• Energy Research

Biodiesel as an alternative to diesel fuel produced from vegetable oils or animal fats has attracted more and more attention because it is renewable and environmentally friendly. Compared to conventional diesel fuel, biodiesel has slightly lower performance in engine combustion due to the lower calorific value that leads to lower power generated. This study investigates the effect of multi-walled carbon nanotubes (MWCNTs) as an additive to the rice bran methyl ester (RBME). Artificial neural network (ANN) and response surface methodology (RSM) was used for predicting the calorific value. The interaction effects of parameters such as dosage of MWCNTs, size of MWCNTs and reaction time on the calorific value of RBME were studied. Comparison of RSM and ANN performance was evaluated based on the correlation coefficient (R2), the root mean square error (RMSE), the mean absolute percentage error (MAPE), and the average absolute deviation (AAD) showed that the ANN model had better performance (R2 = 0.9808, RMSE = 0.0164, MAPE = 0.0017, AAD = 0.173) compare to RSM (R2 = 0.9746, RMSE = 0.0170, MAPE = 0.0028, AAD = 0.279). The optimum predicted of RBME calorific value that is generated using the cuckoo search (CS) via lévy flight optimization algorithm is 41.78 (MJ/kg). The optimum value was obtained using 64 ppm of < 7 nm MWCNTs blending for 60 min. The predicted calorific value was validated experimentally as 41.05 MJ/kg. Furthermore, the experimental results have shown that the addition of MWCNTs was significantly increased the calorific value from 36.87 MJ/kg to 41.05 MJ/kg (11.6%). Also, the addition of MWCNTs decreased flashpoint (−18.3%) and acid value (−0.52%). As a conclusion, adding MWCNTs as an additive had improved the physicochemical properties characteristics of RBME. To our best knowledge, no research has yet been performed on the effect of multi-walled carbon nanotubes-additive in physicochemical property of rice brand methyl ester application so far.

Abstract Microalgae has been identified as a potential feedstock for biodiesel production since its cultivation requires less cropland compared to conventional oil crops and the high growth rate of microalgae. Research on microalgae oils often are focused on microalgae oil extraction and biomass harvesting techniques. However, energy intensive and costly lipid extraction methods are the major obstacles hampering microalgae biodiesel commercialisation. Direct biodiesel synthesis avoids such problems as it combines lipid extraction techniques and transesterification into a single step. In this review, the potential of direct biodiesel synthesis from microalgae biomass was comprehensively analysed. The various species of microalgae commonly used as biodiesel feedstock was critically assessed, particularly on high lipid content species. The production of microalgae biodiesel via direct conversion from biomass was systematically discussed, covering major enhancements such as heterogeneous catalysts, the use of ultrasonic and microwave- techniques and supercritical alcohols that focus on the overall improvement of biodiesel production. In addition, this review illustrates the cultivation conditions for biomass growth and lipid productivity improvement, the available harvesting and lipid extraction technologies, as well as the key challenges and future prospect of microalgae biodiesel production. This review serves as a basis for future research on direct biodiesel synthesis from modified microalgae biomass to improve profitability of microalgae biodiesel.

Abstract Effective methods of biomass characterization are needed for energy production due to the increase in biomass to bioenergy conversion capacity and the availability of various biomass sources. The utilization of biomass has been enhanced through thermochemical conversion techniques such as torrefaction, pyrolysis, and gasification. The biomass analytical techniques have been developed to decrease the time and energy required for biomass conversion performance. Thermogravimetric analyzer (TG) and Fourier transform infrared spectroscopic (FTIR) analytical techniques facing several limitations when applied individually. Thus, TG coupled with FTIR (TG-FTIR) was used to analyze the main parameters of biomass and improved the energy crop growing developments. In addition, TG-FTIR can determine the suitable ratio for two different biomass or coal blending during the co-pyrolysis and co-gasification to achieve the optimum synergetic interaction. In this review, thermochemical conversion processes such as torrefaction, pyrolysis, and gasification are presented. The analysis of the thermochemical conversion of biomass with the use of TG and FTIR individually are then discussed. Lastly, this review aims to discuss the applications of TG-FTIR techniques that have been applied to the analysis of evolved gas from the thermochemical processing of biomass to biofuels.

