V. Scholz* and J. Ellner
Abstract: Fuel cells are a promising alternative to conventional combined heat and power units for biogas plants. Up to now more than ten fuel cells (SOFC, PEMFC, MCFC, PAFC) fuelled with biogas or a similar gas were tested worldwide in lab and in pilot scale. One of the major problems is the irregular and changing composition of biogas. In addition to the main components, methane and carbon dioxide, it contains various harmful trace compounds such as hydrogen sulphide (H2S) and other volatile sulphur compound (VSC). Because of their high reactivity, some of these trace gas compounds limit fuel cell performance and cause operational problems. In order to guarantee adequate durability and reliability of the fuel cell system, potential contaminants have to be identified. Biogas from different commercial biogas plants and laboratory fermenters fed with various substrates was analysed, using gas chromatography and mass spectrometry (GC-MS). Besides hydrogen sulphide also carbonyl sulphide (COS), methanethiol (MeSH), ethanethiol (EtSH), dimethyl sulphide (DMS) and carbon disulphide (CS2) were detected and quantified and correlations could be found between the fermentation and substrate type and the amount of these trace gases in biogas. In selected cases the chronological sequence of these compounds were measured during the entire digestion process.
Keywords: Fuel cell, biogas, PEM, H2S, VSC.
N. Laosiripojana* and V. Champreda
M. Barz* and M.K. Delivand
Abstract: Since Thailand is an agricultural-based economy, there are various resources of agricultural residues which can be used for electricity Generation. To what extent those residues penetrate future energy markets depends on various aspects, e.g. the availability of the resources, the logistic frame conditions for the fuel supply, the state of the art of conversion technologies and opportunities for technological developments, the costs of electricity generation and last but not least environmental, social and institutional factors. This paper indicates which agricultural sources could be used as promising energy sources and analyzes the potential contribution in terms of electricity generation. An overview about the viable conversion routes and technologies is presented and discussed.
Keywords: biomass, agricultural residues, energy potential, logistics, conversion routes, combustion, gasification, biomass IGCC, biogas, rice straw, rice husk.
Abstract: This paper presents an overview and experiences of implementation and research studies of biomass gasification in Thailand. An overview of biomass utilisation and status of biomass conversion technologies especially power generation via gasification route is described. Then, the research experiences in biomass fluidized bed gasification studies at JGSEE are reviewed and discussed, which include the investigation of synthesis gas potential in terms of both technical and economic aspects, cogasification of high-moisture biomass with other fuel wastes, and the investigation of tar formation in bubbling fluidized bed gasifier. The future research activities will focus on the development of an efficient and affordable tar reduction process.
Keywords: Biomass; Gasification; Fluidized Bed; Power Generation; Tar.
Shabbir H. Gheewala
Abstract: The utilization of biomass for energy, particularly power and transportation fuels, is being promoted in many countries for various reasons such as use of local materials and the apparent environmental benefits. However, biomass utilization is not renewable and sustainable unless certain conditions are satisfied. The evaluation of environmental impacts requires the consideration of the entire life cycle to ensure that the impacts from one phase are not simply displaced to another, showing undue environmental advantages. Using the examples of three biomass chains – sugarcane, oil palm and jatropha – experiences are drawn from studies conducted on energy and environmental assessment using a life cycle approach. The results show that importance of using life cycle assessment (LCA) as the tool for evaluating environmental impacts of bioenergy systems. The LCA studies also reveal that for the utilization of biomass resources to be sustainable, it is important that all the by-products are efficiently utilized. The development of biomass conversion facilities in the form of biorefineries is highlighted as a means to this end.
Keywords: Biomass, Bioenergy, Biofuels, Life cycle approach, Sustainable utilization.
Mitra Kami Delivand, Mirko Barz and Savitri Garivait
Abstract: The financial feasibility assessment for rice straw-based power combustion projects of different scale and the environmental LCA are performed for conditions in Thailand. Straw-based cumbustion facilities are financially feasible and profitable, assumed that the specific capital cost is approximately lower than 70,000 Baht/kWe, which can be reached if the capacity of the power plant is 8 MW or greater. The subjective probability of a financially successful 10 MWe straw-based power plant could be as high as 86-90%, whereas, it is as low as 24-32% for an 8 MWe project. Implication of learning rate (LR) shows that the 4th power plant capacity of 10 MWe can compete with an alternative fossil-fuel power plant within 8 years after initiating the first strawbased power combustion project. Furthermore, the effect of Carbon Certified Reduction (CER) revenues can significantly lower the production costs to 2.26 Baht/kWh in a 10 MWe straw-based combustion facility. The life-cycle Green House Gas (GHG) emission reductions indicate that 0.378 tCO2eq/t straw(db) (0.496 kg CO2eq/kWh) and 0.683 tCO2eq/t straw(db) (0.959 kg CO2eq/kWh) could be avoided if rice straw substitutes natural gas or coal in the power generation sector, respectively. Furthermore, using rice straw as energy source in Thailand could result in considerable annual savings on primary energy imports of around 7-9%.
Keywords: Rice straw combustion; Subjective probability; LR; CER; GHG impact.
