Hi, I hope this helps answer a few questions. I have quickly extracted a few facts that I had used in two papers I submitted to a University earlier this year.
• Because ethanol is compatible with gasoline, it makes it an ideal “fuel extender” enabling fuel reserves to be increased through the blending of gasoline with ethanol.
• The general trend is that the greater the concentration of ethanol blended with gasoline, the greater the reduction in regulated tailpipe emissions.
• The blending of ethanol in gasoline is mandatory in some global regions due to government environmental or energy security policy.
• Ethanol can potentially yield, depending on the growth and processing methodology employed, up to 25% more energy than the energy invested into its production.
• Best guess estimates from several studies for the reduction in green-house gas emissions of Ethanol during its “growth”, processing and combustion are 12% to 13% when compared to the gasoline it displaces.
It is my opinion that the addition of Ethanol is “bridging strategy” to try and lengthen the life of gasoline supplies till emerging technologies such as fuel cell and battery technology become technically viable to generate a significant shift in consumer buying. Ethanol also has the following impacts which must be considered before any increase in its use can be mandated:
• Ethanol produced from feed stocks such as corn, wheat, barley, sugar beet and sugar cane increase the demand for these crops and as a result, “drives up” the price of food products.
• Ethanol produced from feeds stocks is very water intensive and would compete for this resource.
• Ethanol produced from feed stocks is land intensive. According to Pearson et al “wheat straw and rapeseed biodiesel would require approximately 45% and 40% respectively of the UK arable land area to supply 5% of the UK energy demand”. Therefore mass domestic production of ethanol from feedstock is restricted due to land mass and high population density. However it must be noted that many companies are investigating the viability of creating ethanol from waste vegetation or organic material as this has the potential to improve the environmental gains of ethanol.
As a side discussion point, the drive in some regions for a bio fuel substitution of gasoline is for energy security and not environmental drives. Consider the countries which have the largest oil reserves and then consider their relationship with the west! Another issue with ethanol is that the fertilisers used during the growth of the ethanol food stock (such as corn, wheat, sugarcane etc.) can be significantly damaging to the environment and are a source of greenhouse gas emissions (which are included in the 12 to 13% reduction in greenhouse gas emissions total quoted earlier) however they impact the environment by leaching into the ground water changing the bio diversity of lakes and streams.
With regard to the stickers being on Lotus fuel caps in the 1970’s warning about the use of Ethanol being place in the fuel system it could be because of the following reasons:
• In the early 1970’s Brazil started their energy security policy of synthesising ethanol from sugar cane, therefore Lotus may have placed these stickers on the fuel cap just in case their products were exported.
• During the fuel crisis of the 1970’s, when fuel supplies were erratic, Lotus may have wanted to mitigate the risk of owners adding untested fuels, such as ethanol or methanol, to their engines.
With regard to water absorption, ethanol is hydroscopic. This water absorption property makes it a safer alternative to gasoline when on fire (despite producing a colourless flame when burning) as it can be extinguished using water. However this property has the significant disadvantage of phase separation of the blended fuel.
Phase separation occurs due to water ingress through atmospheric absorption. The ethanol breaks its bond with the gasoline molecule and creates a stronger bond with the water molecule. As a result the heavier than gasoline water-ethanol molecule is dragged to the bottom of the tank and separates from the more buoyant gasoline molecules. This has the potential to make the E10 in the tank unsuitable for internal combustion due to the high water content and the separation of the two combustible liquid fuels. According to a report generated by Hemming’s in the states:
“A gallon of gasoline/ethanol blend containing 10% ethanol can suspend nearly 4 teaspoons of water per gallon.” Because of the phase separation phenomena, the shelf life of blended gasoline is 3 months/90 days, (I believe, however I haven’t found conformation of it anywhere) that the typical shelf life of un-blended gasoline can be up to 2 years.
To combat this issue, “Hemming’s” in the USA advise the following (
http://clubs.hemmings.com/clubsites/nap ... thanol.pdf):
“Since water increases corrosion, always take precautions to eliminate any introduction of moisture into the fuel system. The tank should be kept full during storage to minimize condensation on the tank walls (alternate is, run dry).”
“Gasoline should not be stored for long periods of time, especially during seasonal changes that usually have large temperature fluctuations associated with them. Care should be taken not to allow water into the fuel system, while filling fuel tanks or in the form of rain or splash, for example.”
“Aside from any ethanol “problem” gasoline stored for extended periods will "oxidize" resulting in the formation of gums which contribute to fuel system and engine deposits. Gasoline is typically stable for a period of at least 90 days but may be 30 days old when you purchase it.”
In the USA fuel stabilisers are now available for classic cars.
I hope this has helped answer a few questions.
Jim
