Automotive shredder residue (ASR) for clean energy systems (pyrolysis and gasification) to produce sustainable green energy

Abstract

One of the major challenges facing the automotive industry is meeting the recycling and recovery targets set by the revised European End-of-life Vehicles directive (which has set a target of 95%wt for recovery from vehicles by 2015). The remaining non-recovered material is 20–25%wt (known as automotive shredder residue (ASR)). It is this material which must be processed to meet the higher targets. Currently, the residue is disposed of, which in many cases is landfill. The option to recover material to meet European target is currently limited to mechanical sorting via post-shredder technologies (PST). Thermal treatments options for ASR in within new emerging waste to energy plants is debatable. This is making it difficult to fully implement the requirements of the directive and the future application of the circular economy package.

This work has investigated the detailed syngas compositions and solid residue (char) characteristics produced from ASR thermal treatment (pyrolysis) in a pilot-scale rotary kiln at 800-1000oC. The concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and the toxicity levels in the char were determined. New data on critical factors for the processing of char and its subsequent use are presented. In addition, the results of raw ASR (obtained from UK shredder plant) characterisation were used to assess commercial thermal plants from around the world. The assessment study undertaken has identified potential pathways and barriers for commercial thermal treatment of ASR. Whilst there were many claiming that processing of ASR was possible none have so far shown both the technological capability and economic justification.

High pyrolysis efficiency was maintained throughout the operating/experimental conditions and varying process temperatures. The results of pyrolysis by-products analyses suggest that thermal treatment may represent a viable process for ASR waste and allow the char or syngas to contribute to meeting the EU Directive targets. PST for the reduction of cables and wiring in the raw ASR will need to be employed in order to achieve the required energy recovery efficiency by the removal of both chlorine and catalytic metals which lead to dioxins and furan production.