As the largest carbon dioxide (CO₂) emission source in China, decarbonization of coal-fired power plants (CFPPs) is crucial for China to achieve carbon neutrality before 2060. Carbon capture utilization and storage (CCUS) is currently the only technology choice to realize deep cut in CO₂ emissions from CFPPs. The Integrated Environmental Control Model (IECM) is applied to calculate the cost and CO₂ capture of the selected CFPPs with CCUS. Based on the distribution patterns and potential of CO₂ storage sites, an optimal source-sink matching assessment model is applied to evaluate the priority CCUS layout scheme under the carbon neutrality target. In order to optimize infrastructure construction and reduce costs through economies of scale, the cluster analysis is applied to identify the CCUS cluster-hub. Then, the improved minimum spanning tree method is used to obtain the optimization strategy of CO₂ transport pipeline networks for above CCUS cluster-hub projects. To achieve carbon neutrality goal of the power sector, 300 existing CFPPs with an installed capacity of approximately 355 GW are required to be retrofitted by CCUS. The cumulative CO₂ emissions reduction potential of these CFPPs with CCUS is 19 Gt. By the development of industrial hubs with shared CO₂ transport and storage infrastructures, the total pipeline length and the total CO₂ transport cost could be reduced largely. The CCUS clusters of CFPPs are mainly distributed in Central, North and Northwest China and matched with the Songliao Basin, Bohai Bay Basin, Subei Basin and Ordos Basin which are considered as the priority areas for the implementation of the CCUS projects.

China has achieved the first century goal to build a moderately prosperous society, but rural revitalization is one of the key issues to be faced and solved towards the second century goal of building a socialist modern country. At present, China’s rural areas are still facing multiple problems such as economic development, clean energy use, environmental protection and carbon emission reduction. Through rural energy transformation, a new rural energy system can be built. This could not only achieve the “dual carbon” goal of rural China, but also be the main solutions to promote the development of rural industries and rural ecological governance, and an important foundation to realize the rural revitalization strategy. In this paper, the potential, technical route, financing mode and significance of developing roof-top distributed photovoltaic system in rural China are thoroughly discussed and quantitatively analyzed. The results show that rural China are facing multiple problems including energy, environment and economic development. The development of new rural energy system based on distributed photovoltaic system on rural rooftops is one of the most effective pathways to solve issues of agriculture, rural areas, and rural people. This is also the breakthrough point for China to build a new power system and achieve low-carbon energy system.

Hydrogen is one of the important technology choices for the low-carbon transition of China’s energy system and the carbon neutrality goal by 2060. According to the source, hydrogen can be divided into 3 kinds: green, blue and gray hydrogen. There are big differences in the cost and carbon emission intensity among them. Based on the current status of China’s hydrogen production. A levelized cost of hydrogen (LCOH) model was established with a learning curve. The cost trend of different hydrogen production methods was measured from 2020 to 2060. Results show that the cost of gray hydrogen is the lowest, and that of green hydrogen is the highest at present; by 2030, the cost of green hydrogen will drop to CNY 20-25/kg; after 2050, green hydrogen will become the lowest cost hydrogen (considering the cost of carbon emissions), the cost of hydrogen from PEM (proton exchange membrane) electrolysis will be lower than that of AE (alkaline) electrolysis, and the cost of hydrogen from photovoltaic power + PEM electrolysis will be reduced to CNY 12/kg. The decrease in the cost of electrolyzer and renewable electricity generation will be the main driving factors for the cost reduction of green hydrogen. Sensitivity analysis shows that operation & maintenance cost and learning rate of key technologies will significantly affect the cost reduction rate of green hydrogen.

Xinjiang Uygur Autonomous Region, as a major region for power production in China, also has a severe scarcity of water resources. Water footprint is a widely used comprehensive indicator that quantifies one area’s water consumption in the electricity production and its impact on the water environment. This paper used a combined model based on input-output and life cycle analysis to quantitatively analyze Xinjiang’s water footprint of power production in 2012 and 2017, and also investigated the water footprint contribution departments of various power generation technologies. The findings revealed that the water footprint per unit of electricity generation in Xinjiang decreased from 4.26×10^-3 m³/(kW∙h) to 3.08×10^-3 m³/(kW∙h) from 2012 to 2017 due to the change of electricity production structure and technological innovation of thermal power generation. We also discovered that the indirect water footprints of coal power and hydropower were primarily from mining and heavy industry, accounting for 60.3% and 52.8%, respectively, after analyzing the water footprint contribution departments of different power generation technologies. When it came to wind power and photovoltaic power generation technology, heavy industry and light industry accounted for 38.1% and 56.0% of the indirect water footprints, respectively. Furthermore, the high proportion of renewable energy generation from 2017 to 2050 will reduce the unit water footprint of Xinjiang’s power production by 75%, according to the analysis of the changes in the water footprint influenced by the transformation of Xinjiang’s power structure under China’s carbon neutrality target.

