• Energy Research

The development of photobioreactor is important for sustainable production of renewable fuels, wastewater treatment and CO2 fixation. For the design and scale-up of a photobioreactor, CFD can be used as an indispensable tool. The present study reviews the recent status of computational flow modelling of various types of photobioreactors, involving fluid dynamics, light transport, and algal growth kinetics. An integrated modelling approach of hydrodynamics, light intensity, mass transfer, and biokinetics in photobioreactor is discussed further. Also, this reviews intensified system to improve the mixing, and light intensity of photobioreactors. Finally, the prospects and challenges of CFD modelling in photobioreactors are discussed. Multi-scale modelling approach and development of low-cost efficient computational framework are the areas to be considered for modelling of photobioreactor in near future. In addition, it is necessary to use process intensification techniques for photobioreactors for improving their hydrodynamics, mixing and mass transfer performances, and algal growth productivity.

Being declared a global emergency, the COVID-19 pandemic has taken many lives, threatened livelihoods and businesses around the world. The energy industry, in particular, has experienced tremendous pressure resulting from the pandemic. In response to such a challenge, the development of sustainable resources and renewable energy infrastructure has demonstrated its potential as a promising and effective strategy. To sufficiently address the effect of COVID-19 on renewable energy development strategies, short-term policy priorities should be identified, while mid-term and long-term action plans should be formulated in achieving the well-defined renewable energy targets and progress towards a more sustainable energy future. In this review, opportunities, challenges, and significant impacts of the COVID-19 pandemic on current and future sustainable energy strategies were analyzed in detail; while drawing from experiences in identifying reasonable behaviors, orientating appropriate actions, and policy implications on the sustainable energy trajectory were also mentioned. Indeed, the question is that whether the COVID-19 pandemic will kill us or provide us with a precious lesson on future sustainable energy development.

AbstractCurrently, the supply of diminishing fossil fuel reserves, and the rise in challenges in environmental, political and economic consequences have caused the great concerns in the development of modern society; these have forced the policy-makers and researchers to look for the renewable and green energy sources. Deemed as a promising renewable alternative to traditional fossil fuels, 2,5-dimethylfuran (DMF, chemical formula C6H8O)—a derivative of furan—has the potential to relieve the growing shortage of fossil fuels while satisfying the increase in global energy demand and minimizing the adverse effects of climate change. DMF can be used as a clean source of liquid transportation biofuel given the fact that it is directly obtained from biomass-derived carbohydrates. In reviewing current DMF production methods, this review paper analyzes and presents the comparison of catalytic performance in the conversion of biomass into DMF. In addition, the applicability of DMF in spark-ignition (SI) engines is thoroughly analyzed based on the spray and flame, combustion, performance, and emission characteristics of SI engines running on DMF compared with ethanol and gasoline. More interestingly, the knocking, lubrication, and wear characteristics in SI engines fueled with DMF are also evaluated and discussed. Nonetheless, further investigation on optimization strategies on DMF production process should be conducted prior to the initiation of large-scale commercialization as well as the application of DMF to real-world SI engines.

Wastewater treatment may help to reduce water shortages, whilst concurrently recover energy and nutrients, leading to some of the exploitation of important sources being offset. Compared to other approaches, wastewater purification via adsorption is highly-desirable. The reason is that with this simple and better-to-regenerate technique, heavy metals could be removed even under lower concentration of metal ions. Due to numerous advantages and tunable physicochemical properties, biochar has received most attention for the control of water contamination. This contributes to the solving ecology issues. Significantly, the link between biochar and the rehabilitation of resources should be studied, so that the role of biochar during the wastewater and environmental treatment is well-comprehended and scale-up. In this review, the biochar production from biomass through different routes and their critical properties are critically reviewed and presented. In addition, the activation methods of biochar are also presented and thoroughly compared. More importantly, the application of biochar in heavy metal removal is scrutinized. The factors that affect the heavy metal adsorption capacity and performance are critically evaluated. Finally, limitations and future perspectives for biochar production and application in the removal of heavy metal from wastewater are highlighted in this review.

The production of chemicals and fuels from renewable biomass with the primary aim of reducing carbon footprints has recently become one of the central points of interest. The use of lignocellulosic biomass for energy production is believed to meet the main criteria of maximizing the available global energy source and minimizing pollutant emissions. However, before usage in bioenergy production, lignocellulosic biomass needs to undergo several processes, among which biomass pretreatment plays an important role in the yield, productivity, and quality of the products. Acid-based pretreatment, one of the existing methods applied for lignocellulosic biomass pretreatment, has several advantages, such as short operating time and high efficiency. A thorough analysis of the characteristics of acid-based biomass pretreatment is presented in this review. The environmental concerns and future challenges involved in using acid pretreatment methods are discussed in detail to achieve clean and sustainable bioenergy production. The application of acid to biomass pretreatment is considered an effective process for biorefineries that aim to optimize the production of desired products while minimizing the by-products.

