We will be talking about the energy output of fuels such as Methane, Gasoline, Diesel, and Ethanol and how they play in industry as far as usage as a fuel. I did this as a benefit to me as an engineering student and for those cretins on strafeRight. This information is my study on the value of Ethanol as a fuel source. Note I will not be talking about the environmental effects of this fuel in either it's E85 form or as a mixture with 90/10. I did this study for fun and will not be receiving a grade on it. Hopefully you'll find some beneficial information from this. As well I did not attempt to figure the amount of loss from 90/10 Gasoline. I may do that later if I get enough requests for it. Hope you enjoy!

The following are Higher Heating Values (HHV) basically the amount of output a fuel can produce if there was 100% combustion of the fuel.

Methane: 55,530 kJ/kg

Gasoline: 47,300 kJ/kg

Diesel: 46,100 kJ/kg (note this is light diesel and their is a form of heavy diesel)

Ethanol: 29,670 kJ/kg

You can see that Ethanol produces the smallest amount of energy per kg of fuel used, this also would explain why vehicles using Ethanol requiere more fuel to transfer the same distance as a normal gasoline vehicle would. Because of the addition of 10% Ethanol to much of the Gasoline we use today you can expect an overall decrease in MPG and a decrase in total HP and Torque since you cannot provide the same amount of energy in the motor as 100% gasoline. Is ethanol worth it though?

An average car consumes about 5L of gasoline a day and on average has a fuel tank of about 50L. Density of gasoline is 0.68 - 0.78 kg/L. Density of ethanol is .790 kg/L. We will use the Lower Heating Value(LHV) of Gasoline and Ethanol to accomidate for incomplete burn rates and possible contamination of the fuel. So..

Gasoline LHV: 44,000 kJ/kg

Ethanol LHV: 26,810 kJ/kg

The mass of gasoline used per day is:

m = (pV) = (0.75 kg/L)(5L/day) =3.75 kg/day

Energy supplied by gasoline to the car per day:

E = (m)(LHV) = (3.75 kg/day)(44,000 kJ/kg) =165,000 kJ/day

Amount of mass per day of ethanol to equal gasoline:

E = (m)(LHV)Amount of liters of ethanol used per day to equal gasoline:

m = E/LHV = 165,000 kJ/day / 26,810 kJ/kg =6.15 kg/day

We can see that it takes 7.78 L/day of ethanol to be able to travel the same amount as gasoline which only takes 5L/day. Are the savings worth it? Lets find that out.Average cost of ethanol in peak season of August 2008: $3.08 per gallonm = (pV)V = m/p = 6.15 kg/day / .790 kg/L =7.78L/day

Average cost of gasoline in peak season of August 2008: $3.74 per gallon

Convert to Liters:

$3.08 per gallon x gallon / 3.785 L =$0.81 per liter of ethanol

$3.74 per gallon x gallon 3.785 L =$0.99 per liter of gasoline

Cost per day:

$0.81/L x 7.78 L/day =$6.30 per day of ethanol

$0.99/L x 5L/day =$4.95 per day of gasoline

Looks like ethanol is actually more expensive!