# Our boiler burns only biomass. Do we still have Scope 1 emissions?

Canonical: https://senseible.earth/answers/biomass-boiler-ch4-n2o-still-scope-1

Yes, a little. The CO2 from burning biomass is reported separately as biogenic, outside the Scope 1 total, but methane and nitrous oxide from combustion stay in Scope 1. IPCC defaults for wood are 30 kg methane and 4 kg nitrous oxide per terajoule, roughly 2 tonnes of CO2e per terajoule.

## How to calculate

1. Tonnes of biomass times its net calorific value gives terajoules.
2. Times 30 kg CH4 and 4 kg N2O per TJ.
3. Convert with global warming potentials, stating which IPCC report you used.

## Report three numbers

- Scope 1 CO2e from methane and nitrous oxide.
- Biogenic CO2, shown separately.
- Any fossil fuel used for start-up, such as diesel or coal.

## Evidence on the biomass

Buyers and verifiers ask where it came from. Keep supplier invoices and note whether it is residue, waste or plantation wood.

## What Senseible does here

Senseible reads fuel invoices, gas bills and delivery documents into dated, fingerprinted records, so each tonne of CO2 traces back to the document behind it.

- [Biomass or waste fuel in a boiler](https://senseible.earth/answers/biomass-or-waste-fuel-in-boiler-scope-1)
- [Firewood bought by the quintal](https://senseible.earth/answers/firewood-by-quintal-emissions)
- [Coal, PNG or biomass boiler](https://senseible.earth/answers/coal-vs-png-vs-biomass-boiler-emissions)

Sources: [IPCC 2006 Guidelines, Volume 2 Energy](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html), [IPCC AR6 Working Group I](https://www.ipcc.ch/report/ar6/wg1/), [GHG Protocol Corporate Standard](https://ghgprotocol.org/corporate-standard)

Last reviewed 2026-10-22.