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Gasification of biomass is an industrial process utilized to produce product gas that can be used in electrical power generation with internal combustion engines. However, there remain huge challenges with regards to tar and other pollutants, thus their removal before further use is necessary. Non-thermal plasma method can be considered as a novel and efficient way for treatment of tar from product gas. In this work, a laboratory-scale, reverse vortex flow gliding arc plasma reactor was developed and tested for the removal of tar model compound using naphthalene as surrogate. Effects of total gas feed rate in the range of 20–60 L/min, applied voltage in the range of 50–220 V, hence, power input in the range of 300–460 W with initial naphthalene concentration of 610 ± 50 mg/m3 on removal and energy input were investigated. It was found the tar removal efficiency increased with increasing applied voltage. Maximum naphthalene removal efficiency of 85% was achieved at applied high voltage of 15 kV and specific energy input of 0.13 kWh/m3 with energy utilization efficiency of about 4.60 g/kWh. From the findings, non-thermal plasma technology appeared to offer great potential in the removal of biomass tar from gasification. The technology may be promising for possible application to real biomass tar cracking and upgrading of product gas from gasification.

Torrefaction combined with densification for upgrading biomass to torrefied biomass pellets is increasingly of great interest since torrefied biomass pellets are considered as a major renewable energy source. Especially in the application of co-firing with coal, torrefaction may be easily integrated into an existing co-firing power plant, whose flue gases from the power plant could be used to torrefy biomass pellets. This could also help to improve the overall carbon efficiency of the power plant and reduce emissions of greenhouse gases. In the present work, a torrefaction plant for corn residue pellets to produce torrefied solid fuels using flue gases as a main heat source was simulated in Aspen Plus® software. Torrefaction module was successfully modelled by an RYield reactor, which was programmed with the two-steps-in-series kinetic for the decomposition of biomass pellets as well as the volatile formation for by-products. The model can, therefore, provide the distribution and yield of both torrefied biomass pellets and volatile by-products. From the validation, the simulation results appeared to show good agreement with available experimental data in the literature. At the suggested conditions of 260 °C wet flue gas and 20 min residence time, thermal energy of 460 J/g and 380 J/g were required for the drying and the torrefaction modules, respectively. At these conditions, the performance of the whole process was found to be almost 95%. This plant produced 75% w/w torrefied biomass pellets yield with HHV of 21.9 MJ/kg. The by-products mainly included 10.7% w/w water, 7.4% w/w CO2, and 1.7% w/w CO. Our findings provide a feasible outlook for integrating a torrefaction process of biomass pellets into a co-firing power plant, utilizing a realistic heat of waste flue gases for the process.

In this work, the catalytic upgrading of a bio-oil model compound via esterification with ethanol was studied using 12-tungstosilicic acid as the catalyst. The response surface method was used to investigate and optimize the process variables, which include the ethanol to acid molar ratio, catalyst loading, reaction temperature, and reaction time for maximum conversion of the organic acid for esterification under atmospheric conditions. The effect of high He pressure on acid conversion for esterification was also studied. The maximum acid conversion was almost 90%, which can be achieved at reaction temperature of 77 °C, ethanol to acid molar ratio of 5:1, catalyst loading of 4.0% w/w, and reaction time of 8.3 h. Pressurizing the reaction with inert He did not have any effect for acid conversion at this optimum condition and had a slight negative effect under the studied conditions. After upgrading, the esterified products were found to improve the heating value from 17.6 to 23.2 MJ/kg and appeared to enhance fuel properties.

Utilization of agro-residues from maize production as biorenewable energy source is considered to be a very good and sustainable waste management method. Hydrothermal carbonization (HTC) is a thermochemical conversion process for solid organic materials at elevated temperature and pressure in the presence of water. Through hydrolysis, dehydration and decarboxylation, a solid hydrochar as well as gaseous and aqueous products are generated. The energy density and the macromolecular structure of the solid product are improved, giving rise to a carbonized product that is simpler to convert to heat, power or fuel than the starting materials. This study was about applying HTC to upgrade maize residues. The residues used were cobs derived from a maize processing factory. The HTC experiments were carried out in a batch 10-dm3 pressure reactor equipped with 14 kW heaters and internal temperature control. About 0.5 kg of biomass was loaded with 5 dm3 of deionized water into the reactor. The effects of temperature (180–250 °C) and time (60–360 min) were examined. The hydrochar was recovered by filtration and dried for subsequent analyses. With increasing temperature and time, the amount of hydrochar was found to decrease, while the gaseous and aqueous products increased. Hydrochar yields were in the range of about 35%–72%. From the analysis result, hydrochar produced was found to have improved fuel qualities Its elemental composition was coalified with H/C and O/C atomic ratios moving towards that of lignite. Keywords: Agricultural waste, Biomass conversion, Hot compressed water, Renewable energy, Wet pyrolysis

