Towards a low-carbon future for China's power supply chain: Critical sectors identification and scenario analysis

The power sector is a significant contributor to global carbon emissions and has received widespread attention from scholars; however, the path to achieving supply chain-wide carbon reductions in China from a provincial perspective remains unclear. This study combined multi-regional input-output and betweenness-based methods to identify the critical upstream sectors that indirectly drive large amounts of carbon emissions through power supply chains. The point source data of coal-fired units were collected to ensure the accuracy of the disaggregated input-output table. In addition, a scenario analysis was conducted to examine the effects of different electricity policy combinations on supply chain-wide emissions during the 14th Five-Year Plan (FYP). Our findings indicate that the embodied carbon intensity of the coal-fired power sector in Northwest China is among the highest in the country, ranging from 36.39 to 82.10 tons/10000 CNY. Therefore, the shift of the power sector to Western China during the 14th FYP will partially offset the positive emission reduction effect of the structural transformation of the power system. To achieve a low-carbon power supply chain, it is necessary to improve the production efficiency of critical transmission sectors and the low-carbon technology levels of major emitting sectors. Our results provide valuable insights for provincial governments to plan low-carbon transformation paths for the power sector.

CO2 emission accounting and emission reduction analysis of the steel production process based on the material-energy-carbon correlation effect

This paper develops a process-level carbon emission calculation model for iron and steel enterprises through the carbon emission mechanism of the whole production process. The relationship between material, energy and carbon flows is considered and combined. The carbon emissions of enterprises are divided into industrial emissions and combustion emissions, and the indirect emissions of purchased intermediate products and electricity purchased from the grid are also considered. Carbon emission targets and corresponding emission reduction strategies are formulated at the enterprise and process levels. For example, consider an iron and steel enterprise. The different types of carbon emissions are accounted for, with their reduction potential analysed based on the carbon material flow analysis method. The results show that the carbon emission of this enterprise is 1930.87 kgCO2/t (CS), and the combustion emission caused by energy flow is the main contributor to the enterprise's carbon emission, accounting for 57.02% of the total emission. The carbon emission during iron-making accounts for 69.06% of the entire process and is critical in any carbon emission reduction of the enterprise. Among them, process emissions from the blast furnace process account for 81.79% of industrial emissions of the whole process, which is 356.51 kgCO2/t (CS), and is the main challenge of low carbon transformation in this extensive process. This study highlights that increasing the integrated steel-making scrap ratio and electric furnace steel production can break through the existing emission reduction limits. A 65.02% carbon emission reduction can be achieved, and using green electricity can reduce emissions by 24.15%. Reasonably determining the amount of purchased coke and paying attention to the high-value recycling of byproduct gas resources in the plant are essential to achieve low-carbon economic development of steel.

Towards sustainable transport: quantifying and mitigating pollutant emissions from heavy-duty diesel trucks in Northeast China

Heavy-duty diesel trucks (HDDTs) have caused serious environmental pollution in China. Accurate estimation of their pollutant emission characteristics is essential to reduce emissions and associated environmental and public health impacts. To achieve sustainable development for transport emissions in Northeast China, we developed localized emission factors and a high-resolution emission inventory of HDDTs, based on on-board test, Guidebook and international vehicle emission (IVE) model. The results show that the total emissions of CO, NO, NO2, and PM from HDDTs in Northeast China in 2020 were 172.2 kt, 531.5 kt, 11.2 kt, and 921.4 t, respectively. In terms of spatial distribution, emissions decreased from the city center to the city fringe. Temporally, the NOx emission variation curves of different types of roads presented a "single-peak" emission characteristic, which was different from the peak of traffic flow. Three emission reduction scenarios are further developed in the paper. Scenario analysis shows that elimination of HDDTs that follow the old China III emission standard and installing tailpipe treatment devices are the most effective pollutant reduction measure. The reduction percentages for CO, NO, NO2, and PM ranged from 62.9 to 83.89%. The results of our study could inform policymakers to devise feasible strategies to reduce vehicle pollution in Northeast China.

Impact of introducing net-zero carbon strategies on tropospheric ozone (O3) and fine particulate matter (PM2.5) concentrations in Japanese region in 2050

In this study, we estimated the future emission inventory of primary air pollutants in Japan in 2050 after introducing net-zero carbon technology based on the results of the socio-economic model provided by the Japanese government. The results suggested that introducing net-zero carbon technology would contribute to a 50-60 % decrease in primary NO_x, SO₂, and CO emissions and a ~30 % decrease in primary emissions of volatile organic compounds (VOCs) and PM_2.5. The estimated emission inventory and future meteorological conditions in 2050 were applied as inputs to a chemical transport model. A scenario involving the application of future reduction strategies with relatively moderate global warming (RCP4.5) was evaluated. The results showed that the concentration of tropospheric ozone (O₃) was highly reduced compared with that in 2015 after applying net-zero carbon reduction strategies. On the other hand, the fine particulate matter (PM_2.5) concentration under the 2050 scenario was expected to be equal or higher because of the growth in secondary aerosol formation caused by the increase in short-wave radiation. Finally, the premature mortality change from 2015 to 2050 was analyzed, and the change in air quality contributed by net-zero carbon technology will contribute to a ~4000 decrease in premature deaths in Japan.