Search

The emerging study of hydrogen energy is receiving substantial attention in the scientific community due to its efficiency in approaching net zero and environmental sustainability. Meanwhile, bioethanol is a sustainable and carbon–neutral fuel for hydrogen production. This research aims to assess various ethanol reforming routes, including ethanol steam reforming, partial oxidation, and autothermal reforming, and evaluate the differences in hydrogen production as a function of catalyst physicochemistry and experimental parameters. For all three techniques, 75 % hydrogen selectivity is attained at 400 °C. In the ethanol steam reforming, non-noble metals (Co and Ni) are more reactive than noble metals (Rh and Ru). However, the sequence of hydrogen selectivity is featured by Rh > Ir > Ru > Pt > Ni > Co in autothermal reforming of ethanol. The partially filled d-orbitals of various transition metals can uptake or provide electrons to various reagents, thereby controlling reaction activity. Non-noble metals are inexpensive, making these catalysts appealing for a variety of reforming processes. The small crystal size <10 nm and the large Brunauer-Emmett-Teller surface area of the metal-support particles regulate the dispersion and reactivity of the catalyst. Hydrogen selectivity is lower in partial oxidation and autothermal reforming, while CO and CO2 exhibit no specific selectivity trend. The reactivity of intermediate reactions such as dehydrogenation and decarbonylation positively correlated with the reaction temperature and the steam/oxygen/ethanol ratio, which regulates syngas product distributions. Overall, this review provides a vision for sustainable hydrogen production and decarbonization to achieve the net zero target.

Methanol is regarded as an important chemical precursor in the chemical industry and has huge potential to replace gasoline and diesel as vehicle fuel. Biomass to methanol is a sustainable and green production method, but its economic and environmental viability is contingent on production technologies and geographic context. This study proposed a carbon-negative methanol production method that integrated four modules of bagasse pyrolysis, physical activation, chemical looping, and methanol synthesis in the context of China. Three scenarios, including co-production of methanol and biochar, co-production of methanol and activated carbon, and co-production of methanol and activated carbon with extra hydrogen, were put forward and simulated in Aspen Plus. An evaluation system was established to quantitatively assess the carbon and energy efficiencies and economic and environmental benefits of the three scenarios. The results suggested that the addition of hydrogen effectively increased the methanol yield in Scenario 3, leading to high carbon and energy efficiencies. Scenarios 1 and 2 exhibited better economic and environmental performance with low payback periods of 6.53 and 5.80 years and low global warming potentials of −1631.18 and −710.28 kg CO2-eq/t methanol. However, Scenario 3 would be economically and environmentally feasible by decreasing hydrogen production costs and implementing green hydrogen production methods in the foreseeable future. This study provides a viable approach for sustainable methanol production in China, thereby aligning with the current imperative of achieving carbon neutrality.

The deoxidizing packing material (DPM) in a microbial fuel cell (MFC) was improved by adding a deoxidizing agent (DA) to its surface to form DPMDA-out, causing the DA effectively to consume dissolved oxygen in the anode tank. The removal efficiencies by MFC using DPMDA-out of isopropanol and styrene were 8.72–30.5 % and 2.50–15.7 % greater than the removal efficiencies by adding DA to the interior of the DPM to form DPMDA-in, respectively. This results suggest that MFC processes hydrophilic isopropanol more easily than hydrophobic styrene. The maximum voltage outputs of a DPMDA-out-based MFC for isopropanol and styrene are 1.08 and 1.16 times those of a DPMDA-in-based MFC and the power densities are 1.31 and 1.57 times as large, respectively. Even though the removal efficiency of styrene (15.7 %) in the modified MFC is less than that of isopropanol (30.5 %), the electricity production by the MFC with styrene as its substrate exceeds that by the MFC with isopropanol. A kinetic analysis revealed that the effectiveness of improving the anode material was more easily reflected by the reaction rate constant (k) of isopropanol. The improved DPMDA-out enhances the removal efficiency of targeted pollutants and the production of power by the MFC.

Sustainable fuel production techniques and feedstocks are essential to meet the future energy demand. In this context, the present study is aimed at sustainably producing low-density biodiesel from Chlorella pyrenoidosa microalgae by heterotrophic means and processed using enzymatic transesterification. To assess the potential of the low-density biodiesel, the fatty acid methyl profile is analyzed and homogenized with diesel fuel at 10, 20, 30, and 40% (v/v/) and tested in a light commercial compression ignition engine at maximum throttle pedal position condition. Furthermore, to identify the optimal mixture proportion and predict the engine outputs, statistical tools like multivariate principal component analysis–desirability approach are employed. From the study, it was inferred that the biomass concentrations of the cultures from 100, 200, and 300L stir tank bioreactor reached up to 5.15, 4.24, and 4.36 g/L on scaling-up. The maximum biodiesel conversion rate of 98% was achieved at an optimal reaction time of 12 h and temperature of 37 °C during enzymatic transesterification. During engine testing, the lowest fuel consumption of 0.41 kg/kWh was attained at full load condition while operating on 40% biodiesel composition. At 20% biodiesel composition, hydrocarbon, nitrogen oxides, and smoke emissions reduce by 44.26, 23.55, and 11.69% as compared to diesel fuel at full load condition. Maximum in-cylinder pressure and heat release rate were achieved by CP30D70 at full load condition as compared to diesel fuel. The optimal biodiesel proportion was identified as 20 and 30% based on the cluster similarly index of 89.67% and desirability value.