This work studied generation of producer gas using oxygen-enriched air and steam mixture as gasifying medium. Corn residues consisting of cobs and stover were used as biomass feedstock. Both corn residues were pelletized and gasified separately with normal air, oxygen enriched air and steam mixture in a fixed bed reactor. Effects of oxygen concentration in enriched air (21-50%), equivalence ratio (0.15-0.35), and steam to biomass ratio (0-0.8) on the yield of product gas, the combustible gas composition such as H2, CO, and CH4, the lower heating value (LHV), and the gasification efficiency were investigated. It was found that the decrease in nitrogen dilution in oxygen enriched air increased proportion of combustible gas components, improved the LHV of producer gas, but gasification efficiency was not affected. The increase in equivalence ratio favoured high product gas yield but decreased combustible gas components and LHV. It was also observed that introduction of steam enhanced H2 production but excessive steam degraded fuel gas quality and decreased gasification efficiency. The highest gasification efficiency of each oxygen concentration was at equivalence ratio of 0.3 and steam to biomass ratio of 0.58 for cob, and 0.22 and 0.68 for stover, respectively. ©2019. CBIORE-IJRED. All rights reserved

Agricultural residues are one of the large untapped sources of bio-energy in Thailand, with over 30 million tons available per year. They may be utilized to generate renewable liquid and so...

Biomass conversion by gasification process is increasingly becoming attractive, especially for ceramic making industry, to transform biomass materials into combustible fuel gas called producer gas. This producer gas can then be used to fully or partially substitute liquefied petroleum gas in ceramic firing process. However, air gasification is known to generate low calorific value of gaseous fuel (3-6 MJ/Nm3) which may not be able to generate sufficiently high temperature (> 1200 oC) flame required by ceramic firing process. Use of oxygen enriched air is therefore of great interest if medium to high calorific value producer gas is required. In this work, a modified equilibrium model of global gasification reactions is developed to predict the resultant distribution of combustible gas species in the producer gas and to study the effect of operating parameters (oxygen content in air, and equivalence ratio) in a gasification process of agro-residues in a fixed bed downdraft gasifier at a fixed temperature. The modified equilibrium model of global gasification reactions developed in this work is based on thermodynamically stoichiometric approach due to its simplicity and reduced computational time. Model predictions of reaction kinetic constants for gasification reactions and gas concentration are validated by comparing with available experimental data. Simulation of influence of oxygen content in air (21-50%) and equivalence ratio (0.15-0.35) on composition of combustible gas and its heating value is carried out. The preliminary model simulation is found to give good qualitative prediction of experimental results. For maximum calorific value of producer gas generated, oxygen content in air should be 50%, and the equivalence ratio should be 0.15, respectively. For better accuracy of this modified equilibrium model, unconverted char and tar should be further considered.

Operational management of multiple reservoirs and hydropower plants based on Nam Ngum river basin near Vientiane, Laos PDR was investigated for optimal power generation. The system consists of three reservoirs namely Nam Ngum1, 2 and 5. Analysis of water balance, storage and discharge relationship for each reservoir was carried out using the HEC-ResSim 3.0 simulation software package. Historical monthly records of these reservoirs between 1975 to 2018 were used to derive representative dry, normal and wet years to be input for the simulation. Operational management of available water was optimized for maximum power generation based on particle swamp optimization technique. From the simulated results, it was possible that for a representative wet year, electricity production of Nam Ngum1 hydropower plant can be increased from 1217 to 1348 GWh/y, an increase of about 11%, compared to current operational practice. Total power production of all three reservoirs of 4380, 3816 and 3400 GWh/y could be increased to 4727, 3860, and 3426 GWh/y, respectively. The technique proved to be useful in the operation of reservoirs and hydropower plants. Keywords: Multi-reservoirs, Hydropower, HEC-ResSim, Optimization, Renewable energy

