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The limitation of fossil fuel sources and negative environmental impact persuade scientists around the world to find a solution. One possible solution is by using renewable fuel to replace fossil fuel with an inexpensive, fast, and effective production process. The objective of this study is to investigate the biodiesel production from crude Reutealis trisperma oil using the conventional and the ultrasonic bath stirrer method through the esterification and transesterification process. The result shows that the most effective reaction time with an optimum condition for the esterification and transesterification of Reutealis trisperma oil is at 2 h 30 min by using the ultrasonic bath stirrer method. The optimum conditions at a temperature of 55 °C for the esterification and at 60 °C for transesterification with 2% (v/v) of sulphuric acid with catalyst concentration of 0.5 wt.% were a methanol-to-oil ratio of 60%, and agitation speed of 1000 rpm. This optimum condition gives the highest yield of 95.29% for the Reutealis trisperma biodiesel. The results showed that the ultrasonic bath stirrer method had more effect on the reaction time needed than using the conventional method and reduced half of the conventional method reaction time. Finally, the properties of Reutealis trisperma biodiesel fulfilled the ASTM D6751 and EN 14214 biodiesel standards with density, 892 kg/m3; pour point, −2 °C; cloud point, −1 °C; flash point, 206.5 °C; calorific value, 40.098 MJ/kg; and acid value, 0.26 mg KOH/g.

Due to global warming and increasing price of fossil fuel, scientists all over the world have been trying to find reliable alternative fuels. One of the most potential candidates is renewable energy from biomass. The race for renewable energy from biomass has long begun and focused on to combat the deteriorating condition of the environment. Palm oil has been in the spotlight as an alternative of bioenergy sources to resolve fossil fuel problem due to its environment-friendly nature. This review will look deep into the origins of palm oil and how it is processed, bioproducts from this biomass, and oil palm biomass-based power plant in Malaysia. Palm oil is usually processed from oil palm fruits and other parts of the oil palm plant are candidates for raw material of bioproduct generation. Oil palm biomass can be turned into three subcategories: bioproduct, biofuels, and biopower. Focusing on biofuel, the biodiesel from palm oil will be explored in detail and its implication in Malaysia as one of the biggest producers of oil palm in the world will also be emphasized comprehensively. The paper presents the detail of a schematic flow diagram of a palm oil mill process of transforming oil palm into crude palm oil and it wastes. This paper will also discuss the current oil palm biomass power plants in Malaysia. Palm oil has been proven itself as a potential alternative to reduce negative environmental impact of global warming.

With the ever-increasing energy demands, fossil fuels are gradually depleting and eventually, these nonrenewable sources of energy will be exhausted. Hence, there is an urgent need to formulate alternative fuels that are both renewable and sustainable. Biomass is one of the reliable sources of energy because it is replenishable. Rice is the staple food in many countries, particularly in Asia. The number of paddy fields has increased tremendously over the years and is expected to increase in the future in response to the growing world population. This will lead to significant amounts of agricultural wastes annually, particularly rice straw. In some countries, open burning and soil incorporation are used to manage agricultural wastes. Open burning is the preferred method because it is inexpensive. However, this method is highly undesirable because of its detrimental impact on the environment resulting from the release of carbon dioxide and methane gas. Hence, it is important to develop an energy-harvesting method from rice straw for power generation. More studies need to be carried out on the availability and characteristics of rice straw as well as logistic analysis to assess the potential of rice straw for power generation. This paper is focused on reviewing studies pertaining to the characteristics and potential of rice straw for power generation, current rice straw management practices, and logistic analysis in order to develop a suitable energy-harvesting method from rice straw in Malaysia.

Anaerobic digestion is a process where microorganisms degrade organic matter in the absence of oxygen to produce biogas, mainly composed of methane and carbon dioxide. Recent years have seen a strong development of anaerobic digestion units worldwide, especially in USA, Europe and China. Countries like China, Germany, USA, Italy, UK and France are seen leading in the biogas sector in the world due to long establishment, intensive research and government incentives for renewable energy as well as waste management solution option. Asian countries have also shown their interests in the biogas technology. With more proper research and studies on-going, Asia will see the growth of biogas sector in the next few coming years. Even though African countries are in their primary phase to develop this biogas technology and there are still more hurdles to overcome, there have been interests, development and implementation work to apply this technology for its potential renewable energy production as well as its waste management solution.

Nowadays, increased interest among the scientific community to explore the Calophyllum inophyllum as alternative fuels for diesel engines is observed. This research is about using mixed Calophyllum inophyllum-palm oil biodiesel production and evaluation that biodiesel in a diesel engine. The Calophyllum inophyllum–palm oil methyl ester (CPME) is processed using the following procedure: (1) the crude Calophyllum inophyllum and palm oils are mixed at the same ratio of 50:50 volume %, (2) degumming, (3) acid-catalysed esterification, (4) purification, and (5) alkaline-catalysed transesterification. The results are indeed encouraging and satisfy ASTM D6751. CPME shows the high heating value (37.9 MJ/kg) but low kinematic viscosity (4.50 mm2/s) due to change a higher proportion of shorter-chain and unsaturated FAMEs, which tend to lower viscosity compared to Calophyllum inophyllum methyl ester (CIME).). The blended fuels exhibit higher brake-specific fuel consumption (BSFC) and NOx emissions, along with lower brake thermal efficiency (BTE) and reduced CO and HC emissions compared to diesel fuel across the entire range of speeds. Among the blends, CPME5 offered better performance compared to other blends fuel ratios.

