reportProcessingResiduesForestry
Source:R/reportProcessingResiduesForestry.R
reportProcessingResiduesForestry.RdReports processing residues from timber production available for energy use.
Processing residues are sawmill byproducts (sawdust, bark, slabs, offcuts) generated during conversion of industrial roundwood to finished products. They are NOT currently tracked as a variable in MAgPIE's GAMS code and represent additional biomass supply for REMIND's bioenergy sector.
Note: Logging residues (branches, tops) tracked in v73_prod_residues are NOT included
here because they already feed into MAgPIE's woodfuel supply equation (q73_prod_woodfuel)
and would be double-counted if reported separately for REMIND.
Details
Full mass balance of timber harvest
When 1 hectare of forest is harvested, the total biomass removed is:
Stem biomass =
im_growing_stock(tDM/ha)Logging residues (branches, tops) = 15% of stem, tracked in
v73_prod_residuesTotal removed = stem x 1.15
The model splits stem production between industrial roundwood (vm_prod("wood"))
and woodfuel (vm_prod("woodfuel")). Only the industrial roundwood fraction enters
processing facilities and generates processing residues. Woodfuel is burned directly.
Logging residues already feed into MAgPIE's woodfuel supply (NOT reported here).
1 hectare harvested -> total biomass = stem x 1.15
|
+-- Stem (100% = vm_prod, split between "wood" and "woodfuel" by the model)
| If allocated to industrial roundwood (vm_prod("wood")) -> processing facilities:
| |
| +-- Sawnwood pathway (~57% of IR):
| | +-- 50% finished sawnwood
| | +-- 43% processing residues (sawdust, slabs, bark, offcuts) -> THIS FUNCTION
| | +-- 7% losses
| |
| +-- Pulpwood pathway (~35% of IR):
| | +-- 95-100% utilized (black liquor burned internally at pulp mill)
| | +-- 0-5% solid residues available externally
| |
| +-- Other industrial roundwood (~8% of IR):
| +-- Assumed similar to sawnwood (43% residue rate)
|
+-- Logging residues (15% of stem = branches, tops)
-> Already in MAgPIE woodfuel via v73_prod_residues (NOT reported here)Processing residue rate
The rate is derived from FAO product composition of industrial roundwood
(from f73_prod_specific_timber, stable at these shares across 1965-2015)
and product-specific recovery rates:
| Product | Share of IR | Recovery | Residue rate | Source |
| Sawnwood (sawlogs + veneer) | ~57% | 50% | 43% | FAO/UNECE; Mantau 2012 UNECE DP-51 |
| Pulpwood | ~35% | 95-100% | 0-5% | Black liquor burned internally |
| Other industrial roundwood | ~8% | ~50% | 43% | Assumed same as sawnwood |
Production-weighted rate: 0.57 x 0.43 + 0.35 x 0.025 + 0.08 x 0.43 = 0.29 Rounded to 0.30 (stable at 30-35% across 1965-2015 FAO data).
Why only industrial roundwood, not woodfuel
Processing residues are computed from industrial roundwood supply (ov_supply("wood"))
only. Woodfuel (ov_supply("woodfuel")) is excluded because it is burned directly
for energy — it does not pass through sawmills or pulp mills and therefore generates
no processing residues.
Why all processing residues go to energy
In reality, some processing residues are used for pulp or particleboard. However,
MAgPIE models all wood products as aggregate "industrial roundwood" (kforestry = wood).
The downstream split into sawnwood, pulp, and panels is not modeled — there is no
competing use for processing residues within MAgPIE. Therefore, all processing
residues are assumed available for energy use.
Construction wood
calcConstructionWoodDemand in mrcommons applies a factor 2 to construction wood demand,
reflecting a 50% sawmill recovery rate (Churkina et al. 2020). This means half of the
harvested roundwood for construction becomes processing waste. These residues are clean,
uniform offcuts with high energy recovery potential. Reported separately from general
processing residues.
What this function does NOT include
Logging residues (branches, tops): already in MAgPIE woodfuel (
v73_prod_residues)Post-consumer waste wood (demolition, furniture): excluded for consistency with
carbonLTS, which tracks CO2 from HWP decay using IPCC first-order decay (half-lives: sawnwood 30yr, construction 60yr, pulpwood 2yr). Adding end-of-life energy recovery would require splitting HWP outflow into burned vs decayed fractions — assumptions not currently in the model. The CO2 from HWP decay is already reported; the energy from burning waste wood is not tracked to avoid parallel lifetime assumptions.Black liquor: burned internally at pulp mills, not available for external energy
References
FAO/UNECE conversion factors for sawnwood recovery rates
Mantau, U. (2012). Wood flows in Europe (EU27). UNECE/FAO Discussion Paper 51 (DP-51).
Oswalt et al. (2019). Forest Resources of the United States. USDA.
Churkina et al. (2020). Buildings as a global carbon sink. Nature Sustainability.
Variables
| Name | Unit | Meta |
| Residues for energy|Forestry|+|Processing residues from construction wood | PJ/yr | Sawmill waste from construction wood (50% of demand) |
| Residues for energy|Forestry|+|Processing residues from other roundwood | PJ/yr | 30% of non-construction roundwood |
| Residues for energy|+|Forestry | PJ/yr | Total forestry processing residues for energy |