Electrolysis is a promising approach for biodiesel production. However, low electrical conductivity of a reaction mixture results in a low reaction rate. Thus, this study developed a novel catalyst-free electrolysis process using an ionic liquid as a supporting electrolyte for biodiesel production. Various ionic liquids were assessed, and 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) exhibited the highest electrical conductivity (4.59 mS/cm) and the best electrolytic performance for transesterification. Electrolysis in the presence of [Emim]Cl was subsequently optimized using response surface methodology to maximize biodiesel yield. A maximum biodiesel yield of 97.76% was obtained under the following optimal reaction conditions: electrolysis voltage, 19.42 V; [Emim]Cl amount, 4.43% (w/w); water content, 1.62% (w/w); methanol to oil molar ratio, 26.38: 1; and reaction time, 1 h. Notably, [Emim]Cl could be efficiently reused for at least three cycles with a corresponding biodiesel yield of 94.81%. Moreover, the properties of the synthesized biodiesel complied with EN and ASTM standards. The findings of this study indicate that catalyst-free electrolysis using [Emim]Cl as a supporting electrolyte is an eco-friendly and efficient method for biodiesel production.

The global municipal solid waste (MSW) generation rate is 2.01 billion metric tonnes annually with an average of 0.74 kg waste/person/day. Approximately 92 % of the MSW originates from organics composition (e.g., food waste; plastic; paper; garden waste/woods, and textile), where 33 % of overall MSW is improperly managed in an efficient and environmentally safe manner. One of the promising methods to solve MSW management issues is to convert MSW into refuse-derived fuel (RDF) that can be used for the clinker burning process in cement kiln to replace the usage of fossil-based solid fuel. Thus, the potential of local MSW composition in energy recovery; suitability of RDF production technology; as well as international-industry requirement on RDF in co-processing and environmental concerns are discussed. Due to heterogeneous composition and sizes in nature, high moisture, and substantial amount of chloride content in MSW, it needs to undergo pre-treatment processes to enhance the RDF's physio-chemical properties that comply with RDF ASTM/EN standards, where expected high heating value (HHV) is > 20 MJ/kg, ash (<10 %), Chloride (Cl) (<0.80 – 1.00 %), Sulphate (S) (<1.50 %), Nitrate (N) (<1.00 %). As the development of upgraded MSW to RDF is still new in the commercial phase, there is minimal information and data on the techno-economic analysis, as well as recent industrial-scale of thermos-chemical conversion technologies for RDF preparation. Hence, the present work provides a clear picture on overview of municipal solid waste (MSW) generation, MSW composition, MSW pretreatment, and application as co-processing in cement industry are discussed. Besides, recent thermochemical upgrading process (torrefaction, dry carbonization, and hydrothermal carbonization) of MSW from R&D to commercial scale was further highlighted. In summary, this review serves as basic criterion and strategies to explore the new path of upgrading the waste into RDF for the purpose of sustainable ene

This review delves into the potential of renewable biomass for green diesel production. Deoxygenation technology offers a promising method for converting biomass-derived oxygenates oil into high-grade hydrocarbon factions. Hence, various deoxygenation pathways of biomass conversion under free‑hydrogen environment were explored. Additionally, the prospects of acid-base bifunctional catalysts to facilitate deoxygenation was discussed, highlighting the correlation between the physicochemical properties of the catalysts and catalytic activity. However, it should be noted that the acid-base characteristics of the catalysts contribute to the breaking of C–O bonds of oxygenated oil via undesirable pathways, which contributed to unfavorable by-product and catalyst deactivation.

This study examined hybrid nanofluids of graphene nanoplatelets (GNP) and graphene oxide (GO) in terms of their stability and performance as a working fluid in a flat plate solar thermal collector. Instead of functionalisation, this experiment utilises the synergetic effect of GO, which stabilises GNP nanofluids by acting like an amphiphilic surfactant. Experimental results found that stability is significantly improved with a sufficiently high concentration of GO. Stability improved as the proportion of GO was increased. In particular, the sample with an equal 50:50 ratio of GNP and GO showed good stability in sedimentation measurements, retaining over 90% of its concentration over one month. Stability was also measured under working pipe flow conditions in a solar collector test rig. This type of data has not previously been reported in the literature. Measurement of the change in concentration showed that in addition to sedimentation, concentration loss can occur via an alternative mechanism: deposition of the nanoparticles inside the pipes. The pristine GNP sample lost over 80% of its concentration over one day of running in the test rig, despite showing moderate stability over one month under still conditions. This shows that measurement of stability in still conditions does not fully describe the stability of nanofluids intended to be working fluids in heat transfer. The sample with a 50:50 ratio of GNP and GO retained around 66% of its concentration over five days of running in the test rig, and the concentration seemed to stabilise, reaching equilibrium, implying no further decreases. Viscosity measurements showed a small increase. Despite the moderately encouraging stability results, however, solar collector testing showed no discernible change in heat transfer performance when using nanofluids compared to water, making these nanofluids unsuitable for this particular flat plate solar collector design.

