Carbon dioxide emissions are a matter of growing concern. Some potential liquid fuel sources produce more carbon than others. For example, oil from Canadian tar sands produces 5 to 15% more green house gases than average crude oil.[i]
Despite this seemingly small difference, Shell and the Canadian government are spending $1.3 billion to sequester CO2 from tar sands at a cost of $72/ton.[ii]
Production of oil from oil shale can also produce excess green house gases compared to conventional oil. Estimates of carbon intensity for processes like Shell’s ICP process, which uses electrical resistance heaters, produce motor fuels at an intensity of 311 grams of carbon dioxide per kilometer driven, versus conventional oil’s 218 g/km.[iii] This is a difference of almost 43% more carbon dioxide — a major disadvantage of oil shale produced by the ICP process.
However, if shale oil is produced by the ICP insitu process, but GFCs are used instead of electrical resistance heaters, then the carbon intensity of shale oil falls to 183 g/km.[iv] This is 16% less than conventional oil.
The huge gap between in situ production of shale oil with GFCs instead of electric heaters is due to the “profound benefits of utilization of waste heat for retorting”.[v] Using GFCs will allow us to produce shale oil from the world’s vast reserves of this unconventional oil stock while producing less carbon dioxide than from other sources including conventional oil.
[i] “Oil Sands, Greenhouse Gases, and US Oil Supply”, IHS CERA, (Cambridge Energy Research Associates) Cambridge, 2010.
[ii] “Shell Launches First Canadian Carbon Capture Project”, The Globe and Mail, Calgary, Nathan Vanderklippe. Sept 5, 2012. http://www.theglobeandmail.com/globe-investor/shell-launches-first-canadian-oil-sands-carbon-capture-project/article4520968/
[iii] “Oil Shale as an Energy Resource in a CO2 Constrained World: The Concept of Electricity Production with in Situ Carbon Capture”, Energy & Fuels 2011, 25, Hiren Mulchandani and Adam R. Brandt. Table 5, p. 1639.
[v] Ibid. p. 1638.