Sulphuric acid: Emissions

A chemical that can be carbon negative

What this tab covers The greenhouse-gas footprint per tonne, split by lifecycle phase (feedstock, production, movement, use, end of life), the global total, other environmental impacts, levers and low-carbon routes, India's position, and where the investment opportunity lies. Emission intensity 0.05 t CO2e per t range about -0.05 to 0.15 · cradle-to-gate; recovered sulphur at 0.1 t CO2e/t S x 0.33, small process and transport emissions; steam export credits can make it negative Global emissions per year 12.0 Mt CO2e per year 2025 · 0.05 t/t x 230 Mt derived output; excludes credits for exported steam and power

Per t of 100% H2SO4, cradle-to-gate, sulphur-burning route. Intensity: Sulfur tile (ecoinvent-based by-product values, indicative); derived. Global total: Derived (indicative).

Share of footprint by lifecycle phase

Feedstock 66% Production / process 20% Movement 14%

Footprint by lifecycle phase

Phase	Intensity	Share	Main sources of emissions	Notes	Source
Feedstock	about 0.033 t CO2e per t acid	66%	Claus recovery and forming of sulphur; pyrite mining in China	Sulphur carries little upstream burden under economic allocation	Sulfur tile (indicative)
Production / process	about 0.01 t CO2e per t acid before steam credits	20%	Blower power, catalyst, acid cooling	The reaction is strongly exothermic; burners export 1.2-1.4 t steam per t (indicative)	Indicative
Movement	about 0.007 t CO2e per t acid	14%	Sulphur and acid shipping	Long-haul acid tankers add more	Indicative
Use	not applicable as CO2	–	Acid is consumed in reactions	Neutralising acid with limestone releases CO2; phosphogypsum is the main downstream waste	Indicative
End of life	not applicable	–	Spent acid regeneration	Refinery acid is regenerated; most other acid ends up as sulphate salts or gypsum	USGS MCS 2026

Other environmental impacts

SO2 and acid mist emissions from plants and smelters; acid mine drainage where pyrite is roasted; phosphogypsum (about 4.5-5 t per t P2O5) from the main use.

Levers to cut emissions

Heat recovery systems that capture absorption heat as low-pressure steam, raising energy export (indicative)
Using smelter acid instead of new sulphur burning where logistics allow
Regenerating spent acid rather than neutralising it
Using exported steam to replace fossil power at phosphate and chemical complexes

India

India's acid is mostly made in fertiliser and smelter complexes whose footprint is small per tonne; the bigger exposure is supply security for imported sulphur. India's emission data for acid were not found.

Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.

Low-carbon routes

Route	Intensity	Cost premium	Status	Source
Sulphur burner as a low-carbon power source	net negative where steam displaces coal power (indicative)	none; improves economics	standard at large phosphate complexes such as Jorf Lasfar (indicative)	Indicative
Recovered acid from HPAL tailings and gypsum	not published	not published	Vale and Huayou studying sulphur recovery from Pomalaa HPAL tailings (Oct 2026)	CRU BCInsight teaser (7 Oct 2026)

For a climate investor Acid itself is low carbon, so the climate opportunity is in supply security and circularity rather than abatement. Projects that recover sulphur or acid from waste streams (HPAL tailings, gypsum, spent acid) and smelter acid capture near battery and fertiliser hubs reduce dependence on Gulf sulphur. For this to work, offtake must be local, because acid is costly to ship. Vale and Huayou in Indonesia and Asian smelter builders are active.