The first proposed pathway to zero carbon for primary aluminium production was unveiled at the ALUMINIUM Online Showcase ‘Green Technologies’ session earlier this week, by Geoff Matthews, Futurist, Future Aluminium Forum Advisory Board Member, and Energy Sector Lead for EnPot Ltd.

Geoff Matthews says the development of the Pathway, which was co-authored by Dr. Mark Dorreen and Dr. Nick Depree, was stimulated by the International Energy Agency’s June 2020 update for aluminium production.

“The IEA gave the aluminium industry fail a mark with ‘more effort needed’, and this promoted us to dive more deeply into what a pathway compatible with the IEA’s Sustainable Development Scenario (SDS) would look like.”

“We wanted to understand what it would mean for the industry in terms of the technological innovation required, the potential roadblocks and cost implications, as well as the most effective allocation of capital. We also wanted to understand what the first steps were for smelter owners globally, as with any journey, they are often the hardest to take,” Geoff Matthews says.

Matthews says that the trio were initially quite shocked with some of the resulting analysis. “It made quite sobering reading, and it is absolutely clear that if as an industry we don’t respond quickly to these challenges, no one in aluminium production globally will be left unaffected.”

Matthews says that under the current trajectory, primary aluminium production will emit 52.7 trillion tonnes of CO₂ into the atmosphere from 2020 – 2050, predominantly from the emissions from coal-fired power generation.

“By 2050 primary aluminium production will be emitting 2.83 trillion tonnes per annum, which is the equivalent of over 90% of the CO₂ emissions from all of the passenger vehicles in the world today. That makes a mockery of any CO₂ gains from using aluminium to lightweight vehicles that is being promoted by the industry today.”

“Primary Aluminium production will also be left as the single consumer responsible for 100% of the CO2 from fossil fuel power generation globally, as the rest of the power system will be decarbonised”, he says.

“This scenario is not only unsustainable, but it is unacceptable”, Matthews says. “On this trajectory, aluminium will become the asbestos of 2050’s, that is the toxic material that no one will want to touch.

Matthews says that if steps are taken now the future for aluminium may be completely different, as the metal has the potential to be one of the most environmentally friendly materials on the planet.

Matthews, Dorreen and Depree say the only credible pathway to zero emissions for the industry is a trifecta of continuing to reduce energy intensity, the adoption of inert anodes, and the shift to using 100% renewably generated power.

Matthews says the adoption of inert anodes, and improving energy intensity to a current-day vision target of 10kWh/kg will reduce the current 2050 CO₂ trajectory by around 30%, and comes at an estimated cost of $US127 billion. “Delivery of inert anodes and a specific energy consumption of 10kWh/kg will mostly likely require replacing 50% of current smelting capacity with new, and upgrading the other 50%.

“The capital cost is off-set by operational savings from reduced electricity consumption however, so the pay-back period is only around 13 years, for an annual saving of 911 million tonnes of CO₂ by 2050.

Matthews says the adoption of modern energy modulation technology will reduce the 2050 CO₂ trajectory by a further 30%, through the replacement of coal-fired electricity generation with low-cost clean variable renewable energy. “The capital cost of adopting modulation technology across the entire smelting fleet is estimated to be around US$50 billion with a return on investment period of around seven years.

This technology is commercially ready for roll-out so work could start today. If it was in place today, the cumulative savings over the next 30 years would be a not insignificant 13.7 trillion tonnes of CO₂.

Matthews says the remaining 1000 million tonnes annually of CO₂ left by 2050, after inert anodes, energy efficiency and energy modulation is fully implemented, is a lot harder to abate.

“It will be reliant on four things; freedom of renewables, the overbuilding renewable generation capacity, technological innovation in the power system, and collaboration and partnership with other energy users in the grid.

“Fortunately, aluminium smelters can be used as huge virtual power plants for the power system, and providing demand side response these services to the electricity grid will become critical leverage when trying to secure firmed contracts for the 60% of electricity supply that smelters will need as constant load.not be able to modulate.

Matthews says the cost of replacing all coal-fired power generation that is used to supply aluminium smelting today is estimated to be US$131 billion. “It’s a big bill, but again its off-set by annual operational savings, so has a return on investment period of around 18 years.

“In terms of CO₂, the reduction is significant on a global scale,, if it was possible to implement this today it would reduce reducing a cumulative avoid 42 trillion tonnes of CO₂ entering the atmosphere over the next 30 years.

Overall, Matthews says, while the current trajectory is confronting, a credible pathway to zero carbon by 2050 can be embarked on. “Nothing is stopping us adopting modulation technology today and increasing our use of clean low-cost variable renewable energy, while we wait for the technological developments over time that will deliver inert anodes and efficiency improvements.