The Intergovernmental Panel on Climate Change (IPCC) coal methane factor is per tonne of raw coal. How do I apply it to the washed coal I buy?
The IPCC factors apply to raw coal production. If you buy washed coal, more raw coal was mined than you received: the Guidelines put rejects at typically around 20 percent of the raw feed. On that default, 1 tonne of washed coal came from 1.25 tonnes of raw coal, so scale up by 25 percent.
What the Guidelines say
Volume 2 Chapter 4, Section 4.1.3.3: the activity data for Tiers 1 and 2 are raw coal production. "Where coal is upgraded, some coal is rejected in the form of coarse discards... The amount of waste is typically around 20 percent of the weight of raw coal feed, but may vary considerably by country." Where data are saleable coal, "an estimate should be made of the amount of production that is washed. Raw coal production is then estimated by increasing the amount of 'saleable coal' by the fraction lost through washing." Unwashed coal needs no adjustment, because then raw coal equals saleable coal.
The arithmetic and a wording point
If rejects are 20 percent of the raw weight, saleable coal is 80 percent of raw, so raw = saleable / 0.8 = 1.25 x saleable. The Guidelines' sentence about "increasing... by the fraction lost" can be misread: applying 20 percent to the saleable weight would give 1.20 instead of 1.25, although read as 20 percent of the raw feed it also gives 1.25. We use 1.25 because the 20 percent is defined against raw feed. That is our reading.
The Guidelines also allow the other route for mines whose raw output includes roof or floor rock: use saleable coal with emission factors "referenced to the clean fraction of the coal", and note this in the inventory. Do not mix the two routes.
What to ask the supplier
- Is the coal washed, and what share of the raw feed is rejected? A supplier's actual yield beats the 20 percent default.
- Which mine, and is it underground or opencast, so you know which factor family applies.
- Whether the invoice tonnes are washed or raw, and at what moisture, since the Guidelines note moisture of 5 to 10 percent in coal data.
1,000 tonnes of washed coal from an underground mine
- Raw coal mined: 1,000 / 0.8 = 1,250 tonnes
- Average factors: 18 + 2.5 = 20.5 cubic metres of methane per raw tonne
- Methane: 1,250 x 20.5 = 25,625 cubic metres, and 25,625 x 0.67 kilograms per cubic metre = 17,169 kilograms
- Without the adjustment: 1,000 x 20.5 = 20,500 cubic metres, and 20,500 x 0.67 = 13,735 kilograms
- Difference: 17,169 / 13,735 = 1.25 times
The 1,000 tonnes and the underground mine are examples. Replace the 20 percent with the supplier's reject share if you have it.
What Senseible does here
Senseible reads fuel invoices and electricity bills into dated records, so the coal tonnes bought each month are on file. It does not know whether the coal was washed, so ask the supplier for the yield and keep the reply with the invoices.
- Coal mine methane factor by mine depth
- Coal washery electricity per tonne
- Coking coal mine methane in Scope 3
Sources: IPCC 2006 Guidelines, Volume 2 Chapter 4 (Section 4.1.3.3 and Equations 4.1.3 and 4.1.4)
Last reviewed 2026-11-05. The 20 percent rejects figure is the Guidelines' typical value and varies by country and mine.