They are not technically petroleum, but a sludge that can be turned into oil if washed and cooked with steam (which is not an abundant natural resource in the boreal forest of northern Alberta, especially during the Canadian winter). Turning tar sands into oil requires almost as much energy input as they contain at the end of the processing - so they are barely a "source" of energy. To date, vast quantities of natural gas have been used to make the steam to process the tar sands to create something resembling petroleum, but natural gas has its own supply problems that make dedicating gas to tar production difficult to maintain. There are serious proposals to build nuclear reactors next to the tar sands, which is a sign of lunacy, to be polite about it.

Tar sands extraction causes enormous ecological destruction. The process begins with clearcutting the boreal forest, destroying habitat and soil. The trees are either milled into lumber, which releases some of the carbon into the atmosphere, or the trees are burned as slash, which releases nearly all of the carbon into the atmosphere. The carbon reserves locked up in the forest soils are also released into the atmosphere.

After the land is cleared, the "overburden" subsoils and rock are strip mined using enormous dump trucks the size of a house. Eventually, the mine reaches the layer where the tar sands congealed eons ago, and then the tar sands are mined. It is possible that the tar sands are the single largest strip mine anywhere on Earth.

The waste "tailings" left over when the mining is finished are a toxic slurry that is poisonous to life. In addition to huge amounts of energy, vast quantities of water are also needed in the tar sands industry. While Canada has more water than any other country -- it is the Saudi Arabia of water -- polluting the planet's largest supply of fresh water for a short term burst of energy production is one of the most insane behaviors imaginable. After the era of fossil fuels winds down, and the era of climate change starts up, access to clean drinking water will be unbelievably important. Tar sands production threatens to turn much of central Canada's water reserves into oily wastes unfit for consumption.

Perhaps the saddest aspect of the rise of the tar sands industry is that all of this destruction is only expected to supply a small amount of the demand for oil. In 2007, about one million barrels per day of tar sands is produced in Alberta -- about one percent of the global consumption of about 85 million barrels per day. It is predicted that with considerable investment, Canadian tar sands production might reach a couple million barrels per day within a decade. This means that an area the size of Florida will be totally deforested, strip mined, drained of clean water, and doused with toxic effluent to meet a small percentage of global oil demand for a couple of decades (at best).

A reader of this website [  http://oilempire.us/ ] suggests that the rush to mine tar sands resembles an indigent cigarette addict looking through ashtrays to find a couple of butts that can be relit to get a couple final (nasty tasting) drags of tobacco smoke.

For additional reading:

 http://www.oilsandstruth.org/ good activist website about tar sands

 http://www.sacbee.com/101/story/553568.html Grabbing for oil U.S. thirst powers push for Canada fuel By Tom Knudson Sunday, December 9, 2007

MacLean's Magazine (Canada) October 8, 2007  http://www.macleans.ca/article.jsp?content=20071008_110103_110103&source=srch Doomsday: Alberta stands accused A huge fight between East and West -- over the oil sands -- is just starting