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With the rising concerns about climate change and technological developments, the deployment of low carbon technologies (LCT) is gaining importance for reliable and sustainable power system operation. To decarbonize the heat and transportation sectors, LCTs such as heat pumps (HP) and electric vehicles (EV) are integrated into the power system from the low voltage (LV) distribution network, where predominantly end-users are connected. However, the increasing penetration of EVs and HPs, together with distributed photovoltaic (PV) systems on the demand side, can cause technical challenges in LV distribution networks, such as under/over voltages at the far end of the feeders. Therefore, the hosting capacity of a grid for LCTs is limited due to network constraints such as line ampacity, bus voltage, and frequency. In this paper, voltage-constrained management approaches for LCTs are proposed to improve the grid hosting capacity in a real large-scale distribution network. Moreover, HPs, PVs, battery energy storage systems (BESS), and EVs as well as their vehicle-to-grid (V2G) feature are evaluated as LCTs. The uncertain behavior of these technologies is taken into consideration for more realistic analyses. In addition, the charging and discharging interactions of BESSs are controlled by following the power consumption profiles from the economic point of view. Furthermore, the hourly carbon data is used to control BESSs from an emission-sensitive aspect. To demonstrate the effectiveness of the proposed algorithms, a series of tests is conducted on a real distribution network model. The results show that the hosting capacity of the considered LV network can be increased from 35% to 50% using the proposed algorithms. The promising results obtained in this study pave the way for future active LCT management studies to improve hosting capacity in urban networks, and pilot demonstrations in the field.

This paper investigates the deployment over time of a shipping infrastructure to enable carbon capture and storage from Norwegian industries. In particular, optimal transport investments, routing, shipping portfolio, and transport conditions required cost-efficiently connect nine Norwegian and Swedish industrial facilities to the Northern Light Initiative are identified based on a multi-period mixed-integer model. Optimization of the shipping portfolio allows us to analyze the potential benefits of economics of scale and how sailing multi-stop routes can utilize the potential benefits. Analyses show that the transport cost can be reduced by 12% when the optimal shipping portfolio is implemented instead of operating an independent transport chain for each emission source. Shipping at 7-bar is expected to result in lower costs compared 15-bar shipping, but a significant drawback is the technological maturity of the 7-bar transport technology. The model proposes two transport chains run in parallel as cost optimal, the average transport cost of the 15-bar chain is 32.4 €/ton, and the 7-bar has an average cost of 25.4 €/ton. A net present value criterion is used to identify the conditions for when retrofitting of the 15-bar transport chain is economically sound. Break-even is achieved when the ship's re-sale price is 60% of the purchase price, and the cost of retrofitting a 15-bar conditioning plant to a 7-bar is 40% of the investment cost. While retrofitting may be an attractive solution, the decisions lead to a less robust shipping portfolio, and the retrofitting of a fully operating carbon capture and storage value chain is regarded as unlikely.

Managing the transition to a low carbon economy is a complex challenge that needs both early wins and a longer-term alternate technologies leapfrog, to better supplement existing public policies. Relative to the significant investment and policy focus on renewable energy generation and Electric Vehicles (EV) - both globally and in India - Stationary Energy Storage systems (ESS) have received far lower investment and policy attention. This is an important issue to redress for two key reasons. Firstly, ESS is a key rate limiting constraint to achieve the desired benefits of further increasing the share of renewables in the energy generation mix, in India's case from the current 20–25% to a target 40%+ range by 2030. Secondly, several ESS applications are already/very nearly economically viable. Although the dominant discourse focuses on EVs, our analysis in this paper shows that there is a bigger near term opportunity in India for Stationary Battery Energy Storage Systems (BESS) to replace diesel gensets for power backup. Interestingly India offers a meaningful level of scale for power-backup applications, for adoption directly by end-users. BESS as an alternative to Diesel Generator (DG) for power backup is economically viable in the Telecom sector and for roof-top solar installations; further non-subsidy levers e.g. differential tariffs and an annual cess on DG use, can drive economic viability in large campuses e.g. residential, schools and commercial buildings. These applications could offer a BESS demand ranging from 40 to 145 GWh over the next three years – which is more than the BESS demand estimates for EV segment of 40 GWh. Our study is verified and supported by experiential insights derived through primary research, personal interviews and hosting round-table discussions with relevant private and public policy experts. The conclusions from this paper raise the interesting public policy and business strategy implications, 1 of given the economic viability and significant demand why has the adoption up to this potential not yet taken off, and what will it take to achieve this potential?