Energy consumption of liquefied petroleum gas (LPG) in ceramic firing process accounts for about 15–40% of production cost. Biomass derived producer gas may be used to replace LPG. In this work, a premixed burner originally designed for LPG was modified for producer gas. Its thermal performance in terms of axial and radial flame temperature distribution, thermal efficiency and emissions was investigated. The experiment was conducted at various gas production rates with equivalence ratios between 0.8 and 1.2. Flame temperatures of over 1200 °C can be achieved, with maximum value of 1260 °C. It was also shown that the burner can be operated at 30.5–39.4 kWth with thermal efficiency in the range of 84 – 91%. The maximum efficiency of this burner was obtained at producer gas flow rate of 24.3 Nm3/h and equivalence ratio of 0.84.

Management of waste is a main concern and one of the most crucial issues in modern society. Effective waste management considers prevention, recycling, and handling of waste in such a way that most effectively protects human health and the environment. Energy recovery is one of the accepted options in managing solid waste. In the present paper, a waste-to-energy conversion plant utilizing refuse derived fuel (RDF) with appropriate combustion technology was proposed for a local municipality in Lampang, Thailand. Realistic waste quantity and composition were estimated. Mass and energy analyses as well as an economic feasibility survey were carried out to evaluate performance and benefits of the proposal. With up to 220 tons of RDF available daily, it was suggested that a power plant project between 5 to 13 MWe generation capacity may be developed. For a baseline case of 5 MWe, the project is economically feasible with tolerance to ± 50% fluctuation in total capital cost, electricity sale price and tipping fee.

Ceramic products are manufactured in many countries worldwide. Ceramic manufacturing industry is vital in terms of employment and economics. The industry is very energy intensive, consuming large amount of fuels. Liquefied petroleum gas (LPG) and natural gas are usually used, representing a significant portion of the total production cost. Switching to alternative gaseous fuel such as biomass derived producer gas may result in lower energy cost. Producer gas generated from biomass gasification process contains H 2 , CO and CH 4 which are combustible. Under carefully controlled conditions, burning of producer gas can provide suitable firing atmospheres for manufacture of ceramic products. In this work, attempt has been made to develop a 600 kW th biomass gasification system for ceramic firing. Woodchips were used as fuel. Product gas was generated and analyzed for its composition and energetic content. Firing of this fuel gas in place of LPG with modified gas burners in a firing chamber and preliminary testing at a local ceramic factory were carried out and demonstrated. It was found that required heat outputs and high temperature conditions were realized. Acceptable quality of the ceramic products was obtained. A simple economic analysis yielded an attractive return on investment. This proved to be a very promising energy option for substitution of fossil based gaseous fuels in ceramic industry.

Animal fats are by-products from slaughterhouses that may be utilized as renewable energy source. This study was about biodiesel production from high free fatty acid beef tallow waste using two-ste...

In thermochemical utilization of biomass, ash produced during the process is a major problem that can result in decreased performance and increased in difficulty during operation. Preliminary assessment of potential ash related troubles prior to the use of a specific biomass is valuable, even if it is only a general guideline. In this work, tendency of ash slagging, fouling and agglomeration in thermal processing of biomass was evaluated. Reference peered reviewed data including mineral content and fusion temperature of selected biomass ash were used to calculate multiple indicators (base to acid ratio, slagging index, fouling index, agglomeration index, slag viscosity index, and ternary diagram of main biomass ash composition) adopted from coal research. Major ash forming elements (Fe, Ca, Mg, K, Na, Al, Si) were found to be of relevance to ash melting and deposit behavior. For conventional biomass available locally, woody biomass (wood and wood sawdust) may be combusted without slagging or fouling problem, while non-woody biomasses (bark, husk, straw) are highly probable to experience some of these problems. The ash fusibility predictive models for woody and non-woody biomass were found to be effective. Mitigation can then be designed possibly via fuel blending to avoid or minimize the impact of biomass ash related trouble.

Bio-oil from fast pyrolysis of biomass has great potential to be one of the main renewable energy sources. At present, there are only a small number of commercial bio-oil plants because their operation is rather complicated and the return is not attractive. With funding from the government sector, a small biomass pyrolysis plant (capacity of 20-30 dm3 of bio-oil per day) was built and operated in Phrae, Thailand. In this paper, practical stepwise methodologies were presented to technically analyze the production and energy consumption of bio-oil production based on the data from this demonstrated plant. Mass and energy balance calculations were carried out to assess the performance and improve process design. An economic analysis was also performed to study the potential of biomass-to-bio-oil conversion costs and viability of commercialization. From the investigation, it was found that the operation cost of crude bio-oil production was about 30-35 Thai baht per dm3. Even though the operating cost of the fast pyrolysis units is excessively high under current situation, the biomass plant still has potential to generate attractive economic return if the upgrading process is employed as well as assistance from the government is available to subsidize the sale price.

