• Energy Research
• 2021-2025close
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A range of optical fibre-based sensors for the measurement of ethanol, primarily in aqueous solution, have been developed and are reviewed here. The sensing approaches can be classified into four groups according to the measurement techniques used, namely absorption (or absorbance), external interferometric, internal fibre grating and plasmonic sensing. The sensors within these groupings can be compared in terms of their characteristic performance indicators, which include sensitivity, resolution and measurement range. Here, particular attention is paid to the potential application areas of these sensors as ethanol production is globally viewed as an important industrial activity. Potential industrial applications are highlighted in the context of the emergence of the internet of things (IoT), which is driving widespread utilization of these sensors in the commercially significant industrial and medical sectors. The review concludes with a summary of the current status and future prospects of optical fibre ethanol sensors for industrial use.

In the backdrop of COVID19 recovery, Pakistan is still struggling to cope with the economic challenges and disruptions caused in the energy supply chain. On one hand where COVID has brought serious socio-economic costs and prolonged delays, it has also provided opportunity for developing countries such as Pakistan to “build-forward-better” their economies in a more sustainable and climate friendly manner. This study particularly highlights the impact of COVID on energy supply and demand sectors of Pakistan, its near- and long-term impacts, and what policy interventions can be adopted to put Pakistan on-track to achieve its Nationally Determined Contributions (NDCs). The economic focus in on “Green Recovery” and what key interventions will foster a rapid transition towards decarbonization in Pakistan. Low Emission Analysis Platform (LEAP) model is used to provide energy sector outlook (2020-2040) of Pakistan under different scenario i.e., Pre COVID growth, Business-as-Usual, Slow Recovery, and Green Recovery from COVID. The results obtained from the model depicts that following a green recovery scenario, Pakistan can reduce around 10 Mtoe (9%) of its total energy use, 53 TWh of electricity, 19 Mt of emissions from demand sectors, and 11 Mt of emissions from the power sector by 2030. For total levelized cost of the power sector, the green recovery scenario represents a generation cost of $13 billion by 2030 which further highlights that energy efficiency could lead to cost savings of approximately $3 billion each year by 2030. Green recovery is however still a daunting task as it would require economic stimulus of $8 billion only to recover to its pre COVID scenario and total investments of $120 billion by 2030.

The energy crisis and increasing fossil fuel prices due to increasing demands, controlled supplies, and global political unrest have adversely affected agricultural productivity and farm profitability across the globe and Pakistan is not an exception. To cope with this issue of energy deficiency in agriculture, the best alternate strategy is to take advantage of biomass and solid waste potential. In low-income countries such as Pakistan, the greenhouse heating system mostly relies on fossil fuels such as diesel, gasoline, and LPG. Farmers are reluctant to adopt greenhouse farming due to the continuously rising prices of the fossil fuels. To reduce reliance on fossil fuel energy, the objective of this study was to utilize biomass from crop residues to develop an efficient and economical biomass furnace that could heat greenhouses to protect the crop from seasonal temperature effects. Modifications made to the biomass furnace, such as the incorporation of insulation around the walls of the furnace, providing turbulators in fire tubes, and a secondary heat exchanger (heat recovery system) in the chimney, have increased the thermal efficiency of the biomass furnace by about 21.7%. A drastic reduction in hazardous elements of flue gases was observed due to the addition of a water scrubber smoke filter in the exit line of the flue. The efficiency of the biomass furnace ranged from 50.42% to 54.18%, whereas the heating efficiency of the diesel-fired heater was 71.19%. On the basis of the equal heating value of the fuels, the unit material and operating costs of the biomass furnace for wood, cotton stalks, corn cobs, and cow dung were USD 2.04, 1.86, 1.78, and 2.00 respectively against USD 4.67/h for the diesel heater. The capital and operating costs of the biomass furnace were about 50% and 43.7% of the diesel heater respectively, resulting in a seasonal saving of about 1573 USD. The produced smoke was tested as environmental friendly under the prescribed limits of the National Environmental Quality Standards (NEQS), which shows potential for its large-scale adoption and wider applications.

Renewable energy has become more popular since it is cost-effective and more efficient than conventional energy sources. Biomass-based renewable energy is primarily used in emerging economies to ensure environmental sustainability. This study examines the asymmetric correlation between biomass energy consumption and CO2 emissions in the top-10 biomass energy consumer countries (Brazil, Canada, Thailand, China, Italy, India, Germany, USA, UK, and Japan). A new approach "Quantile-onQuantile (QQ)" is employed by utilizing the data from 1991 to 2018. Biomass energy consumption, with the exception of Thailand, significantly mitigates CO2 emissions at various quantiles in selected countries. As a robustness check, we used the quantile regression test, whose findings are consistent with the outcomes from the quantile-on-quantile method. However, the degree of asymmetry in the biomass energy-CO2 nexus varies by country, necessitating extra attention and government vigilance when developing biomass energy and environmental policies.

