Wacker successfully captures CO2 in silicon production

HOLLA, Norway—As Wacker Chemie A.G. moves toward its 2045 net zero emissions goals, the Munich-based company has successfully tested CO2 capture from the silicon metal production process.

Results from the joint pilot project between Wacker, SLB and Aker Carbon Capture were announced Sept. 11.

"The results of the pilot study are a huge success for us," said Wacker CEO Christian Hartel. "We've shown that this technology makes it possible to remove CO2 effectively. Capturing carbon dioxide prevents its release into the atmosphere as a greenhouse gas. It can then be put to other uses, such as creating synthetic fuels (e-fuels) or synthesizing methanol as a starting material for other chemical processes."

Storing it underground (carbon capture and storage, CCS) also is an option, Hartel said.

In Holla, Wacker combines quartz and carbon to make silicon for use in its silicone products, such as the polysilicon used microchips and solar panels and refined silicon for silicone rubbers.

But the process itself creates CO2, so Wacker developed a process (on a small scale) that reuses or stores this greenhouse gas and prevents its release back into the atmosphere.

The waste gas generated from silicon production was routed to the pilot plant, where carbon dioxide was captured through "amine scrubbing."

"This makes use of an amine-containing solvent that selectively extracts CO2 from the gas mixture," Hartel said. "In large-scale industrial processes, the CO2 is then released from the solvent by desorption before it is cooled, condensed under pressure and purified."

The test campaign that ended in June achieved capture rates of more than 95 percent, according to Wacker. The project team also validated the process parameters for large-scale implementation.

Wacker said it is working on a larger plant to capture 180,000 metric tons of CO2 annually.

"The project represents an important step on the road to closed carbon cycles," Hartel said. "What we need now are customers that will buy the CO2 from us and a regulatory framework that can help us build the business case."

Wacker will look to lower its emissions by 50 percent by 2030, and 100 percent by 2045, the company stated.

"Silicon production in Holla is a major piece of that puzzle," the firm said. "The objective for this site is full CO2-neutral production."

Wacker already has virtually eliminated Scope 1 emissions, using 100-percent green electricity from sources such as hydroelectric power since 2022.

"And the gradual switch from bituminous coal to biogenic sources of carbon is to be complete by 2030," Wacker said. "The amount of carbon dioxide released during silicon production is the most critical factor in the carbon footprint of silicones. The use of CO2-neutral metallurgical-grade silicon from Holla could significantly reduce the carbon footprint of the company's silicone products."