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One of the most important concerns in the planning and operation of an electric power generation system is the effective scheduling of all power generation facilities to meet growing power demand. Economic load dispatch (ELD) is a phenomenon where an optimal combination of power generating units is selected in such a way as to minimize the total fuel cost while satisfying the load demand, subject to operational constraints. Different numerical and metaheuristic optimization techniques have gained prominent importance and are widely used to solve the nonlinear problem. Although metaheuristic techniques have a good convergence rate than numerical techniques, however, their implementation seems difficult in the presence of nonlinear and dynamic parameters. This work is devoted to solving the ELD problem with the integration of variable energy resources using a modified directional bat algorithm (dBA). Then the proposed technique is validated via different realistic test cases consisting of thermal and renewable energy sources (RESs). From simulation results, it is observed that dBA reduces the operational cost with less computational time and has better convergence characteristics than that of standard BA and other popular techniques like particle swarm optimization (PSO) and genetic algorithm (GA).

Aligned with Denmark’s growing smart energy networks encompassing district heating and electricity grids and in harmony with the country’s ambitious energy and environmental objectives, this study aims to elevate the investigation from individual buildings to consider districts and cities. In pursuit of this objective, a case study of an Odense district in Denmark was considered for modeling, simulation, and energy performance improvement. The selected residential area was modeled using City Energy Analyst, an open-source urban scale modeling tool, accounting for different building attributes as well as the particulars of energy networks and supply systems. The validation of a baseline scenario is predicated upon real-world data collected on-site to serve as the benchmark for exploring and evaluating various scenarios and measures for enhancing energy efficiency. Consequentially, eight distinct energy enhancement packages were designed, modeled, and simulated individually. The results were analyzed, and it was shown that an energy improvement package consisting of retrofitting buildings’ constructions, indoor thermal comfort setpoint management, heating system upgrade, photovoltaic-thermal unit installation, and heat pump integration, along with a seasonal energy storage system, is capable of enhancing the overall energy efficiency quotient of the area, establishing a positive energy district with an excess in heat and electricity production.

Abstract In order to improve the accuracy, validity, reliability and reproducibility of reported power conversion efficiencies for solar cells, the journal, Solar Energy Materials and Solar Cells (SOLMAT), wishes to define how power conversion efficiencies should be reported. This expands upon what is specified in our Guide for Authors. This editorial also serves as a guide on how efficiency data should be checked within the reporting laboratory before sending cells or materials for testing at an independent laboratory. The threshold where the accuracy of efficiency values is important to the journal is whenever power conversion efficiencies require external quantum efficiencies (EQE) values above 50% over a large range of wavelengths or when reported power conversion efficiencies exceed 2.5%. Extra care should be taken in submitted manuscripts to document the measurement's quality, relevance and independent verification.

