A group of researchers at UC Berkeley has analyzed the risks of substitutes for conventional petroleum (SCP). They found that gasoline refined from unconventional oil produces 30 to 70 percent more greenhouse gas emissions than that made from regular crude oil. More than one million barrels a day of gasoline are being refined in Alberta, Canada now from tar sands. The study says that if oil is going to be produced from alternative sources, significant steps need to be taken to mitigate the significantly increased greenhouse gas emissions, such as carbon sequestration and reduced consumption.
[Source: Institute of Physics via GreenCarCongress]