Key Engineering Materials Vol. 849

Abstract: National energy needs have been met by non-renewable energy resources, such as natural gas, petroleum, coal and so on. However, non-renewable energy reserves are depleting and there will be an energy crisis. Conversion of biomass into energy is one solution to overcome this. Indonesia, with its biodiversity, has enormous biomass potential, especially from oil palm plantations and also sugar cane plantations. From the oil palm plantation point of view, oil palm shells and oil palm empty fruit bunches are side products. These wastes can be treated with gasification technology to produce gas fuel. The gasification tool model used in this study is a downdraft gasifier equipped with a cyclone to separate gases with solids or liquids resulting from the gasification process. The results of the gasification process show that the more feeds are introduced, the more syngas is produced during the gasification process. The more feeds, the longer the syngas release time. The two variables have a correlation, that is, between the weight of syngas and the time for syngas removal to increase in line with the addition of the amount of feed entered. Syngas analysis of oil palm empty fruit bunches contains 4.959% H₂ and 5.759% CO. Whereas the analysis of syngas of oil palm shells contained 2.524% H₂, 6.391% CO, and 0.895% CH₄.

Abstract: Energy has an important role in the survival of the tea processing industry. The costs for energy generation and application have a large contribution to the total cost of the tea processing. The use of fuel oil and electricity, especially in the drying process is the biggest energy user stage. In line with the development of Indonesia's tea processing industry, it is felt necessary to immediately utilize the source of biomass in tea plantations through the application of gasification technology. The development of tea processing in the future should pay more attention to aspects of energy and the environment as the main discussion. This study aims to examine the development of gasification technology in converting biomass as thermal energy to meet gas quality in the tea drying process. The hypothesis is that through the gasification biomass technology of tea plantations, will produce gas as thermal energy that meets the quality of the tea drying process. The target to be achieved is in the form of laboratory technical data for the design, operation of the process, scale-up and evaluation of the performance of the gasifier which includes flame propagation, simulation of combustion and optimum operating conditions with temperature process variables, air flow rate and gas products, tea biomass capacity, and the length of the gasification process.

Abstract: Currently, microalgae have attracted as potential feedstock for biofuel production. Hydrothermal liquefaction was proposed as technology to convert microalgae into bio-crude oil. Microalgae used in this study was Indonesia-cultivated Chlorella sp., This work investigated the effect of temperature (200°C, 225°C, 250°C), biomass weight-water ratio (1:20, 2:20, 3:20), and residence time (10, 20, 30 minutes) on bio-crude oil yield of non-catalytic hydrothermal liquefaction. The highest bio-crude oil yield was 2.25%, obtained at temperature of 250°C biomass weight-water ratio of 1:20, and residence time of 10 minutes. The highest component of bio-crude oil was alcohols. The low bio-crude oil yield was caused by the longer residence time of cooling step (driving gas conversion), low amount of carbon-hydrogen content and high amount of oxygen-ash content in biomass. Furthermore, the highest component of bio-crude oil was alcohols, stimulated by low carbon content coupled with high oxygen content in Chlorella sp.

Abstract: Indonesia is a tropical country which become one of the largest producer country of biomass especially from agricultural and forestry sector. One of the biomass source that has not been widely utilized is sago. Sago is an alternative source of carbohydrates besides rice, especially in the eastern region such as Papua. The potential of sago in Papua was 66,593 tons in 2018. This potential produces sago waste from processing sago starch, which can pollute the environment. Utilization of sago waste in the form of sago production waste as a source of biomass for electricity generation is an alternative solution. The result shows that sago pulp can be processed into briquettes with the calorific value of 6,327.4 kcal/kg – 6,946.7 kcal/kg. Sago production waste generated from the processing of sago starch is 14% so that the daily waste potential is 25.54 tons/day. Based on this potential, OWRS technology using pyrolysis-gasification obtained 6.6 tons/day of sago charcoal briquettes. The potential of heat energy was 42.03 Gcal/day. The potential of electricity that can be produced with updraft-fixed bed gasification from sago charcoal briquettes was 5.18 MWh. The theoretical power is 2.03 MW with an output power of 215.83 kW at 11% efficiency.

Abstract: In dairy waste treatment plant, there was sludge accumulation of material organic sediment on the bottom of the container. This sludge has a very strong odor, brownish and high organic content. Commonly used as fertilizer, animal feed, and biodiesel production. An alternative treatment processed by using anaerobic digestion is used in this study to produce biogas. The sludge was placed in anaerobic fixed bed continuous reactor with packing media support variation using bioball, natural zeolite, and bioring. The reactor was operated in batch 21 days with volume 30 liters. The effect of differences supported media on biogas production was investigated. In this study was obtained that fixed-bed reactor with supported zeolite media was the highest biogas production and sCOD removal up to 89.66%.

