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Abstract Emissions and efficiency of a pellet boiler (40 kW) at nominal load were compared with emissions and efficiency at reduced load, while fired with six biomass pellets. The pellets include reed canary grass ( Phalaris arundinacea ), pectin waste from citrus shells ( Citrus reticulata ), sunflower husk ( Helianthus annuus ), peat, wheat straw ( Triticum aestivum ) and wood pellets. The measurements of emissions comprised of carbon monoxide (CO), nitrogen oxides (NO x ), sulphur oxides (SO x ) and flue dust mass concentrations (using DIN plus and isokinetic sampling techniques). Emissions varied as a function of operational loads, for each type of pellets. The CO emissions were insignificant with reed canary grass (RCG), citrus pectin waste (CPW) and straw pellets at nominal load, however, at reduced load same pellets emitted 1.9, 4.0 and 7.4 times higher CO than wood pellets, respectively. Peat pellets emitted maximum CO at nominal load (4221.1 mgNm −3 , 12.6 times higher than wood pellets) however; at reduced load CO emission was insignificant. The highest NO x emissions were reported with CPW, which were 3.4 and 4.6 times higher than wood pellets at nominal load and reduced load, respectively. Dust emissions were highest with sunflower husk and lowest with RCG pellets, at both operational modes. The best performance was reported with wood pellets, followed by RCG and pectin pellets, however, wood pellets combustion emitted 1.7 and 2.0 times higher dust DIN plus than RCG at nominal and reduced loads, respectively. Not only fuel specific combustion optimization but also operational load specific optimization is essential for efficient use of agro-pellets in this type of boilers.

The growing population and increasing urbanization have led to a surge in domestic wastewater generation, posing significant challenges for effective and sustainable treatment. The present study demonstrates a novel and sustainable approach for the onsite treatment of domestic wastewater using an integrated settler-based biofilm reactor (ISBR) with efficient biogas generation. The ISBR provides an optimized environment for the growth of biofilm, facilitating the removal of organic pollutants and pathogens. Moreover, the ISBR enables the recovery of a valuable resource in the form of biogas, thus enhancing the overall utility of the treatment process. The performance of the ISBR was comprehensively evaluated at laboratory scale through treating the actual domestic wastewater generated from the hostel of Manipal University Jaipur. The ISBR system was operated under an ambient environment at a hydraulic retention time (HRT) of 24 h. The results demonstrated remarkable efficiency in terms of chemical oxygen demand (COD), total suspended solids (TSS), and coliforms removal, with average removal efficiency being more than 90%. According to the COD mass balance analysis, 48.2% of the influent COD was recovered as bioenergy. The chromatogram revealed a high percentage of methane gas in the collected biogas sample. The field emission scanning electron microscope (FESEM) analysis of the accumulated sludge in the ISBR system depicted the morphology of methanogenic bacteria. Both the experimental and theoretical results confirmed the feasibility and sustainability of the ISBR system at the onsite level.

Carbon dioxide (CO2) emission forms the biggest portion of greenhouse gas emissions known to cause global warming, which can lead to climate change. One of the most widely recommended means of tack...

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.

Global, spectral isolation data measured every minute over a four-year period at Dhahran (26° 32′ N, 50° 13′ E) Saudi Arabia, using five Schott filters with cutoff at “285, 500, 530, 630, and 695” nm, and ultraviolet radiation sensor, 295–385nm, are analyzed. Monthly averages of the diurnal variations of these bands are presented. The rainfall, dust/sand storm, cloud and air mass effects on the band radiation are also investigated. Comparisons of the yearly average of band radiation measured at Dhahran and those reported in Goldberg and Klein (1977) for Jerusalem (32° N) and Rockville (39° N) are presented. Monthly average band radiation are also presented. The data showed that the ratio of the monthly average of the diurnal band radiations to the total radiation for winter and summer are nearly the same. The data also showed that the rainfall increases the percentage of radiation in the bands 385–500nm, 500–530nm, and 630–690nm, and it decreases the percentage radiation of the band 690–2800nm and that the opposite is true for dust/sand storm effect. The change in the band radiation due to cloud cover is small. The data also showed that the monthly and yearly averages of the radiation in the bands “630–695, and 695–2800” nm are latitude independent. The monthly radiation values at each band over the year are almost constant.

