David Roberson <[email protected]> wrote: I suspect that the transportation of oil as well as its production cost > would make it desirable to find local sources for the elements needed in > those related products.
As far as I know, the only thing you want in plastic feedstock is "pure hydrocarbon polymers." Hydrogen and carbon. Anything else is contamination. That's what I have read, anyway. I expect that it will eventually be possible to synthesize pure hydrocarbons from water and carbon rather than refining oil, which is rather dirty stuff. Coal may be a good source of carbon if there is not enough organic garbage or recycled plastic, or if it is not convenient to extract carbon from atmospheric CO2. There are still mountains of coal left. A small fraction of the coal mined today would suffice. Here is one source for the "pure" part: http://large.stanford.edu/courses/2010/ph240/hamman1/ Energy for plastic . . . To begin, not all plastics are chiefly composed of hydrogen and carbon like polyethylene. For example, PET is about 33% oxygen by mass while PVC is about 57% chlorine by mass. [13] These additives come from non-hydrocarbon feedstocks. To account for the hydrocarbon feedstock energy, observe that three of the five most widely produced plastics, namely polyethylene, polypropylene and polystyrene, together account for nearly 60% of all plastics production. [4,5] Both polypropylene and polystyrene are pure hydrocarbon polymers with similar heats of combustion as their feedstock counterparts and polyethylene. . . . - Jed
