IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change Magnesium

Magnesium, produced in low volumes, is very energy intensive. Its growth rate has been high due to increasing use of this lightweight metal in the transport industry. SF6 is quite commonly used as cover gas for casting the primary metal into ingots and for die casting magnesium. Estimates of global SF6 emissions from these sources in 2000 range from about 9 MtCO2-eq (2.4 MtC-eq) (US EPA, 2006a), to about 20 MtCO2-eq (5.5 MtC-eq) (EDGAR, 2005). The later value is about equal to energy related emissions from the production of magnesium. Harnisch and Schwarz (2003) found that the majority of these emissions can be abated for <1.2 US$/tCO2-eq (<4.4 US$/tC-eq) by using SO2, the traditional cover gas, which is toxic and corrosive, or using more advanced fluorinated cover gases with low GWPs. US EPA (2006a) report similar results. Significant parts of the global magnesium industry located in Russia and China still use SO2 as a cover gas. The International Magnesium Association, which represented about half of global magnesium production in 2002, has committed its member companies to phasing out SF6 use by 2011 (US EPA, 2006a). Total emissions and reduction potentials

Table 7.7 gives the lower bounds for key emission sources in the non-ferrous metal industry. Total annual GHG gas emissions from the non-ferrous metal industry were at least 500 MtCO2-eq (140 MtC-eq) in 2000. The GHG abatement options for the production of non-ferrous metals other than aluminium are still fairly uncertain. In the past, these industries have been considered too small or too complex regarding raw materials, production technologies and product qualities, to be systematically assessed for reduction options.

Table 7.7: Greenhouse-gas emission from production of various non-ferrous metals

Metal Global emissions (MtCO2-eq/yr) Source and year 
CO2 - Mining and refining 109 IEA GHG, 2000 for 1995 
CO2 - Electrodes 48 IAI, 2006b for 2004 
PFC - Emissions 69 EDGAR, 2005 for 2000 
CO2 - Electricity 300 IEA GHG, 2001 for 1995 
CO2 - Electrode and cell-feed Sjardin, 2003 for 1995 
SF6 - Production and casting US EPA, 2006b for 2000 
CO2 - Electricity Unknown   
CO2 - Other steps in the production process Unknown   
All other non-ferrous metals     
CO2 - Process 40 Sjardin, 2003 
CO2 - Electricity Unknown   
CO2 - Other steps Unknown   
All non-ferrous metals Approximately 500 (lower bound)