Fast development of centralized agricultural biogas plants leads to high amounts of digestate production. The treatment and disposal of liquid fractions after on-site digestate solid–liquid separation remains problematic due to their high organic, nutrient and aromatic contents. This work aims to study the variability of the remaining compounds in the digestate liquid fractions in relation to substrate origin, process parameters and solid–liquid separation techniques. Twenty-nine digestates from full-scale codigestion biogas plants and one waste activated sludge (WAS) digestate were collected and characterized. This study highlighted the combined effect of the solid–liquid separation process and the anaerobic digestion feedstock on the characteristics of liquid fractions of digestates. Two major clusters were found: (1) liquid fractions from high efficiency separation process equipment (e.g., centrifuge and others with addition of coagulant, flocculent or polymer) and (2) liquid fractions from low efficiency separation processes (e.g., screw press, vibrating screen and rotary drum), in this latter case, the concentration of chemical oxygen demand (COD) was associated with the proportion of cow manure and energy crops at biogas plant input. Finally, SUVA254, an indicator for aromatic molecule content and the stabilization of organic matter, was associated with the hydraulic retention time (HRT).

In this study, coconut oils have been transesterified with ethanol using microwave technology. The product obtained (biodiesel and FAEE) was then fractional distillated under vacuum to collect bio-kerosene or bio-jet fuel, which is a renewable fuel to operate a gas turbine engine. This process was modeled using RSM and ANN for optimization purposes. The developed models were proved to be reliable and accurate through different statistical tests and the results showed that ANN modeling was better than RSM. Based on the study, the optimum bio-jet fuel production yield of 74.45 wt% could be achieved with an ethanol–oil molar ratio of 9.25:1 under microwave irradiation with a power of 163.69 W for 12.66 min. This predicted value was obtained from the ANN model that has been optimized with ACO. Besides that, the sensitivity analysis indicated that microwave power offers a dominant impact on the results, followed by the reaction time and lastly ethanol–oil molar ratio. The properties of the bio-jet fuel obtained in this work was also measured and compared with American Society for Testing and Materials (ASTM) D1655 standard.

Global warming and the depletion of fossil fuels have spurred many efforts in the quest for finding renewable, alternative sources of fuels, such as biodiesel. Due to its auxiliary functions in areas such as carbon dioxide sequestration and wastewater treatment, the potential of microalgae as a feedstock for biodiesel production has attracted a lot of attention from researchers all over the world. Major improvements have been made from the upstream to the downstream aspects related to microalgae processing. One of the main concerns is the high cost associated with the production of biodiesel from microalgae, which includes drying of the biomass and the subsequent lipid extraction. These two processes can be circumvented by applying direct or in situ transesterification of the wet microalgae biomass, hence substantially reducing the cost. In situ transesterification is considered as a significant improvement to commercially produce biodiesel from microalgae. This review covers the methods used to extract lipids from microalgae and various in situ transesterification methods, focusing on recent developments related to the process. Nevertheless, more studies need to be conducted to further enhance the discussed in situ transesterification methods before implementing them on a commercial scale.

The rapid spread of coronavirus disease 2019 (COVID-19) in early 2020 prompted a global lockdown from March to July 2020. Due to strict lockdown measures, many countries experienced economic downturns, negatively affecting many industries including energy, manufacturing, agriculture, finance, healthcare, food, education, tourism, and sports. Despite this, the COVID-19 pandemic provided a rare opportunity to observe the impacts of worldwide lockdown on global carbon dioxide (CO2) emissions and climate change. Being the main greenhouse gas responsible for rising global surface temperature, CO2 is released to the atmosphere primarily by burning fossil fuels. Compared to 2019, CO2 emissions for the world and Malaysia decreased significantly by 4.02% (−1365.83 MtCO2) and 9.7% (−225.97 MtCO2) in 2020. However, this is insufficient to cause long-term impacts on global CO2 levels and climate change. Therefore, in this review, we explored the effects of worldwide lockdown on global CO2 levels, the impacts of national lockdown on Malaysia’s CO2 emissions, and the influence of climate change in Malaysia.

This study characterized the performance of polyaniline–titanium oxide (PANI–TiO 2 ) composite to assess its use as potential acetone detector in semiconductor gas sensor. Aniline (ANI), which refers to a monomer, has been used for in situ chemical polymerization to produce polyaniline (PANI) and titanium oxide (TiO 2 ) composite. PANI was varied in composition of 20, 30, and 40 wt% loading with TiO 2 . Inclusion of PANI in composite is meant to detect acetone at various concentrations (100–500 ppm) at selected operating temperatures (27, 35, 45, 55, and 65 °C). The results signified that the best structure of PANI loading in TiO 2 is at 30 wt% due to the molecular structure for gas sensor. The sensitivity of PANI–TiO 2 composite pellet for various acetone vapor concentrations had been optimum at 300 ppm with 7.9% sensitivity. The optimum operating temperature was 45 °C with 10.12% sensitivity. Structural characterizations via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer–Emmet–Teller were conducted to correlate with the sensor sensing performance. Indeed, the 30 wt% of PANI–TiO 2 composite has the potential to detect 300 ppm of acetone and displayed exceptional agreement with outcomes retrieved at 45 °C detection temperature.