Interesting, but to what end?
Love the idea, good luck and happy flying to Mr Roswell!
But! 5 tons of plastic yielding 106 gallons of fuel (about, I'm sure) and an estimated 26 million tons of plastic available, that works out to a bit over 500 million gallons of potential fuel (if *all* of the plastic is used) or about 2 days worth of fuel for the entire US.
Yes, every little bit counts and all the options should be considered. Just keep in mind this idea is one of the little bits that on its own isn't going to make much difference. This *plus* any number of other ideas will change the world.