What hasn’t been addressed here, with regard to higher oil prices making oil shale and sands economically feasible, is energy return on investment. Currently, the oil extraction methods waste a heck of a lot of oil and water just to extract the oil from the sands/tar. I don’t know the exact ratio, but I think the energy ROI is something like 1.2:1, and that’s not counting all the water that gets polluted to do this.
Is it really worth extracting the oil if it is not energy efficient to do so? What if we use natural gas to heat up the oil sands, basically burning a clean high-energy resource for a dirtier and less energy-efficient one?