Try cooking down plastics and running the resultant fluid through water to allow the Diesel fuel to rise out and be captured for use ...
One example is set up 2 side by side 55 gallon drums: 1 on top of a fire pit; the other half filled with water.
For the 1 on top of the fire pit, cut a 3-5 inch hole 1/3 the way up from bottom, attach a 3-5 inch pipe to fit and make sure it is 10 feet long to run into the bottom of 2nd 55 gallon drum.
Now, fill the first drum with various plastics cover with a thick screen and cook.
The plastic goop flowing into the 2nd drum will separate out above the water line as usable Diesel fuel.
Would probably work best on farms with a lot of Diesel fuel needs located somewhat close to a landfill.
But wouldn't you still be transforming carbon (and other elements) from a stable bound form into a gaseous form? Would this not effect the net carbon (and other elements/compounds) in the atmosphere and biosphere? Just curious