Case Studies

These case studies illustrate how Alcoa is acting upon its commitment to sustainable development throughout the world. We are pleased with this progress, but look forward to achieving even more.

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Worldwide - 2009

Alcoa Smelters Meet Challenge to Reduce Greenhouse Gas Emissions by One Million Tons Annually


In 2005, Alcoa challenged its global network of aluminum smelters to reduce greenhouse gas emissions from anode effects by a collective 1 million tons on an annualized basis. In 2008, the smelters surpassed this goal by more than 100,000 tons.

An anode effect is an unplanned interruption to the electrolytic smelting process that results in the emission of greenhouse gases known as perfluorocarbons (PFCs). Smelters can reduce greenhouse gas emissions by more effectively managing anode effects through optimization of existing control systems.

Each Alcoa smelter’s process computer captures information about every anode effect, recording when these interruptions occur and for how long. Using this historical information, Alcoa determined that if each smelter consistently closed 90% of the gap with its best month in 2004 in terms of the amount of time anode effects occurred, known as anode effect minutes, a collective 1 million tons of greenhouse gas could be eliminated annually. This effort also would allow Alcoa to further exceed its original goal of a 25% reduction in its global greenhouse gas emissions by 2010 from a 1990 baseline.

To support the smelters, a technical team evaluated each plant’s data on a monthly basis. These performance data were summarized and circulated to all smelters monthly, and feedback was provided to the plants each month from senior business unit management.

Company experts also conducted audits of the smelters to identify plant-specific opportunities for reducing anode effect emissions. In February 2007, Alcoa held a worldwide anode effect reduction workshop to further disseminate best practices and key learnings among all the smelters.

As the 1 Million Ton Challenge evolved, the reaction from the smelters changed from “we’re not meeting our targets and we have reasons for that” to “we can and will meet our targets.” This cultural shift resulted in the smelters collectively reducing greenhouse gas emissions from PFCs by more than 1.1 million tons in 2008, which is 30% lower than their 2007 PFC emissions.

The challenge now is to maintain and enhance these reductions. The smelters have voluntarily lowered their targets for monthly anode effect minutes and created a new plan for achieving additional reductions from 2008 levels by 2013.