There have been interesting technological developments regarding ethanol production that were (i'm sure) not considered in their study.
The University of Iowa this summer filed for patent protection on process their researchers have developed and tested using ultra-sound to boost alcohol yield from starch based ethanol feed stocks. They have achieved a 30% increase in alcohol yield (while reducing energy inputs and costs) by reducing the particle size.
A researcher at Purdue University recently presented his alternative method of producing ethanol from starch based feed-stocks which reduces water required by 90%.
http://www.terradaily.com/reports/New_Ethanol_Process_Offers_Lower_Costs_Environmental_Benefits_999.html I note, however that most of the new ethanol plants being built today are dry mill because they are much more efficient than wet-mill. Wet-mill has an advantage if you are building a facility next to a cattle operation where you can send the un-dried distillers grain (a cattle feed supplement) to the cattle operation WITHOUT drying (at great energy savings). Two new plants are being built to take advantage of the closed loop design.
M.I.T. Engineers have built an ICE using Turbo-charged engine with direct injection of ethanol which they indicate will produce a 30% reduction in gasoline consumption using a ratio of 5% ethanol to 95% gasoline. The higher octane rating of ethanol enables using higher compression from the turbo-chager. This means you can produce more power from a smaller engine. What this means is if all the cars on the highway were using this engine you would get a 30%% reduction in gasoline usage only using an amount of ethanol that would be only
5% of the total fuel supply. Any ethanol production above the 5% could be blended with the gasoline further reducing gasoline usage.
lfee.mit.edu/public/LFEE_2005-001_RP.pdf
"Ethanol biofuel could play an important role in meeting these goals by enabling a
substantial increase in the efficiency of gasoline engines. In this paper, we discuss an
ethanol boosted engine concept where a relatively small amount ethanol is used to
increase the efficiency of use of a much larger amount of gasoline by approximately
30%. Gasoline consumption and the corresponding CO2 emissions would thereby be
reduced by 25%. In combination with the additional reduction that results from the
substitution of ethanol for gasoline as a fuel, the overall reduction in gasoline
consumption and CO2 emissions is greater than 30%. This approach involves only modest
changes to the present gasoline engine systems and fueling infrastructure. The increase in
vehicle cost could be modest (approximately $600). This leveraged use of ethanol could
substantially increase its energy value and help to alleviate concerns about a low energy
output/ input ratio (energy provided by the ethanol/energy need to produce the ethanol)."
http://www.greencarcongress.com/2006/05/ethanol_direct_.html
Ethanol Direct Injection as an Enabler for Aggressive Engine Downsizing
3 May 2006
MIT scientists are exploring the use of ethanol direct injection (DI) to support the use of small, highly turbocharged engines with substantially increased efficiency as a downsizing strategy to reduce fuel consumption and emissions.
The researchers project that ethanol DI could result in a part-load efficiency increase of 30% relative to conventional port-fueled injection engines. The proposed direct injection approach could thus potentially provide a more cost-effective alternative to current generation gasoline-electric hybrids and turbodiesels.
Turbocharged boosting of an engine can contribute to engine efficiency, and thereby support the use of a smaller engine. The application of turbocharging, however, is limited by the occurrence of knock under higher cylinder pressures.
The ethanol direct-injection concept uses the high octane rating of ethanol coupled with the evaporative cooling from direct injection to support the higher-pressure, more efficient engines. For example, a 3.0-liter engine could potentially be replaced by an engine of about half its size, resulting in a 30% increase in fuel efficiency over a typical driving cycle, according to the researchers.
Political considerations - (IMPORTANT) After the World Trade Organization found that the United States was guilty of unfair trade practaices in using Export Subsidies for it's Cotton producers - Congress passsed a bill terminating our export subsidies of cotton (Cost: $4 BILLION per year). This bill has been on Bush's desk since February of this year waiting for his signature.
Now, if Bush signs the bill and export subsidies for cotton are terminated, cotton producers would find it no longer profitable to grow cotton and look for another crop to grow. Given the exploding demand for ethanol, it's quite likely the most promising crop would be feed lot corn for ethanol. (NOte that cotton is one of the most deleterious crops to the soil to grow. Also,unless I'm wrong cotton is not a food crop.)
Given that the amount of acres planted to cotton is almost equal to the number of acres planted to feed lot corn sold for ethanol production - if most farmers currently planting cotton switched to corn you would get almost a doubling of the supply of corn for ethanol - without affecting food production. That would immediately change the estimate of 10% (I've heard 12% without affecting food production, too) to something more like 19%- 20% (note in the some of the South East U.S. conditions might be better for planting sugar cane than corn which would yield more ethanol than corn does).
Now if you considered the adoption of the IOwa State ultra-sound technique (which is likely, in time) that would mean 20% becomes 26%. Considring MIT's direct injection engine using 5% of the ethanol (as a percentage of total fuel supply) to achieve 30% reduction in gas consumption that still leaves 21% (of the total fuel supply) of ethanol left over. Adding that to the 30% reduction in gas consumption due to adoption of the MIT engine, results in a 51% reduction in the consumption of gasoline.
THis is what can happen when smart, committed people set about to work on problem. OFten you find improvements coming from a number of different directions.
these are some things to consider which did not enter into the estimate in the referred to study.