A scenario analysis of Chinese carbon neutral based on STIRPAT and system dynamics model

Spatial-temporal evolution of carbon emissions and spatial-temporal heterogeneity of influencing factors in the Bohai Rim Region, China

The total change in carbon emissions in the Bohai Rim Region (BRR) plays a guiding role in the policy formulation of carbon emission reduction in northern China. Taking the 43 cities in the BRR as an example, the spatial-temporal evolution of carbon emissions in the BRR was analyzed using kernel density estimation (KDE), map visualization, and standard deviation ellipses, and the spatial autocorrelation model was used to explore the spatial clustering of carbon emissions. On this basis, the spatial-temporal heterogeneity of the factors influencing carbon emissions is explained using a Geodetector. The results are as follows: (i) During the study period, the carbon emissions in the BRR were on the rise, the share of carbon emissions in the Beijing-Tianjin-Hebei region (BTHR) and Liaoning Province was decreasing, and the contribution of Shandong Province was gradually enhanced. The spatial distribution of carbon emissions shows a geographical pattern of "middle-high and low-outside." (ii) Carbon emissions from different regions show the characteristics of BTHR > Shandong Province > Liaoning Province. The high-value carbon emission area continues to move from the northwest of Beijing-Tianjin-Hebei to the southeast. (iii) Municipal carbon emissions showed a significant positive spatial correlation in the later part of the study. The high-high aggregation area is in Tianjin, and the low-low aggregation area is in Liaoning Province. (iv) The level of transport development contributes to carbon emissions with the highest growth rate, followed by industrial structure. There are also regional differences in the dominant influences on municipal carbon emission differences. Population size, urbanization, and economic development level are the core influencing factors of carbon emissions in the BTHR, Shandong Province, and Liaoning Province, respectively. In addition, the explanatory power of the interaction between the level of economic development and other factors on carbon emissions is at a high level.

A carbon-neutrality-capactiy index for evaluating carbon sink contributions

The accurate determination of the carbon-neutrality capacity (CNC) of a region is crucial for developing policies related to emissions and climate change. However, a systematic diagnostic method for determining the CNC that considers the rock chemical weathering carbon sink (RCS) is lacking. Moreover, it is challenging but indispensable to establish a fast and practical index model to determine the CNC. Here, we selected Guizhou as the study area, used the methods for different types of carbon sinks, and constructed a CNC index (CNCI) model. We found that: (1) the carbonate rock chemical weathering carbon sink flux was 30.3 t CO₂ km^-2 yr^-1. Guizhou accounted for 1.8% of the land area and contributed 5.4% of the carbonate chemical weathering carbon sink; (2) the silicate rock chemical weathering carbon sink and its flux were 1.44 × 10³ t CO₂ and 2.43 t CO₂ km^-2 yr^-1, respectively; (3) the vegetation-soil ecosystem carbon sink and its flux were 1.37 × 10⁸ t CO₂ and 831.70 t CO₂ km^-2 yr^-1, respectively; (4) the carbon emissions (CEs) were 280 Tg CO₂, about 2.8% of the total for China; and (5) the total carbon sinks in Guizhou were 160 Tg CO₂, with a CNCI of 57%, which is 4.8 times of China and 2.1 times of the world. In summary, we conducted a systematic diagnosis of the CNC considering the RCS and established a CNCI model. The results of this study have a strong implication and significance for national and global CNC determination and gap analysis.

Rheological properties and volumetric isothermal expansivity of bamboo kraft black liquor with high solids content and low lignin content

In this study, a certain percentage of lignin in original bamboo kraft black liquor (BKBL) was separated, and the residual BKBL with low lignin content was expected to be fed into the alkali recovery boiler to reduce the heat transfer load of the alkali recovery boiler. With the decrease in lignin content, the rheological properties/volumetric isothermal expansivity (VIE) of BKBL change. When the lignin content was 70% remaining in the original BKBL, the viscosity of BKBL with low lignin content is close to that of the passivated BKBL at the same solids content, the dynamic viscoelasticity is superior, and the VIE decreases by 57.2%. When the amount of desilication agent is 1.5%, the viscosity of BKBL with low lignin content did not change much, and the VIE increased sharply and was 62.7% higher than that of the passivated BKBL. Therefore, the combination of partial lignin separation process and sodium aluminate desilication process can effectively improve the ability of alkali recovery boiler to deal with BKBL and reduce the influence of "silicon interference".

