TMS QUICK LINKS:
  • TMS ONLINE
  • MEMBERS ONLY
  • MEMBERSHIP INFO
  • MEETINGS CALENDAR
  • PUBLICATIONS

JOM QUICK LINKS:
  • JOM HOME PAGE
  • MORE HTML ARTICLES
  • COMPLETE ISSUES
  • BOOKS REVIEWS
  • SUBSCRIBE

The global aluminum industry has a well-established sustainability initiative, “Aluminium for Future Generations,” overseen by the International Aluminium Institute (IAI), whose directors include senior executives from major global aluminum producers. The 27 IAI member companies represent over 80% of global primary aluminum production. The Aluminium for Future Generations initiative is built on 14 voluntary objectives, covering sustainability issues along the value chain, including not only environmental impacts of production processes, but also benefits associated with the use, reuse, and recycling of aluminum products. The incorindustry’s performance toward these quantitative objectives is measured annually against a set of sustainable development indicators. Annual results are assessed through surveys of both IAI members and non-members and are available through the IAI website.¹

Reduction of greenhouse gas (GHG) emissions was one of the first voluntary objectives formulated by the institute, specifically the reduction of emissions of CF₄ and C₂F₆, two perfluorocarbon (PFC) compounds that are emitted periodically during primary aluminum production upset conditions known as anode effects. While major progress has been achieved by the industry in this area, achieving even greater PFC emissions reduction remains one of the strongest focus areas of the Aluminium for Future Generations initiative.

To assure reliable and accurate reporting of greenhouse gas emissions the industry, working collaboratively with U.S. Environmental Protection Agency (EPA), the Intergovernmental Panel on Climate Change (IPCC), World Resources Institute, and World Business Council for Sustainable Development, has developed a set of protocols and procedures for the measurement, accounting, and reporting of greenhouse gases from the aluminum sector. The Protocol for Measurement of Tetrafluoromethane (CF₄) and Hexafl uoroethane (C₂F₆) Emissions from Primary Aluminum Production² describes specific procedures for obtaining reliable measurement results for PFC emissions from primary aluminum production. The methodology has been used to make over 150 direct PFC emissions measurements in smelters worldwide. The IPCC references the PFC measurement protocol in its highest accuracy Tier 3 method for developing inventories of PFC emissions from primary aluminum production. The smelter measurement data has also been used to develop the IPCC Tier 2 equation technology-specific coefficients, from which PFC emission rates are calculated for smelters where no measurements have yet been made.³ Finally, business level inventory procedures have been developed which incorporate the PFC measurement protocol and the IPCC good practices to develop combined corporate GHG inventories^4,5 that include both PFC emissions and carbon dioxide (and other combustion-related greenhouse gas) emissions from production operations.

The reduction of PFC emissions was one of the earliest voluntary objectives developed by the IAI. Adopted almost a decade ago, the specific objective was an 80% reduction in PFC emissions per metric ton aluminum produced by 2010 from a 1990 baseline. This objective was surpassed ahead of schedule in 2006, the result of strong growth in demand for aluminum products and resulting investment by the industry in new, modern, low-emitting smelting capacity. The response of the IAI directors was to adopt an even more stringent objective, with key components as follows:

• Following the successful achievement of the global goal for an 80% reduction in PFC emissions per metric ton of primary aluminum produced by 2006 (from the 1990 baseline), the aluminum industry will further reduce global emissions of PFCs per metric ton of aluminum by at least 50% by 2020 as compared to 2006.
• The primary aluminum industry seeks to achieve the long term elimination of PFC emissions.
• Coverage of the annual survey of PFC emissions from IAI member and non-member aluminum producers has almost doubled from a global aluminum production of 12 Mt in 1990 to 22 Mt (60% of the industry’s production) in 2009. IAI is striving to increase the global aluminum production coverage of its annual surveys to over 80%.
• Based on IAI annual surveys results, by 2020 IAI member companies commit to operate with PFC emissions per metric ton of production no higher than the 2006 global median level for their technology type.
• Progress will be monitored and reported annually and reviewed periodically by a recognized and independent third party. Interim reviews will ensure progress toward achieving the 2020 objective.

