A seashell inspired material that locks away carbon dioxide could make concrete more sustainable. The process to make this material involves splitting seawater using carbon dioxide and electricity and can also be used to produce hydrogen for fuel adding an additional benefit to the method.
“This research develops a method to capture, convert, and store carbon dioxide in the form of solid minerals, which can be incorporated as supplementary materials in concrete,” said Alessandro Rotta Loria, an associate professor at Northwestern University, who led the research. “This method provides an alternative to carbon dioxide storage in deep ocean beds or geological formations, contributing to decarbonization efforts.”
The process that creates this building material is similar to the natural mineralization process through which seashells are made in the ocean from calcium carbonate, which forms naturally in marine environments. “This research replicates this process electrochemically by facilitating the reaction of dissolved seawater ions with carbon dioxide to produce solid minerals,” explained Rotta Loria.
Recycling energy production byproducts
In recent years, a lot of research has investigated whether splitting water molecules using electricity could be a good source of green hydrogen for energy, as long as the electricity used is also from a renewable source.
Although it holds more technical challenges, such as solving corrosion issues, splitting seawater to produce hydrogen is of particular interest, especially in areas with limited freshwater resources.
When seawater electrolysis takes place, it forms both hydrogen gas and oxygen or chlorine gas. At the same time, mineral deposits such as calcium carbonate and magnesium hydroxide are precipitated into the solution.
“These precipitates are often dismissed as energy-intensive byproducts. However, they have untapped potential as resources for construction, manufacturing, and environmental remediation,” write Rotta Loria and team in an article describing their work.
If additional carbon dioxide is added to the electrochemical process then even more of these minerals are produced, while at the same time allowing storage of potentially polluting carbon dioxide from the atmosphere.
The researchers found that altering factors like electrical voltage, and the flow rate, timing and duration of carbon dioxide injection into the reaction could change the properties of the resulting materials that were produced, although they still had the same chemical makeup. For example, it could make the material more porous, flakier or denser.
“By increasing the pH of seawater electrochemically, dissolved ions precipitate into solid mineral forms, permanently sequestering carbon dioxide,” explained Rotta Loria.
Improving the environmental impact of the building industry
Sand and gravel make up around 60-70% of the composition of concrete. These resources are normally taken from natural sources such as mountains, riverbeds, coasts and the ocean floor, which can damage the environment in a number of different ways. For example, through loss of biodiversity and ecosystems, both on land and in the sea. Sand and gravel mining can also contribute to coastal and riverbank erosion and reduce sediment flow in deltas and estuaries, which makes flooding more likely.
If the method developed by Rotta Loria and colleagues can be done on a larger scale successfully then it will enable production of sustainable sand- and gravel-like material for making concrete. “Scaling up this process is feasible thanks to the optimization of reaction conditions, energy usage, and reactor design—all of which are key drivers of this innovation,” he said.
However, he also acknowledged that reducing costs can be challenging. “This process is more expensive than traditional methods of sourcing aggregates but can be viewed as a competitive carbon sequestration strategy that simultaneously produces valuable materials.”
The building industry is traditionally quite conservative, and price driven when it comes to adopting new innovations, but an increase in consumer interest in sustainability and environmentally friendly practices has helped to drive change in a positive direction. For example, annual growth in the green building market has gradually increased each year over the last decade and there is now a much greater focus on energy efficient buildings than before.
Whether this electrochemical method of producing core materials for cement and concrete will become widely used remains to be seen, but Rotta Loria and his team are working with Cemex, a global building materials company headquartered in Mexico, to assess the commercialization potential of this technique.
“Currently, work is underway to further optimize this technology, with the ultimate aim to bring it to scale,” concluded Rotta Loria.
Reference: Devi N., Gong X., et al. Electrodeposition of Carbon-Trapping Minerals in Seawater for Variable Electrochemical Potentials and Carbon Dioxide Injections, Advanced Sustainable Systems (2025). DOI: 10.1002/adsu.202400943
Feature image credit: Pamela Heckel on Unsplash
