Life-cycle carbon emissions from pilot zero-waste technologies in China

While low-carbon development and low-waste development are being pursued in numerous countries, it is crucial to integrate the benefits of carbon emissions reduction and economic costs to comprehensively evaluate the effectiveness of Zero-waste City technologies (ZWTs). This study provides a system accounting framework for estimating the life-cycle carbon emissions of the ZWTs. It is based on the hybrid method as a combination of the process analysis and the input-output analysis. The indicators of net carbon emissions, carbon emissions reduction, and net economic cost after accounting for carbon emission reductions are proposed to evaluate the integrated efficiency of the ZWTs. Based on the detailed input and output inventory of the ZWTs and the carbon emission intensity database of China, case studies are carried out to calculate the life-cycle carbon emissions of the pilot ZWTs in China. These technologies are divided into three categories as the technology to treat sludge, to treat domestic waste, and to treat mixed waste of sludge and kitchen waste. The results show that most of the pilot ZWTs have co-benefits of mitigating climate change while reducing solid waste. Among them, the dry anaerobic fermentation technology and the cement kiln co-processing technology are shown superior to similar technologies in terms of carbon emission reductions. After integrating the carbon emission reduction benefit to the economic cost, the sludge resource treatment technology and the grate domestic waste incineration technology are revealed cost less than the comparable technology. Finally, due to China's active promotion of renewable energy power generation to replace traditional coal-fired power generation, it is expected that the emission reduction capacity of sludge ZWTs will increase by 12.54% to 26.51% by 2035.