Generations of city development attempt better sustainable guidelines. This reflects on the number and areas of sustainable land plots therein. Nevertheless, city development goes without evaluating potential sustainable sites. This requires further spatial study to support sustainable site selection (SSS). Hence, this paper discusses SSS in new city development and locates potential land plots which comply with The Leadership in Energy and Environmental Design (LEED) credits' criteria in two categories: on the project level ‘Sustainable Sites’ (SS) and the context level, the ‘Location and Transportation’ (LT). This discusses two generations of city development in Egypt, taking a case study for each: the 10th of Ramadan city (first generation) and Badr city (second generation). This pilot study is based on reliable data obtained from the General Organization for the Physical Planning (GOPP) database in Egypt. A comparative Geographic Information System (GIS)-discrete Multiple-criteria decision-making (MCDM) method was adopted. This consisted of the following steps; 1) database layering and Geo-referencing maps were carried out using the GIS, 2) LEED credits' were used to populate the database to develop a weighted sum model (WSM) through a weighted-sum overlay technique, 3) a Land Suitability Index (LSI) was computed using GIS natural breaking classification to rank potential sites into ‘Yes’, ‘Maybe’ and ‘No’ scoring, 4) SSS raster maps were developed based on point-scoring contribution (PSC) of each city towards the environmental features described in each LEED credit. The result showed that Badr city (second generation) had more qualified sustainable sites compared to the 10th of Ramadan city (first generation). This was because the second generation of city planning guidelines provided more land plots with surrounding densities and diverse uses, access to quality transit, reduced parking footprint and more open spaces. Furthermore, land plots in both cities had more potential to obtain points under the SS category rather than the LT category due to missing sustainable local planning regulations. Also, the final weighted-sum overlay analysis showed that only 10% and 27% of total land areas in the 10th of Ramadan city and Badr city, respectively, were qualified to obtain points under both categories. The output interactive maps were made available for public use via a public domain website and the outcome of the study was tested among practitioners for validation. This showed major interest for planners and researchers, followed by investors and policymakers. Accordingly, this study can be replicated to create mapping criteria for sustainable sites in new development areas and consider it for a resilient urban planning policy.

Growing economic crisis and strict government policies and regulations regarding the environment have forced the battery industries to practice the recycling process for both economic and environmental benefits. Moreover the consideration of sustainability issues makes the recycling process more significant, successful implementation of recycling activity in the battery industry requires several strategic decisions. Among these decisions, a complex decision faced by the management is to identify the suitable location for the establishment of a formal Battery Recycling Plant (BRP). In this research work, a three-stage hybrid methodology with the combination of ISM (Interpretive Structural Modeling), fuzzy AHP (Analytic Hierarchy Process), and fuzzy COPRAS (Complex Proportional Assessment of Alternatives) methods was proposed to select the best sustainable location from the available options for BRP in India. In this study, a total of eight experts were selected from both academia and industry. Initially in this paper, 4 main sustainable criteria and 20 sustainable sub-criteria were considered from the literature review and field visits along with experts’ opinions for evaluation of alternatives. This work contains three stages. In the first stage, the ISM method was used to filter 18 important sustainable sub-criteria from the primary list of 20 sub-criteria, based on its higher driving power. Then, fuzzy AHP was applied in the second stage to compute the criteria weights. In the last stage, the fuzzy COPRAS was used to rank and choose the best sustainable location for BRP. The findings emphasize that the Environmental protection level, Distance from residential areas, Distance from water source, Capital investment, Government policies, Social acceptance, Availability of scrap batteries, and Availability of utilities were the most significant criteria in the sustainability dimension. Thus, the present work helps the management in the selection of an appropriate sustainable location for BRP.

