New Study on Tar Sands Refinery Emissions
Just forwarded: an advance copy of a new study accepted for publication in Environmental Science and Technology (subscription required). In a nutshell, it strengthens the scientific evidence of what many people have been saying: that refining tar sands bitumen creates much higher greenhouse gas emissions than refining lighter forms of oil. It’s not as much the fuel produced as the refining process itself that’s significantly more carbon intensive. Author Greg Karras, senior scientist with the California-based Communities for a Better Environment, states: “a switch to heavy oil and tar sands could increase the greenhouse gas emission intensity of petroleum energy by as much as 17-40%, with oil extraction and processing rather than tailpipe emissions accounting for the increment.” Communities for a Better Environment is an environmental justice group that organizes fenceline communities negatively affected by industrial pollution in their neighborhoods, so refinery pollution is right up their alley.
From the study’s introduction:
The greenhouse gas emission intensity of reﬁning lower quality petroleum was estimated from fuel combustion for energy used by operating plants to process crude oils of varying quality. Reﬁnery crude feed, processing, yield, and fuel data from four regions accounting for 97% of U.S. reﬁning capacity from 1999 to 2008 were compared among regions and years for effects on processing and energy consumption predicted by the processing characteristics of heavier, higher sulfur oils. Crude feed density and sulfur content could predict 94% of processing intensity, 90% of energy intensity, and 85% of carbon dioxide emission intensity differences among regions and years and drove a 39% increase in emissions across regions and years. Fuel combustion energy for processing increased by approximately 61 MJ/m3 crude feed for each 1 kg/m3 sulfur and 44 MJ/m3 for each 1 kg/m3 density of crude reﬁned. Differences in products, capacity utilized, and fuels burned were not confounding factors. Fuel combustion increments observed predict that a switch to heavy oil and tar sands could double or triple reﬁnery emissions and add 1.6-3.7 gigatons of carbon dioxide to the atmosphere annually from fuel combustion to process the oil.
Houston, we have a problem.