That's just magical thinking. Nothing suggests that it is in the realm of possibility.

What is the energy potential in the materials in a landfill? How much is wasted by scouring them and trying to properly extract it? Compared to preventing the capture of those materials there in the first place?

Putting the survival of our species on the possibility of some pixie dust is not rational. It is hard to face the truth, but burying your head in the sand is counter-productive.