City-level water withdrawal in China:Accounting methodology and applications

In the context of the freshwater crisis, accounting for water withdrawal could help planners better regulate water use in different sectors to combat water scarcity. However, the water withdrawal statistics in China are patchy, and the water data across all sectors at the city level appear to be relatively insufficient. Hence, we develop a general framework to, for the first time, estimate the water withdrawal of 58 economic–social–environmental sectors in cities in China. This methodology was applied because only inconsistent water statistics collected from different data sources at the city level are available. We applied it to 18 representative Chinese cities. Different from conventional perceptions that agriculture is usually the largest water user, industrial and household water withdrawal may also occupy the largest percentages in the water-use structure of some cities. The discrepancy among annual household water use per capita in the urban areas of different cities is relatively small (as is the case for rural areas), but that between urban and rural areas is large. As a result, increased attention should be paid to controlling industrial and urban household water use in particular cities. China should specifically prepare annual water accounts at the city level and establish a timetable to tackle water scarcity, which is a basic step toward efficient and sustainable water crisis mitigation

Local strategies for China's carbon mitigation: An investigation of Chinese city-level CO2 emissions

This paper provides a systematic analysis that identifies the driving forces of carbon dioxide (CO2) emissions of 286 Chinese prefecture-level cities in 2012. The regression analysis confirms the economic scale and structure effects on cities' CO2 emissions in China. If China's annual economic growth continues at the rate of 7%, CO2 emissions will increase by about 6% annually. In addition, climate conditions, urbanization and public investment in R&D are identified as important driving forces to increase the CO2 emissions of Chinese cities. While an increment of the urbanization rate by 1% increases the CO2 emissions by about 0.9%; An increase in R&D investment by 1% can help reduce CO2 emissions by 0.21%. As cities in our study vary greatly based on their industry composition, development stage and geographical location, the patterns of their CO2 emissions are also variable. Our study improves the comprehensiveness and accuracy of previous carbon accounting method by distinguishing the scope 1 and scope 2 CO2 emissions and establishing a high spatial resolution dataset of CO2 emissions (CHRED). The analysis covers almost all Chinese prefectural cities and derives useful implications for China's low carbon development

City-level water-energy nexus in Beijing-Tianjin-Hebei region

Water-energy nexus in a city can either prompt or undermine its development. Yet in China, the relevant research is rarely found. This study accounts the city-level water-energy nexus in Beijing-Tianjin-Hebei region in 2012 from both production and consumption perspectives, where input-output analysis based on city-level input-output tables are applied to conduct consumption-based accounts. Regarding water for energy, Beijing, Tianjin and Tangshan occupy the largest amounts of water for production in the energy sector, at 203 million tonnes (Mt), 148 Mt and 118 Mt, and they also consume most water for energy, at 6690 Mt, 1328 Mt and 1476 Mt. In terms of energy for water, Shijiazhuang and Tianjin have the largest amounts of CO2 emissions for production and consumption respectively, at 28 thousand tonnes (Kt) and 1746 Kt. Furthermore, local authorities should prioritise electricity sector as it holds 69% and 72% of the total water amounts for production and consumption in the energy sector. Besides, integrated management is crucial for cities with low water and energy efficiency (Baoding and Zhangjiakou), and for large CO2 emitters in Hebei province in order to ensure their water and energy sustainability without stunting their economic growth

Performance Analysis of Ultra-Scale Downwind Wind Turbine Based on Rotor Cone Angle Control

The theoretical feasibility of the power output strategy based on rotor cone angle control for ultra-scale downwind wind turbines is studied in this paper via the Open FAST simulation platform. The performance of five cases, namely UW, DW, DWC, DW6, and DW6IC, which have different rotor parameters or control strategies compared with the reference DTU 10 MW wind turbine, are calculated and analyzed. It is found that the downwind rotors have significant advantages in reducing the blade root load. The DW case reduces the peak load at the blade root by 22.54% at the cost of 1.57% annual energy production loss. By extending the length and redesigning the stiffness of the blade, the DW6 case achieves 14.82% reduction in the peak load at the blade root and 1.67% increase in the annual energy production under the same blade weight as that of the UW. The DWC case with rotor cone angle control has the same aerodynamic performance as the DW case with the same blade parameters. However, when the wind speed achieves or exceeds the rated speed, the blade root load decreases at a greater rate with the increasing wind speeds, and achieves minimum load with a wind speed of 16 m/s. Compared with the UW case, the DW6IC case with the improved rotor cone angle control reduces the peak load of the blade root by 22.54%, leading to an increase in annual energy production by 1.12% accordingly

City level water withdrawal and scarcity accounts of China

In the context of China’s freshwater crisis high-resolution data are critical for sustainable water management and economic growth. Yet there is a dearth of data on water withdrawal and scarcity regardless of whether total or subsector amount, for prefectural cities. In administrative and territorial scope, we accounted for water withdrawal of all 63 economic-socio-environmental sectors for all 343 prefectural cities in China, based on a general framework and 2015 data. Spatial and economic-sector resolution is improved compared with previous studies by partitioning general sectors into industrial and agricultural sub-sectors. Construction of these datasets was based on selection of 16 driving forces. We connected a size indicator with corresponding water-withdrawal efficiency. We further accounted for total blue-water withdrawal and quantitative water scarcity status. Then we compared different scopes and methods of official accounts and statistics from various water datasets. These disaggregated and complete data could be used in input-output models for municipal design and governmental planning to help gain in-depth insights into subsector water-saving priorities from local economic activities