This paper proposed a Fuel Cell Electric Vehicle (FCEV) power system model which was validated by Hardware-in-the-Loop (HIL) real-time emulation. Multi-stack Fuel Cell (MFC) system was used to increase the system redundancy. Nickel-metal Hydride (NiMH) battery pack (BAT) was selected as the secondary energy source. Dual-input single-output Boost converters were connected with MFC system to satisfy the voltage requirement of DC bus. Bi-directional Buck-Boost converter was connected with BAT and then both discharging and charging modes were controlled. Close loop control strategies were developed for converters to assure their stabilities. Rule-based Energy Management Strategy (REMS) was proposed to distribute the required power among Proton Membrane Exchange Fuel Cells (PEMFCs) and BAT. The proposed model was evaluated by HIL real-time emulation, using the Supplemental Federal Test Procedure US06 (SFTP-US06) driving cycle. MicroLabBox, in which real-time processor and Field Programmable Gate Array (FPGA) were embedded, was selected as the HIL real-time validation platform. The MFC system, BAT model, REMS and low-level controllers were executed by real-time processor while the converter general models were built in FPGA. According to the results, the proposed model and method effectively driven MFC system operating in high efficiency region and successfully kept BAT State of Charge (SOC) in the desired range.

This paper investigates the success of sustainable product innovation in the textile, clothing, and leather industry. Basing on the typology of Medeiros et al. (2014) a literature review was conducted to update the critical success factors. To investigate the importance of the factors, this research made use of a mixed methodology. 1634 digital news magazine articles and corporate communications were collected in a database describing the development and introduction of 176 new products from 158 companies using low-waste, circular, or “fair” production processes and new materials such as organic, recycled, bio-based synthetic fabrics. From the product and innovation managers responsible, a sample of 33 respondents participated in a survey, where their products had to be evaluated using operationalizations of three success aspects and fourteen success factors. Additionally, five sustainable textile product innovation experts characterized all 176 products in a similar manner, based on the information in the database. Relying on an indirect benchmarking approach both samples produce similar conclusions. The most important success factors are customer expectation fulfillment (in first place) followed by compliance with laws and regulations, green creativity, knowledge about factors that drive sustainable buying, investments in R&D infrastructure, and competitor monitoring. While the importance of market acceptance and the understanding of customers’ perspectives is highlighted, the research makes a contribution to the literature on success factors of sustainable textile innovations.

Small and medium-sized enterprises (SMEs) play a very important role in national production, and provide more than 60% of the employment opportunities for the society. The benign development of small and medium-sized enterprises determines the sustainability of economic operation. In recent years, small and medium-sized enterprises have faced increasing operational pressure. Due to scale limitations, insufficient funds and weak bargaining power, small and medium-sized enterprises are often at a disadvantage when dealing with suppliers. One the one hand, large suppliers rely on the imbalance of bargaining power to increase the transaction costs of small and medium-sized enterprises; On the other hand, small and medium-sized suppliers with poor reputation may use legal loopholes to commit fraud, which may even threaten the survival of small and medium-sized enterprises in severe cases. However, the existing literature focuses more on the situation of large organizations facing complex and diverse suppliers. Therefore, this paper constructed a supplier selection evaluation framework for small and medium-sized enterprises, and proposed an extended PROMETHEE Ⅱ method to achieve sustainable supplier selection process. First, establish a sustainable supplier selection evaluation framework from the three dimensions of product and service capability, cooperation degree and risk factors; Second, combine the PROMETHEE Ⅱ approach with subjective preference parameters and probability language term set (PLTS) to obtain an extended PROMETHEE Ⅱ approach; Last, use the methodology of this paper to implement sustainable supplier selection for a small and medium-sized enterprise (M company) in China. The practical case and sensitivity analysis showed that the evaluation framework and method proposed in this paper were applicable and effective. Actual cases and sensitivity analysis showed that cost, credit and corporate irregularities were the three most important aspects for small and medium-sized enterprises to evaluate supplier performance.