This article presents a study on using portable biomethane for domestic cooking in Thailand in domestic stoves. Thailand presently uses approximately 20,000 tonnes of LPG every day. It is estimated that Thailand has the potential to produce the equivalent of 3,000 tonnes of LPG equivalent energy from compressed biomethane gas (CBG) per day. This assumes full conversion of all agricultural, industrial and municipal wastes into CBG. Since CBG is a form of renewable energy, the use of it for domestic cooking purposes will help to reduce Thailand's dependence on imported energy and have a positive impact on the environment. The difficulty arises when a cylinder of biomethane, which is processed biogas comprising of at least 85% methane, is used instead of LPG, which is comprised of propane and butane, in a cooking stove. The Wobbe index for LPG is approximately double that of biomethane indicating that they are not interchangeable gases. The density of LPG is also 2 - 3 times that of biomethane which ...

Biogas is one of the most important renewable energy sources in modern societies. Generated from livestock manure and industrial wastewater, it can provide considerable savings in energy costs and reducing environmental impacts. Thailand is reported to have the potential to produce over one billion m 3 of biogas a year. The biogas is generally utilized for heating, mechanical shaft works, and electricity generation. If pipeline networks or purification and compression facilities are not available, use of biogas is normally limited to only within and around farm areas. Alternatively, biogas may be converted via reforming reactions into synthetic gas. Because of presence of sulphur compounds in biogas, a catalytic reformer may face serious poisoning problem. In this work, non-catalytic, plasma assisted reforming of biogas was carried out at atmospheric pressure and room temperature in an 800 W, laboratory microwave discharge reactor. Effects of CH 4 /CO 2 ratio (1, 2.33, 9), feed flow rate (8.33 – 50 cm 3 /s), and oxygen addition in terms of CH 4 /O 2 ratio (1, 1.5, 2) on reactor performance (yield, selectivity, conversion, H 2 /CO and energy consumption) was investigated. It was found that biogas was successfully reformed into synthetic gas by a microwave plasma reactor under room temperature and non-catalytic conditions. For dry reforming of biogas, high H 2 and CO yields were obtained at low energy consumption. Presence of oxygen enabled partial oxidation reforming that produced higher CH 4 conversion, compared to purely dry reforming process. By varying CH 4 /CO 2 as well as CH 4 /O 2 ratios, synthetic gas with a wide range of H 2 /CO ratios can be generated. From the findings, it was suggested that the microwave plasma reactor may be practically used to reform biogas to produce more valuable intermediates or products such as synthetic gas.

This paper is concerned with the process of switching from non-renewable LPG to renewable biomethane for domestic cooking in Thailand. Most domestic stoves in Thailand use liquid petroleum gas (LPG), supplied in portable tanks. Switching to biomethane requires a method of (a) biomethane production, (b) biomethane storage and (c) stove modification to allow biomethane combustion. This paper will outline a solution to each of these three hurdles. A production plant was developed, a storage and delivery solution was designed and a methodology was developed and implemented for converting stoves for biomethane use. The results show that biomethane can be produced, delivered and combusted safely and efficiently in domestic Thai stoves. These results provide a roadmap for certain local communities to utilize renewable energy in a sustainable fashion.

Biogas is an important renewable energy source. Its utilization is restricted to vicinity of farm areas, unless pipeline networks or compression facilities are established. Alternatively, biogas may be upgraded into synthetic gas via reforming reaction. In this work, plasma assisted reforming of biogas was investigated. A laboratory gliding arc plasma setup was developed. Effects of CH4/CO2ratio (1, 2.33, 9), feed flow rate (16.67–83.33 cm3/s), power input (100–600 W), number of reactor, and air addition (0–60% v/v) on process performances in terms of yield, selectivity, conversion, and energy consumption were investigated. High power inputs and long reaction time from low flow rates, or use of two cascade reactors were found to promote dry reforming of biogas. High H2and CO yields can be obtained at low energy consumption. Presence of air enabled partial oxidation reforming that produced higher CH4conversion, compared to purely dry CO2reforming process.