Hydrogen production from different fuels has received extensive study interest owing to its environmental sustainability, renewability, and lack of carbon emission. This research aims to investigate how artificial neural networks (ANNs) are employed to optimize operating parameters for the catalytic thermochemical conversion of methanol and ethanol and their impact on hydrogen production. According to the ANN model, peak methanol conversion (99%) occurs at lower temperatures of 300 °C with a maximum hydrogen yield of 2.905 mol, whereas peak ethanol conversion (85%) occurs at 500 °C owing to dehydrogenation and the C-C bond-breaking process. A steam-to-carbon (S/C) ratio of (3.5) was advantageous for methanol steam reforming (MSR), and a high ethanol concentration of 10–15 vol% was favorable for ethanol steam reforming (ESR). Ni (10 wt%), and Co (10 wt%) were the optimum metal combinations in the catalyst for ethanol reformation at a reforming temperature of 450 °C. The optimum metal catalysts for producing hydrogen and converting ethanol were those synthesized through co-precipitation. The peak hydrogen yield was attained at the sintering temperature of 560–570 °C. ANN technique is cost-effective, quick, and precise, with vast potential to produce hydrogen energy, and may give significant benefits for industrial applications.

Sustainable energy sources are a solution to the increase in energy demand as a result of population growth. Pyrolysis and gasification are thermochemical processing techniques that can be used to convert biomass and plastic waste into energy. Co-processing (co-pyrolysis or co-gasification) has been identified as one of the major thermal techniques, which provides a significant framework for converting waste into fuels with higher hydrogen concentrations. The production of hydrogen from biomass and plastic waste using these techniques is being explored for its high conversion efficiencies and low processing costs. Catalysts and acid pre-treatment are used to improve gas production while reducing tar content. The best gasification agent is steam with oxygen. A thorough review of the literature revealed only a few studies on the co-pyrolysis and co-gasification of plastics and biomass for syngas production, particularly hydrogen-rich syngas. Therefore, this review focuses on H2 production from plastics and biomass by using co-pyrolysis and co-gasification. This critical discussion is aimed at improving the understanding of the subject, its relevant aspects, and its significant perspectives. In addition, it also deals with the mechanism and relevance of these techniques, along with their techno-econome evaluation. Compared to pyrolysis or gasification of plastic waste or biomass alone, co-processing often has significant impacts with improved final products. The reaction of molecules during co-processing and the transition of hydrogen from plastics to biomass derivatives account for these improved properties. H2 concentrations increase with increasing temperature in the presence of different catalysts. Even at lower temperatures, CO2 adsorption increases H2 production and enhances syngas quality while reducing the tar content. Finally, to provide sustainable energy for future generations and enasure an efficient system for sustainable waste management, further research

The ongoing global pandemic of COVID-19 has devastatingly influenced the environment, society, and economy around the world. Numerous medical resources are used to inhibit the infectious transmission of the virus, resulting in massive medical waste. This study proposes a sustainable and environment-friendly method to convert hazardous medical waste into valuable fuel products through pyrolysis. Medical protective clothing (MPC), a typical medical waste from COVID-19, was utilized for co-pyrolysis with oil palm wastes (OPWs). The utilization of MPC improved the bio-oil properties in OPWs pyrolysis. The addition of catalysts further ameliorated the bio-oil quality. HZSM-5 was more effective in producing hydrocarbons in bio-oil, and the relevant reaction pathway was proposed. Meanwhile, a project was simulated to co-produce bio-oil and electricity from the co-pyrolysis of OPWs and MPC from application perspectives. The techno-economic analysis indicated that the project was economically feasible, and the payback period was 6.30-8.75 years. Moreover, it was also environmentally benign as its global warming potential varied from -211.13 to -90.76 kg CO2-eq/t. Therefore, converting MPC and OPWs into biofuel and electricity through co-pyrolysis is a green, economic, and sustainable method that can decrease waste, produce valuable fuel products, and achieve remarkable economic and environmental benefits.

Power and heat production is the leading cause of greenhouse gas emissions in Malaysia, contributing to over 30% of total emissions. The transition from fossil to biomass resources in the power industry is an essential step towards achieving carbon neutrality in Malaysia. Oil palm wastes are the most abundant biomass resources in Malaysia because of the thriving oil palm industry. Consequently, two scenarios: (1) co-production of biochar and electricity, and (2) electricity generation, were proposed and simulated in Aspen Plus. A comprehensive evaluation system for mass and energy balances, techno-economic analysis, and life-cycle assessment was established to assess the two scenarios quantitatively. The results indicated that Scenario 1 achieved better economic and environmental benefits, the payback period was 6.12 to 8.89 years, and the global warming potential ranged from −885.23 to −1311.95 kg CO2-eq/t. The state-level spatiotemporal trajectory of oil palm waste resources and CO2 emission reduction potentials and economic benefits were analyzed. Theoretically, fully utilizing oil palm wastes in Scenario 1 would create economic benefits of 35.36 billion USD and mitigate CO2 emissions by 131.97 million tons in 2021. This study provides useful guidance for exploiting oil palm wastes to achieve carbon neutrality in Malaysia.

