01
Corrosion Rate (mm/year)
• Studies used aggressive test
fluids – not intended for
comparison to fuel effects
• Metal corrosion rates very
low
• Minimal differences in
elastomer swell between E10
and E17
0.03 mm/yr = "low rate of corrosion" in
Kass et al., 2011
1.00E-02
Stainless steel 304
0.0025 mm/yr = "insignificant loss of
materials over a 20-year time span" in
Jones, et al., 2008
1.00E-03
Low carbon steel
Medium carbon steel
1.00E-04
Al 6061
Copper
1.00E-05
Brazing Alloy
1.00E-06
1.00E-07
0
5
10
15
20
Ethanol (Vol%)
Significantly larger differences
between E0 and E10
Differences between materials
much larger than differences
between fuels
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CRC Fuel System Component Testing
2 Fuel
Dampers
10 Fuel
Pumps
7 Entire Fuel
System Rigs
10 Level
Senders
3 Fuel
Injectors
Soak
Soak &
Endurance
Aging
Hot Soak 49
Weeks
Soak and Full
Sweep
Aging 600
million cycles
AVFL 15
Using
Aggressive
E20 Test
Fluid
Choose Most Fluid Sensitive Parts
3 Level
Senders
4 Fuel Pumps
Soak and Full
Sweep
Soak &
Endurance
Aging
AVFL 15a
Using
Aggressive
and non
Aggressive
Test Fluids
Find Parts Which Fail on E15 but not on E10
1 Fuel Pump
But, this pump did not fail on longer testing
with Aggressive E20 Test Fluid in AVFL15
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CRC Engine Durability Study
• CRC Study of 8 engine models (2001-2009)
• Engines removed from vehicles
Tested for 500 hr on drive cycle intended to
simulate 100,000 mi
o Tested on E20, if failing, tested on E15, if
failing tested on E0
o Statistical analysis assumed passing result
for engines not tested
o
• Failure criteria:
o
o
o
o
o
E = Emissions during EOT FTP75 testing
D = Diagnostic Trouble Code detected at EOT
V = Valve clearance measurement on at least
one valve out of OEM specification at EOT
C = Compression measurement on at least
one cylinder out of OEM specification at EOT
L = Leakage measurement on at least one
cylinder above 10% at EOT
Drive cycle engine speeds are too
low to rotate valves (<3500 rpm)
No E10 control testing
Use of dummy data in statistical
analysis biases results and makes
error bars artificially smaller
Older vehicles well beyond full
useful life at EOT
Inappropriate use of leakdown,
typical shop manual criterion is
20-25%
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CRC Engine Durability Results
Failure on emissions
Leakdown
failures
Concluded that two popular engines used in 2001-2009 model
year vehicles
potentially beyond
inconsistent with industry
experienced mechanical failure when operated on E15
full useful life
practice and shop manuals
E20
Vehicle 1
Vehicle 2
Vehicle 3
Vehicle 4
Vehicle 5
Vehicle 6
Vehicle 7
Vehicle 8
Sample A
Waived**
Fail (L)
Pass
Waived* (L)
Waived* (E,D)
Waived* (L)
Pass
Fail (E,C,L)
Sample B
Pass
Fail (L)
Fail (V,L)
Pass
Pass
Waived* (L)
Pass
Fail (C,L)
Sample C
E15
Sample D
Sample E
E0
Sample F
Fail (E)
Fail (L)
Fail (L)
Pass
Pass
Pass
Pass
Pass
Fail (E,L)
Fail (C, L)
Fail (E,C,L)
Fail (E,C,L)
*Waived = Vehicle did not pass specified criteria, but after OEM teardown decision was made not to retest vehicle on E15 or E0
** According to the study text, Vehicle 1, Sample A “The Engine dynamometer based EOT emission test was waived after
technical challenges prevented comparison of the SOT [start of test] and EOT [emission data].”
If all actual test results (i.e. including Vehicle 8 and
excluding dummy data) are used for the analysis, there
is a 32% chance that E15 and E20 failures are
completely unrelated to ethanol content, as opposed to
the 7% chance that is asserted in CRC’s report.