Green development is a common goal pursued globally for carbon neutrality, and whether environmental regulatory system drives it in pollution-intensive industries (PIIs) is puzzled. Using provincial panel data of Chinese PIIs during 2005–2017, this paper applied entropy method to integrate existing environmental regulatory system into three types of environmental regulations, and then explored non-linear effects of them on green total factor productivity (GTFP). Several conclusions are generated. The annual growth rate of GTFP is 10.61% and it presents industrial differences. Technical change is the driving factor, while technical efficiency shows inhibiting effect. The effect of command-and-control environmental regulation on GTFP is a significant inverted U-shape curve, which is currently the primary driving role in green development, but it is too strict and increasingly less effective. Both market incentive and voluntary environmental regulations appear as positive U-shape curves, and their proper enhancement is breakthrough for future green development. Besides, market incentive environmental regulation is more effective in PIIs with relatively low pollution, while voluntary environmental regulation is sensitive to PIIs with relatively serious pollution. The Chinese government should allow environmental regulatory system more marketability and voluntariness, and production characteristics and pollution density of targeted industries should be considered.

Social life cycle assessment (S-LCA) is a tool to address social impacts from a life cycle perspective. This work presents the first S-LCA of the Portuguese pulp and paper sector. It presents the social risks and the positive social impacts of the sector, which have not been extensively covered in the scientific literature. Two different approaches were used to compile the social life cycle inventory based on input-output analysis. Approach 1 was based on impact analysis of changes in added value. Approach 2 was based on structural path analysis, supporting the disaggregation by production levels (or tiers). The functional unit was the production of 1 United States Dollar in the Portuguese pulp and paper sector. In the social life cycle impact assessment, the social risk assessment was conducted using the Social Hotspots Database. The positive impacts were addressed considering indicators of employment and remuneration, namely total employment, number of employees, labor compensation, and compensation of employees. Based on Approach 1, the results of the social risks showed the Portuguese pulp and paper industry, commerce and forestry sectors, and the Spanish forestry sector as the critical sectors. Based on Approach 2, Portugal and Spain continued to be the countries having the greatest social risks. Other contributions of countries were identified at different production levels, particularly China in tier 3. In both approaches, the stakeholder category ‘worker’ was the most critical. Regarding the positive social impacts, Approach 1 showed that Portugal and Spain contribute to the highest employment level linked to the pulp and paper, commerce, and forestry sectors. Approach 2 supported the differentiation of employment and remuneration at different production levels. Tier 2 (direct suppliers) presented the highest employment level and people engaged and the lowest remuneration level. The results showed that Approach 1 provides a faster and more aggregated assessment of social risks and positive social impacts. Furthermore, Approach 2 allowed a more detailed evaluation, providing a better understanding of the social risks and positive social impacts on the supply chain. Thus, Approach 2 is encouraged for different applications since it produces a better understanding of where social risks and positive social impacts occur, providing better guidance for corrective measures and decision-making.

Global environmental goals require immediate action to combat climate change and biodiversity loss. Yet, despite growing public awareness, policies adopted, and research undertaken, societies are far from transitioning to sustainability. The barriers to a transition are complex and diverse. Previous research identified motivational factors that impede societal change: knowledge, values, self-interest, structural problems, concepts of normality and emotions. The aim of this paper is to investigate if these factors are reflected in the casecomments about of meat and animal-derived product consumption. In order to overcome a number of shortcomings of frequently used social research methods (e.g. surveys, focus groups, interviews), we adopt a qualitative content analysis of web news comments. We choose this approach because content analysis is an unobtrusive research method which provides undistorted and hence valuable insights into the attitudes/motivations/emotions etc. of the commentators. The results show that self-interest, concepts of normality as well as emotions such as fear, frustration, anger and lacking trust seem to make a transition to sustainability very difficult. Values appear to both impede and enable sustainable behaviour while knowledge only plays a minor role. These factors in combination with the interdependence of all actors of society might explain why achieving global environmental goals is so very challenging.