Global population growth and rising living standards have significantly impacted global energy consumption [...]

Microalgal biomass has been proved to be a sustainable source for biofuels including bio-oil, biodiesel, bioethanol, biomethane, etc. One of the collateral benefits of integrating the use of microalgal technologies in the industry is microalgae's ability to capture carbon dioxide during the application and biomass production process and consequently reducing carbon dioxide emissions. Although microalgae are a feasible source of biofuel, industrial microalgae applications face energy and cost challenges. To overcome these challenges, researchers have been interested in applying the bio-refinery approach to extract the important components encapsulated in microalgae. This review discusses the key steps of microalgae-based biorefinery including cultivation and harvesting, cell disruption, biofuel and value-added compound extraction along with the detailed technologies associated with each step of biorefinery. This review found that suitable microalgae species are selected based on their carbohydrate, lipid and protein contents and selecting the suitable species are crucial for high-quality biofuel and value-added products production. Microalgae species contain carbohydrates, proteins and lipids in the range of 8% to 69.7%, 5% to 74% and 7% to 65% respectively which proved their ability to be used as a source of value-added commodities in multiple industries including agriculture, animal husbandry, medicine, culinary, and cosmetics. This review suggests that lipid and value-added products from microalgae can be made more economically viable by integrating upstream and downstream processes. Therefore, a systematically integrated genome sequencing and process-scale engineering approach for improving the extraction of lipids and co-products is critical in the development of future microalgal biorefineries.

Edible oil-based feedstocks based biodiesel is still leading the industry around the world. Canola oil (Brassica napus L.) contributes significantly to that race. Process optimisation and the development of reaction kinetic models of edible oil feedstocks are still required since the knowledge of kinetics is needed for designing industrial facilities and evaluating the performance of catalysts during transesterification or other related processes in a biorefinery. This research focuses on the transesterification process for biodiesel production because of its higher output efficiency, reactivity with feedstock, techno-economic feasibility in terms of FFA content, and environmental sustainability. The response surface method with the Box–Behnken model was used to optimise the process. Multivariate analysis of variance (ANOVA) was also performed to investigate the effectiveness of the regression model. The optimal process conditions were found to be 5.89 M methanol, 0.5% (w/w) KOH, 60 °C and 120 min. The predicted yield was 99.5% for a 95% confidence interval (99.1, 99.9). The experimental yield was 99.6% for these conditions. Two different kinetic models were also developed in this study. The activation energy was 16.9% higher for the pseudo-first-order irreversible reaction than for the pseudo-homogenous irreversible reaction. Such a comprehensive analysis will assist stakeholders in evaluating the technology for industrial development in biodiesel fuel commercialisation.

Oil palm wastes (OPWs) are important biomass resources, and approximately 127 million tons of OPWs are generated from the oil palm industry annually in Malaysia. The scientific and reasonable utilization of OPWs is essential to economic and environmental sustainability in the country. Pyrolysis is a mature and revolutionary technology that can convert OPWs into biofuel. The conversion of OPWs into biofuel is in accordance with the national conditions of Malaysia and can simultaneously address the problems of fossil fuel shortage and environmental deterioration. Therefore, Malaysia is the most active country in the research of OPWs pyrolysis and has achieved fruitful results. Bio-oil produced from the catalytic co-pyrolysis of OPWs with hydrogen-rich materials exhibits remarkable fuel properties. Biochar generated from OPWs pyrolysis presents huge application potential as an absorbent, catalyst, soil conditioner, and carbon sequestration agent. Consequently, the paper provides a comprehensive review of OPWs pyrolysis and lays the foundation for the exploitation of OPWs resources.

Non-edible Ceiba oil has the potential to be a sustainable biofuel resource in tropical countries that can replace a portion of today's fossil fuels. Catalytic deoxygenation of the Ceiba oil (high O/C ratio) was conducted to produce hydrocarbon biofuel (high H/C ratio) over NiO-CaO5/SiO2-Al2O3 catalyst with aims of high diesel selectivity and catalyst reusability. In the present study, response surface methodology (RSM) technique with Box-Behnken experimental designs (BBD) was used to evaluate and optimize liquid hydrocarbon yield by considering the following deoxygenation parameters: catalyst loading (1-9 wt. %), reaction temperature (300-380 °C) and reaction time (30-180 min). According to the RSM results, the maximum yield for liquid hydrocarbon n-(C8-C20) was found to be 77% at 340 °C within 105 min and 5 wt. % catalyst loading. In addition, the deoxygenation model showed that the catalyst loading-reaction time interaction has a major impact on the deoxygenation activity. Based on the product analysis, oxygenated species from Ceiba oil were successfully removed in the form of CO2/CO via decarboxylation/decarbonylation (deCOx) pathways. The NiO-CaO5/SiO2-Al2O3 catalyst rendered stable reusability for five consecutive runs with liquid hydrocarbon yield within the range of 66-75% with n-(C15 + C17) selectivity of 64-72%. Despite this, coke deposition was observed after several times of catalyst usage, which is due to the high deoxygenation temperature (> 300 °C) that resulted in unfavourable polymerization side reaction.

