• Energy Research
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International audience; Water, energy and food are three essential resources for the socio-economic system, and they are interlinked. The coordination of their internal relations is worth studying. We conduct a coordination evaluation method to assess the water-energy-food nexus (WEF Nexus) in China’s provinces. By combining the coupling model and the coupling coordination model, we measure the comprehensive evaluation index and coupling coordination degree of China’s 30 provinces from 2005 to 2017. First, the results show the provincial comprehensive evaluation index had a slow upward trend. The comprehensive evaluation index of the southern region was higher than that of the north, and the eastern was higher than the west. Second, the coordination degree of WEF Nexus in China’s 30 provinces has reached high level in the horizontal coupling stage, and the overall degree of coupling coordination was on the rise. In 2017, the WEF Nexus coupling coordination degree of most provinces reached 0.700 or more, which was intermediate-coordinated. In the six years, the 30 provinces have experienced five types of coupling coordination degree: near coordinated, barely coordinated, primary coordinated, intermediate-coordinated, and well-coordinated.

This study aims to identify the role of design and operational parameters in energy costs for a wastewater treatment plant in a meat processing industry regarding water-energy nexus. In the study, the energy cost index has been calculated using a derived numerical approach. This study recommends a new comprehensive methodology for energy cost estimation for an industrial wastewater treatment plant. The model is developed based on organic load, amount of wastewater, and energy consumption required to treat wastewater. Particularly, the impact of design and operational organic load parameters on energy costs has been investigated in this study. Biological oxygen demand (BOD) and chemical oxygen demand (COD) have been regarded as organic load indicators. The results show that the energy cost index of operational organic load is higher than that of the design for two parameters. Energy costs of COD removal are higher than BOD removal. The costs of COD removal are 726.6 and 65,520 €/m3 wastewater for design and operational conditions, respectively, whereas the energy costs related to BOD removal are 90.9 and 7224 €/m3 wastewater for design and operational conditions, respectively. Operational COD removal leads to maximum energy costs for the plant. The lowest energy cost is related to BOD removal of design conditions. In terms of water-energy nexus, wastewater reuse could be considered to reduce energy costs. The possibility of wastewater reuse as boiler feed water has been reported as 50.38%. According to the simulated results, energy costs could be minimized at approximately 49% if wastewater reuse were applied in the plant.

Abstract This paper evaluates the metabolism-based performance of a number of centralised and decentralised water reuse strategies and their impact on integrated urban water systems (UWS) based on the nexus of water-energy-pollution. The performance assessment is based on a comprehensive and quantitative framework of urban water metabolism developed for integrated UWS over a long-term planning horizon. UWS performance is quantified based on the tracking down of mass balance flows/fluxes of water, energy, materials, costs, pollutants, and other environmental impacts using the WaterMet2 tool. The assessment framework is defined as a set of key performance indicators (KPIs) within the context of the water-energy-pollution nexus. The strategies comprise six decentralised water reuse configurations (greywater or domestic wastewater) and three centralised ones, all within three proportions of adoption by domestic users (i.e. 20, 50, and 100%). This methodology was demonstrated in the real-world case study of San Francisco del Rincon and Purisima del Rincon cities in Mexico. The results indicate that decentralised water reuse strategies using domestic wastewater can provide the best performance in the UWS with respect to water conservation, green house gas (GHG) emissions, and eutrophication indicators, while energy saving is almost negligible. On the other hand, centralised strategies can achieve the best performance for energy saving among the water reuse strategies. The results also show metabolism performance assessment in a complex system such as integrated UWS can reveal the magnitude of the interactions between the nexus elements (i.e. water, energy, and pollution). In addition, it can also reveal any unexpected influences of these elements that might exist between the UWS components and overall system.

Rapid population growth and industrialization have contributed to a dramatic decline in the supply of freshwater. As a result, desalination is an important choice to solve the global problem of water scarcity. Nevertheless, the hyper-saline by-product, the high capital costs, and the high energy demands currently met by fossil fuels are key obstacles to the widespread adoption of desalination systems. Furthermore, desalination plants powered by fossil fuels have negative environmental impacts due to greenhouse gases (GHGs) emissions. In contrast to fossil fuels, renewable energy is abundant and clean and is therefore a promising alternative for powering desalination plants. This is why the water-energy nexus is a crucial step towards a sustainable future. Therefore, the integration of renewable energy sources (RES) into desalination is very important. The main objective of this review to analyze and evaluate desalination technologies (thermal-based and membrane-based) and RES (solar, wind, hydropower, geothermal, and biomass) that could be combined as an integrated process. Social-economic factors, environmental concerns, current challenges, and future research areas for both desalination and RES are discussed.

The energy potential of high-organic loaded agro-industrial effluents receiving biological treatment is often neglected, particularly in emergent regions, because of different technical and regulatory drawbacks. In addition, small alternative bioenergy sources are forced to compete disadvantageously with conventional energy supply, hindering their more extended exploitation. Thus, smart strategies to prove the environmental/economic potential of biogas and sludge produced in biological wastewater treatment systems (Bio-WWTs) are required to promote them as truly sustainable energy sources. In this view, the present study depicts a refined methodological framework for a more appropriate appraisal of Bio-WWTs promoting bioenergy recovery. Life cycle assessment (LCA) and emergy analysis (EmA) methods were merged around the statement of some identified and stated Principle–Criteria of Sustainability (PCS) for this kind of “water-energy nexus.” As a result, a novel set of four single sustainability development indicators (SDIs) and one aggregated SDI were obtained to address sustainable conditions for valorization of bio-energy from agro-industrial Bio-WWTs. These indicators were made up of an environmental term coming from an LCA based on a system expansion approach as well as a second or “eco-economic” term obtained by means of EmA. This work introduces and shapes the “additionality” notion as an expression of overall sustainability and uses novel sustainability charts to interpret the obtained SDIs and their shifting or changes for different Bio-WWTs’ life cycle scenarios. The “proof of concept” of this methodology is discussed along the obtained results for two case studies in Colombia.

The water industry plays an important role in reducing greenhouse gas (GHG) emissions and therefore, moving to a low-carbon urban water cycle is of great importance. However, traditional performance assessment of water companies ignores GHG emissions. To overcome this limitation and to compare productivity change estimations of water companies excluding and including GHG emissions, this study computes the Luenberger productivity indicator (LPI) and the Malmquist-Luenberger productivity index (MLPI), respectively. Moreover, in a second stage, we investigate the impact of exogenous variables on environmentally sensitive productivity change estimations. The empirical application conducted for a sample of water and sewerage companies in England and Wales over the period 201–2019 has illustrated that when GHG emissions were considered in the assessment (i.e., MLPI estimations), average productivity decreased. By contrast, when productivity estimation ignored GHG emissions (i.e., LPI), average productivity increased. Hence, it is concluded that the inclusion of GHG emissions in productivity analysis impacted the results. This finding is very relevant from a policy perspective as it illustrates the importance of considering GHG emissions when evaluating the performance of water companies for regulatory purposes.