Developing and Verifying a Bottom-up Methodology for Bulk Material Flow Analysis in China’s Urban Infrastructure Sectors

Abstract

With rapid urbanization rate in China, cities will use more cement, one of the most important construction materials, to build new infrastructure to satisfy the dramatically increasing urban population in the next few decades. In 2010, China’s cement industry contributed 11% of nation’s total fossil-fuel carbon dioxide emissions. However, little research has been done on studying cement use in cities, which is an essential part in order to learn the details of cities’ current cement use and to provide policy makers as well as governors with a powerful tool to organize a city’s future cement use. This thesis achieves two goals. The first one is to develop construction cement intensities for China’s cities’ infrastructure, which are classified into 9 sectors: road, public transit, building, gas supply, heat supply, solid waste disposal, wastewater treatment, storm water control, and water supply. The second goal is utilizing a bottom-up method to estimate annual cement use in three of China’s cities: Beijing, Tianjin and Shanghai, then compare the estimation result with at-scale apparent cement use data to verify the method. Our results find cement intensities in the various sectors, i.e., the cement intensity for highway, urban road, and residential building is 0.71 tons/m, 0.034 tons/m2, and 0.19 tons/m2 respectively. Our bottom-up citywide method estimates cement use in new construction to be around half (50%) of each city’s yearly total cement use (from 2004 to 2012), which is useful for evaluating the cement distribution and relevant environmental problems. The three main cement use sectors for new construction are residential building, other building, and road system (urban road, highway, subway & light rail, railway, and bridge) in these three cities. We believe that the unaccounted cement may be for maintenance of old stock, which was confirmed by conducting a first-order estimation that yield overall difference between bottom-up method of this paper and at-scale numbers from the city to be less than 15%. While cement use of residential buildings is decreasing during the past years in Beijing and Shanghai, Tianjin keeps a very stable status on cement use in this sector. Prior to this research, there is no study that shows cement use by infrastructure sectors, indicating the value of conducting bottom-up estimates.