Cette étude examine les caractéristiques des profils de vitesse, de champ thermique et d'entropie pour l'écoulement de nanofluides hybrides traversant une feuille d'amidonnage avec un rayonnement thermique. Les nanotubes de carbone (SWCNT et MWCNT) sont utilisés comme nanoparticules avec flux de chaleur Cattaneo-Christov (CC). L'éthylène glycol est utilisé comme fluide de base dans ce cas. Pour obtenir une solution améliorée, l'écoulement de fluide sur les propriétés géométriques est conçu en utilisant des PDE hautement non linéaires, et les équations gouvernantes doivent être converties en systèmes d'équations non similaires sans dimension en utilisant le schéma de Keller-box bien connu et très efficace dans le logiciel de calcul Matlab. La faisabilité pratique de ces solutions est déterminée par la plage des paramètres de contrôle. La distribution de vitesse diminue à mesure que l'estimation des paramètres magnétiques augmente, cependant, le champ de température et la production d'entropie augmentent à mesure que la fluctuation des paramètres magnétiques diminue. Au fur et à mesure que le paramètre de glissement augmente, le champ de vitesse diminue. Le champ thermique est amélioré pour augmenter le paramètre de rayonnement, et le profil d'entropie est renforcé pour augmenter les valeurs des paramètres de Brinkman. Les résultats de cette recherche pourraient avoir un impact significatif sur les industries où le refroidissement et le chauffage locaux par jets d'impact sont nécessaires dans les appareils électroniques, les dissipateurs thermiques, les technologies de séchage, etc. À la connaissance des auteurs, il s'agit du premier effort visant à utiliser un nanofluide hybride pour analyser la formation d'entropie due au flux magnétohydrodynamique sur une feuille d'amidonnage. Este estudio examina las características de los perfiles de velocidad, campo térmico y entropía para el flujo híbrido de nanofluidos que pasa a través de una lámina de almidón con radiación térmica. Los nanotubos de carbono (SWCNT y MWCNT) se utilizan como nanopartículas con flujo de calor Cattaneo-Christov (CC). El etilenglicol se utiliza como fluido base en este caso. Para lograr una solución mejorada, el flujo de fluido sobre las propiedades geométricas se diseña utilizando PDE altamente no lineales, y las ecuaciones gobernantes deben convertirse en sistemas de ecuaciones no similares adimensionales utilizando el conocido esquema de Keller-box altamente eficiente en el software computacional MATLAB. La viabilidad práctica de estas soluciones está determinada por el rango de los parámetros de control. La distribución de velocidad se reduce a medida que aumenta la estimación del parámetro magnético, sin embargo, el campo de temperatura y la producción de entropía aumentan a medida que la fluctuación del parámetro magnético se aclara. A medida que aumenta el parámetro de deslizamiento, el campo de velocidad disminuye. El campo térmico se mejora para aumentar el parámetro de radiación, y el perfil de entropía se aumenta para aumentar los valores de los parámetros de Brinkman. Los hallazgos de esta investigación podrían tener un impacto significativo en las industrias donde se necesita refrigeración local y calefacción a través de chorros de choque en dispositivos electrónicos, disipadores de calor, tecnologías de secado, etc. Según el conocimiento de los autores, este es el primer esfuerzo para emplear un nanofluido híbrido para analizar la formación de entropía debido al flujo magnetohidrodinámico sobre una lámina de almidón. This study examines the characteristics of the velocity, thermal field and entropy profiles for hybrid nanofluid flow passing through a starching sheet with thermal radiation. The carbon nanotube (SWCNT and MWCNT) are used as a nanoparticles with Cattaneo-Christov (CC) heat flux. Ethylene glycol is utilized as a base fluid in this case. To achieve an improved solution, the fluid flow over the geometric properties is designed using highly non-linear PDEs, and the governing equations must be converted into dimensionless non-similar equation systems using the highly efficient well-known Keller-box scheme in computational software MATLAB. The practical feasibility of these solutions is determined by the range of the controlling parameters. The velocity distribution reduces as the magnetic parameter estimate increases, however, the temperature field and entropy production increase as the magnetic parameter fluctuation esclates. As the slip parameter is increased, the velocity field diminish. The thermal field is enhanced for rising the radiation parameter, and the entropy profile is boosted for increasing Brinkman parameter values. The findings of this research might have a significant impact on industries where local cooling and heating via impingement jets are needed in electronic devices, heat sinks, drying technologies, and so on. To the best of the authors' knowledge, this is the first effort to employ a hybrid nanofluid to analyze entropy formation due to magnetohydrodynamics flow over a starching sheet. تبحث هذه الدراسة في خصائص ملامح السرعة والحقل الحراري والانتروبيا لتدفق السوائل النانوية الهجينة التي تمر عبر ورقة النشا مع الإشعاع الحراري. يتم استخدام الأنبوب النانوي الكربوني (SWCNT و MWCNT) كجسيمات نانوية مع تدفق حراري Cattaneo - Christov (CC). يستخدم جلايكول الإيثيلين كسائل أساسي في هذه الحالة. لتحقيق حل محسّن، تم تصميم تدفق المائع عبر الخصائص الهندسية باستخدام PDEs غير خطية للغاية، ويجب تحويل المعادلات الحاكمة إلى أنظمة معادلات غير متشابهة بلا أبعاد باستخدام مخطط Keller - box المعروف عالي الكفاءة في البرنامج الحاسوبي MATLAB. يتم تحديد الجدوى العملية لهذه الحلول من خلال نطاق معلمات التحكم. ينخفض توزيع السرعة مع زيادة تقدير المعلمة المغناطيسية، ومع ذلك، يزداد مجال درجة الحرارة وإنتاج الإنتروبيا مع تذبذب المعلمة المغناطيسية. مع زيادة معامل الانزلاق، يتناقص مجال السرعة. يتم تعزيز المجال الحراري لرفع معلمة الإشعاع، ويتم تعزيز ملف تعريف الإنتروبيا لزيادة قيم معلمة برينكمان. قد يكون لنتائج هذا البحث تأثير كبير على الصناعات التي تحتاج إلى التبريد والتدفئة المحليين عبر نفاثات الاصطدام في الأجهزة الإلكترونية وأحواض الحرارة وتقنيات التجفيف وما إلى ذلك. على حد علم المؤلفين، هذا هو أول جهد لتوظيف مائع نانوي هجين لتحليل تكوين الإنتروبيا بسبب تدفق الديناميكا المائية المغناطيسية على ورقة النشا.

