How Dirty are the Tar Sands?

View of Tar Sands mining (from Pembina Institute)

Note: Some of the numbers from this post have been updated as of 3/5/2012. Please see: "How Clean Are Electric Cars--Revised"  However, the discussion below is still valid.

My previous post argued that electric cars (EVs) are a cleaner than internal combustion engine (ICE) vehicles, even if gasoline is refined from light crude oil.  EVs are still a little bit cleaner even when the electricity is generated by coal, but coal is still something we should move away from asap.

But what if the oil is mined from tar sands?  Extraction of light crude oil produces about 1.5 pounds of CO2 per gallon  (.18 kg/liter).  Estimates vary for the extra energy required to extract tar sands oil.  The Pembina Institute estimates 4.5 pounds of CO2 per gallon and the National Energy Board estimates 6.5 pounds per gallon.

Note one source of confusion about the tar sands.  I read in the Washington Post coverage of the Keystone XL pipeline issue that the tar sands only increase CO2 by “5 – 15%” compared to extraction of light crude oil.  This seemed wildly different than the 3 – 5 times more energy that I had read about the tar sands requiring.

It turns out that both numbers are correct.  For the whole life cycle of extraction, refining, and burning, the tar sands oil adds 3 – 5 pound per gallon, which is an increase of 11% - 19% on top of the 27.5 pounds per gallon that the whole process currently creates.  However, the extraction energy is 3 – 5 times the amount of energy required to extract light crude oil.

The real problem with the tar sands is what will happen to the planet if they are all burned.  Canada has about 300 billion barrels ready to mine, and Venezuela has another 200 billion barrels of what they call extra heavy crude oil.  If all 500 billion of these barrels are burned, using 31.5 pounds of CO2 created per gallon, that would add 500 x 42 x 31.5/2200 lbs/tonne  = 300 billion tonnes of CO2. 

Since it takes 7.8 billion tonnes of CO2 to increase the atmospheric concentration of CO2 by 1 part per million (ppm) (see James Hansen, Storms of our Grandchildren, page 117),  300 billion tonnes would add 39 ppm of CO2 to the atmosphere.  We are already adding more than two ppm every year by burning coal, light crude oil, and natural gas.  And at 390 ppm and counting, we are already well beyond the safe level of 350 ppm.  Adding another 39 ppm to the already overheated earth, is a disaster in the making.

To answer the question of how much this changes the CO2 reduction between electric and ICE vehicles, we take 31.5 pounds of CO2 per gallon for an ICE vehicle,  a car that gets 40 mpg, and an average utility that produces 587 g of CO2 per kwh:

ICE car:  31.5 pounds of CO2 ÷ 40 miles/gallon = .79 pounds of CO2 per mile

Electric car:  0.4 pounds per mile

Reduction:  (.79 – 0.40) ÷ 0.79 = 49% reduction

(see previous post for more details on these calculations)

Visit www.tarsandsaction.org to learn more and get involved in the movement to stop mining the tar sands.