Life cycle assessment of alternative technologies for municipal solid waste and plastic solid waste management in the Greater London area

摘要

The aim of this study is to present the results of a life cycle assessment performed for different scenarios reflecting the management, treatment and handling of plastic solid waste as a fraction of municipal solid waste (MSW) in the Greater London area. The study is divided in two parts: Part I comprises a LCA on the current MSW management strategy adopted in the Greater London area. This includes a materials recovery route via a dry Materials Recovery Facility (MRF) and an energy recovery route (incineration unit (IU) with combined heat and power). Part II investigates two alternative thermo-chemical treatment (TCT) technologies for the management of plastic solid waste (PSW): a low temperature pyrolysis (LTP) reactor and a hydrogenation reactor (VCC). The LTP process recovers valuable chemicals and petrochemicals (e.g., gases (C3-C4), liquid fractions (naphtha), waxes (atmospheric residue, AR) and heat in the form of steam), whilst the hydrogenation process produces syncrude and e-gas which is comparable to natural gas. The system expansion methodology was applied to the scenarios developed. A sensitivity analysis investigated different degrees of material recovery and reprocessing for the substitution of the relevant conventional processes. At the same time the study tackled the impact on the environment of introducing TCT units with the aim of petrochemicals' recovery. Results showed that the current waste management system is more environmentally friendly compared with the landfill scenario for all the impact categories investigated. Moreover, the employment of the alternative TCT technologies investigated depends on the market's ability to take-in the petrochemical by-products hence replacing their conventional production. Scenarios including pyrolysis appeared to be more environmentally friendly in terms of Greenhouse gas emissions when compared with hydrocracking, while the reverse was true for the eutrophication potential category.