The IAI conducts an annual global survey of primary aluminum producers (both IAI members and non-members) for anode effect performance.⁶ The survey asks for the average frequency and duration of anode effects occurring on smelter potlines in addition to aluminum production data over the same period. Average potline overvoltage is requested from facilities operating with Rio Tinto Alcan AP technology that relate potline overvoltage (as opposed to “anode effect” frequency and duration) to PFC emissions. The survey also asks if facility-specific PFC measurements have been made that allow the use of IPCC Tier 3 methodology, which produces significantly better accuracy in calculating PFC emission rates than the (technology-specific) Tier 2 methodology. Survey returns are used to calculate emission rates for each reporting facility. Total emissions of CF₄ and C₂F₆ are calculated by multiplying the calculated emission rates, kilograms of CF₄ and C₂F₆ per metric ton aluminum produced, by the production levels. The sum of the two PFC emissions is then calculated as carbon dioxide equivalent (CO₂-e) emissions by multiplying each PFC emission by its global warming potential (GWP). Although more recent GWP values are available, IPCC Second Assessment Report GWP values are used for consistency with UNFCCC reporting⁷ and for tracking performance consistently over time from the 1990 baseline. Respondents are asked to classify their production technology as one of fi ve types, for purposes of the survey: bar broken center work prebake (CWPB), point fed center work prebake (PFPB), side work prebake (SWPB), vertical stud Søderberg (VSS), or horizontal stud Søderberg (HSS). Median emissions, as metric tons CO₂-e/metric ton aluminum, are calculated for each of these technology types. These median emission levels are used to estimate the PFC emissions from the share of primary production outside China that did not participate in the anode effect survey in a given year (6% in 2009), by multiplying available production data for these facilities by the median PFC emission rate for their technology type.

For Chinese producers a different methodology is used to estimate PFC emissions for non-survey participants. Through 2008 and 2009 there were a number of direct PFC measurements made at Chinese production facilities sponsored by the Asia Pacific Partnership on Clean Development and Climate⁸ as well as additional measurements made by Chinese researchers from the Zhengzhou Light Metals Research Institute (www.rilm.com.cn/english/main_en.asp). As a result of a countrywide modernization program, all Chinese aluminum has been produced from PFPB cells since the end of 2005. The median of 14 PFC measurements made in China is used to estimate the PFC emissions from non-reporting Chinese primary aluminum producers.

The latest anode effect survey data is for 2009, with completed surveys received from facilities producing 60% of global primary aluminum. Outside China producers representing 94% of production responded to the request for anode effect data. However, since China produced 35% of global primary aluminum in 2009, the level of participation by Chinese producers in the survey lowered the overall response rate to 60% of global production. Figure 1 shows the growth in primary aluminum production from 1990 through 2009 by production technology type.

Poor economic conditions in 2009 produced the first downturn in global aluminum production since the anode effect survey began. Total 2009 primary aluminum production was 37.1 million metric tons—almost two times higher than the 19.9 million metric tons produced in 1990, the baseline year for calculation of aluminum industry PFC emissions. The other key feature from Figure 1 is the increase in the proportion of PFPB technology. Start-up of new facilities, operating with modern PFPB cells and modern computer-controlled feed technologies, predominate the growth in primary production since 1990.

Figure 2 shows the key parameters related to the IAI PFC emissions reduction objective. The initial global objective of an 80% reduction in PFC emissions per metric ton aluminum production relative to the 1990 baseline was surpassed in 2006. Results for the most recent year, 2009, show good progress toward meeting the 2020 objective of another halving of PFC emissions from the 2006 performance, an overall 91% reduction from 1990 levels.

The remarkable progress in reducing PFC emissions per metric ton aluminum has led to a major reduction in total PFC emissions to the atmosphere, from 96 million metric tons CO₂-e in 1990 to 22 million metric tons in 2009, even though primary aluminum production has increased by almost a factor of two over the same period.

As noted above the aluminum industry has actively pursued direct measurements of PFC emissions at production facilities around the world, using the measurement protocol established collaboratively between U.S. EPA and IAI. The measurements have been useful in reducing the uncertainty of global emissions calculation by facilitating the most accurate Tier 3 calculation methodology at facilities where measurements have been made and by providing data to develop Tier 2 coefficients for those facilities where measurements have not yet been made. The measurements also confirm the progress made in those facilities operating with the most effective process control systems, where anode effects have been almost eliminated. The best PFPB facilities operate with total PFC emissions of less than 20 kg CO₂-e of PFC emissions per metric ton aluminum produced, a factor 10 times better than the median performance of all PFPB operators reporting in the 2009 survey.

Process Focused
In addition to an objective to reduce (and long-term eliminate) direct greenhouse gas (PFC) emissions from aluminum production, the IAI has objectives to reduce average energy consumption from smelting and refining processes. Specifically, these objectives are, first, a reduction in average electrical energy to produce one metric ton primary aluminum by ten percent by 2010 relative to a 1990 baseline (and therefore indirect greenhouse gas emissions from the smelting process), and second, to reduce energy use per metric ton of alumina produced by ten percent by 2020 versus 2006 levels (and consequently direct GHG emissions from fuel consumption and indirect GHGs from electrical power usage).

While the data from survey responses show that, through 2008 (the latest year for which data is available), the average electrical energy used to smelt one metric ton of primary aluminum has been cut by 4% it does not appear likely that the 10% reduction objective will be met by the 2010 year end. The IAI energy data understates global performance in that Chinese data is not currently incorporated into the database. Chinese producers operate with some of the most energy-efficient technology worldwide and if included would show significantly better energy performance improvement (the 1990 baseline being relatively unchanged, due to the small share of global production represented by China at that time). However, it would not be enough to meet the IAI 2010 voluntary objective.

