Canada's tar sands: Muck and brass

To many critics the broader environmental legacy of the tar sands is reason enough to halt the whole endeavour. To get at the bitumen, the companies bulldoze wetlands to create vast open-pit mines. Inside them, the world’s largest dumptrucks ferry paydirt to nearby separation plants, where the tarry soil is crushed and diluted until bitumen can be skimmed off. This needs lots of water and energy, and yields the notorious “tailings”, a residue of sand, unclaimed bitumen, water, clay particles and contaminants. Some lakes of this have been festering for decades.

Mining accounts for just over half of production. It will become less common as shallower reserves are exhausted. Extracting the deeper stuff is less ugly but also damaging. Typically it involves drilling wells to pump steam into the ground to melt the bitumen and make it easier to suck up to the surface. Heating the steam burns much natural gas, emitting CO2. Both methods, say the tar sands’ critics, threaten local rivers, poison fish, destroy the landscape, kill wildlife and pollute the air.

(Source: azspot)