Help a brotha out:

So you buy a 55 gallon drum of oil from the market. Brent crude, or whatever.

If you only wanted to generate standard quality gasoline from that barrel, how many gallons would you get?

If you only wanted to generate standard quality diesel from that barrel, how many gallons would you get?

Is the tradeoff 1:1, or is it the case that some parts of the refining process generate diesel and others gasoline, and they can't substitute? Is the shortage due to requiring too much diesel generation from each barrel, or is it from there just not being enough barrels of anything?

In petro-land, it’s 42 gallons per barrel. :-)

Crude oil consists of a welter of different hydrocarbon molecules that vary in size, structure and characteristics. Refining is basically the process of separating them out into different "fractions", or types of molecules. Light gases (butane, propane) and gasoline are lighter fractions out of the barrel. Diesel is a "middle distillate"--not as heavy as heavy fuel oil and lubricants, heavier than gasoline.

What you end up with depends (a) on the composition of the oil you use as a feedstock and (b) on the different number of process steps you add distill and crack the hydrocarbons--and remove contaminants that would otherwise end up as pollutants, such as sulfur.

Refineries, to put it another way, upgrade crude oil to higher-value products. And not only is not all oil equal, there are big differences between the different types.

So, for example, to tackle your first question, a barrel of sweet crude (light, low sulfur) will give me a basic yield of about 30% gasoline; a barrel of medium sour about 21% gasoline, and a barrel of heavy sour crude of about 14% gasoline.

Overall refinery yield in the US in 2004, though, saw about 49% gasoline yield. The increase from the basic yield comes from the upgrading processes.

Similarly, sweet crude will yield about 34% middle distillates (diesel, jet fuel, heating oil); medium sour, about 26%; heavy sour, about 22%. Average 2004 US refinery distillate production: 32%.

That's the reason why "light crude" with less sulfur is more valuable than heavier crude with more sulfur. It's easier (i.e., cheaper, fewer steps) to refine gasoline from the lighter crude.

Delivering more diesel will require the upgrading of refineries with additional processing capability to upgrade the heavier segments for diesel processing specifcally ("dieselization")--and to desulfurize it to the coming norms of ULSD.

And yes, swinging the needle more to the diesel side would come at the expense of gasoline yield.

Thanks, Seth. I don’t know what the theoretical maximum diesel yield you could wring out of different types of crude might be given a focus on maximizing that particular product.

The numbers in the comment above reflect current US refinery configurations, which worked out in 2004, to yields of 49% gasoline, 32% distillate (diesel, jet fuel, heating oil).

There were a series of studies done about 10 years ago on the impact of a projected "dieselization" in the US--I’ll rummage around and see if I can find those, and if they shed any light on your question in the sense of maximizing remaining petroleum resources while working toward a different fuel solution.

Shelby:

Thanks. I've seen charts like that before. But, here's my (second?) question:

From the barrel in the linked page. diesel is 10 gallons, gasoline is 19.7.

If one wanted to squeeze 11 gallons of diesel from the barrel, what would the quantity output of the other forms of oil? What would be the net additional refining cost? How about 12? 13? etc.

So, I'm interested in the marginals. What's the marginal cost (in both dollars AND other products of the barrel) for an additional gallon of diesel. This is the critical question. If, for example (and I'm making this up), the marginal cost of going from 10 gallons diesel to 15 gallons diesel (+5d) was 5 gallons gasoline (-5g), and a net added cost of $0.10, then we're not running out of diesel anytime soon, since all that's really needed is to increase the refining capacity of the diesel output.

But, if the marginal cost of going from 10 gallons diesel to 12 gallons diesel (+2d) was 5 gallons gasoline (-5g) and a net added cost of $5.00, then we're in a heap of trouble, since the added fuel cost actually makes a barrel of oil move vehicles a shorter distance, and at a higher cost.

Obviously, both examples are extremes. But, these are the essential questions when asking are we running out of diesel?.

Much of europe is in deep poop because bio isnt very viable and tranporting bio is expensive.. add to that they mostly dont have enough coal to convert to fuel and well .... heck in a handbasket...


And to make matters 100 times worse they depend on fuel taxes for a huge amount of revenue...

Can someone answer the following: Out of a barrel of LS crude, how many gallons of gasoline or how may gallons of low sulfur diesel can be produced? Is there a substantive difference in mileage per gallon for each of these products? Is part of the 'solution', albeit temporary, to our energy deficit, the production of fuels that have higher yields per barrel, higher mileage per gallon or some combination?