MadSci Network: Environment & Ecology

Re: how long does it take for the earth to produce 100 litres of oil?

Date: Sun May 16 18:24:33 2004
Posted By: David Smith, Director of Professional Development
Area of science: Environment & Ecology
ID: 1084603462.En

This is a difficult question to answer because the rate of oil production 
depends on the history of climate, oceanography, and life.  In addition it 
depends on the history of sedimentation and tectonics.  There are times 
when organic productivity is very high and the disolved oxygen content of 
the oceans drops and a lot of microorganisms reach the bottom without 
decaying and the raw materials for a lot of oil accumulate in the geologic 
record.  Sometimes these conditions are golobal (Cretaceous period), 
sometimes they are local (Miocene epoch in California).  Most oil is 
relatively young (last 500 million years or so), mostly because older 
rocks are much more likely tohave been exposed to metamorphic 
temperatures, which break oil down into graphite, CO2, and water.

If we assume oil production was constant, which we know is a flawed 
assumption, then we can calculate the AVERAGE rate of production.  But 
first some units... 100 liters is about 6/10 of a barrel of oil - barrels 
(abreviated bl) are named for the 42 gallon barrels oil used to be shipped 
in and they are the standard measure of oil volume.  

The generally accepted number for the grand total amount of recoverable 
oil is 1750 billion (1750,000,000,000) barrels.  This includes all the oil 
that has already been used.  There is a lot more oil in the ground that is 
not recoverable, but no one ever bothers to count this because it will 
never be economically valuable.  

Rounding off and simplifying a lot, this means that roughly 3,000 barrels 
of oil have been produced each year.  Rounding off again, that's roughly 8 
barrels a day or one every three hours.  To make 6/10 of a barrel, or 100 
liters would take about 2 hours.  By the way, the United States alone 
consumes 17,000,000 barrels of oil each day.  That means that it takes us 
only 3/1000 (or .003) SECONDS to burn that 100 liters of oil!

You can find these numbers and lots more interesting information about 
world oil supply and use at  The name of this 
site refers to "Hubbert's Peak" a book by Kenneth Defeyes, geology 
professor at Princeton University, available at

David Smith (who took economic geology from Dr.Deffeyes 20 some years ago)
Discovery Center of Science and Technology, Bethlehem, PA

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