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 CO2 is released as a byproduct of limestone (CaCO3) decomposition. Electrochemical reactors can decarbonize cement production by using electricity instead of heat to convert CaCO3 into Ca(OH)2, a cement clinker precusor, while releasing the CO2 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 H2 byproduct from the cathode compartment into protons for CaCO3 decomposition. A techno-economic model shows that this use of H2 decreases the cost of cement production by $36/tcement compared to the use of H2 as a kiln fuel. This work describes an energy-efficient cement electrolyzer and advances the feasibility of electrochemical cement production.