For deep carbon emission reductions beyond decarbonization of the energy supply, among reduction streams, recycling-induced elimination of materially retained carbon (MRC) releases to the atmosphere have a great direct reduction potential. Moreover, the use of recycled materials indirectly avoids the manifestation of cradle-to-gate carbon footprints of virgin materials that would otherwise enter anthropogenic cycles. These facts have been individually revealed by preceding studies on lifecycle assessment of recycling technologies and carbon footprint accounting. However, the limited focus on specific wastes and technologies for recycling might narrow the range for the future development of recycling activities. This study comprehensively quantifies the carbon emission reduction potential of recycling activities through an input-output based material flow analysis. Here, we reveal the Japanese economy-wide potential emission savings, both direct (12.8 × 106 t-CO2) and indirect (17.5 × 106 t-CO2), that could have been achieved through maximal MRC recycling from households (i.e. post-consumer recycling) in 2011, outweighing potential energy recovery through waste incineration (3.1 × 106 t-CO2). Further, we found that incineration of plastic-containing products currently not covered by recycling laws is likely to cause 3.9 × 106 t-CO2 emission. These are first-order estimates of reduction potentials of post-consumer recycling encompassing the entire national economic structure. Energy-induced carbon emissions in recycling activities are excluded from these estimates, allowing for deduction of acceptable energy usage for recycling activities. The identified structures of direct and indirect reductions on value chains allow for efficiently directing the advancement of recycling technologies and policies toward the deep decarbonization of society.
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