Wolfram Scharnhorst
Mobile communication, in particular mobile telephony, is a service whose nonexistence nowadays is unimaginable. The ongoing, ever increasing penetration of mobile communication equipment, presently intensified by the transition from second generation1 to third generation2 mobile telephone technology, raises the necessity for environmentally sound production, operation and End-of-Life3 treatment. In order to determine potentials to improve the overall environmental performance of large technical systems, such as mobile phone networks, Life Cycle Assessment4 is increasingly accepted as the state-of-the art tool. Up to now, this tool has been primarily used to determine the environmental effects of the production and the use phase. The environmental consequences related to the EOL treatment of mobile telephone electronic scrap has been addressed only marginally. A reliable assessment of the overall environmental consequences however, requires a comprehensive analysis of all life cycle phases. The focus of the present thesis is directed towards the environmental assessment of the EOL treatment of scrap of mobile phone networks that comply with present and forthcoming mobile phone standards in order to provide in-depth knowledge on the related environmental effects. Additionally, reliable environmental data for future studies shall be generated. After a brief introduction in Chapter 1, the application of LCA for the environmental analysis of mobile phone networks is outlined in general in Chapter 2 (LCA method applied to mobile phone technology). A decomposition5 of the mobile telephone network infrastructure is proposed in order to investigate the network components separately (hierarchical classification of the network components into classes A-D). Technical background knowledge, compiled in parallel, is used in order to assemble a mobile phone network model used for network recomposition later on. Similar to the network decomposition, a dissection of the End-of-Life6 phase is proposed in order to explore and model the processing of the electronic scrap in the EOL phase appropriately. Subsequently, the infrastructure and communication techniques of the presently applied 2G and 3G mobile telephone networks are described in detail in Chapter 3 (Technical characterisation of mobile phone technology). Using the decomposition approach the mobile phone network infrastructure is characterised in detail. Technique related effects are explained. Applying the subdivision approach, the various EOL stages are presented. Chapters 4 and 5 compile the results of LCA studies performed for a separate network component and an entire network. The objects of the studies both comply with the modern Global System for Mobile communication standard7. The Screening LCA of an antenna station rack (Chapter 4) is based on comprehensive inventories of an antenna station rack8 and currently applied EOL treatment. The environmental impacts related to the End-of-Life treatment of the rack are investigated. Six different EOL treatment scenarios are developed to find an environmentally acceptable treatment alternative. System expansion, i.e. inclusion of the production phase, is applied to all scenarios in order to consider different amounts of recycled materials. The production of primary rack materials to substitute lost materials, especially that of palladium (which accounts for almost 40 % of the ecotoxicity impact category), dominates the overall environmental impact. Emissions of heavy metals from landfilled rack components/ materials and of by-products to the environment greatly influence the overall impacts on human health and ecosystem quality. The final disposal of rack components contributes to about 70% of the non-carcinogenic effects. Landfilled dust from steel production contributes to nearly 11% of this impact category. The results suggest that all precious metals containing electronic scrap should be treated in specially equipped metal recovery plants. A complete rack disassembly before processing in high-standard metal recovery plants is not necessary. An elaborated pre-treatment and fractionation of the scrap prior to precious material recovery does not lower the environmental impacts and is not mandatory and would only become environmentally interesting if high recovery of heavy metals is achieved. To avoid the formation and release of volatile and toxic heavy metals, incineration of electronic scrap and of by-products prior to landfilling should be avoided. To reduce the overall environmental load, standardisation of the sizes of rack components is recommended in order to facilitate their re-use. The LCA of a GSM Network (Chapter 5) comprises a life cycle assessment based on a detailed life cycle inventory for a typical GSM mobile phone network and related EOL treatment infrastructure. The environmental relevance of the three life cycle phases: production, use and EOL treatment has