Actually, it's a bit more complicated than that....
The diesel/gasoline yield of a barrel of crude oil is somewhat
dependent upon the source (and hence the composition) -- Arabian
"sweet" crude yields much more gasoline than diesel since it has more
light volatiles in it, than, say, Illinois Basin crude (the local stuff
here) that is "sour" with a lot more high molecular weight hydrocarbons
and sulfur (and looks like thin road tar).
Large hydrocarbons can be "cracked" into smaller hydrocarbons easily,
but it's fairly difficult to make big ones form little ones, hence the
higher energy consumption to "make" diesel from sweet crude.
Diesel fuel is mostly just a boiling point range "cut" of crude oil
with very little else done to it -- hence the high variability in
quality and performance between stations we all know about. It should
be cheaper than gasoline, since it takes quite a bit less refining to
"make" it from crude, whatever the wags say. It's really just "raw
distillate" off the cracking columns. Gasoline is somewhat more
"refined", not in the traditional sense of higher purity, but in the
sense that a whole lot more chemical changes are made to the straight
distillate "gasoline" fraction.
It takes the same amount of energy to remove sulfur from diesel as from
gasoline, since the sulfur is removed first, refining is done second as
I understand it.
Anybody need a couple dozen truckloads a week of molten sulfur?
The gallon of low-sulfur diesel also contains considerably more BTU
than that gallon of gasoline (and weighs more, too!), so the energy
comparison is off somewhat.
Petroleum people aren't known for providing straight information about
fuels, if you know what I mean -- profit comes first, everything else
last.
Peter
