There is more than enough oil shale and coal (gassification) to end our dependence on foreign oil and to last us for longer than we need. When conventional oil reaches and maintains a certain cost, these will become viable.
All the articles I have read in the past say that price is $50/barrel. The prices is now close to $80.
The greens hate the shale oil, they look at it as just perpetuating the use of carbon based fuels and the massive strip mining to dig up the shale. They love this grease energy but even if all the grease in the US was turned into fuel would it even put a dent in demand for gasoline? I can imagine this grease thing taking off and people lining up at McDonalds for grease and McDonalds charging for it and then all of a sudden its not so cheap to run your vehicle on grease anymore.