Cement is produced at an extraordinary scale, with roughly four billion tonnes manufactured globally each year. The industry currently contributes an estimated 5 to 8 percent of worldwide carbon dioxide emissions. A major share of those emissions does not come from burning fuel, but from the chemistry of making cement itself. During calcination, limestone—or calcium carbonate—is heated to high temperatures and breaks down into quicklime, or calcium oxide, and carbon dioxide. This unavoidable chemical reaction releases CO₂ even when the kiln is powered by clean energy.

The ETH Zurich team, led by André Bardow, examined whether this process could be redesigned to capture those emissions while also extracting additional carbon dioxide from the air. The study was conducted with Heirloom Carbon Technologies, a US company developing calcium-looping DAC systems. In this process, limestone and related calcium compounds circulate through a chemical cycle. The researchers’ analysis suggests that integrating DAC with cement production could reduce the climate impact of cement manufacturing by as much as 78 percent by 2050 through kiln electrification and direct capture of process emissions alone.

The proposed system relies on a kiln powered by electricity instead of coal, gas or other fossil fuels. Electrifying the kiln eliminates emissions from combustion, while the CO₂ released when limestone decomposes can be captured before it enters the atmosphere. Because this stream is not mixed with combustion exhaust gases, it is comparatively concentrated and easier to separate. The captured carbon dioxide can then be compressed and transported to underground storage, preventing it from returning to the atmosphere.

The system can also be designed to remove additional carbon dioxide from ambient air. Once water is added to quicklime, it becomes slaked lime, a calcium compound that can react with CO₂ in the atmosphere and convert back into limestone. Air contactors—large structures that move atmospheric air across reactive material—promote this absorption. The regenerated limestone can subsequently be processed again for cement production, while the carbon dioxide captured directly from the air is separated and permanently stored. Repeating the calcium cycle increases the amount of atmospheric CO₂ removed before the material is used in cement.

This combination offers an unusual industrial advantage: DAC based on calcium looping and cement manufacturing already depend on closely related materials and high-temperature processing. Instead of constructing an entirely separate chemical industry, the technology could potentially be attached to established cement supply chains. The changes would still require additional air-contacting equipment and low-carbon electric kilns, but the underlying chemistry is familiar to the cement sector. That compatibility could make the approach easier to scale than systems requiring entirely new industrial infrastructure.

The study is the first prospective life-cycle assessment of industrial-scale calcium-looping DAC, according to the researchers. Rather than examining only the operation of a capture plant, the analysis considered environmental impacts across the full chain, including raw-material extraction, equipment construction, energy consumption, plant operation and the underground storage of captured CO₂. The researchers also evaluated whether removing carbon would shift environmental pressure toward other areas, such as water consumption or land use.

Energy emerged as the dominant factor determining the system’s environmental performance. Capturing carbon dioxide from air is inherently energy-intensive because the gas makes up only a small fraction of the atmosphere. The team therefore tested several electricity scenarios, including the current US power mix, a heavily decarbonized grid supplied largely by wind and solar power, and an autonomous system using photovoltaic generation paired with battery storage. The cleaner the electricity, the greater the net climate benefit of the DAC-cement system.

Across the scenarios projected for 2050, the commercial calcium-looping plants analyzed by the researchers removed more CO₂ than they generated over their entire life cycle. Their estimated carbon-removal efficiency ranged from 85 to 96 percent. For every tonne of CO₂ captured and stored, between approximately 40 and 150 kilograms were emitted elsewhere in the process chain, depending largely on the energy source. Renewable electricity delivered the strongest performance, while more carbon-intensive power reduced the amount of net removal.

The concept is already being tested against real industrial data. Heirloom has operated a calcium-looping DAC facility in California since 2023, with a nominal annual capacity of 1,000 tonnes of CO₂, and plans a substantially larger plant in Louisiana. However, important uncertainties remain. Indirectly heated electric calcination kilns are not yet widely deployed at industrial scale, and the economics of integrating DAC into cement plants were outside the scope of the study. The researchers say future field trials must determine whether the technology can operate reliably and affordably while delivering the deep emissions cuts predicted by the life-cycle models.

Subject of Research: Integration of calcium-looping direct air capture with cement production to achieve net-negative emissions.

Article Title: Life cycle assessment of solid calcium-looping direct air capture and its synergistic dual use for net-negative cement.

News Publication Date: 4 June 2026

Web References: https://doi.org/10.1016/j.checir.2026.100041

References: Bolongaro V, Shu DY, McQueen N, Bardow A. “Life cycle assessment of solid calcium-looping direct air capture and its synergistic dual use for net-negative cement.” Chem Circularity, 4 June 2026. DOI: 10.1016/j.checir.2026.100041

Image Credits: Heirloom Carbon Technologies

Keywords

Direct air capture, carbon dioxide removal, cement production, calcium looping, carbon capture and storage, climate technology, industrial decarbonization, net-negative emissions, electrified kilns, renewable energy

Leading the research is Professor Charles McCrory, a noted chemist and an associate professor at the University of Michigan. He, alongside collaborative teams from the University of California, Davis, and the University of California, Los Angeles, spearheaded a project that explores methods of capturing carbon dioxide and transforming it into useful compounds. This collaborative effort illustrates the power of interdisciplinary research in the pursuit of pioneering solutions to environmental problems. The collaboration between different institutions brings together diverse expertise, which is vital for tackling complex scientific challenges.

