It is amazing to see what the human race can come up with when presented with challenging problems.

Most of us wouldn't be here if lots if consecutive things weren't successfully solved for millennia before now.

With plastics recycling one of the challenges is the ridiculously low value of the recycled product, hovering at zero to quite negative net dollars without subsidies.

This leads to an even more ridiculous state of affairs where the more of the human race that's involved with marginal plastic "recycling", the fewer that will be available to carry out activities that are orders of magnitude more effective for the same effort and energy expended.

I don't know how many miles of railcars you have walked on top of that were filled with virgin plastic pellets, but these things are so cheap because they are made by polymer plants big enough to produce them by the mile.

There is some possibility that any plastic recycling operation that is actually scaled to handle one whole railcar of prime waste at a time, would still not be financially sustainable as a standalone business if they started with a railcar that was virgin pellets instead of prime waste anyway.

How would they compete on price, selling one railcar at a time when that doesn't provide enough profit to pay for labor to even move the railcar? And ideally-fully-processed recycled plastic, for instance all-PE, clean & ready for blending with virgin on industrial scale, still needs to sell for less than virgin since it is physically less useful on its own for so many applications.

Now chemical recycling, where the prime waste is basically dissolved in toxic and/or flammable solvents, has been up for consideration. There is really no miraculous solvent that does a recognizable good job of dissolving plastic well, only usually adequate if more pounds of solvent are used than pounds of plastic. Virgin solvents are petrochemicals that may not be as expensive as they could be, but cost can be about 10x as much as designated fuel hydrocarbons (like diesel or gasoline which are optimized to be cheap enough to burn rather than for further use as industrial material). Once a hydrocarbon plastic (PE PP PS) without significant non-hydrocarbon content (no PET, ABS, PVC, etc) has been successfully dissolved into a compatible hydrocarbon solvent, it can then be sold for further hydrocarbon processing such as blending with fuels to a limited extent if the specifications can be maintained, or with crude oil for complete re-refining. This may not be fully legitimate in every jurisdiction, and any expensive solvent involved ends up being sold at prevailing fuel prices or below, along with the pounds of plastic dissolved in it. Less solvent can be used to dissolve the plastic, or solvent-recovery schemes are possible but that ends up relying on heat.

If you are going to use heat, might as well consider pyrolysis. You're just going to need a bigger heater. You really can't afford to do this unless you get the heat energy for close to free though, because it takes about the same energy or more than it did to make the virgin plastic. Now some people are good at this and do seem to be able to wrangle up some apparently free energy without any unbelievable shenanigans, so I would expect them to take it forward more than most. Definitely easier to come up with raw plastic waste for free, these are the two major inputs to the process, what could go wrong? Solvents may not be needed in the production of the pyrolysis oil, however something equally effective will be needed on an ongoing basis for routine cleanup. Should not be a major item like energy though.

But if you ever saw (or smelled) pyrolysis oil you might find yourself in the majority who would probably rather not have it exist at all. Too late. Some people think the toxic solvent vapors are worse, but not most. My findings are inconclusive so far but right now it looks like some toxic components of these type of plastic pyrolysis oils are so different from the ones found in "conventional" pyoil, that will be the first time those exact not-fully-characterized constituents have found their way into tankcars in any significant quantity or concentration.

Anyway some of these intended recycled plastic outcomes under ideal conditions are blendable as hydrocarbons, as long as the quality is there and the price is cheaper than what they are being blended with. Certainly then the carbon formerly sequestered in the native plastic, basically in the form of "solid waste" from the moment the virgin plastic leaves the polymer plant[0], then meets the same fate as the bulk hydrocarbons it was blended with; being largely burned for fuel and releasing more CO2 into the atmosphere than if it were landfilled. For the most part these type of liquid recycling processes require traditional oil & refining companies to be thriving well enough to already have a suitable hydrocarbon stream for blending, sizable enough to overwhelm the full amount of recycle liquid so there is not disagreeable amounts of degradation to the receiving stock when they accept it.

Depends on how you do the math but might as well just burn waste plastic directly for energy without all the recycling hassle beforehand, or even more environmentally sound, landfill solid plastic as soon as discarded. You think in some places real estate is too expensive for that? Maybe not after you bury enough toxic waste under the property :/

And for affordability, that's not counting the testing fees which can be pretty expensive by the tankcar. Unless you've got a lot of tankcars to make up a bulk parcel, but we're still going to get you on sampling fees.

[0] Only awaiting official Solid Waste designation upon discard.