AbstractBiodiesel from vegetable oils has attracted a great deal of interest as a alternative fuel for fossil diesel. This effort able to reduce the dependence on petroleum based fuels and provides a fuel with more benign environmental. Non-edible vegetable oils are attracting more attention than edible oils due to the concern on food versus fuel and other environmental issues. Cerbera manghas oil is one of the promising non-edible feedstocks. Biodiesel production from cerbera manghas vegetable was first time reported and investigated. The viscosity of crude oil was 32.83 mm2/s and 12.64mg KOH/g for acid value which is far above the 2%. Therefore, cerbera manghas methyl ester (CMME) was produced via two step acid-alkaline transesterification using H2SO4 as acid catalyst and KOH as alkaline catalysts. Hence 98.5% of biodiesel was achieved with 9:1 methanol in presence of 1% sodium hydroxide. Moreover, blending of CCME with diesel resulted in an improvement which the viscosity is reduced to 3.54 mm2/s. On the other hand, the blending of CMME also shown the remarkable improvement in oxidation stability (14.55hours). The properties of cerbera manghas methyl ester fell within the recommended biodiesel standards. It can be conclude that cerbera manghas oil is promising feedstock for future production of biodiesel

Abstract The world today is faced with serious global warming and environmental pollution. Besides, fossil fuel will become rare and faces serious shortage in the near future. This has triggered the awareness to find alternative energy as their sustainable energy sources. Biodiesel as a cleaner renewable fuel has been considered as the best substitution for diesel fuel due to it being used in any compression ignition engine without any modification. The main advantages of using biodiesel are its renewability and better quality of exhaust gas emissions. This paper reviews the production, performance and emission of palm oil, Jatropha curcas and Calophyllum inophyllum biodiesel. Palm oil is one of the most efficient oil bearing crops in terms of oil yield, land utilization, efficiency and productivity. However, competition between edible oil sources as food with fuel makes edible oil not an ideal feedstock for biodiesel production. Therefore, attention is shifted to non-edible oil like Jatropha curcas and Calophyllum inophyllum. Calophyllum inophyllum oil can be transesterified and being considered as a potential biodiesel fuel. Compared to Palm oil and Jatropha biodiesel industry, biodiesel from Calophyllum inophyllum is still in a nascent state. Therefore, long term endurance research and tribological studies need to be carried out before Calophyllum inophyllum oil base biodiesel can become an alternative fuel in future.

Increasing number of population, advanced technology and economics growth somehow has caused energy depletion. The development of biofuel such as biodiesel, bioethanol and biogas is extremely needed to overcome these crises. Biofuel is derived from biological sources or biomass which are more environmental friendly, less toxic, reduce greenhouse gas emission and less cost. Algae comes from the third generation product of both biodiesel and bioethanol. Algae based biofuel has various advantages such as non-toxic, does not require fresh water to grow, higher growth rate, biodegradable and not used arable land. Thus, this review summarizes enzymatic reaction for production of all biofuels; biodiesel and bioethanol. The enzymatic reaction is safe, less contaminating and seems to produce higher yield of biofuel compared to chemical reaction. Overall finding of this study suggests that immobilization method and efficiency of the enzyme is the main factor in biofuel production. Finally, further studies are recommended to overcome the major constraint of high enzyme cost by improving the immobilization technique and processes.

Abstract Exploring and improvement of biodiesel production from non-edible vegetable oil is one of the effective ways to solve limited amount of traditional raw materials and their high prices. The main objective of this study is to optimize the biodiesel production process parameters (methanol-to-oil ratio, agitation speed and concentration of the potassium hydroxide catalyst) of a biodiesel derived from non-edible feedstocks, namely Jatropha curcas and Ceiba pentandra, using response surface methodology based on Box–Behnken experimental design. Based on the results, the optimum operating parameters for transesterification of the J50C50 oil mixture at 60 °C over a period of 2 h are as follows: methanol-to-oil ratio: 30%, agitation speed: 1300 rpm and catalyst concentration: 0.5 wt.%. These optimum operating parameters gives the highest yield for the J50C50 biodiesel with a value of 93.33%. The results show that there is a significant improvement in the physicochemical properties of the J50C50 biodiesel after optimization, whereby the kinematic viscosity at 40 °C, density at 15 °C, calorific value, acid value and oxidation stability is 3.950 mm2/s, 831.2 kg/m3, 40.929 MJ/kg, 0.025 mg KOH/g and 10.01 h, respectively. The physicochemical properties of the optimized J50C50 biodiesel fulfill the requirements given in the ASTM D6751 and EN14214 standards.

Abstract DHS (District Heating System) is one of the most efficient technologies which has been used to meet residential thermal demand. In this study, the most accurate forecasting of the residential heating demand is investigated via soft computing method. The objective of this study is to obtain the most accurate prediction of the residential heating consumption to employ forecasting result for designing optimum DHS system as a possible substitute of a pipeline natural gas in BAHARESTAN Town. For this purpose, three Support Vector Machine (SVM) models namely SVM coupled with the discrete wavelet transform (SVM-Wavelet), the firefly algorithm (SVM-FFA) and using the radial basis function (SVM-RBF) were analyzed. The estimation and prediction results of these models were compared with two other soft computing methods (ANN (Artificial Neural Network) and GP (Genetic programming)) by using three statistical indicators i.e. RMSE (root means square error), coefficient of determination (R 2 ) and Pearson coefficient (r). Based on the experimental outputs, the SVM-Wavelet method can lead to slightly accurate forecasting of the monthly overall natural gas demand.