Emissions & Waste


In addition to greenhouse gas emissions, we are actively working to reduce other air emissions and our solid waste streams.


We continued the trend of declining sulfur dioxide (SO2) emissions in 2013, achieving an 8% reduction over 2012 due mainly to facilities like our San Ciprián Refinery in Spain switching to cleaner fuels.   


Our nitrogen oxide (NOx) emissions remained steady in 2013 despite our reduction efforts. These included investing more than US$1.33 million (€1 million) in low-NOx regenerative burners at our rolling mill in Amorebieta, Spain.


In 2013, our European smelters reduced absolute fluoride emissions by 34% and fluoride intensity by 10% compared to 2012. The reductions resulted from process improvements and production curtailments in Italy.

Air Emissions
  Sulfur Dioxide
Thousands of metric
Nitrogen Oxide
Thousands of metric
Kilograms per metric ton of aluminum produced
2009 16.3   2.7   0.60  
2010 16.5   2.9   0.60  
2011 17.2   3.3   0.38  
2012 13.8   2.5   0.40  
2013 12.8   2.5   0.36  


Landfilled Waste

Our efforts to meet the Alcoa global target of a 75% reduction in landfilled waste by 2020 and 100% by 2030 from a 2005 baseline experienced a setback in 2013. The factors behind the 10.7% increase in 2013 included more non-production wastes, such as demolition debris. Due to efforts to improve process efficiency, we also generated more production wastes with no disposal alternatives other than landfilling.


Helping to somewhat offset these developments was a 6.5% increase in wastes that we could sell or reuse.

Solid Waste
Thousands of metric tons
  Landfilled Waste Wastes Sold or Recycled
2009 41.4 244.8
2010 41.0 241.3
2011 40.0 278.6
2012 31.8 264.3
2013 35.2 281.4


Spent Pot Lining

Spent pot lining (SPL)—a waste from our smelting process—is generated when the carbon and refractory lining of smelting pots reaches the end of its serviceable life. 


In 2013, our European smelters generated 43% more SPL per metric ton of aluminum produced compared to 2012. This was due to removing SPL from curtailed pots at some sites and issues with process stabilization at our newer smelter in Iceland.


Globally, we have led the aluminum industry in finding ways to transform SPL into a raw material for other industries, such as cement manufacturing. In 2013, 78% of the SPL we generated in Europe was recycled or reused. One of our challenges in reaching a 100% recycling rate is that there are no facilities to process the SPL generated by our two Norwegian smelters for reuse.

Spent Pot Lining
Kilograms per metric ton of aluminum produced

2009 11    85   
2010 17    62   
2011 18    81   
2012 14    76   
2013 20    78   


Bauxite Residue

Bauxite residue, which is generated during the alumina refining process, is made up of two components of roughly equal quantity—sand and mud—along with some residual caustic soda. The residue is stored in impoundments that are capped and re-vegetated when full.   


Globally, we have three strategic sustainability targets related to the land required to store the material, rehabilitation of the storage areas, and recycling and reuse of the residue. The latter goal is proving to be the most challenging globally, although we are making progress in developing and testing possible solutions.


In 2013, our refinery in San Ciprián, Spain, generated 0.75 metric tons of bauxite residue per metric ton of alumina produced. This 17% increase over 2012 was due primarily to lower alumina content in the bauxite processed.

Bauxite Residue
Metric tons per metric ton of alumina produced

2009 0.71   0    
2010 0.67   0    
2011 0.66   0    
2012 0.64   0    
2013 0.75   0