Not all Primary Aluminum is Created Equal: Life Cycle Greenhouse Gas Emissions from 1990 to 2005
Primary aluminum ingot is a globally traded commodity, and large regional differences in technology and electricity fuel mixes exist among the industry's smelters. A life cycle assessment model is developed to calculate absolute emissions and emissions intensities of greenhouse gases (GHGs) from the production, trade, and consumption of primary ingot in six world regions. Global production emissions are estimated at 283 (±18) Mt CO2-eq (14.7 (±0.95) kg CO2-eq/kg primary ingot) in 1990 and 468 (±26) Mt CO2-eq (14.7 (±0.80) kg CO2-eq/kg primary ingot) in 2005. In total, the production of primary aluminum accounts for 0.78 and 0.93% of world GHG emissions in 1990 and 2004, respectively. Regional production GHG intensities in 2005 range from 7.07 (±0.69) kg CO2-eq/kg primary ingot in Latin America to 21.9 (±3.0) kg CO2-eq/kg primary ingot in Asia. The GHG implications of expanding global trade of primary ingot are examined in terms of the emissions embodied in the imports and exports and the consumption-weighted emissions intensities of each region.