Most of you are missing the main point, namely how long it takes the CO2 produced by burning hydrocarbons to be sequestered back as hydrocarbons and Carbonate rocks.
Suppose their was no shortage of oil the consequences of using it as fuel at present rates will increase global warming to the point where human life will be seriously compromised.
The point about Bio fuels is that the Carbon cycle time is very short (a few years tops) oil takes millions of years to form or if it's "exuded" from non-organic sources of Carbon then the cycle time is infinite!

PP