L. David Roper
http://arts.bev.net/RoperLDavid/
22 December, 2009
The article “Physics in the oil sands of Alberta” in the March 2009 issue of Physics Today was very informative. However, the authors did not adequately answer two of the most important science questions that need to be answered about extracting petroleum from oil sands:
The article prompted me to look into the depletion of Canadian oil sands. Using the extraction (not “production”, resources are “extracted” not “produced”) data for 2000-2008 and the generalized Verhulst function, which allows time asymmetry, to fit the meager data, the red curve in the graph is the best fit.
However, the article states that “Alberta’s bitumen reserves-the amount that can be recovered economically with current and foreseeable technology-are estimated at 172 billion to 315 billion barrels.” Fixing the amount to be eventually extracted at 200 billion barrels yields the fit given by the orange curve in the graph and fixing the amount to be eventually extracted at 300 billion barrels yields the fit given by the blue curve in the graph. The latter two fits are only slightly less good than the best fit of 73.5 billion barrels to be eventually extracted. Future data over the next few decades are needed to determine a reliable depletion curve for the extraction.
World crude-oil and other petroleum liquids are peaking about now (2009) at about 25x109 barrels/year. Compare this to the possible peak of 5x109 barrels/year at about year 2045 for oil from Canadian oil sands:
One has to ask: Is it better to spend valuable water and landscape to get oil from oil sands or to develop renewable energy?
Politicians and citizens need information such as these curves, net energy and carbon dioxide emitted to make informed decisions about whether to allow processes such as extraction of petroleum from tar sands.