Greenhouse gas, water, and economic implications of permeable pavements: Quantification for pilot sponge cities in China

Abstract

Climate change has exacerbated the occurrence of extreme storms, resulting in urban flooding. However, rainwater is a potential source of water for various end uses of municipal water. In this context, permeable pavements are promising for mitigating floods and alleviating water stress in cities. Herein, a process-based life-cycle inventory modeling approach was used to quantify the life-cycle greenhouse gas (GHG) and water footprints of different road pavements in 28 pilot sponge cities in China. Three asphalt pavements were considered in this study: permeable-surface, permeable-base, and conventional nonpermeable pavements. Moreover, life-cycle cost analyses were performed to reveal the cost-effectiveness of these pavements. Results showed that permeable-base pavements exhibited the highest levelized GHG emissions (5.9 kg CO2e/m2/yr), followed by nonpermeable (5.5 kg CO2e/m2/yr) and permeable-surface pavements (3.8 kg CO2e/m2/yr). In terms of levelized water footprint, permeable-base and permeable-surface pavements enabled water savings (433.8 and 304.1 kg/m2/yr, respectively), while nonpermeable pavements consumed 30.6 kg/m2/yr of water. The levelized life-cycle costs of permeable-surface, permeable-base, and nonpermeable pavements were 32.8, 35.4, and 40.5 yuan/m2/yr, respectively. With regard to transitioning from nonpermeable to permeable pavements in urban road construction, Chongqing and Shenzhen presented favorable potential for GHG mitigation (22 and 26 kt CO2e/yr, respectively) and water savings (196 and 187 Mt/yr, respectively). Contrarily, Hebi, Yuxi, Sanya, Qianan, Chizhou, and Xining were not cost-effective in terms of GHG emission reduction. Moreover, in this study, GHG–water–cost tradeoffs were identified among different pavements, highlighting directions for unlocking the green benefits of installing permeable asphalt pavements in China.