Beach tourism in an important industry in many countries, and in the Mediterranean it supposes an extra pressure on the seawater quality. Concern about this aspect led the European Union to issue a first directive on the quality of bathing water in 1976 and modify it in 2006. This regulation establishes a mandatory control, in all European Union (EU) countries, of the proliferation of bacteria (specifically Intestinal enterococci and Escherichia coli) that can cause serious harm to public health. Meanwhile, the Blue Flag program born in 1987 as an award granted by the Foundation for Environmental Education, to which all municipalities that so wish can voluntarily participate, aimed to publicly value beaches. This award adds to the beaches that receive it a commitment to superior water quality, among other requirements, to that required by the European Union which attracts tourists. The aim of this paper is to obtain empirical evidence of beaches awarded with a Blue Flag (BF) have cleaner waters than those ones that have not in the three main tourist destinations in the Mediterranean that represents circa 5000 coastal monitoring points: Spain, France and Italy. The results point out that the BF areas have significantly cleaner waters than the monitoring points that are not in these areas.

Energy is essential for socio-economic development and due to the increase in energy consumption it is necessary to look for renewable and clean energy over the coming decades. Wind energy has received more attention than other sources due to better economic conditions as well as lack of environmental pollution and unlimited wind resources. This paper describes a practical method for measuring the potential of wind resources with the ability to generate electricity, using the geographic information system and considering the selection criteria of wind farms. The present study analyzed a multi-criteria decision support system to define wind energy resources in western Iran. In the method of calculating wind potential in this paper, the desired items are considered with equal importance and these criteria include technical, environmental, economic and geographical factors. The aims of this research are measuring the potential of areas suitable for generating electricity from wind energy for large turbines according to international standards, stating the standards and criteria for measuring the potential of wind resources and finally implementing the items mentioned in regional electricity. The results show that assuming the use of Gamesa G58 turbine, a maximum of 1897 MW of wind power can be generated in the study area, which is 26% of the region's electricity supply in 2025 horizon. The method used in this study can be applied for future wind potential measurements and it is recommended to be integrated with fuzzy AHP method to enhance the accuracy of the results.

Currently, agriculture uses about 70–80% of global water resources and, in the Mediterranean area, it accounts for the high pressure of freshwater demand. This study provides a useful framework for the meso-level assessment of the Water Footprint (WF) in agriculture. Particularly, the WF methodology is used to quantify the water consumption and pollution of olives, grapes and tomatoes, traditional crops widespread both in the Apulia region, in Southern Italy, and in the Mediterranean area. Hence, from a meso-level assessment of the Water Footprint of Apulian agriculture, a general level of evaluation of the use of Mediterranean water resources was provided, estimating the Virtual Water (VW) too. Furthermore the climate change effects on the Water Footprint of the traditional crops identified were predicted, proposing some scenarios useful to reduce the grey component, which values for olives were evaluated by a sensitivity analysis. The results highlight that olives present the highest value of the WF and that grapes are the most affected by the variations according to the climate change scenarios, increasing over 200% of the green component and 77% of the blue one. Finally, a Circular Economy proposal, based on the reuse of the wastewater from a meso-scale perspective, highlights saving up to 70% of the water resource. The research questions proposed displayed the novelty of this paper, particularly as concerns the use of the Water Footprint analysis on a meso-level evaluation. Particularly, the new insights of this research addressed the needs of stakeholders in areas suffering from drought, such as the Mediterranean, to integrate and systematize a data-set of indicators to rationalize and plan water resource usage and safety in agriculture.