been analysed using IMPACT2002+. The environmentally preferable EOL treatment alternative was identified adopting the six earlier developed EOL treatment scenarios. Results indicate that environmental impacts attributable to the use phase dominate the environmental impacts during the entire life cycle of the network. The impacts of the production phase are primarily attributable to the energy intensive manufacturing of Printed Wiring Board Assemblies9. The EOL phase dominates impacts on ecosystem quality. In particular long-term emissions of heavy metals cause critical effects. Detailed analysis of the EOL phase shows that recycling of network materials in general leads to a two fold reduction of environmental impacts: in the EOL phase itself as well as by means of the avoided primary production of materials that are recovered in the EOL phase. An increase in the material quality of the secondary precious and rare materials leads to a significant reduction of impacts on human health. The EOL phase is assessed in-depth by developing different EOL treatment scenarios. Comprehensive experimental results on the volatilisation of heavy metals from PWBA during thermal EOL treatment are presented in Chapter 6 (Heavy metal partitioning from electronic scrap during thermal End-of-Life treatment). Samples of identical PWBA have been incinerated in a Quartz Tube Reactor10 in order to detect the volatility of selected key heavy metals in electronic scrap. In preparation, evaporation experiments were performed using a Thermo-Gravimeter11 in connection with an Inductively Coupled Plasma Optical Emissions Spectrometer12. The QTR-experiments were performed under reducing and under oxidising conditions at 550 and 880°C. The volatilisation has been determined for As, Cd, Ni, Ga, Pb, Sb and Zn using ICP-OES. The results were evaluated by thermodynamic equilibrium calculations and in comparison with similar studies. Neither As nor Cd nor Ga could be detected in the incineration ash residuals, expressing a high volatility. Ni remains as stable compound in the ash. Zn shows an increasing volatility with increasing temperature and depending on the supply of oxygen. Sb shows a high volatility nearly independent on temperature and oxygen supply. The results imply that, if electronic scrap is incinerated, attention has to be paid in particular to Sb, As and Ga. These metals are increasingly used in new electronic equipment such as mobile phone network equipment of the third generation. The series of the core chapters is finalised by presenting results of a comparative LCA study performed for mobile phone networks complying with the GSM and Universal Mobile Telecommunication System standard13 (Chapter 7: LCA of of Second Generation (2G) and Third Generation (3G) Mobile Phone Networks). The environmental performance of presently operated GSM and UMTS networks was analysed, concentrating on the environmental effects of the EOL phase using the LCA method. The study was performed based on comprehensive life cycle inventory and life cycle modelling. The environmental effects were quantified using the IMPACT2002+ method and the robustness of the results was tested with other LCIA methods. Based on technological forecasts, the environmental effects of forthcoming mobile telephone networks were approximated. The results indicate that a parallel operation of GSM and UMTS networks is environmentally detrimental and the transition phase should be kept as short as possible. The use phase (i.e. the operation) of the radio network components account for a large fraction of the total environmental impact. In particular, there is a need to lower the energy consumption of those network components. Seen in relation to each other, UMTS networks provide an environmentally more efficient mobile communication technology per bit transferred than GSM networks and a slightly higher absolute impact. In assessing the EOL phase, recycling the electronic scrap of mobile phone networks has clear environmental benefits. Under the present conditions, material recycling could help to lower the environmental impact of the production phase by up to 50%. Based on the recapitulation of the achievements of the thesis and an outline of the thematic limitations, challenges for future studies are formulated in Chapter 8. The results documented in the thesis are supported by the complementing appendices (A-D). ---------- 1 2G. 2 3G. 3 EOL treatment. 4 LCA. 5 In the context of network modelling the term "decomposition" is used to denote the disaggregation of the entire network into the separate network components and their sub-components. 6 EOL phase. 7 GSM. 8 Technologically this rack complies with the Global System for Mobile communication standard (GSM). 9 PWBA (Printed Wiring Board Assemblies are boards populated with Integrated Circuit (IC) components such as micro controllers, memory elements, diodes, etc.). 10 QTR. 11 TG. 12 ICP-OES. 13 UMTS.
EPFL2006