Modeling and simulation analysis of vehicle pollution and carbon reduction management model based on system dynamics

The vehicle exhaust pollution has become an important source of air pollutant and CO2 emissions, with the continuous growth of the number of vehicles. Focusing on the increasingly serious problems of vehicle exhaust pollution and CO2 emissions, a management model of vehicle pollution reduction and carbon reduction was established by using system dynamics. Taking Beijing as the case study city, different emission reduction scenarios were designed. Different scenarios are analyzed, and the results reveal the following: (1) Although the carbon tax policy for motor vehicles can play a role in vehicle pollution reduction and carbon reduction to a certain extent, but as the simulation time goes on, the policy effect is gradually weakened. The emission reduction effect of new energy vehicle promotion policy is not significant, and there is a "lag effect" and a "seesaw effect." (2) The science and technology policy has multiple effects of environmental, economic, and health. It can significantly reduce vehicle pollution and carbon emissions, and achieve the peak carbon by 2030. (3) It is not that more policies are better for CO2 emission reduction, and there is a "crowding out effect" in the CS. (4) From the perspectives of long term, the science and technology policy is a more effective way to achieve the co-control of CO2 and PM2.5 and achieve the carbon peaking goal compared with other emission reduction scenarios. These results can provide reference for relevant departments to formulate emission reduction policies and realize the management of motor vehicle pollution reduction and carbon reduction.

Analysis on the dynamic evolution of the equilibrium point of "carbon emission penetration" for energy-intensive industries in China: based on a factor-driven perspective

In order to achieve the carbon peaking and carbon neutrality goals, energy-intensive industries in China, as the main sectors of energy consumption and carbon emissions, had huge pressure to reduce emissions. In addition, the reduction of vegetation area led to a decline in carbon sink capacity, which further exacerbated the imbalance of mutual penetration between carbon source and carbon sink. Therefore, this article considered the role of carbon source and carbon sink and defined and calculated the "carbon emission penetration" (CEP) of the six energy-intensive industries from 2001 to 2020. The KAYA formula and the LMDI method were used to decompose the driving factors of CEP in the three aspects of scale, intensity, and structure. The combined model of STIRPAT and the environmental Kuznets curve (EKC) was used to simulate and analyze the equilibrium points of energy-intensive industries in China from the perspective of factor driving. The analysis results indicated that there were differences in the fluctuation trend of CEP in the six energy-intensive industries, which can be divided into three types: "two-stage growth," "steady growth," and "single peak." Secondly, the driving factors from the three aspects of scale, intensity, and structure-emission intensity (CE), energy consumption intensity (EI), industrial structure (IS), economic scale (GP), and carbon sequestration scale (PCA)-had differences in industry and time dimensions. And the realization time of the CEP equilibrium points of six industries showed a three-level gradient feature significantly. This can provide some reference for the low-carbon transformation of six energy-intensive industries and optimization of China's environmental management under the carbon peaking and carbon neutrality goals.

Evolutionary Analysis of Prefabrication Implementation in Construction Projects under Low-Carbon Policies

In the context of carbon peak and carbon neutral policies, low-carbon construction has been the focus of most countries worldwide. As one of the most effective ways to achieve green construction, many countries have launched low-carbon policies to promote the development of prefabrication. However, the effectiveness and influencing factors of low-carbon policies on prefabrication need to be further verified under the dynamic game between the government and the construction enterprise. Therefore, this study considered subsidy and carbon tax policies and developed an evolutionary game model to promote the development of the prefabricated construction market. The evolutionary stable strategy of the government and construction enterprise under different scenarios was obtained. Subsequently, a numerical analysis was conducted to further investigate the impact of the key factors on the stable strategy. The results showed that an appropriate hybrid policy of subsidies and taxes could positively promote the prefabrication implementation of the construction enterprise. The government should adopt an appropriate policy intensity according to the maturity of the market. This study can provide effective guidance and practical enlightenment for the government to achieve low-carbon, green, and sustainable construction.