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Structures of the natural gas project of the Hydro Alunorte refinery

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How a switch of energy source in world's largest alumina refinery enables low-carbon products

When buying a product, you want to make sure it is produced in the best possible way, with minimal footprint, both in the production and usage phase. Here is why a switch of energy source at the world’s largest alumina refinery is doing wonders for the carbon footprint of aluminium.

The aluminium production process starts with bauxite extraction, a common element in the soil. Hydro extracts high quality bauxite at the mine in Paragominas, Brazil, and transports it through a 244-kilometer-long bauxite ore pipeline to the Alunorte refinery in Barcarena. Here it is converted into alumina, which is the main ingredient of primary aluminium.

Refining bauxite to alumina depends on its source and quality

Alumina, or aluminium oxide, is the raw material used in aluminium production. The energy needed to refine bauxite to alumina through the Bayer process is highly dependent on the source and quality of bauxite.

At Hydro’s bauxite mine in Paragominas, the bauxite is very high quality and is washed before it arrives at Alunorte, which means a reduction of temperature in the digestion process. This makes Alunorte one of the most energy efficient alumina refineries in the world.


Alunorte is the fifth highest energy efficient alumina refinery in the world and largest outside of China. Source: CRU and Hydro analysis

Hydro has used fuel oil to power part of the process for a long time, which leads to a high amount of carbon emissions. That is about to change as Hydro switches energy source to liquified natural gas.

Two initiatives to reduce emissions at Alunorte

To determine the greenhouse gas (GHG) emissions, the source of energy is critical.

Alunorte uses heavy fuel oil and coal, but have made a final building decision to invest BRL 1.3 million replacing fuel oil with natural gas. The fuel switch project will reduce the refineries' annual GHG emissions by 700,000 tonnes. Read more about the fuel switch project here.

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Production of aluminium requires on average two tonnes of alumina. With Alunorte’s industry leading energy and GHG footprint, Hydro is able to deliver aluminium with less than 4t CO2e/ton aluminium, with 1.3 attributed to the alumina refining and 1.6 to the electrolysis/aluminium smelting process. Source: CRU, Hydro analysis

In addition, Hydro is planning to reduce emissions from Alunorte by an additional 400,000 tonnes by 2025, through replacing coal fired boilers. Alunorte is already positioned in the first quartile of GHG emission intensity and is 35 percent lower than the industry average. By 2030, the aim is to fully decarbonize all processes, except the calcination process.

Key initiative to enable decarbonization of the aluminium value chain

The two initiatives to reduce emissions at Alunorte are the key enablers to deliver primary aluminium with a footprint of 2 kilo CO2 per kilo of aluminium by 2030.

Hydro REDUXA is Hydro’s brand of low-carbon primary aluminium. By 2030, Hydro expects to be able to deliver Hydro REDUXA with a footprint below 2 kg CO2e per kg of aluminium produced, including the entire value chain of aluminum and associated scope 3 emissions in the production process. The footprint of Hydro REDUXA is verified by both DNV and through a life-cycle assessment, which serves as a basis for the environmental product declaration.


Hydro REDUXA is Hydro's brand of low-carbon primary aluminium

Significant contribution to Hydro’s sustainability ambitions

Hydro’s climate strategy towards 2030 will reduce GHG emissions by 30 percent and the company has committed to be net zero by 2050, or earlier.

Hydro’s roadmap to achieve this is through sourcing more renewable power, switching from natural gas to green hydrogen, and reducing the process emissions from primary aluminium production through carbon capture and storage in addition to Hydro’s proprietary HalZero technology under development. 

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