Pure gasoline has an energy density of 115,600 BTU per gallon while ethanol has an energy density of 75,670 BTU per gallon. If gasoline costs $3.50 per gallon, (a) what would the cost of pure ethanol have to be in order for the energy costs of the two fuels to break even? (b) What would the price of E85 (85% ethanol, 15% gasoline) have to be for its energy cost to be the same as that of pure gasoline?
What will be an ideal response?
(a) Calculate BTU/dollar for gasoline and set equal to cost for ethanol
115,600/3.50 = 75,670/x
x = $2.29
(b) Energy in E85 = 0.85(75,670) + 0.15(115,600)
= 81,660 BTU/gallon
115,600/3.50 = 81,660/x
x = $2.47
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