Are Tar Sands Dirtier Than Regular Oil? Laser Talk

Yes, they are [1]. Using the more appropriate “full fuel cycle” analysis, which includes all emissions from extracting the fuel out of the ground, to refining it and burning it in your automobile, tar sands produce 15%-20% more greenhouse gas emissions than regular oil. Less usefully for understanding the true climate impacts, the State Department’s analysis of the Keystone XL did not consider a full fuel cycle analysis, which is a big part of why it was more favorable towards them.

Tar sands produce 15%-20% more greenhouse gas emissions than regular oil.

The Science of Tar Sands

The reason tar sands have these higher emissions is because they contain bitumen, a heavier hydrocarbon than conventional oil. It’s kind of like tar, and doesn’t flow very well (such properties make it is harder to clean up than conventional oil; witness the spill into the Kalamazoo river that occurred in July 2010 which still isn’t cleaned up [2, 3]).

While you can put conventional oil directly into a pipeline, bitumen from the oil sands must be pre-processed, or “upgraded” by diluting it with a light hydrocarbon like a natural gas liquid so it will flow through the pipeline. Because it either requires an upgrading step on-site before it’s shipped, or more intensive refining to produce the same gasoline or diesel, the energy intensity and emissions from producing fuels from the oil sands tend to be higher, on average, than conventional crude oil.

In addition, more CO₂ is released from bitumen per megajoule of energy produced because they are heavier hydrocarbons. For example, fuels produced from a typical oil field such as the North Sea of Europe will range somewhere in the high 80s to mid 90s [CO2/MJ]. The oil sands are going to be typically somewhere in the range of 105 to 115. 15-20% may not sound like a lot, but, for instance, if you are in California and you need a 10% reduction over the next 10 years in fuel carbon intensity, a 20% increase makes a big difference.