For a food processing plant, how much do emissions change if organic waste goes to compost or biogas instead of landfill?
A lot. Food waste rotting in a landfill releases methane, so landfill factors per tonne are far higher than those for composting or anaerobic digestion. Check the current DESNZ waste disposal table for the values. Moving most organic waste away from landfill or open dumping is often a large Scope 3 waste cut for a food plant.
Why landfill is so much worse
Food waste is mostly carbohydrate, fat and protein. Buried without air, it breaks down over years and releases methane, a gas with a 100 year warming potential of about 27 to 30 times CO2. The IPCC 2006 Guidelines model this with a first order decay method. Composting is aerobic and anaerobic digestion captures the methane as biogas, so both release far less.
The CO2 released from the food itself is biogenic and is not counted in the waste factor; the figures are CO2e because they cover methane and nitrous oxide.
Which factors to use
These factors are built for UK and US conditions; check the DESNZ methodology paper for its landfill assumptions. Open dumpsites in South Asia and Southeast Asia behave differently: shallow, unmanaged dumps can produce less methane per tonne than a deep landfill, while burning at dumpsites adds other emissions. Say which factor you used and why.
- UK DESNZ conversion factors: a waste disposal table with food and drink waste by route (landfill, composting, anaerobic digestion, combustion). Use the current edition.
- US EPA GHG Emission Factors Hub and the EPA WARM model as a cross-check.
- Factor = tonnes of waste sent by each route x the factor for that route.
Which scope the waste falls in
- Waste collected and treated by a third party, including a municipal body or a biogas operator: Scope 3 Category 5, waste generated in operations.
- A compost yard or digester you own and run on site: its methane and nitrous oxide are your Scope 1, and the biogenic CO2 is reported separately.
- Biogas you burn in place of LPG or furnace oil cuts your Scope 1 fuel use. Count that through lower fuel invoices, not as a negative waste figure.
Records to keep
Weighbridge slips or waste contractor invoices showing tonnes by waste type and destination, and the contractor's statement of how the waste is treated. Without tonnes and route, a waste figure is a guess.
Worked example: 500 tonnes of food waste a year (illustrative)
- Landfill, illustrative factor 600 kg CO2e per t: 500 x 600 = 300,000 kg, about 300 t CO2e
- Composting, illustrative factor 10 kg CO2e per t: 500 x 10 = 5,000 kg, about 5 t CO2e
- Difference: 300 t minus 5 t = about 295 t CO2e a year
Both factors are illustrative numbers chosen to show the arithmetic, not official DESNZ values. Use the exact figures from the current edition, and treat results for unmanaged dumpsites as uncertain.
What Senseible does here
Senseible keeps waste contractor invoices in the separate Scope 3 supplier evidence trail, each file with a SHA-256 fingerprint so duplicates are not counted twice. Emissions are activity times a published factor: no factor, no figure.
Sources: UK DESNZ Greenhouse gas reporting: conversion factors for company reporting, waste disposal, GHG Protocol Technical Guidance for Calculating Scope 3 Emissions (2013), Category 5, 2006 IPCC Guidelines, Volume 5, Chapter 3 (solid waste disposal)
Last reviewed 2026-10-15. UK and US waste factors may not reflect unmanaged dumpsites in South and Southeast Asia; treat regional results as uncertain.