Mitigation of carbon dioxide by accelerated sequestration in concrete debris

Carbon capture and storage is becoming increasingly feasible. This study provides a novel quantitative analysis of the global CO2 mitigation potential through accelerated carbon sequestration in concrete debris separated from construction and demolition waste. We consider the economic and environmental tradeoff. Based on data collection from 14 large regions and countries, we created a method to estimate and project the generation of concrete debris, recycling and carbonation rates, and cost. The overall concrete debris generation was more than 3.0 (+/- 0.6) billion tonnes (Bt) in 2017 worldwide, mainly from emerging countries such as China and India. This debris has the potential to mitigate 62.5 (+/- 8.9) million tonnes (Mt) CO2 under optimal carbonation conditions determined by pressure, temperature, humidity, time, CO2 concentration, and debris size. Our scenario analysis reveals that the global cumulative carbonation of concrete debris could be as high as 3.0 Bt CO2 between 2018 and 2035, which equals approximately one third of the total CO2 emissions from fuel combustion of China in 2016. In our scenarios, the economic benefits of storing CO2 by concrete debris are mainly from recycled concrete aggregate rather than carbon sequestration, but also consider the current carbon price in major carbon markets. These findings highlight an effective and practical approach to reuse concrete debris as well as enhancing economic benefits. This approach could be helpful to better manage the fast-growing concrete debris and need for carbon mitigation as well as bridging the gap of CO2 sequestration by concrete debris between research and application.