Are emissions from burning rice husk, biomass or waste in my boiler counted in Scope 1?
Partly. The CO2 from burning biomass such as rice husk is biogenic and is reported separately, outside the scopes. The methane and nitrous oxide from the same combustion do count in Scope 1. For waste fuels, the fossil part, such as plastic, counts in Scope 1 as CO2.
The three pieces of a biomass boiler's emissions
- Biogenic CO2: carbon the plant absorbed while growing. The GHG Protocol asks you to report it as a separate figure, not inside Scope 1.
- Methane (CH4) and nitrous oxide (N2O): formed during combustion. These go in Scope 1, converted to CO2e with global warming potentials.
- Fossil CO2 from start-up or support fuel: diesel or coal used to light or co-fire the boiler is ordinary Scope 1.
How to calculate the CH4 and N2O
- Find the energy content: tonnes of fuel x net calorific value (NCV), in terajoules (TJ). Use a lab test of your fuel if you have one.
- Multiply by IPCC 2006 default factors for solid biomass in industrial boilers: 30 kg CH4 and 4 kg N2O per TJ.
- Convert with GWPs from the IPCC assessment report you use, and state which one.
Waste and mixed fuels
Waste such as packaging, rubber or mixed industrial waste usually contains fossil carbon. Estimate the fossil share from composition data or tests, and report that share of the CO2 in Scope 1. Only the biomass share, such as paper or wood, is biogenic. Treat used oil and tyre-derived fuel as fossil.
What to write in your report
- Scope 1 total, including CH4 and N2O from biomass combustion.
- Biogenic CO2 from combustion, as a separate line outside the scopes.
- Fuel quantity, NCV source, factors and GWP set used.
- Do not report biogenic CO2 as zero without saying so, and do not claim it as a removal.
Labelled estimate: 1,000 tonnes of rice husk in a year
- NCV: 11.6 TJ per thousand tonnes, the IPCC default for other primary solid biomass (rice husk often tests higher)
- Energy: 1,000 t = 11.6 TJ
- CH4: 11.6 x 30 = 348 kg; x 28 (AR5 GWP) = 9,744 kg CO2e
- N2O: 11.6 x 4 = 46.4 kg; x 265 (AR5 GWP) = 12,296 kg CO2e
- Scope 1 from the boiler: about 22.0 t CO2e
- Biogenic CO2, reported separately: 11.6 TJ x 100,000 kg per TJ = 1,160 t
Factors are IPCC 2006 defaults. Use your own fuel test for NCV where available.
What Senseible does here
Senseible applies published fossil fuel factors and gives biomass lines a biogenic CO2 value of zero, never counted as a credit. It does not calculate CH4 and N2O from biomass combustion or report biogenic CO2 separately, so add those yourself.
Sources: GHG Protocol Corporate Standard (biogenic CO2 reported separately), IPCC 2006 Guidelines, Volume 2, Chapter 2 (stationary combustion)
Last reviewed 2026-10-15.