The evaluation on simulated runoff over China from the five regional climate model ensemble simulations was conducted. Based on these simulations, future changes in runoff under the high emission scenario RCP8.5 were also projected. The results show that the ensemble mean simulations can well capture the observed features of runoff. The simulation on spatial pattern of annual runoff performs well, while certain biases exist, especially the positive biases over the middle reach of Yellow River basin, the Haihe River basin, and the Song-Liao River basin. The simulations on the monthly contributions perform relatively poor over Southeastern, Southwestern, and Northwestern rivers basins among nine basins of China. From now to the end of 21st century, national mean annual runoff will mostly increase, with the magnitude of less than 5%. There are spatial differences in annual runoff changes, with roughly “increase in north, decrease in south”. However, the climatic pattern of runoff ranging from wet south to dry north will not change. The area-averaged trends are significant positive over the Yellow River, Southwestern and Northwestern rivers basins, significant negative over the Huaihe River, Yangtze River, and Southeastern rivers basins, and there are no significant trends over the Haihe River, Song-Liao River and Zhujiang River basins. At the end of 21st century, the changes are mostly within ±30% across China, and the agreements on change sign are high. At the end of 21st century, the overall characteristics of monthly contributions over each basin will change little, with the peak months mostly unchanged. The changes in monthly contributions will be within ±2%, and there are large differences among nine basins in increases or decreases at certain month or season.

The unprecedented drought on record occurred in the Yunnan-Guizhou region of China (YGR) during 2009/2010 and the central-south region of China (CSC) during the summer of 2013 in recent decades. The developing speed of the two drought events was analyzed. Based on the principle of water budget, the physical process that affects the development of drought was diagnosed. The results showed that before the development of CSC drought, temperature increased, evapotranspiration enhanced, soil moisture decreased, and high temperature and precipitation decrease had a triggering effect on the drought; while the decrease of precipitation in YGR caused the drought to develop. The CSC drought event developed rapidly, while the YGR drought event developed slowly. At the same time, the maintenance and recovery time of drought in the former is shorter than that in the latter. These differences are related to the strength of the evapotranspiration process. During the developing stage of the CSC drought event, the evapotranspiration process was strong, with an average of 4.7 mm/d and within 8 days, the soil moisture decreased from 45% to 20%, prompting the rapid formation of drought (flash drought). During the YGR drought developing stage, the evapotranspiration process was weak, with an average of 1.7 mm/d, and the reduction of soil moisture from 45% to 20% lasted more than 2 months (traditional drought). The strength of evapotranspiration is mainly related to the net divergence of water vapor in the regional atmospheric column. During the drought developing stage of CSC, its water vapor net divergence in the atmospheric column reached 3.1 kg/m² per day, which enhanced the land-atmosphere water exchange, making the evapotranspiration much greater than precipitation, and the rapid decline of soil moisture, accelerating the development of drought. The net divergence of water vapor in the regional atmospheric column of YGR was 1.1 kg/m² per day, which was only 1/3 of that of CSC, which slowed the development of drought. The net divergence of atmospheric column water vapor of the two drought events mainly occurred in the meridional direction, that is, caused by the relatively strong meridional water vapor outflow at the northern boundary of the region.

The Meili Snow Mountains (MLSM) is characterized as high topographic relief and diversified climate patterns in Southwest China. Characterizing spatial-temporal changes of temperature and precipitation is helpful in the quantification of glacier changes and hydrological process in the region. The lack of observations and low spatial resolution in reanalysis data are the main constraints to comprehensively characterize the meteorological conditions in this area. In this study, the bias corrected and downscaled ERA5-Land product with 1 km resolution was applied to explore the heterogeneity and altitudinal effect in precipitation and temperature changes during 1990-2020. Results are as follows. There is a significant upward trend at a rate of 0.15℃ / (10 a) in air temperature with spatial and seasonal differences. Precipitation shows a significant downward trend at a rate of -41.19 mm/(10 a). The whole area has a tendency becoming “warming and drying”. The warming is not obvious in areas when the altitude is below 4000 m or above 5000 m, in-between, the warming is elevation dependent. Precipitation also has a significant altitudinal gradient. When the altitude is lower than 5000 m, the precipitation on the west slope decreases with the increase of altitude, but increases with the increase of altitude when the altitude is above 5000 m. Precipitation on the eastern slope increases with elevation from 2000 m to 6000 m. The atmospheric circulation background and complex geographical environment together determine the spatio-temporal differentiation of climate change in MLSM. Continued warming and reduction of precipitation may further aggravate the loss of water resources and accelerate glacial retreat in this area.

