74-25 AW
Effects of Methanol-Gasoline
Blends on Emissions
March 1974
Test and Evaluation Branch
Emission Control Technology Division
Environmental Protection Agency
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Background
The Test and Evaluation Branch of the Emission Control
Technology Division is responsible for investigating any
approach to control technology which-•?shows promise of
producing significant reductions in emissions. There has
been considerable interest expressed in the effect on
emissions of blending methanol with gasoline. A test
program was set up to determine what influence the addition
of methanol to gasoline would have on a car which was not
designed to be operated on such a blend.
Test Program
Two blends of gasoline and methanol were tested. One blend
contained 7% methanol and the other contained 11%. These
blends have a lower heating value or energy content per
volume than pure gasoline, approximately 3% and 4% lower
respectively. The test vehicle was a 1970 Chevrolet equipped
with a 350 CID engine and an automatic transmission.
All tests were run as specified in the 1975 FTP (Federal
Register, No. 221, Vol. 37, November 15, 1972). A total of
10 tests were performed. Initially, two baseline tests were
run using Indolene HO (unleaded) gasoline for fuel. Following
the baseline tests, three tests were run on each of the
two blends. The base fuel used for the blends was Indolene HO
(unleaded).
The blends of gasoline-methanol were briefly evaluated to
determine whether or not phase separation would occur when
exposed to low ambient temperatures.
Test Results
The 11% blend caused a 17% increase in HC, a 41% decrease in
CO, a 35% decrease in NOx and an 8% decrease in fuel economy
in miles per gallon. The 7% blend caused a 10% increase in
HC, a 34% decrease in CO, a 24% decrease in NOx and a 6.5%
decrease in fuel economy in miles per gallon. Fuel economy
on a BTU per mile basis was somewhat lower for blend operation
when compared to baseline. To investigate the phase separation
question, one pint of the 11% blend was placed in outside
ambient conditions (10*F) for an overnight soak. After standing
for approximately 15 hours, the 11% gasoline and methanol blend
had separated into two phases. Another pint of the 11% blend
was stored in a freezer (O'F) for the same time period.' This
bottle showed no evidence of separation.
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Conclusions
It appears that the use of a methanol-gasoline blend in a
production vehicle not designed to run on such a blend can
produce significant reductions in CO and NOx. However, the
accompaning increase in HC found in this test may have been
due to lean misfire due to the effective leaning of the
air/fuel ratio by the addition of methanol. Since lean
misfire is not a desirable operating conditon, changes would
have to be made to the carburetion to correct this situation
on those vehicles exhibiting that problem. The vehicle also
exhibited poor driveability (backfiring, stalling, etc.)
when running on the methanol-gasoline blend, again typical
characteristics of overlean operation.
The separation of the methanol-gasoline blend exposed to low
ambient temperatures and moisture would indicate potential
problems requiringyextensive investigation and resolution
prior to the widespread use of such blends.
Significant deterioration in fuel economy on both a volume
and energy basis resulted from use of the methanol-gasoline
blends.
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Methanol-Gasoline Blend
1970 Chevrolet 350 CID
1975 Federal Test Procedure
(mass emissions in grams/mile)
HC CO NOx MPG
Baseline 1.78 12.2 3.68 12.0
2.05 14.0 3.43 12.5
Average 1.92 13.1 3.56 12.3
11% Blend 2.08 7.3 2.40 10.8
2.10 7.7 2.48 11.2
2.54 8.1 2.59 11.8
Average 2.24 7.7 2.39 11.3
% Change
from baseline +17% -41.2% -32.9% -8.1'
7% Blend 2.08 8.5 2.34 11.8
2.19 8.9 2.90 11.3
2.08 8.4 2.91 11.4
Average 2.12 8.6 2.72 11.5
% Change
from baseline +10.4% -34.4% -23.6% -6.5'
* US. GOVERNMENT PRINTING OFFICE: 1979- 651-112/0095
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