Linde and aluminum producers test hydrogen’s potential to cut CO2 emissions

It’s not every day that competitors willingly join forces to tackle a common challenge.

But that’s exactly what happened recently when representatives from competing aluminum producers spent the week together at Linde’s Combustion Technology Centre in Älvsjö outside Stockholm.

Even though the companies they represent compete fiercely in the marketplace, a group of Norway-based engineers and metallurgists arrived in the Swedish capital united by a common mission: taking steps to help reduce CO₂ emissions in the aluminum industry.

“We have to find a solution to get to zero CO₂,” says Linde’s Sjur Bjarte Dalsbotten, an application engineer based in Oslo.

Dalsbotten helped convince several of his Norwegian customers to travel to Linde’s one-of-a-kind combustion Technology Centre near Stockholm to collaborate for a series of ground-breaking tests.

Specifically, they wanted to learn whether hydrogen could replace carbon-based fuels like propane and methane in the melting of aluminum.

“Everyone in the aluminum industry is looking for solutions so they can eliminate their CO₂ footprint from melting aluminum,” explains Yngve Langsrud, chief metallurgist from BENTELER Automotive who was among those on hand for the tests.

Previous tests at Linde’s facility in Älvsjö were instrumental in demonstrating that hydrogen could replace fossil fuels for the heating of steel.

As hydrogen in Sweden can be produced using electricity from renewable power sources, the shift to hydrogen can help pave the way for a paradigm toward fossil-free production for the country’s steel producers.

But heating steel is quite different from melting aluminum. The chemical properties of molten aluminum make it highly susceptible to oxidation, which renders the aluminum unusable.

Molten aluminum can also absorb hydrogen, which can adversely affect the quality of the finished product. As a result, using hydrogen as a combustion fuel for melting aluminum is fraught with uncertainty.

“There are currently no good measurements of how hydrogen as a combustion source affects aluminum,” explains Martin Syvertsen a senior research scientist with Norwegian research institute SINTEF, one of the leaders of the experiments.

“Understanding how burning hydrogen will affect the quality of aluminum is the first step towards being able to use hydrogen in the melting of aluminum,” says Syvertsen.

To tackle the question of how hydrogen can replace fossil fuels, the team conducted a series of tests with different fuel blends and furnace atmospheres, steadily increasing the amount of hydrogen.

Linde’s Combustion Technology Centre is uniquely suited for conducting these types of tests. 

“It's the only Technology Centre that I know of where we can really test industrial atmospheres like those in a melting furnace in the aluminum industry,” he says.

The results could have a big impact in Norway, where aluminum is big business.

The largest producer of primary aluminum in western Europe, Norway exports nearly 1.5 million ton of the metal annually. In 2020, Norwegian aluminum exports were valued at $3.3 billion in revenues, making it the third largest export by value behind only petroleum and fish.

Thanks to abundant renewable electricity, Norway’s aluminum producers have already taken great strides in reducing emissions tied to production.

But increasing demands from customers for supply chains with lower CO₂ footprints means pressure is mounting on aluminum and other raw materials producers to reduce their emissions even further.

Primary metal from electrolysis is transferred to the casting furnaces in the molten state, Langsrud from BENTELER explains, so the focus is cold metal melting performed by, like BENTELER do for producing extrusion ingot.

“We are starting to see the first signs that the auto industry is actually willing to pay to reduce its CO₂ footprint,” explains BENTELER’s Langsrud.

“These tests can give a competitive edge to suppliers that have the ability to deliver parts with a lower CO₂ footprint. It also shows that we’re at the forefront because this hasn’t been done before.”