Holding half its weight in carbon dioxide, the material could replace sand in concrete and other construction materials while trapping greenhouse gas. Northwestern University
The escalating global climate crisis has spurred research into carbon capture and storage (CCS) technologies.
The cement industry is a major source of global carbon dioxide emissions. Scientists are now turning this excess carbon dioxide into a sustainable solution.
The Northwestern University team has found a way to create carbon-negative building materials using seawater, electricity, and CO2.
They have introduced a new method for capturing CO2 and transforming it into construction materials (concrete, cement, etc.). This process permanently stores the CO2 and also produces clean hydrogen gas.
Carbon-negative building material. Northwestern University
Nature inspired technique
The study is inspired by nature, mimicking how coral and mollusks create their shells. The process replaces the biological energy used by organisms with electrical energy to drive chemical reactions in seawater.
Researchers use electricity to split seawater, creating hydrogen and hydroxide ions.
They then introduce CO2 into the seawater. This triggers a chemical reaction in which the hydroxide and bicarbonate ions combine with naturally occurring calcium and magnesium in seawater. Altogether, it leads to the formation of solid minerals like calcium carbonate and magnesium hydroxide.
These minerals effectively capture and store CO2, making the resulting material carbon-negative.
The researchers can control the texture and density of the resulting mineral materials (from flaky and porous to dense and hard) by varying experimental conditions.
“We showed that when we generate these materials, we can fully control their properties, such as the chemical composition, size, shape, and porosity. That gives us some flexibility to develop materials suited to different applications,” said Alessandro Rotta Loria, who led the study.
Replacing sand in concrete
These materials are made up of calcium carbonate and/or magnesium hydroxide.
Interestingly, the newly created mineral materials can replace sand and gravel in concrete. Furthermore, these materials can serve as the basis for cement, plaster, and paint.
“Cement, concrete, paint and plasters are customarily composed of or derived from calcium- and magnesium-based minerals, which are often sourced from aggregates –– what we call sand. Currently, sand is sourced through mining from mountains, riverbeds, coasts and the ocean floor,” Loria added.
“In collaboration with Cemex, we have devised an alternative approach to source sand — not by digging into the Earth but by harnessing electricity and CO2 to grow sand-like materials in seawater.”
What’s even more remarkable is that these materials can store over half their weight in CO2.
The storage capacity depends on its mineral composition – a 50/50 mix of calcium carbonate, and magnesium hydroxide allows it to store over half its weight in CO2.
In nature, calcium carbonate forms limestone, a rock that stores vast amounts of carbon over geological timescales. Therefore, this process offers a way to mimic nature’s long-term carbon storage solution.
Plus, the process produces hydrogen gas, a clean fuel suitable for transportation and other applications.
“We could create a circularity where we sequester CO2 right at the source,” Rotta Loria said in the press release.
RECOMMENDED ARTICLES
The author concluded: “And, if the concrete and cement plants are located on shorelines, we could use the ocean right next to them to feed dedicated reactors where CO2 is transformed through clean electricity into materials that can be used for myriad applications in the construction industry. Then, those materials would truly become carbon sinks.”
The findings were published in the journal Advanced Sustainable Systems.
0COMMENT
ABOUT THE EDITOR
Mrigakshi Dixit Mrigakshi is a science journalist who enjoys writing about space exploration, biology, and technological innovations. Her work has been featured in well-known publications including Nature India, Supercluster, The Weather Channel and Astronomy magazine. If you have pitches in mind, please do not hesitate to email her.
