Analysis of the relationship between water and energy in China based on a multi-regional input-output method

Assessing the eco-efficiency of milk production systems using water-energy-labor-food nexus

Globally, massive resource inputs and undesired outputs hindered the further development of the dairy industry. This study proposed a method applying data envelopment analysis to the water-energy-labor-food nexus to assess the eco-efficiency of the milk production system (MEE) from a systemic perspective. Using national statistics on scale farms for the period 2014-2021, we illustrated the effects of scale and intensification on MEE in China. In the study period, the production cost increased by 23 % and milk production rose by 30 % at the same time. Despite the increases in both water and energy inputs, the rise in milk production weakened the resource burdens and thus lifted MEE by 24 %. The resource investment pattern shifted from water- and labor-oriented to energy-oriented. Under current conditions, production technology and system management were at higher superiority to advance than farm scale, while mechanization and on-farm clean energy production are the keys to further lifting MEE.

Minimizing energy footprint of seawater desalination system via wind power generation in coastal areas

Wind power has become an essential direction for transforming energy structures in energy-intensive seawater desalination under the dual goals of carbon peaking and carbon neutrality. In this study, the energy footprint of the case project is analyzed by combining the hybrid life cycle analysis and environmentally extended input-output modeling, which is compared with the traditional thermal desalination processes from the whole life cycle perspective. The analysis revealed that the total energy consumption of the seawater desalination driven by wind power generation can be reduced by 79.77% compared with the traditional thermal drive mode under the same water production scale. Although the energy consumption in the construction phase accounts for 24.97% of the total, the energy consumption per unit of water production can be reduced by about 80% after adopting wind power technologies. The payback period is 7.2 years, that is, the energy consumption can be balanced after around 7 years during the operation phase. The results showed that the wind-driven seawater desalination system can significantly decrease the energy consumption of the project, which attempts to provide implications for the upgrading of energy-intensive seawater desalination in coastal areas towards low-carbon transition.

Tele-connecting local consumption to cultivated land use and hidden drivers in China

China faces significant pressure on cultivated land resources due to the accelerated pace of urbanization in recent years. The study of embodied cultivated land offers a new perspective on alleviating pressure on cultivated land between different regions. However, the temporal dynamics characteristic and the intersectoral linkages of embodied cultivated land have rarely been systematically described. Therefore, we applied an environmental extended multi-regional input-output approach to analyze the spatial patterns and flow relationships of virtual cultivated land (VCL) between regional, provincial and sectoral scale in China from 2007 to 2017, considering both temporal and spatial dimensions. Then, we explored the hidden drivers of VCL change using structural decomposition analysis (SDA). Our results showed that trade embodied cultivated land increase by 8.5 % from 2007 to 2017. The flow trend is primarily flowed out from the less developed northwest China but with abundant cultivated land to the more developed regions of the southeast coast. Especially, in 2015, the net outflow of VCL from the northwest region reached 15.82 Mha, which was the maximum value during the study period. In addition, agricultural and construction sector were the major land consumption sector. VCL consumed by the agricultural sector declined 12.51 %, while the VCL consumed by construction sector had a significant growth in 2007-2017. Furthermore, the results of SDA revealed that cultivated land use intensity and per capita final demand were the main factors causing changes in embodied cultivated land. The results can help clarify the responsible parties for land consumption and provide a guarantee for alleviating the pressure on regional cultivated land resources.

Optimized multilateral crop trade patterns can effectively mitigate phosphorus imbalance among the involved countries

