Cement production emits ~8 % of global fossil CO₂, contributing substantially to climate change. During production, CO₂ is released both by the calcination of mineral CaCO₃ into CaO emitting fossil CO₂ and by the combustion of the fossil/biogenic fuel mix driving the calcination reaction. Radiocarbon (¹⁴C) allows the distinction of fossil vs. biogenic CO₂ due to complete decay of this radioisotope over geological timescales.
We measured ¹⁴CO₂ with different sampling methods at a Swiss cement factory. The stack exhaust emissions revealed that the fossil CO₂ content of the combustion reaction may vary by ~25% depending on the chosen fuel mix.

This work was carried out in the group of Prof. Dr. Sönke Szidat.

References:

• D. Geissbühler, T. Laemmel, M. Antoni, P. Gautschi, L. Wacker, S. Szidat;
  "Verification of fossil CO₂ emissions from Swiss cement factories using direct and indirect ¹⁴CO₂ measurements"
  Atmos. Environ.: X, 2025, 27, 100349/1-11; doi:10.1016/j.aeaoa.2025.100349.