Myth: 15% Ethanol Fuel Will Destroy My Engine

[Bill USA]

9. 3 MIT scientists went further, Dirctly Injectng ethanol, turbo-charging & downsizing boosted mpg 30%

...note too, that they are using only ~5% by volume Ethanol. THe other 95% of the fuel being gasoline!

By Directly Injecting the ethanol they can go with even higher combustion chamber pressures as the higher latent heat of ethanol cools the air fuel charge in the combustion chamber allowing even greater combustion chamber pressures.

Patent application
https://www.google.com/patents/US8082735


Here's a more readable presentation of their engine design:

http://www.ethanolboost.com/LFEE-2005-01.pdf

Direct Injection Ethanol Boosted Gasoline Engines:
Biofuel Leveraging For Cost Effective Reduction of
Oil Dependence and CO2 Emissions]

D.R. Cohn*, L. Bromberg*, J.B. Heywood‡

Massachusetts Institute of Technology
Cambridge, MA 02139

*Plasma Science and Fusion Center
‡Mechanical Engineering Dept. and Sloan Automotive Laboratory




Ethanol has a high fuel octane number (a blending octane number of 110) 2. Moreover,
appropriate direct injection of ethanol can provide an even larger additional knock
suppression effect due to the substantial air charge cooling resulting from its high heat of
vaporization. Our calculations indicate that by increasing the fraction of the fuel provided
by ethanol up to 100 percent when needed at high values of torque, an engine could
operate without knock at more than twice the torque and power levels that would
otherwise be possible. The level of knock suppression can be greater than that of fuel
with an octane rating of 130 octane numbers injected into the engine intake.

The large increase in knock resistance and allowed inlet manifold pressure can make
possible a factor of 2 decrease in engine size (e.g. a 4 cylinder engine instead of an 8
cylinder engine) along with a significant increase in compression ratio (for example, from
10 to 12). This type of operation could provide an increase in efficiency of 30% or more.
The combination of direct injection and an a turbocharger with appropriate low rpm
response provide the desired response capability.
(more)

NOte that by achieving 30% BETTER mpg than gasoline this way, this DOUBLES the Dept of Energy figure for Ethanol's mpg relative to gasoline's (Dept of Energy uses .65 - based upon using ethanol in a low compression detuned, for no-lead gasoline, ICE).

NOw, what does this do to ethanol's GHG emissions reduction figure relative to gasoline's?

Since fuel efficiency is doubled, the GHG emissions of ethanol is cut in HALF:

(1.30)/(.65) = 2.0
DoE est of Ethanol's GHG emissions reduction = -.26 (this without the hypothetical Indirect Land Use changes figure, which is without any empirical validation)

... So, GHG emissions for ethanol relative to gasoline is: 1-.26 = .74

GHG emissions factored by the improvement in mpg from the MIT Ethanol Direct Injection turbo-charged engine = .74/2 = .37

Thus, the GHG emissions reduction compared to gasoline for ethanol in the MIT designed engine would be: 1 -.37 = .63


so, using the MIT Ethanol direct injection engine, the GHG emissions reduction for ethanol goes from -.26 to -.63 !