The study of carbon dioxide capture is not new; however, its application towards producing metal oxalates as cement precursors represents an inventive twist. Metal oxalates have not been thoroughly explored for their potential in the cement industry, and their use could lead to more sustainable practices. Cement manufacturing is notorious for its high carbon footprint due to the energy-intensive processes involved, primarily the production of Portland cement. By finding alternatives to conventional cement production, researchers are not just addressing environmental concerns but also paving the way for advancements in construction materials.

One of the unique aspects of this method is the use of lead as a catalyst. While lead is widely regarded as a toxic element, the research team ingeniously minimizes its harmful effects by utilizing trace amounts. Traditional methods that employ large quantities of lead pose significant health and environmental risks, but McCrory’s team discovered that the catalytic process could be fine-tuned. By manipulating the microenvironment around the lead catalyst, they have significantly reduced the required lead concentration to mere parts per billion — a level that minimizes the potential hazards associated with lead exposure.

The chemistry behind this transformation involves a series of electrochemical reactions. At one end of the system, carbon dioxide is converted into oxalate ions through the action of the lead catalyst. Conversely, a metal electrode is oxidized and releases metal ions that bond with the oxalate ions, resulting in a precipitate of metal oxalate that can be harvested as a solid product. This solid form is advantageous for integration into the cement-making process, making it a dual-purpose solution that not only captures CO2 but adds functional value to it.

The implications of this research extend beyond the immediate goal of producing cement precursors. Metal oxalates represent a largely underexplored area in material science. Their properties could be harnessed for carbon dioxide storage solutions, enhancing the scope of potential applications while also contributing to addressing the climate crisis. As a sustainable alternative, metal oxalates promise to play a significant role in a future where construction materials and processes are not only efficient but environmentally responsible.

McCrory emphasizes that the successful production of solid metal oxalates not only represents a triumph in the capture process but ensures that the carbon dioxide is sequestered and won’t re-enter the atmosphere under normal conditions. This permanence transforms a liability into an asset, underscoring the effectiveness of the capture strategies being employed. As researchers continue to innovate, it is imperative that these newly developed methodologies also focus on practical application and scalability.

The researchers are optimistic about scaling up this production process. The foundation for this scalability is being built through ongoing studies aimed at refining the electrochemical process for broader industrial applications. Researchers recognize the challenges inherent in scaling up the production of these solid products but are guided by the idea that reducing the lead catalyst to trace levels is essential for sustainable practices. Such foresight demonstrates a commitment to not just achieving technical advancements, but doing so in a manner that is environmentally conscious and regulatory-compliant.

The collaboration among McCrory’s research group, Velázquez’s lab, and Alexandrova’s lab has truly advanced the conversation around sustainable construction materials. Each team brought their distinct perspectives and areas of expertise, leading to a more robust understanding of the chemical mechanisms involved. The work of Velázquez, particularly concerning understanding the mechanisms of the oxalate synthesis reactions, complements McCrory’s innovations surrounding catalyst microenvironments, encapsulating the importance of teamwork in groundbreaking scientific endeavors.

Professor Anastassia Alexandrova’s contributions also emphasize the role of predictive calculations in catalyst discovery. By employing computational models, her research aids in establishing the viability of processes that were once deemed empirical or incidental. This fusion of computational chemistry with traditional wet-lab experimentation showcases the evolving nature of materials science, where simulation and modeling can streamline experimental approaches.

As researchers further investigate the applications of metal oxalates in carbon capture and their use in alternatives to traditional cement, the potential for this innovative methodology to contribute to a significant reduction in global carbon emissions becomes clearer. By shifting the narrative around industrial waste products and demonstrating their viability as essential materials, these studies could lead to transformative changes in how industries approach sustainability.

In conclusion, the research conducted by the University of Michigan and its collaborators paints an optimistic picture for the future of sustainable materials in construction. The ability to upcycle carbon dioxide into valuable commodities marks a critical step toward creating a circular economy, where waste is minimized, and resources are reused. As McCrory and his fellow researchers pursue further studies, the potential for practical applications of this method appears promising, contributing to both environmental protection and the innovation of building materials.

Subject of Research: Carbon Dioxide Conversion to Metal Oxalates for Cement Production
Article Title: Transforming Industrial Waste: Researchers Convert Carbon Dioxide into Valuable Cement Precursors
News Publication Date: [Not Specified]
Web References: [Not Specified]
References: Advanced Materials, DOI: 10.1002/aenm.202501286
Image Credits: [Not Specified]

Keywords

• Carbon capture
• Metal oxalates
• Sustainable construction
• Alternative cement
• Environmental chemistry
• Electrochemical processes
• Catalyst optimization
• Greenhouse gas mitigation