Abstract Global concerns about CO2 levels in the atmosphere, energy security, and the depletion of fossil fuel supply have been the key motivation to develop bio-based fuel resources, which leads to promising and potential strategies of renewable and carbon-neutral biofuels. Among biofuels being strongly developed, 2,5-dimethylfuran (DMF) is a new alternative biofuel candidate since DMF could be synthesized from available and durable lignocellulosic biomass, as well as DMF's physicochemical properties were found to be similar to those of fossil fuels. Therefore, the comprehensive investigation on DMF is very essential before putting DMF into the commercial scale and the engine application. In this current work, the temporal evolutions of laminar flame characteristics including laminar burning velocities, unstretched flame propagation speed, and Schlieren images were critically reviewed based on the comparison of DMF with other fuels. Besides, flame instabilities were also evaluated in detail. Finally, ignition delay times were thoroughly analyzed with the variation of the initial parameters such as temperature, pressure, and equivalent ratio, suggesting that DMF could become the potential fuel for the spark ignition engine. In the future, the experimental studies on the real engines fueled with DMF should be carefully and completely performed to have a comprehensive evaluation of this promising biofuel class.

This paper reports an experimental investigation focused on nano-enhanced phase change materials (NEPCM). Two different types of phase change materials (RT28 HC and RT26) with relatively low thermal conductivity and reasonable volumetric specific heat capacity were utilized as the base for NEPCMs with four types of nanoparticles (CuO, ZnO, Ag, and graphene). The novel four-phase preparation procedure was thoroughly presented together with a description of the measurement technology which was used for the examination of NEPCM thermal constants. The experimental results revealed that in most cases the thermal constants of samples were improved, such as thermal conductivity and volumetric specific heat capacity in a range of about 4% to 21% and 5% to 33%, respectively. In some cases, significant degradation of certain thermal constants was detected, such as in the case of the Graphene/RT26 nanocomposite. The possible nanomaterial selection strategies also discussed taking into account the economic aspects and experimental results related to the thermal constants. The results revealed that the selection of nanomaterials should be carefully considered with respect to the specific application since it is possible to manipulate the thermo-physical properties of the NEPCM as a unique combination of nanomaterial and PCM.

