Over the years, Debbie Huntzinger’s academic interests migrated from groundwater to the atmosphere, but a fellowship award that will help fund her research in carbon sequestration is bringing her back to her engineering roots.

Huntzinger, assistant professor of climate sciences at Northern Arizona University, recently was named a Bisgrove Scholar award winner by Science Foundation Arizona. She will apply the funding—$200,000 over two years—to her research with a waste byproduct of cement manufacturing, addressing a “small piece” of reducing global CO2 emissions, as she puts it, but one with implications for climate change.

That research took place in a doctoral program at Michigan Technological University, where Huntzinger studied geological engineering. Her initial interest in geology led to engineering, where a focus on groundwater during her undergraduate and master’s studies rose to the surface, and the cement industry, in her doctoral program.

What Huntzinger accomplished in the lab as a Ph.D. candidate was to mimic the natural process of mineral carbonation. In the environment, over long periods of time, the geologic weathering results in the formation of rocks such as limestone, a stable form of carbon. That stability is key for those who seek to find a way to store, or sequester, CO2, reducing its growth rate in the atmosphere.

Some scientists are viewing the problem on a large scale, but their pursuit of a solution often involves mining and processing that requires a great deal of energy consumption.

Cement kiln dust

Extensive lab work has shown that cement kiln dust, a waste byproduct of cement manufacturing, can be used to effectively sequester CO2.

Huntzinger has developed methods to achieve sequestration with cement kiln dust, a powdery byproduct that may end up in a landfill or, in some cases, be recycled. Kilns produce about 0.2 tons of waste product per ton of clinker, the finished product most of us call cement.

“These waste products are already in fine-grain form, so they don’t need to be processed,” Huntzinger said. “All we really need to do is put them in the presence of CO2 and water.”

Huntzinger has developed methods to achieve sequestration with cement kiln dust, a powdery byproduct that may end up in a landfill or, in some cases, be recycled. Kilns produce about 0.2 tons of waste product per ton of clinker, the finished product most of us call cement.

As straightforward as that sounds, much work remains to be done. Huntzinger’s lab work so far has been conducted under ideal conditions. The Bisgrove funding will allow her to introduce real-world complications, with the goal of designing a pilot-scale project within the next two years.

“I’d like to know what this technology would look like at a cement manufacturing facility, and possibly even test a couple of configurations,” Huntzinger said. “One important consideration is figuring out how to capture carbon emissions from the manufacturing processes using the least amount of added infrastructure and energy as possible.”

Because cement manufacturing is an emissions-intensive industry, and because cement plays a crucial role in construction that isn’t going to change anytime soon, Huntzinger’s research takes on added importance.

“In order to create that cement, you also produce CO2,” she said. “About five percent of global emissions of CO2 come from the cement industry. If we’re going to continue to use cement, then we need to start thinking creatively about ways to reduce emissions from the manufacturing process.”

Huntzinger’s concern for the climate manifests itself in her other line of research, which is to develop a better understanding of the exchange of carbon between the land and the atmosphere.

That project involves working with the modeling community to evaluate a myriad of terrestrial carbon cycle models with the goal of improving the ability to model the complex system. With better modeling comes a better understanding of how processes at the land surface influence climate.

“There’s strong scientific consensus that humans are now a dominant driver of climate change,” Huntzinger said. “We’re entering into new territory and we don’t fully know what the response of the earth system will be.”

Motivated in part by the influence of her own mentors, Huntzinger puts her convictions into practice by guiding the next generation of climate-focused students. She is the graduate coordinator for Climate Science and Solutions at NAU, a non-thesis master’s program that prepares students for careers in climate mitigation or adaptation.

“The students come in with many different backgrounds, from public policy, to environmental science, engineering and geology,” Huntzinger said. “They have varying career goals and interests. One of my goals, through teaching and advising, is to help them get to where they want to be professionally.”