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Energy Materials

12: Carbon-free aluminium smelting

Problem:

Nearly all aluminium smelting has for many years been done with hydroelectric power from generators dedicated to the purpose, with the smelters built next to the dams that store the water.

However, smelting is the largest single producer of toxic fluorides worldwide. ‘Scrubbers’ are usually used to remove the majority of fluorides from factory smoke today, but when those scrubbers are spent they are also dumped in landfills where the soluble fluorides absorbed into them can leak out into the soil.

Solution:

In May 2018, Alcoa and Rio Tinto unveiled what they describe as the world’s first carbon-free aluminum smelting process, through a partnership called Elysis, which refers to the electrolysis of alumina, a process at the centre of aluminum smelting.

Apple, which is planning to use the metal in its iPhone and laptop computers, as part of its own efforts to decarbonize its operations and supply chain, is also investing in Elysis.

On August 16, 2019, construction began on the Elysis R&D centre in Quebec’s Saguenay-Lac-Saint Jean region, located within Rio Tinto’s Complexe Jonquière, the site of the Arvida smelter, Vaudreuil refinery and Arvida research and development center.

The project is expected to be fully operational by the second half of 2020, employing 25 technical experts.

By 2024, commercialisation on a world scale could eliminate the equivalent of 7 million tons (6.5 million tonnes) of GHG emissions if fully implemented at existing aluminum smelters in Canada – roughly equal to taking nearly 1.8 million light-duty vehicles off the road. (alcoa.com)

Meanwhile, Russian aluminum giant Rusal En+, which uses hydropower from rivers in Siberia to power most of its smelters, is targeting 2021 to roll out its own line of carbon-free aluminum, based on an inert anode system.

Rusal has teamed up with US manufacturer Braidy Industries to build a mill in Kentucky, which will be the world’s largest low-carbon rolled aluminum producer, as well as the first new greenfield aluminum mill in 37 years to be constructed in the United States.

En+ Group, the holding company for Rusal reckons the trend for lighter and more efficient electric car bodies will boost demand for “green” aluminum. (enplusgroup.com/en)

Discover solution 13: floating neighbourhoods that can adapt to changes in water level

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