# What default carbon dioxide figure does the Intergovernmental Panel on Climate Change use for a tonne of lead, and how does smelting scrap batteries compare?

Canonical: https://senseible.earth/answers/ipcc-lead-production-co2-by-furnace-and-scrap

The Intergovernmental Panel on Climate Change (IPCC) 2006 Tier 1 default is 0.52 tonnes of carbon dioxide (CO2) per tonne of lead, assuming 80% Imperial Smelting Furnace (ISF) and 20% direct smelting. By source: ISF 0.59, direct smelting 0.25, treating secondary raw materials 0.2. Uncertainty on the default is plus or minus 50%.

## The table, tonnes of CO2 per tonne of lead

- From an ISF: 0.59.
- From direct smelting (the Isasmelt-Ausmelt, Queneau-Schumann-Lurgi and Kivcet furnaces): 0.25.
- From treatment of secondary raw materials: 0.2.
- Default: 0.52, which is 80% ISF and 20% direct smelting (0.8 x 0.59 + 0.2 x 0.25 = 0.52).
- Equation 4.32 sums three terms: lead from direct smelting x 0.25, lead from an ISF x 0.59, and lead from secondary materials x 0.2. The 0.2 is the pre-treatment term, added on top of the furnace term, not an alternative to it.

## When to use which

The guide says the 0.52 default should only be used when there is no information on the relative amounts of lead made from primary and from secondary materials. If you do, use the table factors. Most recycled lead comes from scrapped lead acid batteries, which the guide lists as smelted in blast furnaces, ISFs, electric arc, electric resistance, reverberatory, Isasmelt, Queneau-Schumann-Lurgi and Kivcet furnaces. Rotary furnaces are not on that list. Our inference is that a rotary furnace unit should lean on its own coke and coal records.

## Tier 2 uses your reductants

Tier 2 multiplies tonnes of each reducing agent by its carbon content: coke 0.83, coal 0.67 (taken as other bituminous coal), petroleum coke 0.87 kilograms of carbon per kilogram. The guide's uncertainty is about 50% for the default, 20% for process-type factors, and 10% for reducing agent amounts with 15% on carbon contents.

The guide says all process emissions from lead production should be reported under industrial processes, and warns of double counting with energy. Count furnace fuel once, from your invoices.

## A recycler refining 6,000 tonnes of lead a year from scrap batteries (example)

- Tier 1 default: 6,000 x 0.52 = 3,120 tonnes of CO2
- Pre-treatment term, added on top of the furnace term: 6,000 x 0.2 = 1,200 tonnes. If all of it were smelted in an ISF, the furnace term adds 6,000 x 0.59 = 3,540, so 4,740 in all
- Own record: 700 tonnes of coke x 0.83 x 44 / 12 = about 2,130 tonnes, before carbon that stays in slag

Output and coke tonnes are example numbers. They show why a plant's own coke record can sit far from a table factor.

## What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so coke, coal and furnace oil bought each month are on file next to the power bills. The carbon content of each reductant comes from the supplier's analysis.

- [Free calculators](https://senseible.earth/calculators)
- [Lead-acid battery recycling emissions per tonne](https://senseible.earth/answers/lead-acid-battery-recycling-emissions-per-tonne)
- [Lead oxide battery plant CO2 per tonne](https://senseible.earth/answers/lead-oxide-battery-plant-co2-per-tonne)

Sources: [IPCC 2006 Guidelines, Volume 3 chapter 4: Metal Industry Emissions, section 4.6 (Tables 4.21 to 4.23)](https://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_4_Ch4_Metal_Industry.pdf)

Last reviewed 2026-11-04. Factors are from the 2006 IPCC Guidelines, which cite 2003 European data. A plant with its own coke and coal records should prefer them.