Alcohols could be the biggest factor for the improvement of world biofuel economy in the present century due to their excellent properties compared to petroleum products. The primary concerns of sustainable alcohol production for meeting the growing energy demand owing to the selection of viable feedstock and this might enhance the opportunities for developing numerous advanced techniques. In this review, the valorization of alcohol production from several production routes has been exposed by covering the traditional routes to the present state of the art technologies. Even though the fossil fuel conversion could be dominant method for methanol production, many recent innovations like photo electrochemical synthesis and electrolysis methods might play vital role in production of renewable methanol in future. There have been several production routes for production of ethanol and among which the fermentation of lignocellulose biomass would be the ultimate choice for large scale shoot up. The greenhouse gas recovery in the form of alcohols through electrochemistry technique and hydrogenation method are the important methods for commercialization of alcohols in future. It is also observed that algae based renewable bio-alcohols is highly influenced by carbohydrate content and sustainable approaches in algae conversion to bio-alcohols would bring greater demand in future market. There is a lack of innovation in higher alcohols production in single process and this could be bounded by combining dehydrogenation and decarboxylation techniques. Finally, this review enlists the opportunities and challenges of existing alcohols production and recommended the possible routes for making significant enhancement in production.

The present study is to investigate the feasibility of mixed non-edible oils, Sterculia foetida (SFO), and rice bran oil (RBO) for biodiesel production. The transesterification process variables of SFO50RBO50 as the suitable blend were optimised using response surface methodology. The optimum conditions of the transesterification process are as follow; KOH catalyst concentration of 0.7% wt, the ratio of methanol to oil of 42%, the reaction time of 50.64 min, resulted in the methyl ester yield of 98.93%. The result shows that the SF50RB50 methyl ester properties satisfy the biodiesel requirements laid in ASTM D6751 and EN 14214 standards.

The utilization of microalgae in treating wastewater has been an emerging topic focussed on finding an economically sustainable and environmentally friendly approach to treating wastewater. Over the last several years, different types of con microalgae and bacteria consortia have been experimented with to explore their potential in effectively treating wastewater from different sources. The basic features considered while determining efficiency is their capacity to remove nutrients including nitrogen (N) and phosphorus (P) and heavy metals like arsenic (As), lead (Pb), and copper (Cu). This paper reviews the efficiency of microalgae as an approach to treating wastewater from different sources and compares conventional and microalgae-based treatment systems. The paper also discusses the characteristics of wastewater, conventional methods of wastewater treatment that have been used so far, and the technological mechanisms for removing nutrients and heavy metals from contaminated water. Microalgae can successfully eliminate the suspended nutrients and have been reported to successfully remove N, P, and heavy metals by up to 99.6 %, 100 %, and 13%-100 % from different types of wastewater. However, although a microalgae-based wastewater treatment system offers some benefits, it also presents some challenges as outlined in the last section of this paper. Performance in eliminating nutrients from wastewater is affected by different parameters such as temperature, biomass productivity, osmotic ability, pH, O2 concentration. Therefore, the conducting of pilot-scale studies and exploration of the complexities of contaminants under complex environmental conditions is recommended.

The present study presents the climate change impacts on bin weather data and bin method for the city of Senai, Malaysia. Seventeen case simulations were conducted to analyse its impacts on the results of the HVAC energy analysis and determine the suggested lifespan for the bin weather data of Senai. The graph of the mean temperatures has shown a significant increasing trend signalling the occurrence of climate change. Taking the year of 2001 as the baseline, the differences in the number of occurrence hours were grouped into two ranges, which are low temperature (18 °C to 28 °C) and high temperature (28 °C to 38 °C). In 2016, a significant 9.7% of temperature data for the year has switched from low temperature to high temperature. From the case simulations conducted, the annual energy consumption has shown an increasing trend. By using the case simulation of 2018 as the baseline, the degree of deviation ranges from 9.68% to 7.44%. The 10 years of lifespan are suggested at the end of the present study because 75% of the bin weather data beyond 10 years used in the case simulations have a percentage change above 5%.

Micromixers are important modules in medical applications. Novel and excellent biometric micromixers have been designed with an effective mechanism of flow splitting and recombining (SAR). The aim of this study is to modify the prototype of a biometric micromixer by designing the inlet flow channel and generating a better flow geometry in the blood vessel-micromixer. The blood vessel-micromixer was also investigated with different inlet channel angles and various Reynolds number ratios (ReI2 and Rer) for the estimation of their influence on the mixing performance of the micro-mixer. The ReI2 is the inlet 2 and the Rer is the combination of side flow and middle flow effects during the different flow conditions. Results showed that the blood vessel-micromixer with an inlet channel angle of 30° (Ø =30°) can be optimized for future research works. In addition, optimal performance with a Amixing index of 0.88 would be achieved at a condition of ReI2= 1 and Rer = 0.7. These findings will be definitely useful for the improvement of micromixer applications in the future.

