Implications of non-anode effect-related PFC emissions from primary aluminium

Abstract

Smelter exhaust measurements for perfluorocarbon (PFC) emissions were carried out at 13 facilities in China from 2008 to 2010. The work has resulted in better global inventory of PFC emissions from primary aluminium production by having a measurement database of emission factors from Chinese aluminium producers. The measurements made in China revealed that PFC emissions could be produced during primary aluminium production that do not relate directly to anode effects. Although these emissions are much lower than during anode effects, they are generally always present and, therefore, are potentially substantial. Evaluations of two possible causes were completed, however, both were inconclusive. First, whether the non-anode effect (NAE)-related emissions are related to imbalances in anode current. Second, whether emissions were related to imbalances in cell voltage. Further investigations are needed to identify the root cause and to identify options to reduce these emissions. Although these NAE-related emissions were discovered in Chinese smelters, industry should investigate to see whether similar emissions might be occurring in smelters outside China at lower levels. In addition, the discovery of the NAE emissions necessitates the reexamination of the Intergovernmental Panel on Climate Change (IPCC) methodology for calculating PFC emissions. The current methodology is based on the presumption that anode effects are responsible for all PFC emissions and, therefore, PFC emissions can be calculated from anode effect process data alone.