Le développement des ressources en énergies renouvelables est vivement encouragé pour remédier à la pénurie d'énergies fossiles et aux problèmes de pollution qui y sont associés. La production d'énergie à partir de matériaux glucidiques a récemment suscité un grand intérêt en raison de la disponibilité, de la fiabilité et de l'abondance des sources de glucides. De manière significative, la transformation catalytique des glucides résiduels en biocarburants à base de furane, en particulier le 2,5-diméthylfurane (DMF), semble être une solution attrayante aux problèmes énergétiques et environnementaux susmentionnés. Le potentiel du DMF en tant que carburant renouvelable est prospectif, avec ses propriétés physico-chimiques similaires à celles des combustibles fossiles. Par conséquent, le travail actuel se concentre sur la production de DMF, les aspects importants pour un rendement accru en DMF étant résumés ici. Notamment, les catalyseurs importants dérivés de la zéolite, du métal noble, du métal non noble, du cadre organométallique et des matériaux électrocatalytiques sont discutés, ainsi que leurs effets sur la dérivation des glucides en DMF. En outre, les mécanismes de production de DMF ont également été clarifiés, suivis de l'examen minutieux des effets des conditions de réaction, des solvants et des donneurs d'hydrogène sur le rendement en DMF. Enfin, le processus de purification, le potentiel de commercialisation et la faisabilité économique de la production de DMF ont également été incorporés, des orientations futures perspicaces étant identifiées à la fin de notre examen. Cette revue devrait préconiser la production de DMF à partir de matériaux glucidiques, ce qui pourrait atténuer les problèmes énergétiques et environnementaux rencontrés actuellement. Se insta encarecidamente al desarrollo de recursos energéticos renovables para recuperar la escasez de energía basada en fósiles y sus problemas de contaminación asociados. La producción de energía a partir de materiales de carbohidratos ha sido recientemente de gran interés debido a la disponibilidad, confiabilidad y abundancia de fuentes de carbohidratos. Significativamente, la transformación catalítica de los carbohidratos residuales en biocombustibles a base de furano, específicamente 2,5-dimetilfurano (DMF), parece ser una solución atractiva para los problemas energéticos y ambientales mencionados anteriormente. El potencial del DMF como combustible renovable es prospectivo, con sus propiedades fisicoquímicas similares a las de los combustibles fósiles. Por lo tanto, el trabajo actual se centra en la producción de DMF, resumiéndose en este documento los aspectos importantes para mejorar el rendimiento de DMF. En particular, se discuten los catalizadores significativos derivados de zeolita, metal noble, metal no noble, estructura metal-orgánica y materiales electrocatalíticos, junto con sus efectos en la derivación de carbohidratos a DMF. Además, también se aclararon los mecanismos de producción de DMF, seguidos del escrutinio de los efectos de las condiciones de reacción, los disolventes y los donantes de hidrógeno en el rendimiento de DMF. Finalmente, también se incorporaron el proceso de purificación, el potencial de comercialización y la viabilidad económica de la producción de DMF, y se identificaron direcciones futuras al final de nuestra revisión. Se espera que esta revisión defienda la producción de DMF a partir de materiales de carbohidratos, lo que podría aliviar los problemas energéticos y ambientales que se encuentran actualmente. The development of renewable energy resources is strongly urged to recoup the shortage of fossil-based energy and its associated pollution issues. Energy production from carbohydrate materials has recently been of great interest due to the availability, reliability, and abundance of carbohydrate sources. Significantly, the catalytic transformation of waste carbohydrates into furan-based biofuels, specifically 2,5-dimethylfuran (DMF), appears to be an attractive solution to the aforementioned energy and environmental issues. The potential of DMF as a renewable fuel is prospective, with its physicochemical properties that are similar to those of fossil fuels. Therefore, the current work focuses on the production of DMF, with the important aspects for enhanced DMF yield being summarized herein. Notably, the significant catalysts derived from zeolite, noble-metal, non-noble-metal, metal–organic framework, and electrocatalytic materials are discussed, alongside their effects in deriving carbohydrates to DMF. Furthermore, the mechanisms of DMF production were clarified too, followed by the scrutinization of the effects from reaction conditions, solvents, and hydrogen donors onto the DMF yield. Finally, the purification process, commercialization potential, and economic feasibility of DMF production were incorporated too, with insightful future directions being identified at the end of our review. This review is expected to advocate DMF production from carbohydrate materials, which could alleviate the energy and environmental problems encountered presently. ونحث بشدة على تطوير موارد الطاقة المتجددة لتعويض النقص في الطاقة الأحفورية وقضايا التلوث المرتبطة بها. كان إنتاج الطاقة من مواد الكربوهيدرات في الآونة الأخيرة ذا أهمية كبيرة بسبب توافر مصادر الكربوهيدرات وموثوقيتها ووفرتها. بشكل ملحوظ، يبدو أن التحول التحفيزي لنفايات الكربوهيدرات إلى وقود حيوي قائم على الفيوران، وتحديدًا 2،5 -ثنائي ميثيل فوران (DMF)، هو حل جذاب لقضايا الطاقة والبيئة المذكورة أعلاه. إمكانات DMF كوقود متجدد محتملة، مع خصائصها الفيزيائية والكيميائية التي تشبه خصائص الوقود الأحفوري. لذلك، يركز العمل الحالي على إنتاج DMF، مع تلخيص الجوانب المهمة لتعزيز عائد DMF هنا. ومن الجدير بالذكر أنه تمت مناقشة المحفزات الهامة المشتقة من الزيوليت والمعادن النبيلة وغير النبيلة والإطار المعدني العضوي والمواد التحفيزية الكهربائية، إلى جانب آثارها في اشتقاق الكربوهيدرات إلى DMF. علاوة على ذلك، تم توضيح آليات إنتاج DMF أيضًا، تليها التدقيق في التأثيرات الناتجة عن ظروف التفاعل والمذيبات والمتبرعين بالهيدروجين على عائد DMF. أخيرًا، تم دمج عملية التنقية وإمكانات التسويق والجدوى الاقتصادية لإنتاج DMF أيضًا، مع تحديد اتجاهات مستقبلية ثاقبة في نهاية مراجعتنا. من المتوقع أن تدعو هذه المراجعة إلى إنتاج DMF من مواد الكربوهيدرات، والتي يمكن أن تخفف من مشاكل الطاقة والبيئة التي تواجهها حاليًا.