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Along with industrialization and rapid urbanization, environmental remediation is globally a perpetual concept to deliver a sustainable environment. Various organic and inorganic wastes from industries and domestic homes are released into water systems. These wastes carry contaminants with detrimental effects on the environment. Consequently, there is an urgent need for an appropriate wastewater treatment technology for the effective decontamination of our water systems. One promising approach is employing nanoparticles of metal oxides as photocatalysts for the degradation of these water pollutants. Transition metal oxides and their composites exhibit excellent photocatalytic activities and along show favorable characteristics like non-toxicity and stability that also make them useful in a wide range of applications. This study discusses some characteristics of metal oxides and briefly outlined their various applications. It focuses on the metal oxides TiO2, ZnO, WO3, CuO, and Cu2O, which are the most common and recognized to be cost-effective, stable, efficient, and most of all, environmentally friendly for a sustainable approach for environmental remediation. Meanwhile, this study highlights the photocatalytic activities of these metal oxides, recent developments, challenges, and modifications made on these metal oxides to overcome their limitations and maximize their performance in the photodegradation of pollutants.

Air pollution is a vital concern for developing countries, and the growing concentration of air pollutants in Kabul—the most polluted city in Afghanistan—has raised concerns about the health of its citizens. This study examines Kabul’s ambient air quality from a socio-economic and environmental perspective, primarily focusing on some crucial parameters, such as the Air Quality Index (AQI), nitrogen dioxide (NO2), particulate matter (PM2.5), and carbon monoxide (CO). Using multiple regression analysis modeling in R and data from satellite imagery, air quality monitoring stations, and Geographic Information Systems (GIS), this study demonstrates a strong relationship between air quality and urban green spaces, population growth, vehicle count, temperature, and electricity availability. Key results indicate that increasing urban green areas improves air quality, but that population growth and heat make air pollution worse. This study suggests that airborne pollutants could be reduced through efficient emissions management, green energy sources, and urban planning. These observations provide policymakers and urban planners with practical recommendations to enhance Kabul’s air quality and general public health.

The growing global concern for climate change and the need for sustainable energy solutions have driven nations to explore renewable energy alternatives. This research focuses on a developing country heavily reliant on imported electricity and evaluates the potential of renewable energy resources. Using the Analytical Hierarchy Process (AHP), a multi-criteria decision-making method (MCDM), this study prioritizes sustainable energy resources crucial for energy security and environmental sustainability, given the country’s dependence on traditional and imported power and its potential for renewable energy development. This study employs AHP to evaluate and rank various sustainable energy options, emphasizing their technological, economic, environmental, and social impacts. The novelty of this research lies in its comprehensive and systematic approach to integrating diverse expert opinions and utilizing AHP; the development of a robust decision-making model that accommodates the diverse criteria and sub-criteria (SCs) influencing the prioritization of energy resources; and its bridging of the gaps through the integration of varied criteria and SCs, region-specific concerns, and stakeholders’ engagement by creating a comprehensive and inclusive prioritization strategy. The key findings highlight solar energy as the most viable sustainable energy resource, followed by wind and hydro energy. These results underscore the significant potential for solar energy development, considering its current technological advancements, economic affordability, social acceptance, and environmental friendliness. This study not only provides a prioritized list of sustainable energy resources but also offers a methodological framework adaptable for similar assessments in other regions facing energy transition challenges. Readers will find a detailed explanation of the AHP methodology, the criteria used for evaluating energy resources, and the implications of the findings for policy and decision making. This research is particularly relevant for policymakers, energy planners, and stakeholders interested in sustainable energy development and strategic planning in similar contexts.

Harnessing the abundant solar resources holds great potential for sustainable energy generation. This research paper delves into a comprehensive analysis of seasonal tilt and solar tracking strategy scenarios for a 15 MW grid-connected PV solar power plant situated in Kandahar province, Afghanistan. The study investigates the impact of fixed tilt, seasonal tilt, SAHST (single-axis horizontal solar tracking), and SAVST (single-axis vertical solar tracking) on energy yield, considering technical, economic, and environmental aspects. In the first scenario, a fixed tilt angle of 31 degrees was employed. The second scenario explored the use of seasonal tilt angles, with a summer tilt angle of 15 degrees and a winter tilt angle of 30 degrees. The third scenario analyzed SAHST. Finally, the fourth scenario focused on implementing SAVST. SAVST proved to be an exceptional solution, showcasing a remarkable increase in annual energy yield, and generating an additional 6680 MWh/year, 6336 MWh/year, and 5084 MWh/year compared to fixed, seasonal, and SAHST scenarios, respectively. As a result, surplus energy yielded an income of USD 554,440.00 per year compared to fixed tilt. However, the investment cost for the solar tracking system amounted to USD 1,451,932, accompanied by an annual operation and maintenance cost of 0.007 USD/W/year. The analysis revealed a promising payback period of 3 years, confirming the economic feasibility of this investment. The findings underscore the effectiveness of different strategies for optimizing solar power generation in the Kandahar region. Notably, the installation of SAVST emerged as an influential solution, significantly increasing power production. These research outcomes bear practical implications for solar tracking strategies for addressing the load challenges faced by Kandahar province and offer valuable insights for the operators and operation of solar power plants in similar regions.

