IPCC Volume 5 Chapters 4 and 5 · Scope 1
Composting, digestion and incineration
For operators of composting sites, digesters and incinerators. Short equations, each with a trap: recovery that's already counted, a weight basis that changes between tables, and CO₂ that's only partly an emission.
On this page you'll learn
- Composting and anaerobic digestion
- Why incineration writes two rows
- Why a stream's average fractions can't be multiplied together
- Scope
- 1 (biogenic CO₂ outside the scopes)
- Publisher
- IPCC 2006 Vol 5 Ch 4 and 5
- Category codes
biological_treatment,waste_incineration
Composting and anaerobic digestion
Recovery is already inside the digestion factor
IPCC's note: the anaerobic digestion default "already accounts for CH₄ recovery". So R is subtracted for composting and refused for digestion, where it would remove the same recovery twice.
Dry or wet is a choice, not a unit
10 g CH₄ per kg dry against 4 per kg wet. A wet tonnage costed against the dry factor over-reports by 150%, so you state which you measured.
No CO₂
It's biogenic. Reported as unquantified, not zero.
Incineration
Only the fossil share of the carbon is a Scope 1 emission. Burning municipal waste releases carbon from food, paper and wood as well as from plastic. So incineration writes two rows: a Scope 1 row with the fossil CO₂, CH₄ and N₂O, and a sibling outside the scopes with the biogenic CO₂.
- Equation 5.2: per-component product, summed
- 375 t fossil carbon
- Average fractions multiplied together
- 198 t fossil carbon
- Slate uses
- Equation 5.2
The average of the products is not the product of the averages. A test asserts the two disagree.
Composition is required
There's no whole-stream default for municipal waste; the operator supplies the mix, and the shares must sum to 1.
The weight basis changes between tables
Table 2.4 is percent of dry weight; Tables 2.5 and 2.6 are percent of wet. The published row chooses the basis before your tonnage is read.
A published inconsistency, kept
Tables 5.2 and 2.6 disagree on clinical waste's fossil carbon (15.6% against 25% of wet weight). Both are stored as printed.