The IAI has also recently established a new objective to reduce the average energy for production of a metric ton of alumina by ten percent by 2020 relative to the 2006 level. This objective does take into account the one third of global alumina production based in China, through the use of an energy dataset made available through CRU Group (www.crugroup.com). The achievement of this energy reduction goal would translate into additional reductions of overall direct greenhouse gas emissions related to primary aluminum production.

Product Focus
Recycling of aluminum uses only five percent of the energy required for primary production and avoids up to 95% of the greenhouse gas emissions, with 80 million metric tons of CO₂-e saved annually from the recycling of aluminum products. As part of the industry’s commitment to stewardship of aluminum products along the value chain and sustainable use as well as production of the metal, the IAI places major emphasis on increasing further the rate of recycling to meet growing future demand for aluminum products. The institute has developed a mass flow model to identify current and future recycling flows—statistical data on current and historic recycling performance being particularly hard to collect. The industry has committed to reporting regularly on the global recycling performance derived using the mass flow model. Results illustrate that around 44 million metric tons of aluminum, from primary and recycled sources, ended up in finished products in 2008. In the same year, approximately one-third of the metal in products available on the market was sourced from recycled (19 million metric tons) and two thirds from primary (37 million metric tons) metal. Three quarters of all the aluminum ever produced (since commercial production began in the 1880s) is still in productive use. In 2008 this stock had grown to about 640 million metric tons and will someday be available for recycling at the product end of life. Globally, aluminum achieves among the highest material recycling rates, with up to 90% for transport and construction applications. Its economic scrap value and ability to be recycled continuously makes the aluminum beverage can the most recycled container in the world with an average recycling rate of 60% and over 90% in some countries—the IAI has recently developed an objective to increase the global recycling rate of used beverage cans from a 2007 average level of 69% to 75% by the end of 2015.

While increasing efficiency of aluminum production processes and recycling of aluminum products saves millions of metric tons of greenhouse gases every year, the area with the greatest potential to reduce emissions is the use of aluminum products in sustainable applications, in particular in the light weighting of transportation vehicles.

The use of 1 kg of aluminum replacing heavier materials in a car or light truck can save a net 20 kg of CO₂ over the life of the vehicle. This figure is even higher for more weight-sensitive applications (for instance, up to 80 kg CO₂ saved per kg of aluminum used in trains). The 15 million metric tons of aluminum currently used in transport applications every year—cars, buses, trucks, trains, and ships—can save up to 300 million metric tons of CO₂ and 100 billion liters of crude oil over the vehicles’ operating life. As car manufacturers have sought to improve fuel efficiency, the use of aluminum has grown every year for the past 30 years; in 1990, the average passenger car contained between 40 and 80 kg aluminum; in 2009, the average was between 120 and 150 kg. Also, while today aluminum accounts for less than 10% of a car’s total weight it represents up to 50% of the total material scrap value—a fact which goes some way to explain the very high recycling rates (around 90%) for used aluminum vehicle components.

To track and quantify the benefits of aluminum use in transport applications, the IAI has an objective to monitor the shipments of aluminum for use in road, air, rail, and seagoing vehicles. Results show that aluminum semi-fabricated products shipped to the transport sector increased by approximately 22% in the five years from 2003. Projecting forward based on presumed growth in demand for transport globally, greenhouse gas savings from the use of aluminum for light weighting vehicles have the potential to double between 2005 and 2020 to 500 million metric tons of CO2 per year.

CONCLUSION

The global aluminum industry’s sustainability initiative, Aluminum for Future Generations, gives the industry objectives and timeframes for continuous improvements in performance in 14 specific areas that include greenhouse gas emissions reduction and energy efficiency in production processes as well as through sustainable product use and recycling. Progress toward objectives is reported annually by the IAI on its website, www.world-aluminium.org. Excellent progress has been recorded in the reduction of PFC emissions, one of the first industrywide objectives to be adopted. The initial objective of an 80% reduction in PFC emissions per metric ton of primary aluminum produced was surpassed in 2006 and IAI has adopted a new challenge of an additional 50% reduction by the end of 2020 for a total of over 90% reduction from the 1990 baseline. Currently the best PFPB producers operate with near zero anode effects reducing PFC emissions to less than 20 kg of CO₂-e per metric ton of primary aluminum produced. The industry is also working to increase the rate of recycling, already providing a third of total demand for aluminum. Recycled aluminum requires only five percent of the energy as the production of primary product and produces only five percent of the greenhouse gas emissions. The use of aluminum for light weighting vehicles offers perhaps the most promising avenue to reduce emissions, albeit indirectly from one of the largest contributors of greenhouse gases, the transportation sector. Thus the potential for aluminum to be part of the solution to climate change lies as much in its use in well-designed, recyclable, sustainable products as in the efficiency of its production processes.

REFERENCES

Jerry Marks is with J. Marks & Associates, Lees Summit, MO 64064; and Chris Bayliss is Director of Global Projects with International Aluminium Institute, London, UK SW1 Y 4TE. Mr. Marks can be reached at jerrymarks@comcast.net.