We examine the possibility of making useful climate extrapolations in inner basins. Stressing the role of the local geographic features, for a practical example we focus our attention on the Red Sea. We observe that in spite of being an enclosed and relatively small Sea, its climate conditions are heavily affected by those of the larger neighboring regions, in particular the Mediterranean and the Arabian Seas. Using existing high-resolution information of the recent decades, we use both reasoned extrapolation and knowledge of, past and future, longer term general climatic information to frame what is presently possible to assess for the Red Sea. Specifically, the northern part, influenced by the Mediterranean Sea, shows a clear decreasing trend of both the meteorological and wave conditions in the recent decades. However, within a longer span record of 100 years, this decrease appears to be part of a 70-year cycle, which may be overturning, partly at least, in the coming decades. These trends are consistent with the expectations inferred from regional climatic indices, such as North Atlantic Oscillation and Atlantic Multidecadal Oscillation. No similar long term trend has been found for wave, hence implicitly the wind, conditions in the southern part of the basin. As expected, some correlation exists with the typical patterns of the Indian Ocean, but without any specific indication of a future trend. We suggest that, suitably adapted for the specific local conditions and dominant patterns, similar correlation and physical patterns may exist in several of the enclosed areas of the world, opening the possibility of exploring their possible trends in the future decades.

Abstract. The assessment of wind conditions in complex terrain requires the use of Computational Fluid Dynamics (CFD) simulations incorporating an accurate parameterization of forest canopy effects and variable thermal stability effects. This study aims to investigate how incorporating the presence of trees can improve flow predictions. A three-dimensional steady Reynolds-averaged Navier-Stokes (RANS) equations model is set up using OpenFOAM to simulate the flow over a complex terrain site comprising two parallel ridges located near Perdigão, Portugal. A 7.5 km × 7.5 km terrain of the Perdigao site is constructed from elevation data centered around a 100 m met-mast located on the northeast ridge. A 30-min averaged stationary period corresponding to near-neutral conditions on a single met-mast tower is simulated. The impact of incorporating different source terms is studied such as forest canopy, Coriolis forces as well as also buoyancy forces. The prediction capability of the models is analyzed for different groups of towers on the South-West ridge, inside the valley, and on the North-East ridge based on the flow topology. The inclusion of a canopy model is shown to improve predictions close to the ground for most of the towers, while reducing prediction accuracy on top of the ridges, illustrating the need to represent terrain heterogeneity.

Nature-based solutions may actively reduce hydro-meteorological risks in urban areas as a part of climate change adaptation. However, the main reason for the increasing uptake of this type of solution is their many benefits for the local inhabitants, including recreational value. Previous studies on recreational value focus on studies of existing nature sites that are often much larger than what is considered as new NBS for flood adaptation studies in urban areas. We thus prioritized studies with smaller areas and nature types suitable for urban flood adaptation and divided them into four common nature types for urban flood adaptation: sustainable urban drainage systems, city parks, nature areas and rivers. We identified 23 primary valuation studies, including both stated and revealed preference studies, and derived two value transfer functions based on meta-regression analysis on existing areas. We investigated trends between values and variables and found that for the purpose of planning of new NBS the size of NBS and population density were determining factors of recreational value. For existing NBS the maximum travelling distance may be included as well. We find that existing state-of-the-art studies overestimate the recreational with more than a factor of 4 for NBS sizes below 5 ha. Our results are valid in a European context for nature-based solutions below 250 ha and can be applied across different NBS types and sizes.