UltraTech to trial ZeroCal decarbonisation technology

UltraTech Cement Ltd, India's largest cement and ready-mix concrete (RMC) company, announced the signing of a collaboration agreement with the Institute for Carbon Management (ICM) at the University of California, Los Angeles (UCLA) to pilot a groundbreaking new technology called The Zero Carbon Lime (ZeroCAL) developed by ICM. The technology is designed to significantly reduce carbon dioxide emissions from cement production. ICM, in partnership with UltraTech, will build a first-of-a-kind demonstration plant for the technology at one of UltraTech’s integrated cement manufacturing units.

The Zero Carbon Lime (ZeroCAL) process can eliminate nearly 98 per cent of CO₂ emissions associated with limestone decomposition in cement manufacturing. UltraTech will be the first company globally to implement the  process at scale through a demonstration plant that will produce several metric tonnes of zero-carbon lime per day. 

“The ZeroCAL approach is a powerful solution to eliminate carbon emissions associated with the process of cement production within the existing industrial paradigm of ordinary Portland cement (OPC) clinker production and without a need for carbon capture and storage,” said Professor Gaurav Sant, ICM director and the study’s corresponding author and the Pritzker Professor of Sustainability at the UCLA Samueli School of Engineering. “It effectively eliminates the carbon dioxide emissions resulting from limestone’s decomposition while providing clean hydrogen and oxygen to heat the cement kiln,” he added.

The ZeroCAL process, which can be integrated with existing cement plants, uses limestone feedstock to produce calcium hydroxide, which emits no carbon dioxide when heated to produce lime required for manufacturing cement. The ZeroCAL process produces calcium hydroxide by electrochemically decomposing limestone in water without resulting in carbon dioxide emission. The major advantage of the ZeroCAL process is its compatibility with the existing cement manufacturing process. Calcium hydroxide, the key product of the ZeroCAL process, is simply dewatered and is fed as a drop-in replacement (for limestone) into the cement kiln. 

The byproducts of ZeroCAL process include commonly used hydrochloric acid and baking soda as well as oxygen and hydrogen gas. Hydrogen can be used as green fuel replacing coal while oxygen can be used in the cement kiln to improve combustion efficiencies (oxy-combustion).

The ZeroCAL process enables the utilisation of a broader range of limestone grades in the production of cement thus reducing the burden on limestone reserves and allowing for more efficient use of natural resources. 

To accelerate its decarbonisation efforts, UltraTech is collaborating with technology startups to explore the use of emerging decarbonisation technologies including kiln electrification and carbon capture and storage.