En los países del sur de Asia, incluidos Bangladesh, India y Pakistán, el escenario energético actual se considera no sostenible debido a diversas cuestiones, como las opciones económicas, ambientales, geopolíticas y tecnológicas para la explotación de la energía y el volumen insignificante del comercio regional de energía. Sin embargo, dentro de la región, India está liderando una fase de transición energética y transformación económica a través del desarrollo de energías renovables. Los países deben mostrar buenos resultados en el desarrollo de sus fuentes renovables siguiendo el rápido ritmo de las energías renovables en todo el mundo. Este artículo ofrece una visión general del escenario energético, el crecimiento de las energías renovables, la evolución y el enfoque de la política energética al resaltar los desafíos y barreras clave para la combinación energética ecológica de los países. Es importante destacar que el documento evalúa la combinación energética actual en el sur de Asia, destacando la anomalía de sus perspectivas futuras basadas en combustibles fósiles, sus ambiciones de avanzar hacia una menor contaminación ambiental y una combinación energética sostenible a través de un análisis FODA de herramientas estratégicas; fortalezas, debilidades, oportunidades y amenazas (FODA). En particular, este estudio examina las políticas gubernamentales para expandir la implementación de fuentes renovables con una visión de la estructura regulatoria existente del sector energético. Los hallazgos de la investigación presentada sugieren que para lograr el ambicioso objetivo de reducir la descarga de emisiones hasta en un 30% para el año 2030 en el marco de las Contribuciones Previstas Determinadas a Nivel Nacional (INDC), los gobiernos de los tres países deben tomar medidas preventivas. Incluye la reducción gradual de los subsidios a los combustibles fósiles, la integración del mercado dentro de la región y la rápida realización de las iniciativas existentes a través de una fuerte voluntad política, una buena gobernanza, la adopción de las últimas tecnologías y un plan de acción pragmático, y la cooperación energética en toda la región. Dans les pays d'Asie du Sud, y compris le Bangladesh, l'Inde et le Pakistan, le scénario énergétique actuel est considéré comme non durable en raison de divers problèmes tels que les options économiques, environnementales, géopolitiques et technologiques pour l'exploitation de l'énergie et le volume négligeable du commerce régional de l'énergie. Bien que, dans la région, l'Inde mène une phase de transition énergétique et de transformation économique grâce au développement des énergies renouvelables. Les pays doivent bien montrer dans le développement de leurs sources renouvelables à la suite du rythme rapide des énergies renouvelables dans le monde entier. Cet article offre un aperçu du scénario énergétique, de la croissance des énergies renouvelables, de l'évolution et de l'approche de la politique énergétique en soulignant les principaux défis et obstacles pour le mix énergétique écologique des pays. Il est important de noter que le document évalue le bouquet énergétique actuel en Asie du Sud, en soulignant l'anomalie de ses perspectives d'avenir basées sur les combustibles fossiles, ses ambitions de réduire la pollution environnementale et son bouquet énergétique durable grâce à une analyse SWOT d'outil stratégique ; forces, faiblesses, opportunités et menaces (SWOT). En particulier, cette étude examine les politiques gouvernementales visant à étendre la mise en œuvre des sources renouvelables avec un aperçu de la structure réglementaire existante du secteur de l'énergie. Les résultats de recherche présentés suggèrent que pour atteindre l'objectif ambitieux de réduire les rejets d'émissions jusqu'à 30 % d'ici 2030 dans le cadre des contributions prévues déterminées au niveau national (CPDN), les gouvernements des trois pays doivent prendre des mesures préventives. Il comprend la réduction progressive des subventions sur les combustibles fossiles, l'intégration du marché dans la région et la réalisation rapide des initiatives existantes grâce à une forte volonté politique, à une bonne gouvernance, à l'adoption des dernières technologies, à un plan d'action pragmatique et à une coopération énergétique dans toute la région. In the South Asian countries, including Bangladesh, India, and Pakistan, the current energy scenario is considered non-sustainable due to diverse issues such as economic, environmental, geopolitical, technological options for energy exploitation, and negligible volume of regional energy trade. Though, within the region, India is leading a phase of energy transition and economic transformation through renewable energy development. The countries need to exhibit well in the development of their renewable sources following the rapid pace of renewable energies worldwide. This article offers an overview of the energy scenario, growth of renewable energies, evolution, and approach for energy policy by highlighting key challenges and barriers for the ecological energy mix of the countries. Importantly, the paper assesses the current energy mix in South Asia, highlighting the anomaly of its fossil fuel-based future outlook, its ambitions to move towards less environmental pollution, and sustainable energy mix through a strategic tool SWOT analysis; strengths, weaknesses, opportunities, and threats (SWOT). In particular, this study examines the government policies to expand the implementation of renewable sources with an insight into the existing regulatory structure of the energy sector. The presented research findings suggest that to achieve the ambitious target to reduce emission discharge by up to 30% by the year 2030 under Intended Nationally Determined Contributions (INDCs), the Governments of the three countries must take preemptive measures. It includes the stage-wise reduction of subsidies on fossil fuels, market integration within the region, and swift realization of the existing initiatives through strong political will, good governance, adoption of the latest technologies, and a pragmatic action plan, and energy cooperation across the region. في بلدان جنوب آسيا، بما في ذلك بنغلاديش والهند وباكستان، يعتبر سيناريو الطاقة الحالي غير مستدام بسبب قضايا متنوعة مثل الخيارات الاقتصادية والبيئية والجيوسياسية والتكنولوجية لاستغلال الطاقة، وحجم ضئيل من تجارة الطاقة الإقليمية. على الرغم من أن الهند، داخل المنطقة، تقود مرحلة انتقال الطاقة والتحول الاقتصادي من خلال تطوير الطاقة المتجددة. تحتاج البلدان إلى أن تظهر أداءً جيدًا في تطوير مصادرها المتجددة بعد الوتيرة السريعة للطاقات المتجددة في جميع أنحاء العالم. تقدم هذه المقالة لمحة عامة عن سيناريو الطاقة، ونمو الطاقات المتجددة، والتطور، ونهج سياسة الطاقة من خلال تسليط الضوء على التحديات والحواجز الرئيسية لمزيج الطاقة البيئية للبلدان. والأهم من ذلك، تقوم الورقة بتقييم مزيج الطاقة الحالي في جنوب آسيا، مع تسليط الضوء على الشذوذ في توقعاتها المستقبلية القائمة على الوقود الأحفوري، وطموحاتها للتحرك نحو تلوث بيئي أقل، ومزيج الطاقة المستدامة من خلال تحليل SWOT الاستراتيجي للأداة ؛ نقاط القوة والضعف والفرص والتهديدات (SWOT). على وجه الخصوص، تبحث هذه الدراسة في السياسات الحكومية لتوسيع تنفيذ مصادر الطاقة المتجددة مع نظرة ثاقبة على الهيكل التنظيمي الحالي لقطاع الطاقة. تشير نتائج البحث المقدمة إلى أنه لتحقيق الهدف الطموح المتمثل في الحد من تصريف الانبعاثات بنسبة تصل إلى 30 ٪ بحلول عام 2030 بموجب المساهمات المقررة المحددة وطنيًا (INDCs)، يجب على حكومات البلدان الثلاثة اتخاذ تدابير وقائية. ويشمل ذلك التخفيض التدريجي للإعانات على الوقود الأحفوري، وتكامل الأسواق داخل المنطقة، والإدراك السريع للمبادرات القائمة من خلال الإرادة السياسية القوية، والحكم الرشيد، واعتماد أحدث التقنيات، وخطة عمل عملية، والتعاون في مجال الطاقة في جميع أنحاء المنطقة.