One vehicle failed leakdown
and compression on all fuels,
suggesting that engine
speeds were too low
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MnCAR Fuel System Study
• Tested fuel pumps and fuel level senders using
Reference Fuel C, Aggressive TF10 and
Aggressive TF20
Targeted a “broad sample of high volume vehicles on
the road”
o 4000 hr soak and endurance tests
o
• All modern vehicle fuel pumps showed minimal
effect of E20
• All level sending units failed over the course of
the study – on all fuels
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University of Minnesota Fleet Study
• In use vehicle study
• 40 pairs (80 total) of similar 2000 to 2006
model year vehicles with matched usage
patterns
• One fueled with commercially available E0,
the second fueled with E20
• Over the 13 month test period no additional
fuel related maintenance problems emerged
in the E20 fueled vehicles
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Overall Conclusions
• 2001 and newer cars compensate adequately for
higher ethanol content
o
o
No difference in emissions or catalyst durability effect for
E10 and E15
Combustion and exhaust temperatures not significantly
changed
• Materials studies show little difference in effects of
E10 and E15
o
Effect of going from E0 to E10 is much larger
• Fuel system, engine, and whole-vehicle durability
studies, taken together, confirm expectations from
emissions and materials studies
• The use of E15 is likely to have little impact on 2001
and newer model year vehicles
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The authors thank RFA for sponsoring
this study:
ethanolrfa.org
[email protected]
USDOE Catalyst Durability Study
Acquire 2-4 “matched” vehicles for each model, 1 matched vehicle dedicated
to each fuel (E0, E10, E15, or E20) for aging
Baseline
Emissions (E0)
Intermediate
Emissions (E0)
Age on
dedicated fuel
Baseline
Emissions (E0)
Baseline
Emissions (E10)
using MAD or
Intermediate
Emissions (E10)
Intermediate
Emissions (E0)
Intermediate
Emissions (E15)
Intermediate
Emissions (E0)
Intermediate
Emissions (E20)
Intermediate
Emissions (E0)
Test Track
Baseline
Emissions (E0)
Baseline
Emissions (E15)
25,000 to
50,000 miles
Baseline
Emissions (E0)
Baseline
Emissions (E20)
Full-Life
Emissions (E0)
Age on
dedicated fuel
Full-Life
Emissions (E0)
Full-Life
Emissions (E10)
using MAD or
Test Track
Full-Life
Emissions (E0)
Full-Life
Emissions (E15)
25,000 to
50,000 miles
Full-Life
Emissions (E0)
Full-Life
Emissions (E20)
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USDOE Catalyst Durability Study
Vehicle Aging: 82 Vehicles Tested at 3 Sites
Totals
58 Tier 2 (19 models), 24 non-Tier 2 (8 models)
Year
2006
2007
2008
2008
2007
2006
2007
2000
2002
2002
Non-Tier 2
Vehicles
Vehicle
number
Fuels
Chevrolet Silverado
4
E0
E10
E15
E20
Honda Accord
4
E0
E10
E15
E20
Nissan Altima
4
E0
E10
E15
E20
Ford Taurus
4
E0
E10
E15
E20
Chrysler Caravan
4
E0
E10
E15
E20
Chevrolet Cobalt
3
E0
E15
E20
Dodge Caliber
3
E0
E15
E20
Chevrolet Silverado
3
E0
E15
E20
Nissan Frontier
3
E0
E15
E20
Dodge Durango
3
E0
E15
E20
Transportation Research Center (Ohio), test track aging
Year
Vehicle
number
Fuels
2009
Jeep Liberty
3
E0
E15
E20
2009
Ford Explorer
3
E0
E15
E20
2009
Honda Civic
3
E0
E15
E20
2009
Toyota Corolla
3
E0
E15
E20
2005
Toyota Tundra
3
E0
E15
E20
2006
Chevrolet Impala
3
E0
E15
E20
2005
Ford F150
3
E0
E15
E20
2006
Nissan Quest
3
E0
E15
E20
2003
Toyota Camry
3
E0
E15
E20
2003
Ford Taurus
3
E0
E15
E20
2003
Chevrolet Cavalier
3
E0
E15
E20
Environmental Testing Corp (Colorado), mileage accumulation dynamometers
Year
Vehicle
number
Fuels
2009
Saturn Outlook
2
E0
E15
2009
Toyota Camry
2
E0
E15
2009
Ford Focus
2
E0
E15
2009
Honda Odyssey
2
E0
E15
2000
Honda Accord
3
E0
E15
E20
2000
Ford Focus
3
E0
E15
E20
35
Vehicles
33
Vehicles
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Vehicles
17
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Catalyst Durability Overview and Conclusions
• 82 vehicles aged for at least 50,000 miles (many
>100,000 miles)
o
o
EPA’s Standard Road Cycle
Demonstrate if a new fuel will cause or contribute to the
degradation of a vehicle’s emission controls
• Several had over 90,000 miles at beginning of test
and greatly exceeded 120,000 mile full useful life
at end of test
• Of twenty-five 2001 and newer vehicle models,
only five were tested on E10
• No discernible differences in the rates of catalyst
performance degradation between E0 and the
ethanol blended fuels
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Vehicles for Engine Durability
Vehicle
2001 Honda CRV, 2.0L I4
2002 Volkswagen
Jetta, 2.0L I4
2004 Scion xA,
1.5L I4
2005 Chevrolet
Colorado, 3.5L I5
Emissions
Valve Train Design
Tier 1 NLEV
Rocker arm, threaded adjuster
Tier 1 NLEV
Direct acting, hydraulic
Tier 2 Bin 9
Direct acting, mechanical
Tier 2 Bin 9
Roller finger follower, hydraulic
2007 Ford Edge,
Tier 2 Bin 5
3.5L V6
2007 Dodge Ram, Tier 2 Bin 5
5.7L V8
Direct acting, mechanical
2009 Dodge
Caliber, 2.4L I4
Tier 2 Bin 4
Direct acting, mechanical
2009 Chevrolet
Aveo, 1.6L I4
Tier 2 Bin 5/4
Pushrod, hydraulic
Direct acting, mechanical (but
service literature references 2nd
running change design to hydraulic
lash adjuster; type is not
documented by CRC)
*
CRC did not report initial mileage for vehicles tested on E15 or E0.
1
Mileage for E20
OEM specified acceptable
*
vehicles
leakdown rate 1,2,3,4,5,6,7,8
71,412/110,681 No leakdown specification
provided
77,891/106,761 No leakdown specification
provided
61,351/56,671 No leakdown specification
provided
48,109/33,972 “Cylinder leakage that exceeds
25% is considered excessive
and may require component
service.”
17,906/14,450 “Leakage exceeding 20% is
excessive.”
28,597/26,078 “All gauge pressure indications
should be equal, with no more
than 25% leakage.”
11,941/12,494 “All gauge pressure indications
should be equal, with no more
than 25% leakage.”
8,327/3,758 No leakdown specification is
provided, and leakdown is not
even referenced as a
diagnostic tool / method.
Honda Motor Co., Ltd., Service Manual 1997-2001 CR-V, First Edition, October 2000.
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