The US government should require domestic aluminium smelters to switch to inert anodes once they become commercially available, according to environmentalists who say the technology would reduce carbon emissions.
"Aluminum companies need to go beyond the pilot project phase and expedite production of more metal using inert anodes," the nonprofit group the Environmental Integrity Project (EIP) said in a report published last month. "Once the technology becomes commercially available and used at a US smelter, [the Environmental Protection Agency (EPA)] should require operators to adopt it."
Inert anode technology would allow smelters to replace traditional carbon anodes in the aluminium smelting process. Carbon anodes are made from calcined petroleum coke and coal tar pitch and are consumed during the smelting process, contributing significantly to CO2 emissions. Although aluminium has become a leading raw material in the low-carbon transition because its light weight makes it useful for building more fuel-efficient cars and planes, the EIP report said the high electricity consumption and emissions from carbon anodes dents its low-carbon potential.
"Without strong action, the promise of aluminum in attaining a lower-carbon world will prove to be a false one," the report's lead author EIP policy and research analyst Nadia Steinzor said.
Aluminium demand is expected to grow by 40pc by 2030 from 2020 levels, in part because of CO2-reduction efforts, but its potential negative impacts must be considered, the report said.
The EIP report assessed greenhouse gas emissions at the six smelters still in operation in the US and determined they released the equivalent of 16mn t of CO2 in 2021. More than 70pc of this was from electricity, since five out of six of these facilities are reliant on fossil-fuel power. Almost 20pc came from direct production, while the rest was from the production of petroleum coke and alumina, another raw material.
Petroleum coke calciner Rain Carbon presented a study last month at the Argus Global Coke and Carbon Conference in Seattle, Washington, showing that carbon supply chain and carbon-related process emissions made up more than half of total emissions from a Canadian low-carbon aluminium smelter that runs on renewable power.
But requiring inert anodes at US smelters would be a tall order. After decades of development, in 2018, aluminium producers Alcoa and Rio Tinto created the Elysis joint venture to market and develop the inert anode. Elysis aimed to have a technology package ready for sale as early as 2024. But some, like Rain Carbon, have said they expect real progress on the technology will not happen until 2030 or later. Rain has also said it does not believe existing smelters can be retrofitted to use inert anodes, meaning new facilities would need to be built if the US government were to mandate this technology.
EIP also recommends that state and federal regulators require petroleum coke calciners to add SO2 emissions equipment known as "scrubbers" to capture emissions or restrict them from consuming green petroleum coke with more than 3pc sulphur. Local activists in Port Arthur, Texas, home of Oxbow Calcining's 635,000 t/yr calciner, have been pushing for revisions to a state air permit to limit SO2 and other pollutants that could mandate such changes. But scrubbers are costly to install and there is limited availability of less than 3pc sulphur calcinable coke.
The report also urges EPA to finalize a pending proposal to revise the Greenhouse Gas Reporting Program for calciners.