Spatiotemporal Changes of China's Carbon Emissions

Spatiotemporal changes in China's carbon emissions during the 11th and 12th Five‐Year Plan periods are quantified for the first time through a reconstructed nationwide high‐resolution gridded data set. The hot spots of carbon emissions in China have expanded by 28.5% (toward the west) in the north and shrunk by 18.7% in the south; meanwhile, the emission densities in North and South China have increased by 15.7% and 49.9%, respectively. This suggests a clear transition to a more intensive economic growth model in South China as a result of the energy conservation and emission reduction policies, while the expanded carbon hot spots in North China are mainly dominated by the Grand Western Development Program. The results also show that China's carbon emissions exhibit a typical spatially intensive, high‐emission pattern, which has undergone a slight relaxation (up to 3%) from 2007 to 2012 due to a typical urbanization process

A Pitch Angle Controller Based on Novel Fuzzy-PI Control for Wind Turbine Load Reduction

A novel fuzzy rule is proposed to adopt a positive pitch strategy when the error between the measured and rated generator speed becomes large and continues to increase, and to adopt a negative pitch strategy when the error is small. The improved approach is introduced into the normal Fuzzy-Proportional-Integral (Fuzzy-PI) control strategy by dividing the fuzzy rules into four areas and analyzing the design method for each area. Furthermore, a low pass filter is used to reduce the ultimate loads of the pitch driver caused by the novel fuzzy rules. The modeling of the wind turbine load under turbulent wind conditions is conducted in GH Bladed, and MATLAB/Simulink is used to interact with the modeling to verify the novel Fuzzy-PI control. The results show that, compared with normal Fuzzy-PI control, the novel Fuzzy-PI control can greatly reduce the ultimate loads and fatigue loads of the pitch driver. The novel Fuzzy-PI control not only reduces the extremum of power deviation, but also decreases some ultimate loads and fatigue loads of the tower base and the blade root. It can reduce these loads by up to 21.53% under the normal turbulent wind condition and by up to 18.14% under the extreme turbulent wind condition

Determination of Phthalates Released from Paper Packaging Materials by Solid-Phase Extraction -High-Performance Liquid Chromatography

A solid phase extraction (SPE) high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of 10 phthalic acid esters (dimethyl phthalate, diethyl phthalate, dipropyl phthalate, benzylbutyl phthalate, diisobutyl phthalate, dicyclohexyl phthalate, diamyl phthalate, di-n-hexyl phthalate, di-n-octyl phthalate and di-2-ethylhexyl phthalate) released from food paper packaging materials. The use of distilled water, 3% acetic acid (w/v), 10% ethanol (v/v) and 95% ethanol (v/v) instead of the different types of food simulated the migration of 10 phthalic acid esters from food paper packaging materials; the phthalic acid esters in four food simulants were enriched and purified by a C18 SPE column and nitrogen blowing, and quantified by HPLC with a diode array detector. The chromatographic conditions and extraction conditions were optimized and all 10 of the phthalate acid esters had a maximum absorbance at 224 nm. The method showed limitations of detection in the range of 6.0-23.8 ng/mL the correlation coefficients were greater than 0.9999 in all cases, recovery values ranged between 71.27 and 106.97% at spiking levels of 30, 60 and 90 ng/mL and relative standard deviation values ranged from 0.86 to 8.00%. The method was considered to be simple, fast and reliable for a study on the migration of these 10 phthalic acid esters from food paper packaging materials into food

Regional uncertainty of GOSAT XCO_2 retrievals in China: quantification and attribution

The regional uncertainty of the column-averaged dry air mole fraction of CO_2 (XCO_2) retrieved using different algorithms from the Greenhouse gases Observing SATellite (GOSAT) and its attribution are still not well understood. This paper investigates the regional performance of XCO_2 within a latitude band of 37–42° N segmented into 8 cells in a grid of 5° from west to east (80–120° E) in China, where typical land surface types and geographic conditions exist. The former includes desert, grassland and built-up areas mixed with cropland; and the latter includes anthropogenic emissions that change from small to large from west to east, including those from the megacity of Beijing. For these specific cells, we evaluate the regional uncertainty of GOSAT XCO_2 retrievals by quantifying and attributing the consistency of XCO_2 retrievals from four algorithms (ACOS, NIES, OCFP and SRFP) by intercomparison. These retrievals are then specifically compared with simulated XCO_2 from the high-resolution nested model in East Asia of the Goddard Earth Observing System 3-D chemical transport model (GEOS-Chem). We also introduce the anthropogenic CO_2 emissions data generated from the investigation of surface emitting point sources that was conducted by the Ministry of Environmental Protection of China to GEOS-Chem simulations of XCO_2 over the Chinese mainland. The results indicate that (1) regionally, the four algorithms demonstrate smaller absolute biases of 0.7–1.1 ppm in eastern cells, which are covered by built-up areas mixed with cropland with intensive anthropogenic emissions, than those in the western desert cells (1.0–1.6 ppm) with a high-brightness surface from the pairwise comparison results of XCO_2 retrievals. (2) Compared with XCO_2 simulated by GEOS-Chem (GEOS-XCO_2), the XCO_2 values from ACOS and SRFP have better agreement, while values from OCFP are the least consistent with GEOS-XCO_2. (3) Viewing attributions of XCO_2 in the spatio-temporal pattern, ACOS and SRFP demonstrate similar patterns, while OCFP is largely different from the others. In conclusion, the discrepancy in the four algorithms is the smallest in eastern cells in the study area, where the megacity of Beijing is located and where there are strong anthropogenic CO_2 emissions, which implies that XCO_2 from satellite observations could be reliably applied in the assessment of atmospheric CO_2 enhancements induced by anthropogenic CO_2 emissions. The large inconsistency among the four algorithms presented in western deserts which displays a high albedo and dust aerosols, moreover, demonstrates that further improvement is still necessary in such regions, even though many algorithms have endeavored to minimize the effects of aerosols scattering and surface albedo