China's cement demand and CO emissions toward 2030: from the perspective of socioeconomic, technology and population.

China is the largest cement producer and carbon dioxide (CO) emitter in the world. The country has attracted too much attention in calculating and comparing its CO emissions. However, as the second largest CO emitter after the fire power industry, China's long-term cement demand and cement-related CO emission projections were not fully studied. The Chinese government, however, committed that by 2020 and 2030, China's per capita GDP of CO emissions would be lower than that in 2005 by 40-45% and 60-65%, respectively. In this paper, China's cement demand in 2030 was projected based on the population size, urbanization rate, fixed assets investment, and per capita GDP. Furthermore, decoupling study in China's cement industry was also involved based on the GDP and CO emissions during 2001-2015. We also used the diffusion rate of 12 types of CO reduction measures and two changed scenarios of clinker-to-cement ratio, to project the cement CO emission factors toward 2030 after determining the accounting scope. Meanwhile, the CO emissions of China's cement industry through 2030 were projected naturally. The results showed that China's cement output in 2030 will be approximately 2000, 1650, and 937 Mt. based on the fixed assets investment, urbanization rate, and per capita GDP respectively. The projected two scenarios cement CO emission factors were resp. 407.83 and 390.02 kg CO/t of cement which were 42.6 and 45.1% lower than that in 2005. The cement CO emissions were projected to be in the range of 366 to 818 Mt. in 2030. Additionally, China's total cement output value has been decoupling from cement CO emissions from 2012, which is mainly attributed to eliminating backward capacity, reducing excess capacity or the declining cement output. And decoupling economic from China's cement CO emissions may change to be strong or weak decoupling in the near future. As cement production is one of the factors effecting cement CO emissions, the most important measure for controlling cement CO emissions is a reasonable capacity utilization rate. It is therefore important to control the growth of cement CO emissions by regulating the capacity utilization rate within a reasonable range. Eliminating backward capacity, removing excess capacity, controlling new capacity, staggered production, and the "going global" of cement equipment can have great impacts in controlling the total amount of cement output and CO emissions.