Chlorine
Chlorine is a toxic gas made by passing electricity through salt brine; it underpins PVC, polyurethanes, titanium dioxide and safe drinking water.
Commodity chemicals · Acids & alkalis · No. 7
- Single chemical
- Feedstock: Minerals and salts
- about 80 Mt of chlorine a year (2025, indicative, derived); Euro Chlor and the World Chlorine Council publish no world total, and commercial figures of about 92-97 Mt (P Plus 2024; Statista 2022) appear to be capacity-type estimates
- 1.0 t CO₂e per t
- HS 280110
In October 2025 Chinese chlorine makers were paying customers to take their toxic gas away.
Chart: Illustration: Chlorine
Where it comes from
Chart: Map of where it comes from
Electricity splits salt brine into chlorine, caustic soda and a little hydrogen; membrane cells use about 2.5-2.8 MWh per tonne of chlorine.
Three things to know
- Chlorine and caustic soda come out together in a fixed 1 to 1.13 ratio, so plants must find buyers for both.
- Electricity is about half the cash cost; in 2022 a European plant's cost was over twice the Americas' roughly $590 per unit.
- Chlorine is hard to store or ship, so only about 1-2% of output crosses borders; it travels hidden inside PVC instead.
The journey
- 1 Salt brineAbout 1.7 t salt per tonne
- 2 PurificationCalcium and magnesium cut to ppb
- 3 ElectrolysisBrine split; caustic and hydrogen alongside
- 4 DryingDried with sulphuric acid, then compressed
- 5 DerivativesPiped straight into PVC, MDI, HCl