Climate change mitigation potential of kitchen waste utilization in China for combined heat and power production

Given the concerns about climate change, energy sustainability, and public health, the reuse of kitchen wastes (KW) is attracting increasing interest. In China, the municipal solid waste sorting scheme has increased the available KW. To assess the available KW and the climate change mitigation potential of KW utilization for bioenergy in China, three scenarios (base, conservative, and ambitious) were defined. A new framework was implemented to assess the climate change impacts of bioenergy. The annual available KW ranged from 11.450 million dry tons (in metric) under the conservative scenario to 22.898 million dry tons in the ambitious scenario, and had the potential to produce 12.37 × 106–24.74 × 106 MWh heat and 9.62 × 106–19.24 × 106 MWh power. The total potential climate change impacts of KW for combined heat and power were 3.339–6.717 million tons CO2 eq in China. The highest eight provinces and municipalities contributed over half of the national total. Among the three components of the new framework, fossil fuel-derived greenhouse gas emissions and biogenic CO2 emissions were positive. The difference in carbon sequestration was negative and ensured a lower integrated life-cycle climate change impacts than that of natural gas-derived combined heat and power. The mitigation effects of using KW as a substitute for natural gas and synthetic fertilizers were 2.477–8.080 million tons CO2 eq. These outcomes can inform relevant policymaking and benchmark climate change mitigation in China. The conceptual framework of this study can also be adapted for applications in other countries or regions worldwide.