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| Fig. 1: The Hall-Héroult process for aluminum electrolysis. (Source: Wikimedia Commons) |
Aluminum production is one of the most electricity-demanding industrial processes in the United States. The reason why it is different from other metal production processes is that aluminum cannot be smelted, since its oxide is too stable to be chemically reduced. Therefore, aluminum production can only rely on electrolysis, which is a notoriously energy-intensive method because of the extremely high current that is used to reduce alumina. Thus, it is interesting to see the scale of electricity consumption in aluminum production to better understand the trends of this industry in the United States and the world.
Note: although aluminum is not smelted technically, the term "aluminum smelting" is still widely used to refer to the aluminum production process. While this report uses the term "aluminum production", it is the same as "aluminum smelting" elsewhere. The process that those two terms refer to is introduced below.
Modern primary aluminum production relies entirely on a two-stage industrial sequence: (1) the Bayer refining process, which extracts purified alumina (Al2O3) from bauxite ore, and (2) the Hall-Héroult electrolytic reduction process, which converts alumina into metallic aluminum. The schematic of the Hall-Héroult process is shown in Fig. 1. These two steps form the foundation of all global aluminum production today.
In the Bayer process, crushed bauxite is dissolved in hot, concentrated sodium hydroxide solution. This dissolves the aluminum-bearing minerals and leaves behind insoluble residues. As the solution cools, highly pure aluminum hydroxide precipitates out and is then calcined to form white alumina powder (Al2O3).
The purified alumina is then fed into large electrolytic reduction cells used in the Hall-Héroult process, the only industrial method for producing primary aluminum metal. In a reduction cell, alumina is dissolved into a molten bath of cryolite (Na3AlF6), which acts as a flux to lower the operating temperature from ~2000 °C (the melting point of pure alumina) to about 950 °C. The bath is contained in a carbon-lined steel shell that serves as the cathode. Large carbon anodes are slowly lowered into the cell from above. These anodes supply the oxidation half-reaction and are consumed over time. Then, a very large direct current (typically between 300,000 and 600,000 amperes) is passed through the cell. [1] Aluminum ions (Al3+) in the molten cryolite are reduced at the cathode, producing liquid aluminum, which collects at the bottom of the cell and is periodically siphoned off.
Primary aluminum production in the United States has declined significantly over the past decades, but the remaining facilities continue to represent one of the most electricity-intensive segments of domestic industry. According to the U.S. Geological Survey (USGS), the United States had an installed primary aluminum production capacity of approximately 1.36 million metric tons per year in 2024, though actual output has been reduced to 750,000 metric tons in 2023 and 670,000 metric tons in 2024 due to high operating costs and global market competition. Note that although the primary production of aluminum has decreased, the total secondary production from old and new scrap has continued to increase over the past years, with a total production of 3.43 million metric tons in 2023 and 3.6 million metric tons in 2024. This alone can compensate for the decreased primary aluminum production in the United States. Additionally, the total export decreased from 3.29 million metric tons in 2023 to 3 million metric tons in 2024. Therefore, even though the primary aluminum production in the United States keeps decreasing, the increasing demand can still be satisfied. In fact, primary aluminum production only accounts for 10.63% of the total aluminum supply in the United States. [2]
According to a 2007 report prepared for the U.S Department of Energy (DOE), the 2003 U.S average of energy usage in the Hall-Héroult process is 15.0 kWh/kg. [3] While this report estimates that the energy usage may be lowered to 11 kWh/kg by 2020, another study published by the U.S. DOE shows that the current typical energy intensity in the year 2010 remains to be 23,388 Btu/lb (~15.1 kWh/kg), indicating that there had been difficulty in reducing the energy needed for primary aluminum production. [4] At least from the year 2003 to 2010, the estimated energy intensity has not decreased at all. Using these numbers, we can see that the actual total energy used in 2024 for aluminum production is 670,000 ton × 15,016 kWh/ton = 1.006 × 1010 kWh = 10.06 TWh. Considering that only four primary aluminum production facilities are still operational in the US, each facility requires an enormous amount of electricity. Therefore, it is no surprise that aluminum production facilities were often built adjacent to power plants historically. In some cases, the power plants were owned by aluminum production companies and were built specifically to supply electricity to the production facilities.
Primary aluminum production remains one of the most electricity-intensive industrial processes in the United States because aluminum itself cannot be produced by conventional smelting and instead requires the Hall-Héroult electrolytic method. With annual electricity use on the order of ten terawatt-hours, the sector represents a continuous, power-dense industrial load roughly comparable to that of a large power plant. However, due to the shift in industrial focus, the United States is gradually reducing its aluminum production. In contrast, electricity demand from AI-driven data centers is growing rapidly. According to International Energy Agency, the estimated data center electricity demand due to AI in the United States is expected to be between roughly 30 and 80 TWh in 2024, with the potential of growing to 100 and 450 TWh in 2028, which is one order of magnitude larger than the energy consumption of aluminum production. [5] Understanding the scale of these electricity consumptions and competing demands is essential for anticipating future stresses on the U.S. grid and planning accordingly.
© Jason Ye. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] K. Halvor and P. E. Darbløs, "The Aluminum Smelting Process and Innovative Alternative Technologies," J. Occup. Environ. Med. 56, S23, (2014).
[2] "Mineral Commodity Summaries 2025," U.S. Geological Survey, March 2025.
[3] "U.S. Energy Requirements for Aluminum Production: Historical Perspective, Theoretical Limits, and Current Practices," U.S. Office of Energy Efficiency and Renewable Energy, February 2007.
[4] "Bandwidth Study on Energy Use and Potential Energy Saving Opportunities in U.S. Aluminum Manufacturing," U.S. Office of Energy Efficiency and Renewable Energy, September 2017.
[5] "Energy and AI," International Energy Agency, April 2025.
