Electrochemical Cement Clinker Precursor Production at Low Voltages

Cement production is carbon intensive today because fossil fuels are used to heat high-temperature kilns, and because CO 2 is released as a byproduct of limestone (CaCO 3 ) decomposition. Electrochemical reactors can decarbonize cement production by using electricity instead of heat to convert CaCO 3 into Ca(OH) 2, a cement clinker precusor, while releasing the CO 2 byproduct as a pure stream. Herein, we report a “cement electrolyzer” that electrolytically converts limestone into Ca(OH) 2 at a cell voltage of 1.8 V at 100 mA cm –2 . This new benchmark improves upon the previous record of 4.2 V by oxidizing the H 2 byproduct from the cathode compartment into protons for CaCO 3 decomposition. A techno-economic model shows that this use of H 2 decreases the cost of cement production by $36/t cement compared to the use of H 2 as a kiln fuel. This work describes an energy-efficient cement electrolyzer and advances the feasibility of electrochemical cement production.