Yep but E10 reduces our oil imports by 10%
that is somewhat worthwhile.
Not by 10%, it doesn't. There is less energy in a gallon of ethanol than there is in a gallon of gasoline.
With only 2/3 the energy of gasoline, ethanol costs more per mile
The energy of ethanol relative to gasoline
A. 76,000 = BTU of energy in a gallon of ethanol
B. 116,090 = BTU of energy in a gallon of gasoline
C. .655 = 2/3 = GGE of energy in a gallon of ethanol. A / B. (GGE =energy in a gal. of gas)
D. 1.53 = Gallons of ethanol with the energy of 1 gallon of gasoline. D = B / A.
The basic story on ethanol mileage and cost
Some Ethanol proponents claim it doesn't hurt their mileage, but this goes against physics, and you will not find the ethanol lobby making such fraudulent claims--they could be sued. But just to be sure, zFacts analyzed all of EPA's ethanol mileage tests for one year and, big surprise, ethanol gave exactly 2/3 the mileage of gasoline.
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The USDA tells us that ethanol cost 57¢ more per gallon on average over the last 25 years (and it still does). Put that together with the fact that it takes 1.53 gallons to equal a gallon of gasoline.
So E10 will reduce oil imports by 6%.
Furthermore, ethanol takes more energy to produce that it contains.
70 Percent More Energy Required to Make Ethanol than Actually is in Ethanol: Cornell
Adding up the energy costs of corn production and its conversion to ethanol, 131,000 Btu are needed to make 1 gallon of ethanol. One gallon of ethanol has an energy value of only 77,000 Btu. "Put another way," Pimentel said, "about 70 percent more energy is required to produce ethanol than the energy that actually is in ethanol. Every time you make 1 gallon of ethanol, there is a net energy loss of 54,000 Btu."