Tar sands a/k/a oil sands

In a recent post, I noted that the Department of Interior's Bureau of Land Management recently announced that BLM will "take a fresh look at commercial oil shale and tar sands plans issued under the prior administration."  I then tried to answer the question, "What is oil shale?"  In today's post, I try to answer the question -- What are tar sands?

Tar sands also are called "oil sands."  They are a solid-like mix of clay, sand, water, and bitumen (a black, viscous oil).  To commercially develop this energy source, the oil sands are mined, often in a pit mining process.  The solid material can then be transported to a plant where the oil sands are heated by being mixing with hot water.  This separates the bitumen from the sand and clay.  In addition, it makes the bitumen less viscous, in much the same way that heating syrup will make it less viscous so that it flows more easily.  In an alternative method of production, steam is used to heat the oil sands while they still are in the ground.   

Some people criticize the development of oil sands on environmental grounds.  They object to the mining process and the consumption of the energy required to heat the oil sands.  Also, they raise objections relating to water use.  In the heating process, several barrels of water are needed for every barrel of liquid bitumen that is produced.  After the process is complete, the water contains hydrocarbons and tailings (fine solid materials).  The small solids require a significant time to settle out of the water, which sometimes is held in large settling ponds called tailings ponds. 

Most of the world's petroleum is located in oil sands.  Several oil sands deposits are located in eastern Utah.  It is estimated that these deposits contain 12 to 19 billion barrels of oil.  Large deposits also are fond in Venezuela and parts of the Middle East.  One of the largest deposits of oil sands is located in Alberta, Canada.  Oil produced from the oil sands in Alberta are partly responsible for Canada becoming the largest exporter of oil to the United States. 

Plans also are underway for a pipeline to transport oil from Alberta's oil sands to refineries in Texas.  But environmentalists have attacked the proposed pipeline, largely because they object to the development of oil sands, but also in part because they object to the pipeline itself (they raise the possibility of leaks, and also object to the footprint of the pipeline).  The proposed pipeline, the Keystone XL project, would require approval from the United States Department of State, and both proponents and opponents are lobbying the Obama administration, as has been reported in stories by Elisabeth Rosenthal, Sheldon Alberts, and others.

Comments (1)

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kingsley onyebuchi - May 24, 2011 2:01 PM

Am a geology student and i found intresting know about tar sand i would love to know more about it

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