Energy required for gas,diesel, e85

[zpiloto]

Does anyone know or can point me in the right direction on how much total energy is required to produce one gallon of gas, diesel, bio-diesel, e-85. Not having much luck.

EEK! I've gone over the 1000 posts mark.

[northboundtrain]

Good question. I don't have any documentation to back this up, but I've heard that ethanol requires more petroleum to produce than it saves (no wonder gov't and big business are so happy about it). For biodiesel, I think there's a net reduction in petroleum consumption on the order of 3:1.

Hopefully someone here will provide more information. I've been really curious about this too.

[JanGeo]

There is a term used to express the energy yield - ethanol is 1.3 so it takes 1 barrel of oil to make 1.3 barrels of ethanol. Now I have to wonder if that is normalized energy since ethanol contains less energy per volume than oil. Biodiesel is about 1.6 if burned as oil I think instead of converted. Making biodiesel requires heating and stirring which takes grid energy and I am not sure how that enters the energy equation and also takes alcohol to process it. Dino is a positive as well or else they would not be pumping it out of the ground but the shear volume is bind moggeling.

[omgwtfbyobbq]

I took a stab at gas. In terms of useful energy, the average gallon of gas does ~6kwh worth of work, and that equivalent 6kwh of electricity at the consumer's home, needed to get that gas, would do ~3kwh of useful work. I took this approach because EROEI doesn't take into account the efficiency of use, depending on context, which is pretty short sighted imo. So, neway, the electricity, and electricity we could get from the natural gas used, to get useful work from gasoline, can do about half that useful work in an BEV. I'm also pretty sure using gasoline dumps three times more carbon dioxide into the atmosphere, than using the natural gas, to make electricity, and power a BEV would.

Diesel should be better, biodiesel even better if using a waste stream, and ethanol from corn is the worst.

[Lug_Nut]

Ethanol if finally a positive yield due to the increase in interest (both intellectual and financial) in it these past few years. It is close to, if it hasn't yet surpassed, petroleum diesel and gasoline which are holding at about 1.3 kw energy produced for each 1 kw of energy expended.
Some may say "30%! That is terrible." I'd be happy if my 401(k) return was at half that yield.
Biodiesel is still around 3.5 or 4 kw out for each 1 kw in. Maybe I need to invest in a high oil yield algae farm....
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