Silicon dioxide is a common material, coming from quartz rock or sand, so it is not nearly as finite in its mining capacity as other elements used in alloys and chemical production processes.
When combined with a small percentage of carbon under an extreme amount of electricity-driven heat, SiO2 loses most of its oxygen to the carbon, leaving 99.99-percent pure silicon metal.
But converting silicon dioxide requires massive amounts of energy, and since many refineries achieve the required high temperatures from coal, the atmosphere can suffer.
"The production of silicon metal is very energy-intensive," said Robert Gnann, head of Wacker Silicones. "In order to significantly reduce greenhouse gas emissions in such production, the plants must be state-of-the-art. That is exactly what we are aiming for with the capacity expansion and planned infrastructure measures in Holla."
Obtaining cost-efficient sources of energy also are crucial for companies building silicon metal refineries.
In Holla, Wacker said it will look to the "electrification of production processes and the use of electricity from renewable resources."
To this end, Wacker signed a supply agreement with Norwegian electricity producer Statkraft in January for green electricity from hydropower.
Through December 2027, the company will supply Wacker with 2.35 terawatt hours of "certified green electricity" from hydroelectric power.
That represents about 40 percent of the site's annual demand, Wacker said.
"The expansion project is a logical step in our growth strategy and an important building block for halving our greenhouse gas emissions by 2030," Hartel said.
Wacker added it also will look to replace coal as the main reduction agent (for about 60 percent of the energy needs in its current processes) with renewable materials such as charcoal or pellets.
The company believes up to 430,000 metric tons of CO2 per year can be prevented from entering the atmosphere—and stored either for elimination or to be recycled, perhaps as a raw material for chemical products—in Holla.
At its Burghausen, Germany, site, Wacker is planning a 20-megawatt expansion known as Rhyme Bavaria, with a focus on production of renewable methanol (another essential chemical for silicone production) from existing production processes using green hydrogen and CO2.
The goal is net-zero CO2 production for the company by 2045.
To get the Burghausen project off the ground, the company is seeking funding in the "double-digit" millions of dollars range from the European Union, specifically from the European Commission's EU Innovation Fund.
After failing to qualify for money from the EU fund in 2020, Wacker reapplied March 7 for funding for the Burghausen site.
Overall, Wacker expects the investment there to be about $110.2 million for the expansion.
An electricity price of about 4 cents per kilowatt-hour is required (for the renewable methanol process) so that the project does not require further state funding to be profitable.
However, electricity costs in Germany are far higher than that—higher than what competitors pay in other parts of the world—hence the EU fund applications.