The present work has enabled to aspire the enhancement of palm biodiesel viability for compression ignition (CI) engine applications using reformulation strategy by the addition of higher alcohols. In this work, 20% and 30% of 1-decanol and n-hexanol were used for ternary blend preparation along with palm biodiesel concentration as 20–30% and 50% diesel fuels for combustion, emission, and performance behaviour investigation in CI engine. Furthermore, the experimental results were also compared with 100% palm biodiesel (P100) and pure diesel (D100) and a binary blend of D50B50 fuels. The experimental study has revealed that the presence of higher alcohols in the ternary blends has improved the cylinder pressure and heat release rate whereas the same trend was not evident in binary biodiesel blend. All the ternary blends of higher alcohols-biodiesel and diesels have shown higher brake thermal efficiency and reduction in brake-specific fuel consumption. At the same time, decanol and hexanol addition in the palm biodiesel-diesel blends has favoured in all exhaust emission reductions with slight exemption in NO emission. The experimental results are optimized through multivariate and desirability analyses for identifying the effective composition of blend. Multivariate analysis has revealed that the higher alcohol proposition in the ternary blend was more influential than the type of higher alcohol. Furthermore, the desirability study has also validated the prescribed proportion with the maximum error of 6.17% for D50P22DC28 and 4.84% for D50P26HE24. Finally, the research concludes that decanol would be the preferable choice for ternary blend preparation than hexanol due to its overall better performance. x

Demands for the decline of CO2 emissions resulted in a significant transformation of the energy systems working on carbon sources towards more sustainable, clean, and renewable characteristics. Hydrogen is emerging as a secondary energy vector with ever-increasing importance in the decarbonisation progress. Indeed, hydrogen, a green and renewable energy source, could be produced from steam gasification of plant-originated lignocellulosic biomass. In this current review, key factors affect the hydrogen production yield from steam gasification of plant-originated lignocellulosic biomass, including the design of the gasifier, temperature, pressure, and steam-to-biomass ratio, steam flow rate, moisture and particle size of fed biomass, and catalysts were thoroughly analysed. Moreover, the effects of the abovementioned factors on the reduction of tar formation, which is also a key parameter towards ensuring the trouble-free operation of the reactor, were critically evaluated. More importantly, the separation of produced hydrogen from steam gasification of biomass and challenges over technological, environmental, and economic aspects of biomass gasification were also presented in detail. In addition, this paper is also profiling the prospect of Vietnam in fulfilling its hydrogen economy potential because Vietnam has vast biomass due to its tropical weather and availability of arable land, providing abundant lignocellulosic biomass with 45% of agricultural waste, 30% of firewood, and 25% of other sources. Besides, some primary factors hindering the broad application of biomass for hydrogen production were indicated. Finally, some solutions for implementing the hydrogenization strategy in Vietnam have also been discussed.

Unfortunately, the original article contains error in Sect. 3.3. Fuel Composition. The correct data have been provided below in this correction article. 3.3. Fuel composition The fatty acid composition of the produced biodiesel through the optimisation process is shown in Table 8. From the table, it can be seen that Australian canola oil is mostly composed of methyl oleate, with 42.47 wt% included in the composition. This is followed by 27.85 wt% and 16.65 wt% methyl linoleate and methyl linoleate, respectively. A similar FAC was observed by Issariyakul and Dalai (2010) with slight difference in methyl oleate and methyl linolenate percentages. The main component of their canola oil biodiesel is methyl oleate which contains 60.92 wt% of this component. Based on the composition, canola biodiesel contains a total of 12.89 wt% saturated FAME component, 42.61 wt% monounsaturated FAME and 44.5 wt% polyunsaturated FAME. Table 9 compares the properties of produced canola biodiesel and diesel. According to the table, canola oil biodiesel has a 21.5% higher cetane number but a 6% lower LHV than diesel fuel.

© 2019, © 2019 Taylor & Francis Group, LLC. In this study, an investigation has been carried out to examine the tribological features of Rice bran oil (RBO) based biodiesel as an agent to improve lubricity. RBOB was successfully generated by the means of transesterification and the studied fuels were pure biodiesel (RBOB100), 10% (RBOB10), 30% (RBOB30), and 50% (RBOB50) of biodiesel combined with diesel and pure diesel (RBOB0). Examination in agreement with the ASTM D 4172 method was carried out under following conditions for all examined fuels: a constant load of 40 kg, a steady sliding speed of 1200 rpm, a constant temperature of 75°C and a reaction time of 3600 s. Frictional torque was recorded on line in the course of wear examination. Optical microscopy was implemented to investigate the wear scars of tested balls. Result showed that friction diminished with the decrease of biodiesel concentration. Moreover, formation of wear scars increased with increasing the biodiesel concentration. It could be concluded that lubricity decreases due to increasing the biodiesel concentration. Surface morphology analysis showed that pure biodiesel and diesel formed adhesive wears. However, all the wears formed by biodiesel-diesel blends were fallen into the abrasive wear group.

