West LA Times

Researchers at UCLA have developed a new method to significantly reduce carbon emissions from cement production, a major contributor to global CO2 emissions. The method, named "ZeroCAL" for zero carbon lime, was developed by engineers at UCLA's Institute for Carbon Management. It replaces traditional limestone with calcium hydroxide in the production of lime used in cement.

The study detailing this process was published in the American Chemical Society’s journal Sustainable Chemistry and Engineering. The researchers claim that ZeroCAL could eliminate nearly all carbon dioxide emissions from cement production, which currently accounts for about 8% of global atmospheric CO2 emissions. This innovative approach could be integrated into existing cement-production processes as a cost-effective solution to decarbonize the industry.

Traditional cement production methods involve heating limestone in fossil fuel-powered kilns, resulting in significant carbon emissions. In contrast, the ZeroCAL method uses calcium hydroxide, which emits only water when heated. The team led by Gaurav Sant developed a process using limestone dissolved in an acid solution and membrane nanofiltration to produce calcium hydroxide electrochemically.

"The ZeroCAL approach offers an elegant solution to eliminate carbon dioxide emissions associated with the process of cement production," said Sant. "It addresses the carbon emissions resulting from limestone’s decomposition while providing clean hydrogen and oxygen to heat the cement kiln."

While ZeroCAL currently requires more energy than existing methods, ongoing research aims to achieve energy-use parity by optimizing processes and utilizing co-products effectively. Researchers are working with Ultratech Cement Limited in India to build a demonstration plant utilizing ZeroCAL technology.

"It has become crystal clear that mitigating climate change demands urgent, paradigm-shifting actions across many areas to decarbonize our society," said Fabian Rosner, study co-author. "We believe the ZeroCAL process offers a unique pathway to enable accessible and rapidly scalable decarbonization of cement production."

The research received funding from several organizations including the Chan-Zuckerberg Initiative and the U.S. Department of Energy’s Advanced Research Projects Agency–Energy.