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Water shortage in terms of both physical and economic water scarcity is still a major issue globally. The looming climate change threat has increased the adverse threats to water security in different regions. However, policy solutions to water security vary in different geographical regions and at different scales (local, regional, national, etc.). Understanding the successes and challenges of different policy solutions is critical to scaling-up successful policies and addressing water security holistically. This paper aims to explore the effects of implementing policies at different scales in three different case study contexts: 1. two Counties in California in the USA, 2. the City of Cape Town in South Africa and 3. the Country of Bangladesh. These case studies highlight various implemented policies and their effectiveness in each context. We reviewed relevant research papers consisting of peer-reviewed journal articles, conference proceedings and gray literature using a content analysis approach based on keywords such as water scarcity, water shortage, climate change, policies, interventions and solutions. Based on this cross-case analysis, we present key strategies moving forward, including: reallocation of water based on different community and sector needs, the importance of stakeholders engagement and public awareness, and a need to implement both short and long-term management plans. There is no one-size fits all policy solution to water scarcity. Understanding the context, scale, and cultural environment will be a key to future water security-focused interventions and policies.

Abstract Recovery of waste heat in large industrial plants is nowadays an important topic of thermal optimization. In the present study, energy, exergy, and exergoeconomic analysis of an integrated system, Tehran's waste-to-energy power plant coupled with an organic Rankine cycle (ORC), is analyzed. Parametric study of essential parameters (moisture content, pinch point temperature differences of the HROG, steam generator's superheat temperature difference, and steam turbine inlet pressure) is performed thermodynamically. The best system performance achieved using R123 as the working fluid of ORC. After implementation of the waste-heat-recovery system into the WtE plant, with R123 the energy and exergy efficiencies increase from 17.27% to 19.51% and 14.49%–16.36%, respectively. Exergy analysis reveals that the gasifier and steam generator are the main source of exergy destruction in the overall system. Additionally, the results of single-objective optimization based on maximum exergy efficiency and minimum total product unit cost were calculated. Furthermore, multi-objective optimization based on genetic algorithm using MATLAB software is implemented to find the optimum point with respect to exergy efficiency and total product unit cost as the objective functions. The exergy efficiency and total product unit cost at the optimum point, considering multi-objective optimization, are 19.61% and 24.65 $/GJ, respectively.

Abstract Large-scale hydrogen liquefaction (LHL) methods and different approaches of the configuration of hydrogen liquefaction cycles are chronicled. History landmarks of permanent gases liquefaction are quick reviewed and the basic hydrogen liquefaction cycles, the existing in-service LHL plants around the world, and LHL conceptual proposed plants, including the state of the art plants, are recorded and categorized based on the systems’ main parameters. In addition, a novel classification of hydrogen liquefaction systems in terms of heat exchange and expansion process method is introduced. As well as, the authors infer that renewable energy technologies section should be added to the old sectioning of the hydrogen liquefaction plants. In addition, hybrid conceptual hydrogen liquefaction plants, combining with renewable power cycles are reviewed and the increasing contribution of this new approach is demonstrated. Finally, the operational costs of the plants considering the systems’ efficiency are examined, and a trend in specific energy consumption (SEC) and exergy efficiency of hydrogen liquefiers is discussed. Accordingly, considering the existing technologies, SEC reduction of hydrogen liquefaction will not be abrupt in near future and it will remain within the range of 5–8 kWh / kg LH 2 . Moreover, exploiting of isentropic expansion processes instead of isenthalpic one, cascading of refrigerating cycles, using of new mixed refrigerants as working fluid of refrigeration cycles, and hybridization of renewable energy power cycles to refrigeration cycles are the main four growing approaches in the hydrogen liquefaction context.

