* Crude oil will run out in the next 2-5 decades. Most of the discussed polymers in this chapter are produced from crude oil, and when oil supplies run out we will require alternative sources of compounds to continue production. Even though the petrochemical industry currently only consumes 3-5% of the total oil used in the world today, when the oil runs out, it's gone.
* It has been suggested that that since the petrochemical industry uses so little oil as compared in monetary terms to their gross output, when oil production drops and the price of oil rises, the petrochemical industry will be the only industry able to afford the remaining oil, and thus will have the rest of the oil to themselves for several years. However, this eventuality is regarded as a "best-case scenario".
* Ethanol is a prime candidate as an alternative source of ethene, the most valuable hydrocarbon in the petrochemical industry. Ethanol can be produced through fermentation of a variety of agricultural crops, and it can be easily converted into ethene through dehydration.
Hope that helps.
I_F