Abstract Tropical mountain cloud forests (TMCF) harbour a high bryophyte (mosses and liverworts) biomass and diversity. Furthermore, the high air humidity makes these forests well suited for bryophyte‐associated nitrogen (N2) fixation by cyanobacteria, providing a potentially important source of N input to the ecosystem. However, few studies have assessed bryophyte‐associated N input in these ecosystems, and these have focused on epiphytic bryophytes, whereas abundant ground‐covering bryophytes have not been included. In this study, we quantified N2 fixation rates associated with bryophytes, focusing on ground‐covering mosses in a neotropical mountain cloud forest. Furthermore, we identified the effects of climate change (higher temperature 10 vs. 20° and lower bryophyte moisture level 50% vs. 100%) on N2 fixation across bryophyte species and groups (mosses and liverworts). Nitrogen fixation rates associated with ground‐covering moss species were up to 2 kg N ha−1 year−1, which is comparable to other N inputs (e.g. N deposition) in tropical cloud forests. Furthermore, changes in temperature showed little effect on N2 fixation, but low moisture levels significantly suppressed N2 fixation activity. We found low N2 fixation activity associated with the investigated liverworts. Our results demonstrate the importance of ground‐covering, moss‐associated N2 fixation as a N source in tropical cloud forests and suggest that predicted future declines in precipitation in these systems will reduce N inputs from bryophyte‐associated cyanobacteria. Read the free Plain Language Summary for this article on the Journal blog.

SUMMARY This paper analyses the transportation and delivery features of hydrogen as energy market evolves and approaches a fully functional Hydrogen economy. Initially physical aspects have been assessed that affect the flow of hydrogen through the existing pipeline infrastructure. Line pack and compressors are the only identified problems that need to be addressed. This is followed by an investigation into the mixing of hydrogen with natural gas gradually. It was revealed that a mix of up to 17% by volume does not have any significant effect, however higher concentration of hydrogen leads to a changeover of high-pressure grid pipelines as well as the end-user applications. It is suggested that initially hydrogen can be introduced in the distribution system, while emphasizing towards developing means for high-pressure transportation of hydrogen fuel gas. Government policies towards encouraging use of hydrogen in an evolving market is important for widespread and early assimilation in energy mix. Renewable sources of energy are recommended for distributed generation of hydrogen along the pipeline network. Copyright © 2011 John Wiley & Sons, Ltd.

Hybrid electric ships powered by diesel generators and batteries are the main configuration for shipboard microgrids (SMGs) in the current maritime industry. Extensive studies have been conducted for the hybrid operation mode, whereas the all-electric operation mode and the switching between the aforementioned two modes in a system with multiple generators and batteries have not been tested. In this paper, a coordinated approach for a hybrid electric ship is proposed, where two operation modes have been simultaneously considered. More specifically, for achieving an efficient operation with reduced generator wear losses, the governor-less diesel-engine-driven generators have been adopted in the study. According to the practical operation conditions, two operation modes, the all-electric and hybrid modes, are preset. Based on these, the coordination of the generators acting as the main power sources and batteries regulating the power flow and improving the generator efficiency is studied. The governor-less diesel generators are regulated to inject the rated power in order to maximize the generator efficiency, while the DC bus voltage is regulated by DC/DC converters. For the benefit of the overall lifespan of battery banks, power sharing during charging and discharging states have been realized by the state of charge (SoC)-based adaptive droop regulator. For the test of two operation modes, as well as the mode switching, a simulation assessment in a 1 kV DC SMG has been conducted. The simulation results show that the DC bus voltage can be controlled well, and that the power sharing among batteries follows the design. Additionally, smooth transients can be observed during mode switching when the proposed control scheme is applied.