Avoided Landfill: When Does Displacement Become a Real Environmental Benefit?

Avoided landfill is frequently used as an environmental credit.

Sometimes that credit is substantial.

Sometimes it is overstated.

The difference lies in the counterfactual.

Which landfill?

Not all landfill systems are equivalent.

Relevant distinctions include open dump, uncontrolled landfill, engineered landfill, landfill with leachate controls, landfill with gas collection and landfill with gas utilisation.

Avoiding an uncontrolled dump is environmentally different from diverting waste from a well-managed modern landfill.

Waste composition

The type of material diverted also matters.

Biodegradable waste

Organic waste can generate landfill methane under anaerobic conditions.

Diverting biodegradable material can therefore reduce methane-generation potential.

Metals and glass

These materials do not create the same methane pathway.

Their landfill consequence is more strongly associated with lost material value and long-term occupation of disposal capacity.

Plastics

Plastics generally do not create landfill methane in the same way as food waste.

Their consequences may instead include long-term material loss, litter where containment is poor and opportunity cost of forgone recovery.

A single avoided-landfill factor cannot responsibly represent all materials.

Gas collection

Landfill-gas capture can materially change the methane balance.

Captured gas may be flared, used for energy or upgraded.

Collection is not perfect, but it means landfill methane should not automatically be treated as completely uncontrolled.

Leachate

Avoiding landfill can also avoid leachate generation, long-term treatment and containment obligations.

Again, the benefit depends on the alternative.

A treatment producing hazardous residues requiring landfill may merely reduce rather than eliminate disposal.

Alternative treatment

The environmental credit cannot be assessed without examining what replaces landfill.

Alternatives may require transport, energy, preprocessing, pollution control and residue management.

Avoided landfill is one side of the comparison. The replacement system is the other.

Open dumping

Where the real alternative is uncontrolled dumping or burning, the environmental benefit of bringing waste into a controlled collection and treatment system may be much larger.

Double counting

Care is needed not to count the same environmental benefit repeatedly.

For example, avoided landfill methane, avoided landfill climate impact and avoided methane emissions may describe the same causal benefit.

A lifecycle assessment should count it once.

Governing principle

Avoided landfill is not a technology property. It is a comparative consequence.

To quantify it responsibly, GCCEI must define what waste was diverted, from what landfill system, to what alternative, with what resulting emissions and residues.