# How does a copper smelter split its emissions between cathode and the sulphuric acid it sells?

Canonical: https://senseible.earth/answers/dahej-copper-smelter-sulphuric-acid-allocation

Sulphuric acid is made from the sulphur dioxide in smelter gas, so it is a co-product. Most smelters allocate shared emissions by mass or economic value and say which, while the acid plant's own energy goes to acid. Buyers of cathode and acid should each get a figure with the method stated.

## What is shared

- Concentrate drying, smelting and converting fuel and power.
- Oxygen plant electricity.
- Gas cleaning ahead of the acid plant.

## What belongs to acid

The acid plant's blowers and pumps, less any steam it exports. Acid plants often make surplus heat, which some smelters credit.

## Is any of this CBAM?

No. Copper and sulphuric acid are outside CBAM's current goods list, so these are product footprint figures for buyers, not customs data.

## What Senseible does here

Senseible reads fuel, electricity and freight invoices into a dated, fingerprinted record per site, so a copper product figure can be traced back to the documents behind it. Factors outside India are entered from the official source and labelled.

- [Is copper covered by CBAM?](https://senseible.earth/answers/is-copper-covered-by-cbam)
- [Acid plant steam export](https://senseible.earth/answers/sulphuric-acid-plant-emissions-steam-export)
- [Copper cathode footprint](https://senseible.earth/answers/copper-cathode-carbon-footprint-per-tonne)

Sources: [ISO 14067:2018 Carbon footprint of products (iso.org)](https://www.iso.org), [IPCC 2006 Guidelines for National Greenhouse Gas Inventories](https://www.ipcc-nggip.iges.or.jp/public/2006gl/), [GHG Protocol Corporate Standard](https://ghgprotocol.org/corporate-standard)

Last reviewed 2026-10-21.