Existing approaches to reducing environmental impacts along the metal production and consumption chain are focused largely at the plant scale for primary production, rather than considering the whole metal cycle. As such, many opportunities for systemic improvements are overlooked. This paper develops an approach to designing preferred futures for entire metal cycles that deliver reduced carbon footprints. Dynamic material flow models in Visual Basic® are used to provide life-cycle-impact-assessment indicators, which help identify key intervention points along the metal cycle. This analysis also identifies which actors or agents along the value chain are responsible for, or can influence, behaviour which affects environmental performance. With this information, it is possible to evaluate different scenarios for transition paths to achieve reduced impact. These scenarios consider combinations of new technology, increased metal recycling and demand management strategies. A case study for the copper cycle in the USA shows that to meet a CO2 reduction target of 60% by 2050, innovative technologies for primary processing of mined ore will play a limited role, due to their increasing impacts in the future associated with mining ever lower ore grades. To compensate for this whilst meeting demand projections, recycling of old scrap would be required to increase from 18% to 80%, requiring extensive collaboration between primary and secondary producers. An alternate scenario which focuses on demand reduction for copper by 1% per year, meets the CO2 target whilst only requiring an increase in the recycling rate from 18% to 36%. Together, these suggest that there is merit in examining the 'metal-in-use' stage of the metal value chain more closely in order to achieve targeted reductions in CO2. The approach also highlights the inherent trade-offs between different aspects of environmental performance which are required when pursuing CO2 reduction targets.
xxx xxx on 08 Oct 08The road to grid parity for PV power generation will be difficult, needing five or more years to compete with utility power, unsubsidized, on a large scale, noted Mark Thirsk, managing partner at Linx Consulting, at a recent SEMI PV forecast luncheon (Sept. 18) in Santa Clara, CA Most input materials for PV production are in relative oversupply and will not constrain production, Thirsk pointed out - and for this reason manufacturers are conservative about capacity investment. In particular, his PV module production forecast (see Fig. 1, above) shows an overstep in demand in 2008. One reason for suppliers' reluctance to build capacity for entering the silicon supply chain is that it is an inefficient process. "Only about 15% of all the silicon going into the supply chain goes into the wafers, so it's a pretty wasteful and capital intensive process, so there is a lot of reluctance to build capacity," said Thirsk. Despite the efficiency challenges, Thirsk's forecast indicates that an oversupply may occur in 2009 Because >40% of PV grade silicon is lost at the wafering step, Thirsk believes this represents a significant opportunity for the right technology. Additionally, diamond wire is a potential replacement for slurry technology, but this technology is still immature. In the crystalline silicon (c-Si) value chain, Thirsk sees opportunities for optimizing mono-crystalline wafers with metal wrap technology and backside contacts; process optimization and material improvements would improve cell efficiency, and glass, wafer, backsheet, and grid improvements can enable more efficient light capture. Looking ahead, Thirsk told the audience that while thin-film technologies will enjoy strong growth "and may be more attractive to value-add materials and equipment suppliers, thin-film cell production will remain a minority share for the medium term." (see Fig. 3, below) He closed his presentation encouraging the creation of a Moore's Law type of roadmap for the PV
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