A carbon capture system that turns bakery flue gas into concrete-making minerals is set to start operating this fall at the Penn State Bakery in University Park, Pa., according to project developer Matthew Hollingham, a third-year doctoral student in architectural engineering.

The pilot draws CO2 from cooking-boiler flue gas, routes it through a condenser, and injects the dried stream into a mill loaded with basalt. High-energy crushing fractures the rock into reactive fines that absorb CO2 and release calcium ions. The fines then react with the separated acidic water, forming stable calcium carbonate. Both end products can partially replace Portland cement in a concrete batch.

How big is the cement carbon problem?

Cement production generated up to 8% of global CO2 emissions in 2019, according to the International Energy Agency. Roughly half of that comes from the chemical reaction that forms clinker when limestone and silica-bearing material are fired in kilns above 2,600°F. The CO2 intensity per ton of cement has held flat since 2019, the IEA reports.

Hollingham's approach attacks both the calcination step and the process emissions, he said.

"We're hoping to take this carbon byproduct and recycle it into something useful through the carbon mineralization process," Hollingham said. "Imagine if we could see a bakery making a sidewalk."

How does the system work?

Flue gas exits the bakery boilers and enters a condenser. The condenser drains acidic water and sends dry gas — mostly CO2 and nitrogen — into a mill packed with calcium-rich basalt. Mechanical energy grinds the rock, exposing fresh surface area. The reactive fines capture injected CO2; the calcium ions then bond with the previously drained acidic water to form calcium carbonate, a stable solid mineral.

"With the carbon capture system, we avoid using some of the limestone, so we save CO2 there," Hollingham said. "And it also collects waste CO2 in the process. So, it's kind of a two-pronged approach."

The mill discharges two usable streams: calcium carbonate and activated basaltic fines. Both can substitute for a portion of the cement in a standard concrete mix, Hollingham said.

Who is behind the pilot?

Hollingham started the experimental work in 2024 under adviser Anne Menefee, assistant professor in the John and Willie Leone Department of Energy and Mineral Engineering. He has filed a patent application through Penn State's Office of Technology Transfer and co-founded Distributed Materials, a startup aimed at commercial deployment.

Haley Sankey, director of sustainability for Auxiliary and Business Services, approved siting the unit at the bakery because its boilers are accessible and well-sized for a point-source test.

"We are proud to support graduate research that emphasizes sustainable practices," Sankey said. "Capturing CO2 emissions from the Penn State Bakery is an exciting step toward advancing innovative solutions for a more sustainable future."

What decides whether this scales?

The fall start is a single-point demo. Hollingham's dissertation has shifted from bench work to carbon-capture policy, and Distributed Materials is in early conversations with the technology transfer office on licensing. The benchmarks that will matter next: kilograms of CO2 the unit pulls from bakery flue per operating shift, the substitution rate of basalt fines and calcium carbonate in a finished concrete batch, and whether the per-ton cost of the captured mineral matches virgin cement at any meaningful scale.

Funding for the project came from the College of Earth and Mineral Sciences, the Climate Consortium, the Gordon D. Kissinger Graduate Fellowship in Architectural Engineering, and Penn State's Partnership for Achieving Construction Excellence.