Electrochemical Cement Lab

Electrochemical cement (commercialized by MIT spinout Sublime Systems and Brimstone) replaces traditional 1,450°C fossil-fueled rotary kilns with an ambient-temperature water-splitting electrochemical process. An electrolyzer creates an acid zone (pH 1-2) at the anode that dissolves calcium from minerals and an alkaline zone (pH 12-14) at the cathode that precipitates pure, highly reactive calcium hydroxide. When blended with silica and reactive pozzolans, it cures into hydraulic calcium silicate hydrate (C-S-H) cement meeting ASTM C1157 standards with zero coal burning and over 90% CO2 reduction.

In traditional cement making, limestone (CaCO3) is thermally decomposed at extreme heat, unavoidably releasing 550 kg of process CO2 per tonne of clinker. By utilizing non-carbonate calcium silicate rocks (such as industrial electric arc furnace slag, wollastonite, or basalt), calcium is bound to silicon rather than carbon. During electrochemical acid dissolution (CaSiO3 + 2 H+ -> Ca2+ + SiO2 + H2O), the solid silica byproduct is recovered and zero carbon dioxide is emitted, completely eliminating process emissions at the source.

Traditional ordinary Portland cement consumes roughly 3,000 to 3,500 MJ of thermal fuel (primarily coal, petcoke, or natural gas) plus 110 kWh of electricity per tonne of cement. Electrochemical cement operates at room temperature (25°C to 70°C) and consumes approximately 650 to 900 kWh of clean electricity per tonne of finished cement. Powered by clean renewable energy, it completely eliminates fossil fuel reliance while maintaining total primary energy consumption comparable to or lower than thermal kilns.

Because the electrochemical extraction relies on water splitting, the cathodic half-reaction co-produces approximately 16 to 22 kg of pure green hydrogen gas and the anode produces 130 to 180 kg of pure oxygen per tonne of cement. When sold into industrial merchant hydrogen markets or used for onsite clean drying and heavy transport at $3.00 to $4.00 per kg of H2, this co-product generates an economic revenue credit of $50 to $80 per tonne of cement, substantially lowering net cement manufacturing costs.

Capital expenditures are driven by the electrochemical cell stacks, bipolar membranes, DC power rectifiers, and automated slurry filtration presses ($250 to $350 per annual tonne of capacity, which is comparable to or lower than greenfield rotary kiln plants with carbon capture retrofits). With renewable power costs of $25 to $40/MWh and credits for green hydrogen, net Levelized Cost of Cement (LCOC) ranges between $75 and $115 per tonne, achieving economic parity with ordinary Portland cement under carbon pricing or green public procurement policies.