Rising global demand for oil, combined with geological studies that predict that global oil production derived from conventional oil supplies will begin to decline late in this century, or as early as 2040, has led to a search for unconventional oil supplies.

Further, a large amount of that unconventional oil exists in the form of tar sands in Alberta, Canada, the bitumen of which is capable of producing 1.7 billion barrels of synthetic crude. Moreover, if just 10% of this field is actually recoverable, it would still represent the second largest oil reserve in the world.

But, as writer Elizabeth Kolbert outlined in an article on unconventional oil in this week's issue of The New Yorker magazine ("Unconventional Crude"), extracting that resource comes at a price: it's more expensive to extract -- about $1 of energy is needed to generate $3 of unconventional oil -- more CO2 is also released into the atmosphere than from conventional oil, and mines dug to secure the material scar the landscape, if not fully restored.