Turning Seawater into Sustainable Cement? Scientists Say It’s Possible

A groundbreaking new process could transform cement from a major source of carbon emissions into a powerful carbon sink, researchers report in the journal Advanced Sustainable Systems (March 18). This innovation doesn’t just aim to clean up cement — it may also pave the way for other sustainable materials like eco-friendly paint, plaster, and concrete.

Cement production is currently responsible for about 8% of global CO₂ emissions, ranking it as the fourth-largest source of emissions worldwide. A major portion of that pollution stems from extracting raw materials like calcium carbonate from environmentally sensitive areas such as mountains, rivers, and seabeds.

To tackle this issue, a team from Northwestern University in collaboration with Cemex’s innovation division in Switzerland, is exploring a “greener” solution using seawater electrolysis — a process that uses electricity to split seawater into its elemental parts. Typically used for hydrogen production, this method also produces valuable by-products: hydrogen, chlorine, oxygen, and most notably, calcium carbonate — the key ingredient in cement.

While calcium carbonate buildup is often seen as a nuisance in hydrogen-focused electrolysis systems, the researchers saw an opportunity. Instead of discarding it, what if this mineral could be harnessed for sustainable construction?

The challenge? Electrolysis alone doesn’t produce enough mineral volume to meet industrial demand. So, the team conducted experiments to speed up and optimize the process. By adjusting variables such as voltage, the amount of CO₂ added, and water pH levels, they found they could control the volume, density, and structure of the minerals — making them more suitable for different construction uses.

Their findings suggest that this method could be customized to produce various materials needed by the building industry. And importantly, if powered by renewable energy, the process could be carbon-negative, locking away CO₂ for thousands of years — a huge win for climate sustainability.

In short: the ocean may soon play a central role in building the future — literally.