I watched a really good TED talk on recycling plastics. The biggest issue they faced was that separating like plastic was the hard thing, as they all feel like plastic, all look like plastic and weigh pretty much the same for the volume. The challenge in processing recyclable stock was separating types.

You can melt it all down, but there are lots of chlorides and other elements bound onto polymer chains to elicit different properties in the original plastics, In the video I watched these seemed like the biggest impediment to their approach because they wanted to consolidate stock of like materials. They opted for a optical/mechanical sorting approach which I thought was pretty impressive at the time.

The article does suggest that types need to be segregated to different pathways so it may be an issue.

The pathways the paper suggest seem practical. It'll be interesting to see which countries are willing to take this on. It's a very heady industry. And the intent is a carbon neutral outcome.

I wonder if we will just trade the CO2 of making plastic for the shipping cost of plastics from point A to B.

Even if it trades all the CO2 produced by production to shipping that is a net win. It will mean less plastic in the environment. Over time we can make the shipping more efficient which will reduce CO2 and other costs further.

Or maybe we just need biodegradable plastics.

Getting rid of plastics is already a huge cost for cities.

Right now, many large cities burn their platics which also generates co2.

They also burn oil and gas. Burning plastic waste for energy isn't too bad in the grand scheme of things. Sure, not having pumped up the oil and not having turned it into plastic would have been best. And recycling that plastic into something useful would have been better. But burning it as fuel is still pretty good.

Well, shipping could be made using energy from renewable sources, thus removing any need for oil extraction - which I assume is the end goal here (and the truly sustainable outcome we're after).

They can theoretically recicle a lot of the plastic, but they get the 100% assuming that they can transform the part that is transformed to CO2 back to plastic. This part requires a lot of energy, and including it is almost cheating.