Abstract: The non-oxygenated fraction of bio-oil is precursor of the formation of biofuel because it contains hydrocarbon only. Zeolite catalysts have been proved to improve the yields of non-polar fraction of bio-oil in case of fast co-pyrolysis. In the present work, the catalysts were applied to slow co-pyrolysis to investigate their effect on the yields and compositions of non-oxygenated fractions of bio-oil. The co-pyrolysis was conducted in a stirred tank reactor using non catalyst (thermal co-pyrolysis), natural zeolite and H-beta zeolite catalysts with heating rate of 5°C/minute from ambient temperature to 500°C and PP composition in combined feed varied 0, 50, and 100% weight of PP. As biomass, the present study used corn cobs. The results show that synergistic effect on the yield of non-oxygenated fraction in co-pyrolysis involving natural zeolite was lower than that in thermal co-pyrolysis and co-pyrolysis involving H-beta-zeolite exhibited negative synergistic effect. H-NMR analysis of the fraction from co-pyrolysis involving 50% weight of PP shows that the bio-oil contained approximately methyl H of about 55% by mol, methine H of 20% and methylene H of about 15% irrespective of catalysts used. This composition was closer to that of commercial gasoline rather than commercial diesel compositions.

Abstract: In Indonesia, Casuarina montana usually planted as a road shading tree or in the home garden. This tree will be pruned periodically to reduce the amount of the canopy and maintain the beauty of its shape. Pruning biomass usually consists of the tip of the stem, branches, twigs, and leaves. The biomass has potency for energy or chemicals sources. This study aims to know about energy potential of various types of C. montana biomass and charcoal properties in different carbonization temperature. Six types of biomass from pruning waste of C. montana were used as samples. Branch has high potency as α-cellulose source, while bark including twig bark, branch bark, or stem bark have high potency as lignin source. When it is used as direct fuel (firewood), all biomass of C. montana possess quite high calorific value. When it is converted to be charcoal, temperature of 300°C is good for carbonizing the biomass twig, twig bark, branch bark, and stem bark, while biomass branch and stem need temperature of 400°C.

Abstract: Nowadays, energy consumption has increased as a population increases with socio-economic developments and improved living standards. Therefore, it is necessary to find a replacement for fossil energy with renewable energy sources, and the potential to develop is biofuels. Bio-oil, water phase, gas, and char products will be produced by utilizing Spirulina platensis (SPR) microalgae extraction residue as pyrolysis raw material. The purpose of this study is to characterize pyrolysis products and bio-oil analysis with GC-MS. Quality fuel is good if O/C is low, H/C is high, HHV is high, and oxygenate compounds are low, but aliphatic and aromatic are high. Pyrolysis was carried out at a temperature of 300-600°C with a feed of 50 grams in atmospheric conditions with a heating rate of 5-35°C/min, the equipment used was a fixed-bed reactor. The higher the pyrolysis temperature, the higher the bio-oil yield will be to an optimum temperature, then lower. The optimum temperature of pyrolysis is 550°C with a bio-oil yield of 23.99 wt%. The higher the pyrolysis temperature, the higher the H/C, the lower O/C. The optimum condition was reached at a temperature of 500°C with the values of H/C, and O/C is 1.17 and 0.47. With an increase in temperature of 300-600°C, HHV increased from 11.64 MJ/kg to 20.63 MJ/kg, the oxygenate compound decreased from 85.26 to 37.55 wt%. Aliphatics and aromatics increased, respectively, from 5.76 to 36.72 wt% and 1.67 to 6.67 wt%.

Abstract: Nipa palm (Nypa fruticans) spreads abundantly in the mangrove forests of eastern coast of Sumatera Island, Indonesia. Nipa palm sap can be used as a very high-gravity (VHG) substrate for fermentation. In this research, batch fermentation of nipa sap with initial sugar content of 262.713 mg/ml using immobilized Saccharomyces cerevisiae yeast cells was studied. Immobilization of the yeasts in Na-alginate by droplet method and addition of 0.2% v/v Tween 80 and 0.5g/l ergosterol to the immobilized cells were first carried out. Then, the effect of cells weight percentage (5, 10, 15, and 20% w/v) and fermentation time (24, 36, 48, 60, 72, 84, and 96 hrs) on the bioethanol production were investigated. After, the analysis of bioethanol concentration was investigated using Gas Chromatography. The bioethanol production increased with the fermentation time until reaching a maximum value at all cell weights. Except with the 20% w/v, this peak was followed by a decrease in the bioethanol production at cell weights of 5, 10, and 15% w/v. This phenomenon may be explained by degradation of bioethanol into acetic acid resulting in the decreased concentration at the end of fermentation. The formation of acetic acid was characterized by decreases in the pH values of the fermentation medium. On the contrary, the bioethanol level tended to increase until the end of fermentation with the immobilized yeast cells of 20% w/v. High number of available immobilized yeast cells at the end of fermentation, accumulation of bioethanol produced at earlier times, and no further conversion of bioethanol to acetic acid could be the reasons for this increase. The optimum conditions for bioethanol production were 20% w/v cell weight and 96 hr fermentation time, at bioethanol concentration of 17.57% v/v.