A decade of work has led UCLA researchers to produce cement with 98% less emissions than traditional methods.
What they did was decompose limestone to access calcium oxide (lime) without releasing carbon dioxide in the process.
They’ve dubbed the method ZeroCAL which involves dissolving the sedimentary rock feedstock in a water-based solution containing a common industrial acid. Calcium is then separated via membrane nanofiltration and after this an electrochemical process is used to produce calcium hydroxide – a zero carbon precursor for cement and lime production.
University of California team lead Professor Gaurav Sant said this addresses the carbon emissions resulting from limestone’s decomposition while providing clean hydrogen and oxygen to heat the cement kiln.
“It enables onsite decarbonisation while making use of existing kilns and limestone feedstocks without having to build separate carbon-capture and storage facilities,” he added.
However, the team concedes the process needs to be perfected. It uses more energy than traditional methods and still uses a lot of water but research into simplifying unit operations and better use of the electrolytically produced acid and base products is already underway.
The UCLA team is collaborating with Ultratech Cement, India’s largest cement manufacturer, to build a demonstration plant that will produce several tonnes of lime per day using the ZeroCAL process.
The research has been published in the American Chemical Society’s journal Sustainable Chemistry and Engineering.
About the author
Desi Corbett
Desi is the Editor of Concrete in Australia and at the helm of our magazine for 8 years. She was behind the Institute's weekly news bulletins from 2016-2021 and is now writing our focused news items. Desi has been an engineering news and features journalist/editor across all disciplines since 2013 - part of a 30-year career writing for a wide range of industries.