In this paper, the implementation of biogas technologies in animal farms in Thailand and the government policies used to promote these technologies are presented. The Thai government has created a goal of achieving 14% of all energy needs from renewable resources by 2022. As a renewable technology, biogas has the potential to reduce Thailand's dependence on fossil fuels which make up over 90% of Thailand's electricity generation. An unfortunate by-product from animal farm waste is the greenhouse gas, methane. The benefits from capturing and utilizing this gas include increased electric generation, less odor in the local community, less greenhouse gas emissions, more revenue for farmers and production of raw fertilizer material. Thailand has the potential to produce over one billion m 3 of biogas per annum from its agricultural industry alone. Current utilization is only 36% of this potential. This paper will briefly discuss the technology used to capture and use biogas from animal farms in Thailand. The effect of government policies on this technology deployment shall be discussed. This paper demonstrates how technology and policy need to work together in order to best provide a practical solution for energy problems. In 2012, greenhouse gases worth 1400 Gg CO 2 equivalent were saved from entering the atmosphere from animal farms in Thailand.

Cashew nut shells are high energy content residues from cashew nut processing. It can potentially replace fuelwood for thermal application in a factory. However, direct combustion of cashew nut shells was troublesome due to low efficiency and high smoke emission. Alternative thermal conversion of cashew nut shells should be used instead. In this work, a gasifier system was designed, built, and installed at a local cashew nut processing factory. Cashew nut shells were converted to producer gas in the downdraft fixed-bed gasifier. The gaseous fuel was then fed to a burner to supply hot water for the factory. From the results obtained, cashew nut shells were successfully used as feedstock in a gasifier. Satisfactory operation was obtained. Gasification of cashew nut shells could provide required thermal input, with clean fuel to the local food processing factory. Preliminary economic analysis showed that the factory can save around $150 a month, with simple period to positive cash flow of less than a year.

This work combined plasma reactivity and pyrolysis for conversion of solid wastes. Decomposition of refuse derived fuel (RDF) and its combustible components (paper, biomass, and plastic) in an 800 W microwave plasma reactor was investigated at varying argon flow rates of 0.50 to 1.25 lpm for 3 minutes. The characteristic bright light emission of plasma was observed with calculated maximum power density of about 35 W/cm3. The RDF and its components were successfully converted into char and combustible gas. The average char yield was found to be 12–21% of the original mass, with a gross calorific value of around 39 MJ/kg. The yield of the product gas was in the range 1.0–1.7 m3/kg. The combustible gas generated from the pyrolysis of the RDF contained about 14% H2, 66% CO, and 4% CH4 of the detected gas mass, with a heating value of 11 MJ/m3. These products are potentially marketable forms of clean energy.

Biodiesel is one of the major renewable energy sources, produced from vegetable oils. Jatropha curcas L. is considered as a promising energy crop for biodiesel production in Thailand. This study is about continuous biodiesel production from jatropha oil by transesterification in a flow process with microwave heating. Sodium methoxide was used as a catalyst at concentrations between 0.25%–1.5%, with microwave power of 800 W, irradiation time between 10–40 s, and oil to methanol molar ratio of 1:3–1:9, respectively. Results showed that jatropha oil can be converted to biodiesel (96.5%) within 30 s under oil/methanol molar ratio of 1:6 and 1.0% catalyst. The findings indicated that this method can offer alternative means to produce biodiesel continuously.

Lignocellulosic biomass is an important alternative energy source to be utilized for ethanol production. In this work, bamboo (Dendrocalamus asper Backer) was used as biomass feedstock for conversion to fermentable sugars. Pretreatment was carried out with dilute sulfuric acid at concentrations between 0.4 – 1.6% w/w, and residence time between 45 – 135 min at a fixed temperature of 140oC. Prehydrolyzate was later analyzed for total sugars by high performance liquid chromatography. For the conditions considered, maximum glucose and xylose yields were obtained from bamboo to be 25.8 and 78.8 mg/mL, respectively. Water insoluble solids obtained were subsequently hydrolysed with cellulase (Trichoderma reesei) and β-glucosidase (Novozyme 188) for 72 h. It was found that increasing yields were obtained with increasing acid concentrations and residence times. The effects of pretreatment severity and enzymatic hydrolysis greatly increased the sugar concentrations after the hydrolysis.