Even when made using hydro-electricity, aluminum production had a big carbon footprint.
Rio Tinto Alcan and Alcoa (with a big push from Apple) have just announced "a revolutionary process to make aluminum that produces oxygen and replaces all direct greenhouse gas emissions from the traditional aluminum smelting process."
Demand for aluminum is going up dramatically as more and more cars are made of it instead of heavier steel; there simply isn't enough recycled aluminum to go around. Making aluminum takes a huge amount of electricity (13,500 to 17,000 kWh per ton) which is why so much of it is made in Iceland and Canada, where there is a lot of water power. That's why the announcement was made in Canada. The move was announced by Canadian Prime Minister Justin Trudeau:
Today’s announcement will create and maintain thousands of jobs for Canadians, significantly reduce Canada’s carbon footprint, and further strengthen the aluminum industry in North America. It is a truly historic day for the aluminum industry – and for all Canadian aluminum workers – who play such an important role in our economy and our country’s future.
Aluminum made from hydro power is already much cleaner than coal-fired, but still has a footprint. That's because the Hall-Héroult process for getting the aluminum out of alumina requires carbon anodes, which are consumed when the carbon reacts with the oxygen in the alumina, producing carbon dioxide. (More detail on the aluminum smelting process here).
The new process was developed by Alcoa in Pittsburgh, who have replaced the carbon anode with a "breakthrough" proprietary material that eliminates CO2 emissions and produces oxygen. It is now being commercialized, thanks to a big push by Apple (and a C$13 million investment in the first phase of the project). According to Apple's press release,
Apple’s involvement started in 2015, when three of its engineers went in search of a cleaner, better way of mass producing aluminum. After meeting with the biggest aluminum companies, independent labs, and startups around the world, Apple engineers Brian Lynch, Jim Yurko, and Katie Sassaman ... learned that Alcoa had designed a completely new process that replaces that carbon with an advanced conductive material, and instead of carbon dioxide, it releases oxygen. The potential environmental impact was huge, and to help realize it quickly, Alcoa needed a partner.
Apple's business development people then brought in Rio Tinto, who formed a new joint venture that they currently call Elysis, which unfortunately is also the name of a massage parlour in Waterloo, Ontario. Tim Cook of Apple says "we are proud to be part of this ambitious new project, and look forward to one day being able to use aluminum produced without direct greenhouse gas emissions in the manufacturing of our products.”
This is a huge step forward. It does not give aluminum a clean bill of health; demand is still going up, meaning more mining of bauxite, the source of alumina. As Carl A. Zimrig wrote in his wonderful book Aluminum Upcycled: sustainable design in historical perspective:
As designers create attractive goods from aluminum, bauxite mines across the planet intensify their extraction of ore at lasting cost to the people, plants, animals, air, land and water of the local areas. Upcycling, absent a cap on primary material extraction, does not close industrial loops so much as it fuels environmental exploitation.
We still have to recycle more aluminum and reduce demand for it, and stop the coal-fired aluminum production that is still happening all over the world, including the USA where production is going up thanks to the proposed tariff on aluminum imports.
But as the Rio Tinto CEO notes, "This is a revolutionary smelting process that can deliver a significant reduction in carbon emissions. It builds on the key role aluminum has to play in driving human progress, by making products infinitely recyclable, stronger, lighter and more fuel efficient."