What Is in a Barrel of Oil?

by Michael Pruser on 14 October 2010 6 comments

Whether you're watching CNN discuss the effects of the recent oil spill in the gulf, or you're watching MSNBC discuss how the price of oil has shifted throughout the month, you probably hear them use the term "barrel," which defines oil in volume. Not being literate in the language of fossil fuels, I had no idea just how much gasoline was contained in a barrel. Much to my surprise, my guess of 50 gallons of gasoline was way, way off.

A barrel of crude oil is 42 gallons, which is the standard measurement in the United States. Now, this is just a way of measuring crude oil, as it has not been delivered in anything but huge tanker vessels for several decades. This measurement device originated in Pennsylvania way back when crude oil was packaged in barrels. Rather than changing to a different unit of measurement, it is easier to keep the original barrel standard.

Typically, 42 gallons of crude oil will produce 44 gallons of petroleum distillate products. Yes, there is actually a gain in processing of a little more than 2 gallons. The breakdown of distilled products is as follows:

  • Gasoline — 19.5 gallons
  • Distillate fuel (heating oil, diesel fuel) — 9.2 gallons
  • Kerosene/Jet fuel — 4.1 gallons
  • Residual fuel oil (heavy oils and fuels for industry) — 2.3 gallons
  • Liquefied refinery gasses (ethane, propane, butane, isobutene) — 1.9 gallons
  • Still gas (methane, ethane, ethylene, butane, butylenes propane, propylene) — 1.9 gallons
  • Coke — 1.8 gallons
  • Asphalt and road oil — 1.3 gallons
  • Petrochemical feedstocks — 1.2 gallons
  • Lubricants — 0.5 gallons
  • Kerosene — 0.2 gallons
  • Other — 0.3 gallons

As you can see, a great deal of petroleum products is created from one 42-gallon barrel of crude oil, and these items are generally produced during one processing cycle of creating gasoline. That's right, most all of these products are the remnants of turning crude oil into gasoline — otherwise known as by-products. So many of the petroleum products used for home heating, diesel engines, airplanes, heavy manufacturing are derived from the production of gasoline. Basically, what would otherwise be thrown away have become important necessities in our daily lives.

Now, after understanding what is created from one 42 gallon barrel of crude oil, I realize how difficult it will be to become fossil-fuel independent with the use of alternative fuel vehicles and energy production. Crude oil distillation products have permeated every aspect of our lives. Being able to rid ourselves of its use will be an arduous task.


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Amy Lu's picture
Amy Lu

"Yes, there is actually a gain in processing of a little more than 2 gallons." It's mind boggling! The more you know...(the more depressing reality gets.)

Guest's picture
L. Bowser

I'm not sure that "gain" is quite the right word for what is happening... It only appears there is more material, but if one were to weigh it you would find either a slight loss or no change.

There is, however, an increase in volume. This is related to the change in density caused by seperating/producing the products. The density changes because the products are disolved in each other when they are in the crude form, much like salt is disolved in water. If you distill salt water and measure the volumes of the two products (water and salt), you would also finde a volume increase but no change in mass.

As an addendum, what you have listed above is really a "targeted split" based on market demand. Modern refineries have the ability to shift between these products within a certain range using "cat crackers" and "reformers". If market demand shifted to 14.4 gallons of gasoline and 14.3 gallons of diesel, most refineries are fully capable of doing so.

Guest's picture

cat crackers are frickin' scary...

Guest's picture
L. Bowser

You can be scared of the cat cracker, as for me I'll avoid the coker. Nasty things.

As a side-note, we've talked about most of the other streams as by-products. They are probably better referred to as co-products, since each one has significant economic value in its own right. The main exception to this is the coke stream. Horrible stuff. Very low fuel value. Typically has to be burned as a supplemental fuel in a process. Until the boom in Chinese coal fired power plants, you practically had to give it away, if not pay someone to take it...

Guest's picture

I'm guessing the 0.3 gallons for 'other' would be where we produce so many plastics. Plastics have so many uses especially in the medical supply field that I can't imagine our advanced society doing without it. Look how much just the automobile itself is constructed of oil byproducts besides the fact the engine operates on gasoline. I'm of the opinion we will never find an alternative source to 'replace' our use of crude oil so why fight it. There's no way solar or wind sources will power a bulldozer, airliner, or combat armored tank. The key would be to come up with an inexpensive source that will supplement our use of crude. Certain philosophies of others point to the incredible plant called hemp. A plant that grows rapidly in all 50 states and I'm not referring to the popular type that is recreationally smoked either. Hemp could be the 'cash crop' with biblical overtones that supplements our use of crude oil. So many products can be made from hemp that I believe it would be an excellent idea for a WISEBREAD article by itself..... cheers

Guest's picture
L. Bowser


It really is just "other" My guess, it's probably better labeled as the "crap you probably can't or shouldn't be allowed to sell". Petroleum based plastics mainly come from the streams labeled petrochemical feed-stocks, as well as the gas streams like ethane, propane, etc... These are then used to create ethylene, propylene, etc... through a process called reforming (different from the refinery reforming.) Truthfully though, the vast majority of the resin based plastics these days start out as natural gas and not oil. Since natural gas and oil tend to be co-located to some degree, the industries are often found together, giving the illusion of petroleum being a primary feed to the system.

As far as what will ultimately form the basis of a liquid bio-fuel economy, I would be flat out shocked by hemp as a choice. The main reason being that growing hemp requires using land currently used in food production if you want to make a substantive dent in the current fuel needs. Use that land, and you will most likely drive up food prices, which from a policy perspective is rarely desirable. Especially when you consider that the about half of the political base that elect the green leaning politicians in the US tend to be extremely sensitive to the prices of both food and fuel. More probable: algae or switch-grass which can be grown in areas otherwise considered useless from a farming perspective.

Depending upon your belief in AGW, there is another way to reduce American dependence on foreign oil, but it does require that a substantial percentage of all American vehicles convert to diesel. You can partially combust coal to create a hydrogen/carbon monoxide feedstock which will then be fed into a process producing di-methyl ether (DME). DME is a decent diesel substitute (though it tends to gum up in extreme cold). Of course, since coal is a dirty word, the price of petroleum will have to move much higher for a sustained period of time before such a movement would be politically popular.