TAR SANDS 101
1. WHERE THE STUFF COMES FROM
Northern east Alberta Canada
2. WHAT THE STUFF IS
In the ground, it is a mixture of bitumen, sand and clay. Bitumen is also known as asphalt.
In the pipeline, it is called “dilbit,” for diluted bitumen – a mixture of bitumen and dilutents. Which dilutents are used are “trade secrets” to each pipeline company. Enbridge uses one of their pipelines through Wisconsin to pipe their primary dilutent north to Canada.
3. HOW THEY GET IT OUT
This depends on how deep the stuff is below the surface. If it is fairly close (that is, within 200 feet or so), it is more economical to “strip mine” it out of the ground. This is accomplished in several stages: First, clear-cut the forest. Second, bring in the earthmovers to dig out and/or scrape off anywhere up to 130 feet of peat/sand/clay from the top of the bitumen layer (and store this for later “reclamation.” Third, bring in the even BIGGER earthmovers to dig out the mixture of bitumen/sand/clay and transport it to the processing plants. Fourth, wash the stuff with hot water and solvents to separate the bitumen from the sand and clay and anything else that is non petroleum-based in the gunk that came out of the earth – and by the way, two TONS of tar sands are needed for each barrel of synthetic oil produced. And they can only get about 75% of the bitumen out of the gunk they get out of the ground.
TREES THAT GREW IN THE WRONG
PLACE - AFTER CLEAR CUTTING.
|MINING THE STUFF.||ON THE WAY TO THE PROCESSING PLANT!|
If the stuff is too deep to strip mine, they can do what they call “in situ” extraction. “In situ” means “in place.” The miners drill holes into the bitumen formation and inject superheated steam or a solvent which then drives the bitumen away from the sand/clay mixture and out into another drill hole. Yet another method injects oxygen into the formation and then sets fire to part of the bitumen so that the heat will free the remainder for extraction. Any of these methods are immensely energy intensive!
4. HOW THEY GET IT FROM CANADA TO WHEREVER
Most of this dilbit, or synthetic oil, is moved by pipelines from Alberta Canada to refineries in the United States. The amount of dilutent affects the amount of actual OIL in the product delivered to the refinery, so some Canadian companies are now talking about shipping by rail to maximize the actual petroleum content of their product at the refinery.
5. WHAT THEY CAN REFINE OUT OF IT
Bitumen is high in carbon and low in hydrogen. High quality oils such as the “light sweet” crude oil from the Bakken shale are just the opposite. In petroleum speak, “sweet” does NOT refer to the FLAVOR, it refers to the absence of sulfur. Also, if the bitumen arrives at the refinery as “dilbit” (or diluted bitumen), through a pipeline, the refinery must also strip out the dilutent before beginning the refining process.
Much of the carbon in the bitumen needs to be removed in order to convert the remainder into refined products that can be sold. Refineries usually require a special coker unit to remove the carbon from bitumen. To remove this carbon, bitumen is heated in large steel coking drums at higher temperatures and for longer periods of time than a normal oil refinery is capable of. The finished product is called “petroleum coke” or “pet coke” for short.
Pet coke can be used as an additive fuel in coal fired power plants. It has a higher carbon content than regular coal but it is also higher in a variety of other minerals, such as sulfur and heavy metals. Because of the higher carbon content, it also generates more carbon diozide per ton burned than ordinary coal.
After the coking process, what remains from the tar sands is synthetic crude oil, which must then be further refined.