Where possible, plastics are "driven in circles". In the case of PET bottles, for example, this is the case to a certain extent because this "packaging" is made of only one plastic, namely polyethylene terephthalate (PET). PET is a thermoplastic, and thus deformable under the influence of heat, from the polyester family. Since all plastics, regardless of their type, are usually made from petroleum, they possess its energy potential. Waste plastics’ potential can therefore be realized thermally or energetically to generate heat in a combined heat and power plant.
The Waste Framework Directive 2008/98/EC (WFD) of the European Union (EU) lays down a general order of priority for waste management measures, according to which (mechanical) recycling is generally more advantageous than energy recovery (Article 4 of the WFD). However, recycling is not an end in itself, according to the background paper "Chemical Recycling" of the German Federal Environment Agency (UBA) . "Rather, it must correspond to the measure of the best possible protection of humans and the environment, whereby the entire life cycle of the waste must be considered." For this very reason, plastics recycling should be as high-quality as possible with the aim of "recovering substances from the waste stream that replace primary materials and, at best, primary plastics, thereby saving resources".
In other words, preference should be given to the recycling of used plastics in the course of manufacturing high-quality products (upcycling). At this point, the process of chemical or raw material recycling is of great importance.