Tar sands are a mixture of clay, silicates, water, crude oil and other hydrocarbons of various compositions, which are usually a precursor of crude oil. The most important sources are in Canada and Venezuela1.
Defining tar sands…
To begin with, tar sands, more accurately known as oil sands, are an expensive and dirty source of oil1. They are a resource, particularly abundant in Saudi Arabia, Venezuela and Canada, where heavy petroleum is mixed with sand, clay, and water2. In fact, this heavy form of petroleum is called ‘bitumen’2. Bitumen is a thick molasses-like substance1. For that reason, this resource is often called “tar sands”, however the term is not accurate, as bitumen and tar (asphalt) are two very different compounds3.
Scientifically speaking, bitumen is made up of hydrocarbons similar to molecules found in liquid oil and used to produce gasoline and other petroleum products1. This bitumen has a similar consistency with peanut butter4. In fact, bitumen has such a thick consistency, which makes it much more difficult to extract and transport compared to conventional crude oil4. Thus, because bitumen does not flow easily and instead it clings to the sand and clay, it cannot be simply pumped out of the ground through wells like conventional oil5. For this reason, oil sands are mined in two different ways depending on the depth of the deposit: open-pit and in situ mining5.
How are oil sands mined?
Basically, if oil sands are near the surface, they can be surface mined directly and transferred to an extraction plant where the bitumen is removed from the sand, clay, and water5. This process is referred to as open-pit surface mining. On the contrary, if oil sands are too deep for surface mining, the bitumen can be extracted in situ (in place). This occurs by injecting hot steam to lighten the bitumen and enable it to flow through a well to the surface5. This process is referred to as in situ mining.
Where are they located?
For example, Canada and Venezuela contain large deposits of oil sands5. Also, the largest deposits in the United States are located in eastern Utah5.
Source: Alberta Geological Service. Available at: http://history.alberta.ca/energyheritage/sands/origins/the-geology-of-the-oil-sands/the-location-of-oil-sands.aspx
What are the environmental costs?
Even though oil sands are an important energy resource6, the extraction and production of synthetic crude oil from oil sands has a considerable impact on the environment. Environmental challenges include exacerbating climate change, enhancing water consumption and contamination, and devastating wildlife7. The bitumen extraction process can poison rivers and groundwater, harm wildlife and destroy ecosystems such as forests and peatlands8. Also, oil sands produce more greenhouse gases than conventional crude oil. In fact, a gallon of gasoline made from oil sands produces about 15% more carbon dioxide emissions than one made from conventional oil1.
The oil sands industry producing millions of gallons of synthetic crude oil each year is clearly threatening our planet. Shifting from this polluting production process to green energy solution is vital in order to ensure a sustainable future8.
References:
- Union of Concerned Scientists. (2020). What Are Tar Sands? [online] Available at: https://www.ucsusa.org/resources/what-are-tar-sands
- Openei.org. (2017). Definition: Tar Sands | Open Energy Information. [online] Available at: https://openei.org/wiki/Definition:Tar_Sands
- “What Are the Oil Sands | Canada’s Oil Sands Facts & Information.” 2020. CAPP. July 31, 2020. https://www.capp.ca/oil/what-are-the-oil-sands/.
- Oil, A. (2020). Oil Sands Products – Background – Alberta Oil Sands Products. [online] Google.com. Available at: https://sites.google.com/site/noaaoilsandsproject/bitumen
- American Geosciences Institute. (2018). What are tar sands? [online] Available at: https://www.americangeosciences.org/critical-issues/faq/what-are-tar-sands.
- Natural Resources Canada (2014). Oil Sands: Economic contributions | Natural Resources Canada. [online] Nrcan.gc.ca. Available at: https://www.nrcan.gc.ca/energy/publications/18756
- Energyeducation.ca. (2018). Environmental impacts of oil sands – Energy Education. [online] Available at: https://energyeducation.ca/encyclopedia/Environmental_impacts_of_oil_sands.
- Woynillowicz, D., Severson-Baker, C. and Raynolds, M. (2005). SANDS Fever Oil THE ENVIRONMENTAL IMPLICATIONS OF CANADA’S OIL SANDS RUSH. [online] Available at: http://large.stanford