March 25, 2011
The United States imports approximately one million barrels of oil per day from Canada, which is about twice the amount that it gets from Saudi Arabia. A large percentage of that oil comes from tar sand deposits, in which bitumen (a tar-like form of crude oil) is found combined with sand. The tar sands – also known as oil sands – are hugely controversial, as many people state that the process used for extracting the oil from the sand is too ecologically-unfriendly. A new technique being pioneered at Penn State University, however, could drastically reduce the environmental impact of that process.
The current method of separating sand and bitumen involves adding warm water to the two, then agitating the mixture. Unfortunately, it requires a lot of water, which is diverted from nearby rivers. Once the separation process is complete, the now-polluted water is pumped into open air tailings ponds. From there, it can potentially leach its way back into the water table. There's also another risk – despite the presence of bird-scaring devices, in 2008 approximately 1,600 ducks died when they landed in one of the ponds.
Instead of warm water, the Penn State method utilizes room temperature ionic liquids (ILs), which consist of salt in a liquid state – a solvent such as toluene may also be added. When the ILs are introduced to a sand/bitumen mixture and stirred, the resulting combination settles into three distinct layers: a bottom layer of oil-free sand, a middle layer of ILs, and a top layer of bitumen. The bitumen can then be removed and refined, the ILs can be reused, and residual ILs in the sand can be removed using a relatively small amount of water (which can also be reused), after which the sand can be returned to the environment.
Not only is much less water used, but because nothing needs to be heated, there are also substantial energy savings.
The researchers state that the ionic liquids could also be used to clean up beaches devastated by oil spills. Sand could be cleaned and redeposited on the spot, supposedly containing even less hydrocarbons than it did before the spill ever occurred.
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By Ben Coxworth