by shortonoil » Sat 28 Apr 2007, 14:10:57
kmann said:
$this->bbcode_second_pass_quote('', 'W')hy is 18:1 the breaking point? When did we hit it? How did you calculate it?
My analysis is based on the work of Cleveland & Kaufman and their energy profile of the oil industry for the lower 48 states; the only good data that we have. Since the US fields are so extensive and diversified, I feel that it is a reasonable hypothesis that these profiles can be extrapolated to the world in general.
C&K derived the ERoEI of oil at the well head for the period 1954 to 1997. Finished products exhibit an ERoEI of approximately 14 points below the well head numbers. Their data shows, that during periods of intensive exploration and development in the US, that ERoEI for well head numbers dropped somewhere in the region of 10 to 15 points. Finding oil takes a lot of energy. Using the 15 point number, what we could expect from our data, for frantic exploration like we are presently seeing in SA, in just a few major fields could drop the overall ERoEI below 1:1. When this occurs exploration and development backs off. This we are presently seeing in the reduction of deep water exploration in lieu of land base exploration.
Taking the 54’ to 97’ data and using the generally accepted 1930 data point of an ERoEI of 100, allows for the construction of the representative curve. That curve is a decay curve of the form Q=Q’e^-kt, or a decay curve as seen for the decay half-life of radioactive elements and the death of bacterium in a petri dish. Another tale tell sign of this curve’s form is in the Logistics Curve itself, the equation the Hubbert based his model upon. The numerator of the Logistic Curve is merely a form of the decay curve.
The Lower US 48 peaked at an ERoEI of about 18:1, this is hardly a coincidence. Mapping the ERoEI curve to Hubbert’s curve for world oil production puts the world’s ERoEI at about 18:1.
Q.E.D. We have peaked.