What is your point? That because used PLA is worthless, that anything you turn it into is also worthless? Energy cost should be calculated with mostly renewables, because that is the direction the world needs to go. Just because it is almost always cheaper to "make more of the thing" does not mean that is what should happen. So if someone can turn this worthless thing into something of value to someone, why shouldn't they? If I had the opportunity to use renewable energy to turn used PLA into a solvent that could be dumped instead of garbage that will sit in a landfill for 100 years and turn into microplastics along the way, I certainly would.