[FoRK] Authoritative explanation of gas spike in 2007/8?

Reese howell.r at inkworkswell.com
Sat Oct 10 19:15:48 PDT 2009

Ken Ganshirt @ Yahoo wrote:

>> ...It all gets cracked out in the distillation tower,
>> diesel is a different, heavier molecular chain than gasoline. 

To elaborate on this, I believe we all know or should know that the
operative quality measurement for gasoline at the pump is octane, at
the pump this is usually measured by adding the research and method
octane numbers and dividing by 2.

OTOH, the essential element in diesel is cetane. It occurs to me that
there may be common (carrier) elements between gasoline and diesel so
I stand to be corrected if that is the case - but I don't think that
is the case. In the distillation tower, diesel (cetane) is a heavier
molecule that cracks out of the crude at a different temperature, or
elevation, than goes gasoline (octane).

>> A spike in the demand for ULS diesel would not cause a shortage of
>> gasoline, there would be an excess of it.
> That explains something else I've sometimes wondered about: Why does the price of diesel at the pumps go up when demand for gasoline is down?

Marketing and distribution considerations I would suspect.

> Low demand for pump gas = crack less pump gas = lower supply of diesel.
> Lower supply of diesel = higher price.

Pretty much, yeah.


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