The 2030 Agenda for Sustainable Development stipulates 17 Sustainable Development Goals (SDGs). The implementation of this agenda will mobilize countries worldwide to incorporate the SDGs into their national development strategies. The agenda does not specify how these goals are interconnected, thus limiting their implementation. In addition, air quality affects human life and plays a vital role in achieving these SDGs. Clarifying the interconnections between SDGs related to air pollution and other SDGs will accelerate the implementation of air protection and SDGs while simultaneously promoting policy coherence. In this paper, we use the latest calculation of the SDGs in China to construct national and provincial panel data to investigate the trade-offs and synergies among Chinese air pollution-related SDGs. The findings are as follows. First, most air pollution-related SDGs have synergetic relationships, except for SDG12, which has a trade-off relationship with other air pollution-related SDGs. Second, the synergies between air pollution-related SDGs and other SDGs far outweigh the trade-offs. Third, rapidly developing areas are more likely to experience a trade-off between economic development and air pollution problems. Fourth, geographic advantages in reducing air pollution, such as being adjacent to the sea, may weaken the synergies among air pollution-related SDGs and their synergies with other SDGs. These findings indicate that most air-pollution-related SDGs and interactions between air-pollution-related SDGs and other SDGs have substantial synergy; that is, measures aimed at one goal are conducive to the advancement of other goals. However, SDG12 reflects a trade-off relationship between economic development, environmental protection, and resource utilization.

Many studies have verified that zombie firms have serious negative effects in the economic field, but it is unclear whether those effects will extend to the environmental field. Based on China's firm-level data, this paper investigated the impact and mechanisms of zombies on wastewater discharge behavior by normal firms. The empirical study showed that the higher the proportion of zombies in a province is, the greater is the wastewater discharge by normal firms, which proves that zombies also have serious negative effects in the environmental field. The first mechanism is tax burden, which means that an increase in the proportion of zombies will induce the local governments to raise the actual tax rate on normal firms, which will worsen their financial situation and prompt them to increase wastewater discharge. The second one is institution quality, which means that the higher the proportion of zombies in a province is, the worse is the institution quality. In a low-level institutional environment, it is difficult to form effective governance on pollution. The last one is regulation power, which means that the higher the proportion of zombies is, the stronger is the incentive for local government officials to pursue GDP by relaxing environmental regulations. The contribution of this study is an extension of the research on zombies to the environmental field, which is significant to the in-depth understanding of the widespread, global problem of zombies. This study provides an important idea for countries committed to environmental protection. In addition to direct channels such as environmental regulation, indirect channels such as reducing unreasonable government intervention, speeding up the clearance of inferior firms, and creating a healthy market environment are also of enormous importance.

Carbon emission trading mechanism is an important market-based instrument to address global climate change. The auction ratio and price of carbon emission allowances (CEA) are cores of the carbon emission trading mechanism. What combination of CEA auction ratio and auction price is most conducive to carbon emission reduction for emission control enterprises? There are still relatively few studies conducted on this issue, and there is no clear answer from the views of theory and practice. In this paper, the AIM/Enduse model was used to analyze the changes and differences of installed power capacity, power supply, energy consumption and carbon emissions in the Guangdong-Hong Kong-Macao Great Bay Area (GBA) with different combinations of CEA auction ratios and prices. Moreover, the best pathway of energy transition was explored in the power industry of the GBA, and the best combination of CEA auction ratios and prices was identified in the GBA. The results show that: (1)The carbon emission constraint starts to work only when the auction ratio of CEA is increased to 50% and the auction price is increased to 60 CNY/ton (Scenario p3). When the auction ratio of CEA is 100% and the auction price reaches 120 CNY/ton (Scenario p5), a low-carbon transition of the power sector in the GBA can be achieved. (2) Under scenario p5, the total cost of power transition rises and then falls. And the cost of carbon in the power sector increases exponentially as the auction ratio of CEA and the auction price rise. However, the growth in the cost of power supply is relatively flat, which shows that appropriate carbon trading mechanism can improve the economic benefits of power sectors. With the increase of installed capacity of clean low-carbon energy generation and power supply, as well as the decrease of local power cost in the GBA, the proportion of outsourcing power can be appropriately reduced in the future, with an aim to reduce the external dependence of electricity to ensure the security of energy supply. In the end, it suggests that cities in the GBA should give full play to their regional advantages and establish a unified carbon emission trading market in the GBA as soon as possible. This study provides a theoretical basis for the supplementation and improvement of China's carbon emission trading mechanism.