In this study, a novel type of swirler channel was implemented at the inlet of the anode chamber of dual-chamber batch mode MFC, and comparison was done between with and without swirler. To explore the effect of the swirler in detail, four different flow rates (40 mL/min, 20 mL/min, 10 mL/min, and that 5 mL/min) were selected, and their performance was compared. The experimental results showed the swirler system has a maximum current density of 4424.3 mA/m2, a power density of 775 mW/m2, and reduced the internal resistance by 60% at a 20 mL/min flow rate when compared with ‘without swirler’ system (2686 mA/m2; 442 mW/m2 @ 20 mL/min) because of uniform distribution of substrate and enhanced the mixing in the anode chamber. Our results demonstrated that the swirler channel will have a prominent effect on the performance and can be effectively used for applications and in future researches.

As the world attempts to transition from fossil fuels, lignocellulosic biomass (LCB) serves as a promising alternative due to its high abundance. Hydrolysing LCB can generate various bioproducts, such as biofuels and value-added chemicals. However, the presence of lignin inhibits the solubilization of LCBs, presenting a major techno-economic challenge in the biorefinery concept. Therefore, this paper addresses the gaps left by most of the recent review works that fail to comprehensively review different pretreatment methods and the full scope of applications of LCBs, and do not incorporate techno-economic considerations of the technologies, the latter being the greatest bottleneck in the commercialization of the processes. The literature review revealed that while many of the physical and chemical pretreatment methods exhibit great effectiveness, they have a huge dependence on energy, chemicals, water, and/or specialized equipment, and produce harmful waste and inhibitory compounds. The pretreatment of lignocellulosic biomass can account for 40% of total production costs. Biological pretreatment can address these challenges but is limited by long incubation times. For instance, the bacterial pretreatment can noticeably reduce sawdust cellulose, hemicelluloses, and lignin contents by 35.8%, 37.1%, and 46.2%, respectively. Recently, integrated/coupling (hybrid) methods, such as chemical-assisted liquid hot water/steam and microwave or ultrasound-assisted alkaline pretreatment, have been gaining popularity due to their potential to improve chemical yield, but at the expense of the high cost of operation. To make pretreatment processes more techno-economically feasible, there is a need for process integration and the standardization and optimization of process parameters.

Microalgae are the most prospective raw materials for the production of biofuels, pyrolysis is an effective method to convert biomass into bioenergy. However, biofuels derived from the pyrolysis of microalgae exhibit poor fuel properties due to high content of moisture and protein. Co-pyrolysis is a simple and efficient method to produce high-quality bio-oil from two or more materials. Tires, plastics, and bamboo waste are the optimal co-feedstocks based on the improvement of yield and quality of bio-oil. Moreover, adding catalysts, especially CaO and Cu/HZSM-5, can enhance the quality of bio-oil by increasing aromatics content and decreasing oxygenated and nitrogenous compounds. Consequently, this paper provides a critical review of the production of bio-oil from co-pyrolysis of microalgae with other biomass wastes. Meanwhile, the underlying mechanism of synergistic effects and the catalytic effect on co-pyrolysis are discussed. Finally, the economic viability and prospects of microalgae co-pyrolysis are summarized.

The smart control of the biogas-hydrogen engine is needed to improve the overall energy efficiency of the hybrid renewable energy system. The paper presents some simulation results of the optimal control parameters of the engine aiming to achieve the compromise between performance and pollutant emissions of the biogas-hydrogen engine. In neat biogas fueling mode, the optimal equivalence ratio changes from 1.05 to 1.01 as the CH4 composition in biogas increases from 60% to 80%. By adding 20% hydrogen into biogas, the optimal equivalence ratio practically reaches the stoichiometric value, despite the variation of CH4 concentration. At the same operating condition and hydrogen content, an increase of 10% CH4 in biogas leads to a decrease of 2°CA in the optimal advanced ignition angle. However, at a given engine speed and biogas composition, the optimal advanced ignition angle decreased by 3°CA when adding 10% hydrogen into biogas. The optimal ignition angle is independent of the load regime. Under optimal operating conditions, the addition of 20% hydrogen content into biogas is found to improve the indicated engine cycle work by 6%, to reduce CO and HC emissions by 5–10 times; however, it increases NOx emission by 10–15% compared to neat biogas fueling mode.

© 2020 Elsevier B.V. Fuel-like hydrocarbons (also known as biofuel) isolated from the deoxygenation of fatty acids present different advantages as compared with fossil fuels. In particular, the homogeneous and heterogeneous catalytic deoxygenation methods have been the center of attention during recent years. Although catalytic deoxygenation of fatty acids via heterogeneous catalysis has been widely investigated, there is a high demand to review the progress in using the homogeneous catalysis pathways. Among the various homogeneous pathways, radical-based reactions and transition metal catalysis demonstrate the most promising results in the decarboxylation and decarbonylation processes. It is shown that radical-based reactions are more active in decarboxylation meanwhile the transition metal catalysts are rather selective to decarbonylation of fatty acids. Besides, the reaction conditions and type of catalysts are capable of enhancing biofuel production. Homogenous catalysis provides the huge potential for commercializing viability of biofuel via deoxygenation of fatty acids.

