Municipalities are seeking to reduce waste generation and increase recycling rates in order to cut greenhouse gas emissions. Materials that evade recycling are typically landfilled or incinerated.

This study compares cost effectiveness between sorting of mixed waste leftover after separate collection (leftover mixed waste sorting) and the capture of CO₂ from incinerator flue gas for underground storage (carbon capture and storage, CCS).

It has found that the most cost-effective way of delivering system-wide reductions in CO₂ emissions is the sorting system. The least cost-effective means to reduce CO₂ is CCS. Combining the two would achieve the greatest overall reduction and reduce the average cost of reduction to around half the cost of achieving reduction through CCS alone.