If you save 1 billion gallons of gasoline, how many barrels of oil does that translate into?
There are 42 gallons of oil in an oil barrel, so I first thought that there would then be 42 gallons of gasoline in a barrel as well. But as I looked into it it quickly became more complicated that that.
Oil is complex mixture of hydrocarbons (mostly alkanes) of various lengths of which only some are of the length that make up gasoline. It is also turned into diesel fuel, jet fuel, solvents, fertilizers, pesticides, and plastics. Since gasoline doesn't make up the whole barrel, it then seemed like a good idea to figure out what percentage of the barrel was turned into gasoline.
About 10% of the product of the distillation of crude oil is a fraction known as straight-run gasoline. That would mean that a barrel of oil would produce 4.2 gallons of gasoline. It also depends on the type of oil, as Venezuelan crude yields little gasoline (about 5%), whereas Texas or Arabian crude yields about 30% gasoline.
Given the differences I took a look at what the average barrel of oil produces. American Petroleum Institute reports that 1 barrel of oil produced 19.4 gallons of gasoline per barrel based on average yields for U.S. refineries in 2000.
They also report that
The total volume of products made is 2.6 gallons greater than the original 42 gallons of crude oil. This represents “processing gain.”
Hmm, so maybe instead of thinking about 42 gallons per barrel I should start with 44.6. But, I digress.
The
EIA tells us that in 2005, 20.8 billion barrels of oil and 9.16 billion barrels of gasoline (385 billion gallons) were consumed. That gives us a ratio of
18.5 gallons per barrel. The
EIA also tells us that 69% of petroleum use is for transportation, and while I found that factoid interesting enough to let you know, it doesn't pertain to the current analysis so we will keep moving.
If straight-run gasoline only makes up 2-13 gallons per barrel, how did the average get to 19.4 or 18.5? That lead me to read these really interesting
articles on
oil refining and
cracking. Using catalysts, heat, steam and or hydrogen
complex organic molecules (e.g. kerogens or heavy hydrocarbons) are broken down into simpler molecules (e.g. light hydrocarbons) by the breaking of carbon-carbon bonds in the precursors.
From
Chevron:
Today, some refineries can turn more than half of every 42-gallon barrel of crude oil into gasoline. That's a remarkable technological improvement from 70 years ago, when only 11 gallons of gasoline could be produced.
So it looks like using cracking you can turn 1/2 of a barrel of oil into gasoline or
21 gallons.
Or maybe even higher as
Cars.com reports:
More than half of the gasoline used in the United States today is produced by cracking, most by a fluid catalytic cracking process that uses alumina-silica gel powders as catalysts.
By combining all of these processes, 100 liters (26 gallons) of crude oil can yield slightly more than 100 liters of gasoline.
100 liters of crude = 100 liters of gasoline, that would get us back to the
42 gallon mark.
In Winning the Oil Endgame, they take another approach, comparing the amount of energy in a gallon of gasoline with that of a barrel of oil. A
Barrel of oil equivalent has 5.8 million Btu of energy vs.
115,000 Btu for a gallon of gasoline. This gets you up to
50.4 gallons.
While I like this valuation method, energy would be lost converting all the oil into gasoline. I think the cars.com value stating that it is possible to have a 1 to 1 conversion is a better estimate.
So there you are. After all this analysis, we are back where we started. A barrel of oil can produce
42 gallons of gasoline. If the US could cut reduce consumption by 1 billion gallons of gasoline, that would translate to 24 million barrels of oil.
Update: Commenter Tom asks whether drilling, transportation, refining and distribution are accounted for in the estimate. No they weren't. The best estimate I could find for energy loses for these is from a
Wikipedia reference to a Department of Energy "
Petroleum refining and distribution efficiency factor" of 0.83. I tried to figure out how that number was calculated but failed. But, assuming it is an accurate estimate for drilling, transportation, refining and distribution, then 17% of total energy is used for these purposes. Taking the 50.4 gallon number (based on total energy of a gallon of oil) * .83 = 41.8 gallons, which is pretty darn close to the 42 gallon number.
Read More...
Summary only...