Petroleum-based plastics are associated with environmental pollution problems owing to their non-biodegradable and toxic properties. In this context, renewable and biodegradable bioplastics possess great potential to replace petroleum-based plastics in mitigating these environmental issues. Fabrication of bioplastic films involves a delicate mixture of the film-forming agent, plasticizer and suitable solvent. The role of the plasticizer is to improve film flexibility, whereas the filler serves as a reinforcement medium. In recent years, much research attention has been shifted toward devising diverse methods for enhancing the performance of bioplastics, particularly in the utilization of environmentally benign nanoparticles to displace the conventional hazardous chemicals. Along this line, this paper presents the emergence of nanofillers and plasticizers utilized in bioplastic fabrication with a focus on starch-based bioplastics. This review paper not only highlights the influencing factors that affect the optical, mechanical and barrier properties of bioplastics, but also revolves around the proposed mechanism of starch-based bioplastic formation, which has rarely been reviewed in the current literature. To complete the review, prospects and challenges in bioplastic fabrication are also highlighted in order to align with the concept of the circular bioplastic economy and the United Nations' Sustainable Development Goals.

Catalytic reduction of oxygen-containing compounds in palm kernel oil has been studied under H2-free atmosphere condition using microwave system approach over Raney nickel and magnetite activated carbon-based catalysts. The role of porous structure and active O-containing groups of magnetite activated carbon (FeMo/ACB) catalyst during deoxygenation (DO) at 250 °C was investigated. Activated carbon catalysts, obtained from bamboo-derived biochar activation at 800 °C with KOH exhibited large surface area and O-containing group. With the introduction of the FeMo/ACB catalyst, the relative content of bio-jet fuel increased remarkably (∼80%) with the bio-jet fuel selectivity of ∼80%. Noted, the high DO activity also showed strong correlation with the presence of high acidic sites, high porosity and surface on the bamboo-derived carbon support, which in turn allows the active metals Fe-Mo to coat the ACB support thoroughly thus promoting a more efficient DO reaction. In addition, the FeMo/ACB catalyst showed excellent reusability over five consecutive cycles, with hydrocarbon fractions ranging from 62% to 80% and bio-jet fuel selectivity from 65% to 80% and minimum coke formation (< 2 wt%).

Colourants, micropollutants and heavy metals are regarded as the most notorious hazardous contaminants found in rivers, oceans and sewage treatment plants, with detrimental impacts on human health and environment. In recent development, algal biomass showed great potential for the synthesis of engineered algal adsorbents suitable for the adsorptive management of various pollutants. This review presents comprehensive investigations on the engineered synthesis routes focusing mainly on mechanical, thermochemical and activation processes to produce algal adsorbents. The adsorptive performances of engineered algal adsorbents are assessed in accordance with different categories of hazardous pollutants as well as in terms of their experimental and modelled adsorption capacities. Due to the unique physicochemical properties of macroalgae and microalgae in their adsorbent forms, the adsorption of hazardous pollutants was found to be highly effective, which involved different mechanisms such as physisorption, chemisorption, ion-exchange, complexation and others depending on the types of pollutants. Overall, both macroalgae and microalgae not only can be tailored into different forms of adsorbents based on the applications, their adsorption capacities are also far more superior compared to the conventional adsorbents.

With the increasing concern on the global energy security and environmental sustainability [...]

Sustainable Aviation Fuel (SAF) has become an important measure in the aviation industry's efforts to mitigate carbon emissions and reduce their overall environmental impacts. However, commercial usage is relatively stunted due to a plethora of drawbacks in the production process and economic feasibility of the fuel. In this study, the currently accepted technologies for producing synthetic jet fuels under the American Society for Testing Material (ASTM D7566) standard specification for aviation turbine fuel are reviewed. The emphasis is placed in terms of their reactions, type of catalysts used for the conversion pathways of Fisher-Tropsch (FT), Hydroprocessed Esters and Fatty Acids (HEFA) and Alcohol-to-Jet (ATJ), and the use of biomass resources as feedstock. The advancement in the production process and physicochemical properties of the uncertified biojet fuels are reviewed and discussed. Generally, Co- and Fe-based catalysts are commonly used for the FT process, while bimetallic catalysts consisting of Pt, Pd, Ni and Mo have shown excellent activities and selectivities for the HEFA process. For the ATJ process, zeolites such as HZSM-5, beta and SAPO have shown remarkable ethanol dehydration efficiency, while TiO2 and ferrierite have been studied for the combined iso-butanol dehydration and oligomerisation processes. Fundamental factors influencing the reaction efficiency including the feedstock properties, reaction conditions, catalytic reusability and catalyst supports are discussed. Finally, the key challenges and prospects for biojet fuel commercialisation are addressed.