The environmental impact of food waste doesn't end when it leaves your kitchen. Where it goes next makes an enormous difference to its overall footprint.
Food waste sent to landfill decomposes anaerobically (without oxygen), producing methane—a greenhouse gas roughly 25 times more potent than carbon dioxide over a 100-year period.
The Methane Problem
When organic material decomposes in landfill, bacteria break it down in the absence of oxygen. This anaerobic decomposition releases methane (CH4) as a byproduct.
Key facts:
- Landfill is the third-largest source of methane emissions globally
- Food waste is the largest contributor to landfill methane
- Methane traps 25x more heat than CO2 over 100 years (80x over 20 years)
This means the disposal method for unavoidable food waste significantly affects your overall carbon footprint.
Disposal Methods Compared
Different disposal routes have very different emissions profiles:
| Method | Emissions (kg CO2e per kg waste) |
|---|---|
| Landfill | 0.5 - 1.0 |
| Incineration | 0.1 - 0.3 |
| Composting | 0.05 - 0.15 |
| Anaerobic digestion | -0.05 to 0.1 (can be negative) |
Anaerobic digestion is unique in potentially having negative emissions because it captures methane and converts it to energy, displacing fossil fuel use.
The Waste Hierarchy
The waste hierarchy provides a framework for thinking about this:
- Prevention — Best outcome. Don't generate the waste.
- Redistribution — Surplus food to people who need it.
- Animal feed — Converting to productive use.
- Anaerobic digestion — Capturing energy from decomposition.
- Composting — Returning nutrients to soil.
- Incineration with energy recovery — Better than landfill.
- Landfill — Worst option. Avoid where possible.
What You Can Do
Know where your waste goes. Ask your waste contractor about disposal methods. Many don't send food waste to landfill by default anymore, but don't assume.
Segregate food waste. Separate food waste streams enable better disposal options. Mixed waste often goes to landfill; segregated food waste can be composted or digested.
Consider on-site options. For larger operations, on-site composting or digestion may be economically viable.
Ask about alternatives. Waste management companies increasingly offer anaerobic digestion or composting services. The cost difference from landfill is often small.
Reporting Implications
When calculating your carbon footprint, disposal method matters:
- Landfill disposal adds approximately 0.7 kg CO2e per kg food waste
- Composting adds only about 0.1 kg CO2e
- Anaerobic digestion can be carbon-neutral or negative
If you're reporting emissions, the difference is significant enough to require accurate accounting of disposal routes.
The Bigger Picture
Prevention is always better than good disposal. A kilogram of beef not wasted saves 30-50 kg CO2e in production emissions. Even with landfill disposal adding another 0.7 kg, the production savings dwarf disposal impacts.
But for unavoidable waste, disposal method is a meaningful lever. Combined with prevention efforts, it completes the picture of responsible food waste management.
Learn more about food waste environmental impact and how to calculate and reduce your footprint.