Search

The increasing pressures of global warming, population growth and epidemic occurrence are causing challenges in meeting the growing requirements for water, energy and food. In particular, the contradiction between the supply and demand for water, food, and energy is exacerbated by inefficient resource utilization and carbon emission increase. Incorporation of the interlinked aspects of water, energy, food and carbon emissions from agricultural systems into one water-food-energy-carbon nexus facilitates integrated resource management. Biochar application to farmland is a potential strategy for carbon management and agricultural productivity improvement. The integration of biochar systems and the water-food-energy-carbon nexus is an efficient and coordinated alternative method for sustainable agricultural management and a crucial strategy for addressing water, energy and food security issues. Accordingly, this paper proposes an approach for the synergistic regulation of water, land, energy, and carbon emissions in a circular agricultural system by balancing water supply and demand, land allocation, electricity consumption, and economic upgrading principles. A two-stage circular agriculture framework is constructed, with biochar and electricity generated from agricultural residues at the first stage and employed at the second stage. Economic-environmental-energy harmonization is considered in the methodology, and the agrotechnical potential of biochar is quantified via crop yield increase and greenhouse gas emission reduction functions. This approach can assist decision makers in providing the best policy options given certain agricultural resources to achieve the maximum economic performance of the system while minimizing environmental side effects. In this paper, the model framework is applied to the Sanjiang Plain in northeastern China to verify the feasibility of the approach. The results indicate that the external electricity demand is reduced by 87.8% due to the generation of biofuels. Cropland greenhouse gas emissions are reduced by 34.09%–67.06% via the application of biochar. This study proposes an optimization method with important implications for the improvement of regional cropland management techniques and development of sustainable circular agriculture. This methodology can be extended to other agriculture-centered regions with limited resources and environmental problems. • Carbon cycle is integrated in agricultural water-food-energy-carbon (AWFEC) nexus. • An AWFEC nexus based model is developed for agricultural resources recycling. • Biochar and electricity are optimized sustainably for circular agriculture. • Analysis of resources recycling on economic-environmental balance is performed. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with the application of eMergy analysis to the sustainability of Chinese steel production in 1998–2004. Emissions'' impacts were quantified using eMergy synthesis and other methods (dilution method, disability adjusted life years (DALY) method and ecological cumulative exergy consumption (ECEC) method). The results show that its sustainability is very low and declining in this period, emissions obviously reduce the sustainability although their impacts are generally decreasing, and the main reasons lie in its low nonrenewable resources and energies'' efficiencies. Finally, the related suggestions were put forward for improving its comprehensive performance. [Copyright &y& Elsevier]

• Energy sustainability includes security, efficiency, cleanness, low carbon emissions. • Chinese energy sustainability has obvious spatial heterogeneity. • Cleanness and efficiency perform better than security, low carbon emissions in China. • Energy supply, consumption structure and pollution emissions are key impact factors. • Targeted measures are proposed to promote Chinese energy sustainability. Energy sustainability is one of the largest challenges for sustainable development. Energy sustainability in China varies by regions because of the differences in energy resources, technology and economic levels. Previous studies have assessed national energy sustainability, few to none have looked internally on a regional or provincial scale. This paper defined energy sustainability from the four dimensions of security, efficiency, cleanness and low carbon emissions, established an index system and evaluated the energy sustainability levels of 30 provinces in China by the Improved Entropy Weight-Cloud Model (IEW-CM). The results show that: (1) General energy sustainability in Chinese provinces is deficient, and energy cleanness and efficiency perform better than security and low carbon emissions. (2) Chinese energy sustainability has obvious spatial heterogeneity and within the same province, the level is unbalanced in four dimensions. The characteristics of energy sustainability exhibit significant differences in different regions. (3) Energy security and low carbon emissions play a crucial role in achieving energy sustainability. Natural gas deliverability, energy consumption elasticity coefficient, CO 2 emission per unit of energy and share of fossil energy consumption are the primary factors affecting energy sustainability differences among provinces. [ABSTRACT FROM AUTHOR]