One year since its BRL 1.3 billion (USD 234 million) investment to phase out fuel oil and switch entirely to natural gas, Hydro’s Alunorte refinery in Pará, Brazil, has managed to cut a staggering 700 thousand tonnes of carbon dioxide annually. The figure is not only a testament to the scale of the project but also a signal to the rest of the global alumina industry that real decarbonisation milestones are achievable — if backed by strategic foresight, capital intensity, and infrastructure reform.
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The fuel switch at Alunorte involved converting six steam-generation units and seven calciners to operate fully on natural gas. To make this feasible in a relatively underdeveloped energy corridor, Hydro partnered with New Fortress Energy, which commissioned a dedicated LNG import terminal and regasification unit (FSRU) in Barcarena, making it the only such hub in northern Brazil. The gas supply agreement, signed for 15 years, secured 29.5 TBtu annually for Alunorte, which now stands as the largest single natural gas consumer in the region. Beyond its emission targets, Hydro’s project has spurred infrastructure development that may unlock gas access for other industries in the Amazon region.
The sheer scale of Hydro’s investment reflects more than environmental optics. Retrofitting a continuous-process alumina refinery of 6.3 million tonnes per year demands a complete overhaul: from burner conversion to gas metering, safety redundancies, automation, and real-time emissions monitoring.
Being located in a tropical and logistics-challenged geography calls for the cost of importing gas infrastructure, adding a lump sum overhead, not to mention the capital needed for long-term emissions strategy alignment.
Yet, Hydro’s move promises energy cost optimisation in the medium term, eligibility for future carbon credit mechanisms, and favourable positioning under evolving European and global ESG mandates.
“Hydro has committed to reducing its emissions and has become a global benchmark. Decarbonization is a priority and already a reality at Hydro. To decarbonise an operation like Alunorte, financial and technological investment is required, but above all, it takes commitment to lead the transformation of operations in pursuit of net-zero,” says John Thuestad, Executive Vice President for Hydro's Bauxite & Alumina business area.
Globally, Alunorte is not the only alumina plant undertaking such a transition. In Ireland, Rusal’s Aughinish refinery (Europe’s largest) had made a similar switch over a decade ago, replacing oil-fired boilers with high-pressure natural gas steam generators. The EUR 15 million (USD 17.3 million) retrofit led to a 5 per cent drop in CO₂ emissions, complete SOₓ elimination, and nearly 40 per cent reductions in both particulate matter and nitrogen oxides. It remains one of the lowest-emitting alumina operations in the world.
In Spain, San Ciprián refinery, then under Alcoa and Alumina Ltd, made its switch from fuel oil to natural gas in 2015. Backed by a USD 25 million investment in pipeline infrastructure, the project delivered a 30 per cent cut in CO₂ emissions and significant operating savings, bringing down energy costs by an estimated USD 20 per tonne of alumina. That move wasn’t just about emissions. It firmly repositioned San Ciprián on the cost competitiveness curve.
In the southern hemisphere, South32’s Worsley refinery in Western Australia began decarbonising in late 2023 by replacing one of its coal-fired boilers with a natural gas alternative. That single retrofit is expected to avoid 208,000 tonnes of CO₂ annually, about 5.5 per cent of the operation’s total emissions. A second boiler is set to follow in 2024, forming part of South32’s broader decarbonisation roadmap to halve operational emissions by 2035 and reach net zero by 2050.
Despite differences in geography, scale, and regulatory pressures, what unites these projects is the recognition that natural gas is not an endgame, but a necessary intermediate step in industrial decarbonisation. While not renewable, it is significantly cleaner than coal or fuel oil and offers flexibility and consistency in thermal-intensive processes like alumina refining. Moreover, these conversions make room for future hybridisation (with solar, hydrogen, or biomass) by enabling cleaner baseload operation.
Alunorte is already among the world’s most energy-efficient refineries, ranking in the top 10 per cent for low-carbon emissions. In addition to natural gas, the refinery introduced three electric boilers that replaced coal, one in 2022 and two in 2025. The three electric boilers are reducing emissions by up to 550,000 tonnes of CO2 annually.
Hydro’s Alunorte project is thus both an engineering and strategic triumph. The 700 thousand tonne carbon cut in one year is not just a metric—it’s a message. It confirms that even in resource-intensive sectors like alumina, high-emission legacies can be replaced with scalable, low-carbon infrastructure if companies are willing to think long term. In combining operational ambition with regional energy transformation, Alunorte may very well have written the playbook for future alumina decarbonisation across Latin America and beyond.
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