This study delves into power system flexibility, with a keen focus on the integration of variable renewable electricity generation into power grids. Two scenarios were analyzed. The base scenario revealed an aging grid, insufficient generation capacity, frequent outages, and little renewable energy generation (1.9%), along with a significant (71.23%) loss of load. In contrast, the investment scenario presented solutions including raising VRE capacity to 44%, adding 1000 MW capacity transmission lines, installing 200 MW capacity grid-scale battery storage, and technological enhancements. These interventions effectively eliminated loss of load, reinforcing energy resilience. Investments in CCGPP and grid-scale batteries proved instrumental in mitigating the variability of renewable energy. Improved transmission promised efficient power exchange and regional collaboration. The elimination of annualized energy spills and the removal of ramping constraints marked significant strides in enhancing power system flexibility. This research underscores the pivotal role of grid flexibility in accommodating VRE sources. By implementing the proposed optimal solutions, Afghanistan can lead the way toward a cleaner, more resilient, and more interconnected energy future. These findings offer a replicable framework for addressing similar challenges in integrating renewable energy sources globally and supporting the transition to sustainable and reliable energy.

Within the framework of this study, the inductive analysis of voltage stability indices’ theoretical formulation, functionality, and overall performances are introduced. The prominence is given to investigate and compare the original indices from three main dimensions (formulation, assessment, and application) standpoints, which have been frequently used and recently attracted. The generalizability of an exhaustive investigation on comparison of voltage stability indices seems problematic due to the multiplicity of the indices, and more importantly, their variety in theoretical foundation and performances. This study purports the first-ever framework for voltage stability indices classification for power system analysis. The test results found that indices in the same category are coherent to their theoretical foundation. The paper highlights the fact that each category of the indices is functional for a particular application irrespective of the drawback ranking, and negated the application of the Jacobian matrix-based indices for online application. Finally, the research efforts put forward a novel classification of voltage stability indices within the main three aspects of formulation, assessment, and behavior analysis in a synergistic manner as an exhaustive reference for students, researchers, scholars, and practitioners related to voltage stability analysis. The simulation tools used were MATLAB® and PowerWorld®.

Population growth and city expansion in developing countries require traditional urban planning practices to be transformed in order to tackle climate change and follow Sustainable Development Goals (SDGs) agendas. Almost every expert in the urban sector believes that future cities should be sustainable, smart, and environmentally friendly, where energy is one of the most critical factors to achieve these goals. They also agree that smart and sustainable energy provision for cities requires a comprehensive and responsive legal and policy framework to be in place at the national level. However, this research’s findings reveal a lack of such frameworks for this group of countries. Considering the challenges and unique nature of Low-Income-Developing (LID) countries, there should be a framework based on the realities in these countries. In this research, key challenges of urban and energy sectors of LID countries, specifically Afghanistan, are identified, and a framework for the integration of sustainable and smart energy in the urban planning processes for LID countries is proposed. To make it easily replicable and adaptable for LID countries, the proposed framework is studied and analyzed around Afghanistan’s urban and energy sectors. This is one of the few frameworks of its kind for LID economies to the best of the authors’ knowledge. This framework lays a solid foundation for sustainable and smart energy integration in the urban planning process of developing countries. This study highlights that sustainable and smart energy systems could ensure climate change mitigation and economic growth enhancement but require close cross-sectoral coordination and policy maker’s commitments and involvement. This research will help many existing and emerging cities in the LID countries’ worldwide use and benefit from the proposed framework in their urban planning processes. It also enables policymakers, urban planners and designers, municipalities leadership, and other stakeholders of the urban, energy, and environment sectors to work together and make smart and rational decisions for the future of their cities and lead them towards smart and sustainable cities.