how much energy is used to extract aluminium

The extraction of aluminum is an energy-intensive process, primarily due to the electrolytic reduction of alumina (aluminum oxide) into pure aluminum. This method, known as the Hall-Héroult process, accounts for the majority of energy consumption in aluminum production. On average, producing one ton of aluminum requires approximately 15,000 kilowatt-hours (kWh) of electricity. This figure can vary depending on the efficiency of the smelting facility and the source of electricity used.

The high energy demand stems from the chemical properties of aluminum. Aluminum oxide has a very strong bond, requiring significant electrical energy to break it down into its constituent elements—aluminum and oxygen. The process involves dissolving alumina in molten cryolite at temperatures around 950°C (1,742°F) and passing a direct current through the solution. This causes the aluminum ions to migrate to the cathode, where they are reduced to molten aluminum, while oxygen ions react with carbon anodes to form carbon dioxide.

Beyond electrolysis, additional energy is consumed in earlier stages of production, such as mining bauxite (the primary ore for aluminum), refining it into alumina via the Bayer process, and transporting materials. The Bayer process itself consumes about 12-14 gigajoules (GJ) per ton of alumina produced. When combined with smelting, total energy use per ton of finished aluminum can exceed 170 GJ in less efficient operations.

Efforts are underway to reduce this energy footprint. Some smelters use renewable energy sources like hydropower or solar energy to lower carbon emissions. Advances in inert anode technology could also cut energy use by eliminating carbon anode consumption during electrolysis. However, until these innovations become widespread, aluminum production will remain one of the most energy-demanding industrial processes globally.