This review showcases a comprehensive analysis of studies that highlight the different conversion procedures attempted across the globe. The resources of biogas production along with treatment methods are presented. The effect of different governing parameters like feedstock types, pretreatment approaches, process development, and yield to enhance the biogas productivity is highlighted. Biogas applications, for example, in heating, electricity production, and transportation with their global share based on national and international statistics are emphasized. Reviewing the world research progress in the past 10 years shows an increase of ~ 90% in biogas industry (120 GW in 2019 compared to 65 GW in 2010). Europe (e.g., in 2017) contributed to over 70% of the world biogas generation representing 64 TWh. Finally, different regulations that manage the biogas market are presented. Management of biogas market includes the processes of exploration, production, treatment, and environmental impact assessment, till the marketing and safe disposal of wastes associated with biogas handling. A brief overview of some safety rules and proposed policy based on the world regulations is provided. The effect of these regulations and policies on marketing and promoting biogas is highlighted for different countries. The results from such studies show that Europe has the highest promotion rate, while nowadays in China and India the consumption rate is maximum as a result of applying up-to-date policies and procedures.

This article reviews existing research and discussions on urban policy in response to the global COVID-19 pandemic. The analysis focuses on the first pandemic period in the European Union and the Middle East. A search was conducted in available databases and search engines (Scopus, Google Scholar). A critical bibliometric analysis of publications from the first pandemic period was carried out. The most frequent topics covered were spatial organization, transport, environment, and social issues. The analysis showed that the quantitative scope and depth of the selected topics in the European Union and the Middle East differ. Activities defined as “exploitative” should be considered a particularly interesting point of reference in both analyzed regions.

Abstract In this study, a regional life-cycle assessment (LCA) framework is developed to assess compressed natural gas (CNG) and liquefied natural gas (LNG) as fuel alternatives to diesel for a transit bus in Victoria, British Columbia, Canada. The driving pattern and road gradient of a public transit bus route are considered in both directions to capture real-world driving behavior. The real-time fuel consumption and emissions of the transit bus configurations are calculated by dynamic vehicle simulation using Simcenter Amesim software. By considering the effect of road gradient, a 12% difference in computed fuel consumption is shown for bus travel in the two opposing directions of the bus line. The results also reveal that the majority of life cycle greenhouse gas (GHG) emissions are associated with on-board emissions. Overall, switching from diesel to CNG or LNG reduces GHG emissions by 4.8% and 8.1%, respectively.

In order to reduce the economic and environmental consequences caused by spent car catalyst, we herein report for the first time a novel promising multi-metal catalyst prepared from spent car catalytic converters to upgrade the pyrolysis bio-oils. The physico-chemical properties of prepared catalyst were characterized by XRD, EDS, FESEM, and FT-IR analyses. The thermal stability of the multi-metal catalyst was studied with TGA. To investigate the activity of the catalyst, Conversion of Cladophora glomerata (C. glomerata) into bio-products was carried out via a fixed bed reactor with and without catalyst at the temperature of 500°C. Although the catalyst didn't catalyze the gasification reaction, bio-oil was upgraded over the catalyst. The main effect of the catalyst on the bio-oil components is deoxygenating of nitrogen compounds and promotion the ketonization reaction, which converts acid to ketone and declines the corrosive nature of bio-oil.

About 25 million tons of food go wasted or lost in Iran which has socio-economic and environmental consequences for both the country and the households. The main objective of this research is to develop a model to examine the relationship between FCM components and the amount of FW of households in Tehran city, with a focus on urban women. By means of a structural model, this study provides a novel approach to exploring relationships between the food-related behavior of urban households and waste control (n = 1197). Besides, this study is the first attempt to quantify food waste in Iran at the household level. According to the adopted self-reporting procedure, in Tehran, every consumer wastes about 27.6 kg of edible food annually. It is found that households with better food consumption management (FCM (have a lower level of food waste. Moreover, the results have proved that other determinants such as demographic factors, economic power, information use, ability, and motivation have direct and indirect significant effects on FCM as well as on the amount of food waste generation. The findings suggest that the above-mentioned determinants are crucial and should be considered when developing a strategically sustainable food waste prevention plan.