# Chlorine and Hydrogen Every tonne of chlorine made by brine electrolysis brings about 30 kg of hydrogen, so chlor-alkali plants are a small but steady source of electrolytic hydrogen whose volume follows chlorine demand. Plants burn it as fuel, combine it with chlorine to make hydrochloric acid, turn it into hydrogen peroxide, or sell it. Source page: https://www.materialinsights.org/links/chlorine-and-hydrogen/ [Chlorine](https://www.materialinsights.org/chemicals/chlorine/) (chemical) and [Hydrogen](https://www.materialinsights.org/chemicals/hydrogen/) (chemical): 4 relationships. ## How they are linked ### 1. Hydrogen from brine electrolysis *Joint production · Strong · Chlorine plants make hydrogen* Brine electrolysis releases hydrogen at the cathode alongside caustic soda, in a fixed ratio to chlorine, so hydrogen output rises and falls with chlorine production. - **0.03 t** hydrogen per tonne of chlorine - **12,915 lakh Nm³** hydrogen produced in India's chlor-alkali industry, FY2023-24 India's chlor-alkali hydrogen of about 1.3 billion normal cubic metres a year is about 0.12 Mt, small next to refinery and fertiliser hydrogen. The US Department of Energy notes that by-product hydrogen from brine electrolysis can be vented, sold as merchant hydrogen or used on site. Sources: [Olin Corporation (US SEC filing)](https://www.sec.gov/Archives/edgar/data/74303/000007430326000027/oln-20251231.htm); [Indian Chemical News (Alkali Manufacturers Association of India data)](https://www.indianchemicalnews.com/chemical/caustic-soda-demand-grew-by-53-soda-ash-by-4-in-fy-2023-24-amai-24335); [US Department of Energy, Hydrogen and Fuel Cells Program](https://www.hydrogen.energy.gov/pdfs/19002-hydrogen-market-domestic-global.pdf) ### 2. Hydrogen plus chlorine makes HCl *Physical flow · Medium · Both combine into hydrochloric acid* Burning the by-product hydrogen with some of the chlorine gives hydrogen chloride, a simple way for a plant to turn both gases into a saleable acid. Olin lists hydrochloric acid among its hydrogen end uses. The reverse also happens: HCl electrolysis, used at isocyanate plants, splits hydrogen chloride back into chlorine and hydrogen, so the two gases cycle through the same chlorine chains. Sources: [Olin Corporation (US SEC filing)](https://www.sec.gov/Archives/edgar/data/74303/000007430326000027/oln-20251231.htm); [thyssenkrupp nucera](https://www.thyssenkrupp-nucera.com/hydrochloric-acid-solutions/) ### 3. Fuel, peroxide or merchant sales *Physical flow · Medium · Hydrogen from chlorine plants to users* Because the hydrogen is pure and already at the site, producers use it to fire boilers, make hydrogen peroxide or amines, or sell it to nearby users. Gujarat Alkalies maximises captive use through an expanded hydrogen peroxide plant and says it is one of the largest sellers of hydrogen gas in its market. Where no buyer is near, some by-product hydrogen is still vented. Sources: [Gujarat Alkalies and Chemicals Ltd (via IndiaInfoline)](https://www.indiainfoline.com/company/gujarat-alkalies/management-discussions/217); [US Department of Energy, Hydrogen and Fuel Cells Program](https://www.hydrogen.energy.gov/pdfs/19002-hydrogen-market-domestic-global.pdf); [Olin Corporation (US SEC filing)](https://www.sec.gov/Archives/edgar/data/74303/000007430326000027/oln-20251231.htm) ### 4. Ready-made electrolytic hydrogen *Transition · Weak · Chlorine plants supply new hydrogen uses* Chlor-alkali cells are electrolysers, so their hydrogen can serve fuel-cell and other low-emission markets before dedicated electrolysers are built, though its volume is capped by chlorine demand. Olin lists hydrogen fuel cells among the uses of its by-product hydrogen. Its emissions depend on the power used, as for any electrolytic hydrogen, and supply cannot be raised without making more chlorine and caustic. Sources: [Olin Corporation (US SEC filing)](https://www.sec.gov/Archives/edgar/data/74303/000007430326000027/oln-20251231.htm) ## For investors ### Key learnings 1. Chlor-alkali hydrogen is a by-product of about 30 kg per tonne of chlorine, so its value is a small credit to the ECU rather than a business in itself. 2. Producers that turn it into hydrogen peroxide or sell it to nearby users, as Gujarat Alkalies does, get more value than those that burn or vent it. 3. Supply follows chlorine demand, so by-product hydrogen cannot respond to hydrogen prices. ### What to track - **Chlor-alkali operating rates**: Set by-product hydrogen volumes (Monthly · AMAI, company reports) - **Hydrogen peroxide prices and capacity at chlor-alkali sites**: Show the value of captive hydrogen use (Quarterly · company reports) ## For policymakers ### Key learnings 1. Indian chlor-alkali plants already make about 1.3 billion normal cubic metres of electrolytic hydrogen a year, a supply that hydrogen policy can count. 2. Using rather than venting this hydrogen, in peroxide, fuel or local sales, cuts waste at little cost. 3. Its volume is tied to chlorine and caustic demand, so it cannot be scaled to meet hydrogen targets. ### What to track - **Chlor-alkali hydrogen production and use**: Show how much by-product hydrogen is captured (Annual · AMAI) - **Rules on counting by-product hydrogen in low-emission hydrogen standards**: Decide whether it can earn green hydrogen incentives (As notified · Ministry of New and Renewable Energy) ## India Indian chlor-alkali plants produced 12,915 lakh normal cubic metres of hydrogen in FY2023-24. Producers such as Gujarat Alkalies use it to make hydrogen peroxide and sell the rest. ## Sources 1. [Olin Corporation Form 10-K for fiscal year 2025](https://www.sec.gov/Archives/edgar/data/74303/000007430326000027/oln-20251231.htm), Olin Corporation (US SEC filing) (2026) 2. [Caustic soda demand grew by 5.3%, soda ash by 4% in FY 2023-24: AMAI](https://www.indianchemicalnews.com/chemical/caustic-soda-demand-grew-by-53-soda-ash-by-4-in-fy-2023-24-amai-24335), Indian Chemical News (Alkali Manufacturers Association of India data) (2024) 3. [Program Record 19002: current hydrogen market size, domestic and global](https://www.hydrogen.energy.gov/pdfs/19002-hydrogen-market-domestic-global.pdf), US Department of Energy, Hydrogen and Fuel Cells Program (2019) 4. [Hydrochloric acid electrolysis](https://www.thyssenkrupp-nucera.com/hydrochloric-acid-solutions/), thyssenkrupp nucera 5. [Gujarat Alkalies and Chemicals: management discussion and analysis, FY2024-25](https://www.indiainfoline.com/company/gujarat-alkalies/management-discussions/217), Gujarat Alkalies and Chemicals Ltd (via IndiaInfoline) (2025)