Plasma gasification is the cleanest mechanism to convert plastics to energy while rendering byproducts inert, there just isn't much will to implement. Energy output can contribute towards direct air capture of carbon to mineralize, the rest can be from renewables.
https://en.wikipedia.org/wiki/Plasma_gasification
https://netl.doe.gov/research/Coal/energy-systems/gasificati...
https://www.sciencedirect.com/science/article/abs/pii/S03783... ("Plasma gasification versus incineration of plastic waste: Energy, economic and environmental analysis")
https://news.ycombinator.com/item?id=38722984 (u/CptFribble: "I am once again asking you to consider plasma gasification. Here is my standard comment, copied again")
https://news.mit.edu/2021/inentec-turning-trash-into-valuabl... (Control-F "Recycling plastic")
HN Discussion stream on the topic: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
(the art project is fine though)