Abstract Hydrogen is considered a potential game changer for world energy systems and a solution to climate change concerns, as it generates zero waste and it is suited for power generation and transportation. Despite its several advantages, there are significant technical challenges in deploying a stable hydrogen economy including improving its process efficiencies, lowering production costs, maintaining cost-effective transmission and distribution, and exploiting inexpensive and sustainable feedstocks. In this context, a detailed study was conducted to analyze the production sources, technologies, storage and transport systems, and global potential exportable feedstocks to produce hydrogen. A comprehensive analysis of current hydrogen production technologies with their energy efficiencies and hydrogen selling prices was reported in this study. Various hydrogen production technologies with their capital investments and CO2 emissions were also presented. Potential feedstocks for hydrogen production were identified and analyzed through a product space model, which characterizes a network of global exportable products based on their similarities and productive knowledge. It was established that the hydrogen production feedstocks and sources currently used are primarily available in six countries: the United States of America, France, Russia, Sweden, the Netherlands, and Spain. Broadly, the results revealed that the United States of America and Russia shared the highest hydrogen feedstock exports, indicating a higher probability of hydrogen production in these countries. Except for Russia, all the studied countries fell in the most desired quadrant, indicating that they can move in all product space directions to exploit unexplored hydrogen feedstocks for better sustainable economic growth.

Abstract This paper presents a conceptual study of a solar PV integrated refrigeration system for a cold storage facility based on the conventional vapor compression system for banana fruit. In the first stage, the conventional system has been thoroughly analyzed. Mathematical modelling has shown that the condenser is oversized, while the evaporator was undersized. Furthermore, the air-conditioning compressor was also found to be oversized by approximately 12 kW after an evaluation at no-load and full-load conditions. In the second stage, the optimized system with reduced consumption was integrated to a solar PV field. The solar field sizing, and performance optimization of the proposed PV hybrid refrigeration system was accomplished in PV*SOL tool. The simulations demonstrated that with a 170 m2 solar field, an optimized PV hybrid refrigeration system can achieve 58.1% solar fraction at a performance ratio of 59.2%, under given climatic conditions. With net metering, the hybrid system shows a high economic feasibility with the payback period of 5.2 years. The comprehensive methodology and all-inclusive results are valuable to generate explicit recommendations for repowering along with renewable integration of cold storage facilities operating in the region.

The synthesis of biodiesel from Jatropha curcas by transesterification is kinetically controlled. It depends on the molar ratio, reaction time, and temperature, as well as the catalyst nature and quantity. The aim of this study was to explore the transesterification of low-cost, inedible J. curcas seed oil utilizing both homogenous (potassium hydroxide; KOH) and heterogenous (calcium oxide; CaO) catalysis. In this effort, two steps were used. First, free fatty acids in J. curcas oil were reduced from 12.4 to less than 1 wt.% with sulfuric acid-catalyzed pretreatment. Transesterification subsequently converted the oil to biodiesel. The yield of fatty acid methyl esters was optimized by varying the reaction time, catalyst load, and methanol-to-oil molar ratio. A maximum yield of 96% was obtained from CaO nanoparticles at a reaction time of 5.5 h with 4 wt.% of the catalyst and an 18:1 methanol-to-oil molar ratio. The optimum conditions for KOH were a molar ratio of methanol to oil of 9:1, 5 wt.% of the catalyst, and a reaction time of 3.5 h, and this returned a yield of 92%. The fuel properties of the optimized biodiesel were within the limits specified in ASTM D6751, the American biodiesel standard. In addition, the 5% blends in petroleum diesel were within the ranges prescribed in ASTM D975, the American diesel fuel standard.