The extraction of oil out of tar sands, for example in Canada (Alberta) is hotly debated. A posting in Science Blogs followed by a debate between advocates and opponents gives a quick introduction to the issues at hand. Apparently there is hardly a trusted source of information available, a sign of large commercial interests and something to hide.
Many people I know advocate that emissions should be compared in two steps: first well-to-tank seperately from tank-to-wheel emissions. Tar sands show why. Apparently the well-to-wheel emissions are “only” 5 to 15 % higher than normal gasoline.
That doesn’t seem much unless you compare this to the effort it takes to reduce emissions by 10 %. If you only compare well-to-tank the picture seems to be much bleaker: 2 to 3 times more emissions. Processing tar sand eats energy.
The really bad thing appears to be the enviromental devastation (land, water, toxic waste) tar sand processing leaves us as a residue. The lakes with toxic waste are enormous.
As you can see over here.