P. Aggarangsi and T. Teerasountornkul
Abstract: The objective of this work is to suggest design considerations and report operational efficiencies of CMU-UF, an up-flow anaerobic digester developed by Chiang Mai University, Thailand based on specific conditions livestock waste. CMU-UF designers have excluded temperature control units as well as mechanical agitation but instead, integrated UASB up-flow capability which can greatly reduce the initial investment. The design was supported by Thailand’s Ministry of Energy to be developed in full-scale and implemented in 34 large swine farms in various regions of the country treating manure from more than 1.0 million standing pigs. Additional monitoring procedures were thus carried out on 20 chosen farms to investigate the efficiency of the installed digesters in terms of waste treatment as well as biogas production characteristics. The results indicate that an average COD removal efficiency of 87.6% can be achieved with a 4.0-6.0 days HRT and approximately 40 days SRT operation conditions. The CMU-UF has an average biogas production of 0.261 m3/kg of removed COD, equivalent to 0.090 m3/60-kg standing pig per day.
Keywords: Up-flow, biogas, livestock, tropical, efficiency.
M. Nelles, A. Schüch and G. Morscheck
Abstract: In the year 2008 the energy consumption of the rapidly industrializing non-OECD economies (including China) even surpassed the OECD consumption for the first time. Worldwide biomass covers about 10 to 13% of the total energy demand and is an important energy system component in developing countries. In some of the developing countries the share of bioenergy is above 90%, since there are no other options for energy supply. Currently the rising interest in bioenergy is also forced by the climate protec-tion goals. Today about 70% of the total share of renewable energy sources in Germany is covered by biomass. The technical poten-tial of bioenergy is estimated to cover 10 to 15% of the primary energy consumption in 2030. The energetic utilization of huge unuti-lized resources, such as bio-waste and biodegradable residues can help to meet the rising energy consumption. For example, in con-sideration of ecological requirements about 100 million Mg of this waste and residues are energetic usable and could supply 4 to 5% of the national primary energy consumption in Germany (Faulstich and Greiff 2007). Various technologies are available for the conditioning and conversion of solid biomass to produce solid, liquid or gaseous biogenic fuels. To support climate protection and to help to secure the energy supply bioenergy can contribute a relevant share to the total energy mix.
Keywords: Bioenergy, renewable energy, biogas, organic waste and residues.
Abstract: The demand of energy has been increased over the years as the sequence by increasing of the world population. Currently, the energy consumption in Thailand was rising in relation to economic growth. Thai government announced its needs to increase the acquired share of alternative energy from 6.4% to 20.3% of commercial primary energy by 2022. In this situation, Thailand with the abundant and varieties of biomass and agricultural wastes should have the great challenge and opportunity for this supply to anaerobic digestion for biogas production accordingly by the strategy of government. Thus, this paper illustrated sources of biogas feedstock from biomass and agricultural wastes, status and potential of biogas production and utilization, biogas technology used, driving forces, and future perspectives in country.
Keywords: Agricultural wastes, Anaerobic digestion, Biogas, Biomass, Potential.
Abstract: Product gas components such as condensable substances, particles and, depending on the gas utilization, certain trace contaminants are responsible for the high gas cleaning demands in gasification technology. In this paper strategies to encounter this challenge are subject of discussion. Primary measures for tar reduction within the gasifier are covered as well as secondary steps for cleaning the produced gases downstream of the gasification reactor. In order to evaluate the success of these measures standardized tar measurement methods have to be used. A short overview about existing and new methods is given. The overall success of gasification technology for biomass feedstocks will depend on technological aspects discussed but also on the biomass supply ensuring all year round good quality and on infrastructure for heat (cold), gas and power transmission or storage respectively.
Keywords: biomass, tar, gasification, fuel gas, synthesis gas, gas cleaning, gas monitoring.
T. Kiatsiriroat* and N. Vorayos
Abstract: This paper presents the results of research studies on biofuels in the terms of bioethanol and biodiesel at Chiang Mai University, Thailand. For bioethanol, the studies are concerned with the selection of ethanol producing microbes and the methods of the microbe cultivation to produceget high yields of ethanol. For biodiesel, various methods have been carried out to achieve high energy efficiency in biodiesel or emulsified oil products to replace diesel in diesel burners and low speed diesel engines. Fewer emissions were observed when the biodiesel and the emulsified oil were utilized. Moreover, bio-oil and bio-char from freshwater algae have been considered. The production process was carried out under a slow pyrolysis. Finally, life cycle impact assessment of the biofuel production has also been undertaken.
Keywords: biofuels, bioethanol, biodiesel, emulsified oil, bio algae-oil.
W. Wichtmann* and S. Wichmann
Abstract: Biomass production should always follow principles of sustainability. This paper describes some effects of biomass production for energy within environmental, social and economic contexts. Important parameters for comparing different biomasses are energy yields per hectare or CO2 mitigation costs. However, most bio-energy production chains obviously cannot compete with non-agricultural alternatives for CO2 emissions mitigation. The “good example” of paludiculture is where biomass production for energy is able to meet all requirements of sustainable production.
Keywords: Biomass production, energy, CO2 mitigation costs, organic soils, peatlands, paludiculture.