Phosphorus imbalance for cropland can greatly influence environmental quality and productivity of agricultural systems. Resolving cropland phosphorus imbalance may be possible with more efficient multilateral crop trade within the involved trading countries; however, the driving mechanisms are unclear. This study calculates phosphorus budgets in China and five central Asian countries and proposes two optimal multilateral crop trade models to mitigate the phosphorus imbalance. Results show that the current trading pattern between China and Central Asia is causing a phosphorus imbalance intensification. Phosphorus surpluses in China and Uzbekistan are 41.7 and 8.9 kg/ha, while Kazakhstan, Kyrgyzstan, Tajikistan, and Turkmenistan exhibit phosphorus deficits with the negative value of -0.7, -1.2, -0.8, and -0.8 kg/ha, respectively. However, under the optimal multilateral crop trade patterns, phosphorus budget of China and Central Asia will become balanced. Phosphorus imbalance intensification for China is reduced to -2525 and -2472 kt under the single- and bilevel-objective-based crop trades. In Kyrgyzstan, it will drop 61.5 % and 50.0 % and change to 321 and 417 kt under the two optimal crop trades. Moreover, changes of phosphorus imbalance mitigations for other central Asian countries range from 11.9 % to 28.2 %. This provides a scientific basis when establishing policies for strengthening optimal multilateral crop trading across the world to promote global phosphorus management.

Further mitigating carbon footprint pressure in urban agglomeration by enhancing the spatial clustering

The increasing environmental pressure of anthropogenic CO₂ emissions is impeding the sustainability of urban agglomerations (UAs). Recent research has shown that the spatial clustering of UA elements reduces CO₂ emissions but underestimates its impact on vegetation carbon sequestration. Using an extended IPAT equation analysis framework and the Logarithmic Mean Divisia Index decomposition approach, this study revealed the positive effects of the economy and population spatial clustering on carbon footprint pressure (CFP) mitigation. Specifically, improving economic spatial clustering mitigated the rise in UA's CFP caused by affluence and population growth. Furthermore, population clustering in core cities effectively mitigated CFP in neighboring cities. Additionally, we found that the efficiency improvement, i.e., the decrease in the ratio of carbon emissions and gross domestic product, should be the dominant driver of CFP mitigation, followed by improved vegetation carbon sequestration. However, these drivers have limited future potential. We believe that by improving UA's spatial clustering of the economy and population, future urban environmental pressures and climate risks will be mitigated.

Virtual Water Flow Pattern in the Yellow River Basin, China: An Analysis Based on a Multiregional Input-Output Model

Research on the Yellow River Basin's virtual water is not only beneficial for rational water resource regulation and allocation, but it is also a crucial means of relieving the pressures of a shortage of water resources. The water stress index and pull coefficient have been introduced to calculate the implied virtual water from intraregional and interregional trade in the Yellow River Basin on the basis of a multi-regional input-output model; a systematic study of virtual water flow has been conducted. The analysis illustrated that: (1) Agriculture is the leading sector in terms of virtual water input and output among all provinces in the Yellow River Basin, which explains the high usage. Therefore, it is important to note that the agricultural sector needs to improve its water efficiency. In addition to agriculture, virtual water is mainly exported through supply companies in the upper reaches; the middle reaches mainly output services and the transportation industry, and the lower reaches mainly output to the manufacturing industry. Significant differences exist in the pull coefficients of the same sectors in different provinces (regions). The average pull coefficients of the manufacturing, mining, and construction industries are large, so it is necessary to formulate stricter water use policies. (2) The whole basin is in a state of virtual net water input, that is, throughout the region. The Henan, Shandong, Shanxi, Shaanxi, and Qinghai Provinces, which are relatively short of water, import virtual water to relieve local water pressures. However, in the Gansu Province and the Ningxia Autonomous Region, where water resources are not abundant, continuous virtual water output will exacerbate the local resource shortage. (3) The Yellow River Basin's virtual water resources have obvious geographical distribution characteristics. The cross-provincial trade volume in the downstream area is high; the virtual water trade volume in the upstream area is low, as it is in the midstream and downstream areas; the trade relationship is insufficient. The Henan and Shandong Provinces are located in the dominant flow direction of Yellow River Basin's virtual water, while Gansu and Inner Mongolia are at the major water sources. Trade exchanges between the midstream and downstream and the upstream should be strengthened. Therefore, the utilization of water resources should be planned nationwide to reduce water pressures, and policymakers should improve the performance of agricultural water use within the Yellow River Basin and change the main trade industries according to the resource advantages and water resources situation of each of them.