The road to net-zero carbon emissions in aluminium production is long, but Hydro has made significant progress in the last three decades. The next advancements will be driven by the phase out of fossil energy sources, more recycling of post-consumer scrap and the development of emission-free production processes in line with Hydro’s decarbonization roadmap. 

With today’s Hall-Héroult electrolysis technology, CO2 is emitted when electricity makes aluminium oxide, or alumina, react with carbon to form primary aluminium. The proprietary HalZero* technology is based on converting alumina to aluminium chloride prior to electrolysis. Chlorine and carbon are kept in a closed loop, therefore eliminating emissions of CO2 and emitting oxygen instead. 

If successful, HalZero will fully decarbonize the smelting of aluminium by eliminating CO2 emissions from both electrolysis and carbon anode baking.

Status and way forward 

At Hydro’s research and development laboratory in Porsgrunn, Norway, technologists have successfully tested and modeled the HalZero process. They are now verifying the technology in test scale.

Significant research is still required to mature the HalZero process toward industrialization, but the process design studies and initial lab tests have shown that an industrial scale HalZero plant will have power consumption and operating expenditure in the same range as current electrolysis technology. Capital expenditure for a full scale HalZero smelter is expected to be comparable to new conventional smelter capacity. HalZero will be applicable for both greenfield aluminium plants or brownfield replacement of obsolete potlines, where the smelter infrastructure can be reused. 

Scaling up pilot testing will require significant investment and public-private partnerships. In 2023, the Norwegian state enterprise Enova granted NOK 141 million for the construction and operation of a test facility in Porsgrunn.

The test facility is an important step towards the goal to make the HalZero technology viable for implementation in new electrolysis capacity. This is where Hydro’s team of world class scientists will be working to mature the different HalZero process steps with the aim to start construction of an industrial concept pilot facility towards the end of the decade.

*The name HalZero alludes to the common way of naming Hydro Aluminium cell technology – HAL – and our ambition to achieve net-zero  emissions by 2050.