When I asked senior energy analyst Glenn Doty to comment on a business plan that contemplates coal and gas to liquids (isobutanol) I received an amazingly complete response — both a crash course in the business of organic chemistry and a comprehensive answer to the questions at hand.
I then dared to ask another favor: a response to the question: What are the basic reasons that the externalities of tar sands are so much higher than they are for crude? Is it simply that more energy is used in extraction, transportation, and refinement, and that there are externalities to generating that incremental energy?
I thought I’d publish his response, so that readers could come up to speed on this as well. Glenn writes:
As I understand it, the primary issues involving tar sands are as follows: First, we’re talking about solids instead of liquids… Crude oil can by hydraulically pumped out of the ground and pumped through pipelines with very little added energy. Tar sands – being solid – have to be scooped up and trucked.
Next, the sands must be heated (energy lost) to separate the bitumen from the waste, then the solid waste must be trucked off somewhere else and dumped.
Then the bitumen, having had fewer ages or epochs to separate from solid deposits, generally has greater levels of metalide and sulfur contaminates… requiring more cleaning and waste disposal steps at the refinery phase, which means more energy lost in refining.
All told, gasoline derived from light-sweet crude pumped out of land-based fields may have a total lifetime GHG emission of ~10 kg-CO2e/gallon (this includes amortized drilling and infrastructure, as well as pumping, refining, and distributing losses, and of course combustion). On the other end of the spectrum, gasoline derived from a deep-water drilling operation of heavy sour crude with high salt content might yield a lifetime GHG emission of ~13 kg-CO2e/gallon. Gasoline from tar-sands gets ~14 kg-CO2e/gallon.
The bigger problem with tar sands is the local environmental impact, which results from the strip-mine style harvesting of the sands, the large-scale dumping of the sand waste, and the toxic tailing ponds filled with mountains of contaminates that are removed… all closely bordering the once beautiful Athabasca river… I think that has caused more concern from environmentalists. Overall it’s still not as bad as coal, but it’s not pretty.