The present research deals with a novel hybrid system comprises of a salinity gradient solar pond (SGSP) integrated with a proton exchange membrane fuel cell (PEMFC) and a thermoelectric generator (TEG). The key novelty of this research is the use of PEMFC waste heat to increase the performance of the low-temperature heat source (solar pond). Also, a thermoelectric generator is employed in the proposed setup for complete waste energy recovery. In this paper, the proposed system's energy, exergy, and economic (3E) performance are investigated, as well as compared with two additional systems that were modelled by excluding TEG and PEMFC to showcase the benefits of the sub-systems in the final configuration. A parametric study is also conducted to investigate the effect of significant parameters on the overall system performance. The simulation results indicated that the integrated system's net output power is 2288.8 kW at a base case operating condition, with energy and exergy efficiency of 11.26% and 13.17%, respectively, and a system cost rate of 394 $/h. In comparison to other components in the integrated system, SGSP alone accounts for 75% of total exergy degradation and has the highest investment cost of 66.70 $/h. Further, to achieve the best system performance, a multi-criteria optimization is performed for the suggested system with net output power, energy efficiency, exergy efficiency, and system cost rate as objective functions. Besides, the multi-criteria decision analysis (MCDA) is also carried out on the obtained Pareto front using TOPSIS decision-maker to select the best operating condition that improves the output power, energy, and exergy efficiency by 52.6%, 49.6%, and 61.8%, respectively, at the expense of 5.2% increase in the system cost rate. The current investigation demonstrates how an appropriate optimized design of an integrated energy system using SGSP, PEMFC, and TEG can improve the overall performance with reasonable cost increment.

Water, energy, and food (WEF) are essential material bases for mankind's survival and development. At the same time, water and energy, as necessary inputs for food production, are of great significance to food security. Scientific understanding of the water-energy-food nexus (WEF Nexus) in food production is conducive to ensuring food security and sustainable utilization of basic resources. However, current research linking the WEF Nexus with food production is lacking. Therefore, we took the WEF Nexus as an entry point to quantify China's food production efficiency and considered the direct and indirect inputs of water and energy in food production in this paper. First, we constructed an evaluation index system of food production efficiency based on the perspective of input-output and used the stochastic frontier production function model to measure the absolute efficiency values of food production. Then, GIS spatial analysis, spatial autocorrelation analysis, and the gravity center model were used to reveal the spatial-temporal pattern, spatial autocorrelation characteristics and barycenter trajectory, respectively. Finally, the Tobit model was applied to analyze the main factors which influenced the spatial pattern changes of food production efficiency. The research results indicated that China's food production efficiency was on the rise and there were spatial differences between provinces. Per capita GDP, natural disaster losses and irrigated areas of food crops were the main factors influencing China's food production efficiency. This paper contributed a new theoretical reference to the study of food production efficiency, and provided a decision-making reference for regional resource management to ensure basic resource security and sustainable development in the future.

As the world encounters insufficient fossil energy and worsening environmental pollution, the significant potential of water surface photovoltaic (WSPV) systems and the remarkable benefits are crucial to promoting cleaner production and sustainable development. This paper proposes installing overhead WSPVs along the open channels of long-distance water diversion projects (WDPs), creating new opportunities for the adaptive traceability and utilization of energy–water resources. A multi-objective decision model for the feasibility evaluation of WSPVs is presented and applied to typical WDPs in China to demonstrate the effects of this modeling framework and explore the co-benefits of WSPV systems. The results indicate that: (1) it is economically and technically feasible to install WSPVs over MLSNWDP with a suggested tilt angle range of 10°–12°; (2) the proposed WSPVs in the eight typical projects evaluated using the decision model with a capacity of 29,486 MW can convert 37,263 GWh of electricity at a 12° tilt angle while saving 3.19×108 m3 of water annually; (3) the adaptive utilization of the saved water and electricity can increase the ecological water level guarantee rate of Baiyang Lake by 12.64%, alleviating potential eco-environmental problems. Moreover, a recommended coverage rate of 50% is proposed to inhibit algae outbreaks. Overall, this research demonstrates the technical and economic feasibility of the construction of WSPVs along WDPs and the co-benefits to address challenging research questions on the sustainable development of energy–water resources.