James Garthe's solution is along these lines, and it overcomes most major impediments in plastic waste management, such as:
1-- Nearly all known plastic re-cycling --or, down-cycling-- methods need sorting of waste by chemical type, a task that requires specially trained eyes
2-- Other pre-processes like cleaning, shredding, drying are often required, which are space-, capital- and labour- intensive.
3-- Plastic waste is dispersed, dirty and fluffy. When stuffed in bags it is too voluminous and uneconomical to transport over long distances.
4-- Down-cycling plants are too few, centralised and, capital- and skill- intensive, and far away from where waste is generated
5-- Energy put into reclamation is often higher than the energy realised in the product, reducing the whole exercise into one of social correctness, without any hard economic value
6-- Markets for reclaimed products are too specialised, controlled; therefore, realisable prices are arbitrarily set.
In short, the logistic, technical and marketing realms of plastic waste management are too opaque, specialised, unfriendly and uneconomical for you and me to be fully involved. The Garthe process addresses and solves all these problems.
The Garthe machine is a hydraulic compactor with a heated die. Roughly shred and cleaned waste is fed into the hopper, from where a ram pushes it into the heated die. At exit, the extrudate is sliced by a hot-knife into nuggets.
As an engineer with the Penn State University working with farmers, Jim Garthe was struck by both plastics' usefulness in agriculture --and the menace they become, as waste. He is therefore a man without any bias in the on-going debate on plastics. About 9 years ago, he built a small table-top machine which would compact rudimentarily shred mixed plastic waste and extrude them into well compacted sausages. These are then sliced by a hot knife into 'Plastofuel' nuggets. The nuggets may then be stored forever and transported economically.
In the Garthe machine, the die is heated just enough to fuse the outer skin of the nugget. The energy required for this is minimal. It is in fact a compaction process, readying the waste for storage and transportation. The calorific value in the plastic waste remains trapped. Thus, the energy gained from nuggets is more than what was put in to create them.