Hazard, exposure and vulnerability are the key factors in the risk assessment of extreme low temperature events. Based on the daily minimum temperature, population and cultivated land in the China-Pakistan Economic Corridor (CPEC) for the period 1961-2015, nine indices including the intensity, frequency and duration of extreme low temperature events, population density, proportion of cultivated land area, vegetation fraction, digital elevation model (DEM), proportion of vulnerable population and gender proportion are selected, and the combination weight of each index is determined by analytic hierarchy process and entropy weight method. The risk assessment of extreme low temperature events in the CPEC has realized the zoning of different risk levels (low, moderately low, moderate, moderately high, high risk) of extreme low temperature events in the CPEC. The results show that there are significant spatial differences in the risk distribution of extreme low temperature events in the CPEC. The risk of extreme low temperature events is greatly affected by the intensity of extreme low temperature events, population density and terrain. Most areas in the region belong to low-risk areas, but include Pakistan’s Azad Kashmir, Gilgit-Baltistan, Federally Administered Tribal Areas (FATA), Khyber Pakhtunkhwa and Kashgar region of China belong to high-risk areas; Among them, the high-risk area in Azad Kashmir accounts for about 35%, and the moderately high risk area in FATA accounts for about 7.7%. In the Gilgit-Baltistan region, the area of moderate risk areas accounts for the highest proportion of about 24.6%. More than 10% of moderate risk areas are Khyber Pakhtunkhwa (12.5%), Azad Kashmir (20%), Kashgar region (14.3%) and FATA (10.2%). The results are consistent with the historical disasters, which can provide reference for regional meteorological disaster risk assessment and disaster prevention and reduction.

Low carbon development of cities plays a vital role for coping with climate change and reaching the goal of carbon peak and neutrality of China, which is significantly affected by territorial spatial master plans under the new territorial spatial planning system. In order to solve the problems existing in city greenhouse gas inventories, a greenhouse gas inventory model for territorial spatial master plan is developed in this paper. The model is tightly connected with urban planning, developed under the framework of spatial layout-land use-sector classification-inventory method, combining the method of top-down and bottom-up. Inventory methods for two levels of city area and central city are developed, which solves the greenhouse gas inventory problems of central city, so that international comparisons can be made. Different accounting methods are developed for greenhouse gas inventory to solve the incomplete energy demand forecast in master plan, which reduces the accounting uncertainty, compared with the method totally based on the land use. Base on the model, core indices and assisting indices are put forward to evaluate the low carbon development of territorial spatial master plan.

Since 2011, the construction of China’s carbon emission trading market has been accelerated, and the carbon emission trading mechanism has been continuously improved. The benchmark method has been determined as the main method of national carbon trading initial allowance allocation method. The electrolytic aluminum sector is a key sector in China’s energy consumption and carbon emissions. Incorporating electrolytic aluminum sector into carbon market as soon as possible is of great significance to the industry’s emission reduction, the in-depth promotion of national carbon market transactions, and the response to the challenge of international carbon tariffs. Based on the carbon emissions related data that directly reported by the electrolytic aluminum sector in 2018, this paper presents a benchmark plan for China’s electrolytic aluminum sector to carry out national carbon trading. The results show that the electrolytic aluminum sector should select 8.12-8.15 t CO₂ per t aluminum as the benchmark value, and there is no need to set the regional difference adjustment coefficient. At the same time, in order to ensure the smooth development of carbon trading in the electrolytic aluminum sector, it is necessary to determine the industry quota plan as soon as possible, further improve the monitoring, reporting and verification of corporate emissions to improve the quality of direct reporting data, and further study the scope of carbon emissions accounting for the electrolytic aluminum industry.

The dry-milling process is an important part of energy conservation and emission reduction technology in ceramic industry. However, it has not been widely applied. This paper evaluates the synergy between pollution reduction and carbon reduction of dry-milling process in the two representative enterprises in the south and the north of China. Through literature research and field research, the emission reductions of air pollutants and CO₂ in dry and wet milling technology were calculated by product coefficient method. Compared with the wet-milling process, the same production of 1 t powder can reduce the CO₂ emission by 51% of the dry milling technology. At the same time, the air pollutants can be significantly reduced, such as PM is reduced by 42%, NO_X is reduced by 45%, and SO₂ is reduced by 42%. The cross elasticity of dry powder collaborative control is positive, which shows that dry milling can realize the synergistic emission reduction of air pollutants and CO₂. Due to the difference in the moisture content of raw materials between the south and the north of China, the energy consumption of dry milling in the north decreased by 51%. The effect of reducing pollution and carbon by dry milling is better in the north with low moisture content of raw materials.