I completely agree with both you and Snow...
The missing variables are all EXPENSES
For example, the high cost of using a catalyst... not just its cost but the down time to manage it, you see it needs to be rejuvenated which means that it has to have the coke removed for it to work... oh, and btw that coke is a result of a significant loss in output so you will see a trade off, as much as 50% less output when using a catalyst.
The addition of expensive stabilizers to treat the synthetic fuel so it won't oxidize.
And lets not forget the real issue which is the rising cost of good feedstock or the needed overhead to process the 'free' stuff.
As for the issue of the missing hydrogen... It is well know by those skilled in the art of hydro cracking that when you take a long chain molecule that is stable, such as plastic, when you crack it you are essentially breaking the long chain to make shorter chains. The simplest hydrocarbon is methane CH4. If you break off a methane from a long chain say C32H66 you end up with C31H63 and an unsaturated CH3, they are now both missing a hydrogen at the break point represented by the 'X'-
..HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
HCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCH
..HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
..HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH........H
HCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCX....XCH
..HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH........H
If you continue to crack the cracked long chain molecule you end up with missing hydrogens on both ends-
..HHHH........HHHHHHH.......HHHHHHHHHHH........HHHHHHHHHH
HCCCCX....XCCCCCCCX....XCCCCCCCCCCCX....XCCCCCCCCCCH
..HHHH........HHHHHHH.......HHHHHHHHHHH........HHHHHHHHHH
These missing molecules are desperately searching for a bond.
This is referred to as 'unsaturated' hydrocarbons.
The most likely free molecule that fills the place of the missing hydrogen is the abundantly free roaming oxygen molecule. This is referred to as oxidation. Just like metal rusts, so does unsaturated fuel. That's the best case, it can get real ugly if the bond is replaced by a molecule other than oxygen.
This is what is responsible for gumming, shellacking, poor fuel efficiency, unburned fuel, smog and engine damage.
It is a serious issue that has stopped many P2O efforts in their tracks.
