• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.306-309
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• 2005

One of the most critical issues in sol id oxide fuel cell (SOFC)running on hydrocarbon fuels is the risk of carbon formation from the fuel gas. The simple method to reduce the risk of carbon formation from the reactions is to add steam to the fuel stream, leading to the carbon gasification react ion. However, the addition of steam to fuel is not appropriate for the auxiliary power unit (APU) and potable power generation (PPG) systems due to an increase of complexity and bulkiness. In this regard, many researchers have focused on so-called 'direct methane' operation of SOFC, which works with dry methane without coking. However, coking can be suppressed only by the operation with a high current density, which may be a drawback especially for the APU and PPG systems. The single chamber fuel cell (SC-SOFC) is a novel simplification of the conventional SOFC into which a premixed fuel/air mixture is introduced. It relies on the selectivity of the anode and cathode catalysts to generate a chemical potential gradient across the cell. Moreover it allows compact and seal-free stack design. In this study, we fabricated honeycomb type mixed-gas fuel cell (MGFC) which has advantages of stacking to the axial direction and increasing volume power density. Honeycomb-structured SOFC with four channels was prepared by dry pressing method. Two alternative channels were coated with electrolyte and cathode slurry in order to make cathodic reaction sites. We will discuss that the anode supported honeycomb type cell running on mixed gas condition.

• Applied Chemistry for Engineering
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• 제23권2호
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• pp.125-130
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• 2012

In these days, there has been increased focus on global warming and the exhaustion of resources recently caused by the heavy consumption of fossil resources. In order to resolve these problems, biomass is increasingly gaining international attention as a renewable energy source. Biogas derived from various biomass is environmental friendly alternative fuel for power generation, heating and vehicle fuel. Large amounts of sewage sludge, food waste and manure are generated from human activity, but these organic wastes contain high levels of organic matter and thus they are potential substrates for producing methane of biogas. The biogas contains 60% of highly concentrated methane, which is expected to be used effectively as energy. In this paper, we investigate the status of biogas in Korea as an alternative energy.

• Journal of environmental and Sanitary engineering
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• 제20권1호
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• pp.64-75
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• 2005

The total production of food waste was about 11,398ton/day('03) in Korea. Also, food waste was treated by landfill, incineration, reuse and anaerobic digestion. The method of food waste treatment depended primarily on landfill. However, the method of landfill causing social problems was prevented to treat food waste in the first of January 2005.12) Thus, anaerobic digestion is an important method to treat food waste because of possibility of energy recovery as methane gas. In this study, the possibility of food waste treatment containing high organic material and low pH in the one stage anaerobic reactor to save cost and time and energy recovery using $CH_{4}$ gas by the hybrid anaerobic reactor (HAR) was measured. The HAR was designed by combing the merits of the anaerobic filter (AF) to minimize the microorganism shock when food waste of very low pH was injected and up-flow anaerobic sludge blanket (UASB) to prevent from plugging and channeling phenomena by large suspended solids when semi solids were injected. Granule was packed in the section of HAR. The purpose of the BMP experiment was to measure the amount of methane generated when organic material was resolved under anaerobic conditions, to grasp bio resolution of organic material. Total accumulated methane production per VS amount was $0.471(m^{3}/\cal{kg}\;VS)$. So, the value was about $81.2\%$ of theoretical methane production which was $0.58(m^{3}/\cal{kg}\;VS)$ by elementary analysis and organic matter removal velocity (K) was $0.18(d^{-1})$. From these results, food waste was treated by anaerobic treatment. From this study, $CH_{4}$ generation from food waste (11,398 ton/day) could be estimated. By using an energy conversion factor of Braun's study, $5.97KWh/m^{3}\;CH4,\;60\%\;of\;CH_{4}$ gas generation, the amount of total energy producing food waste is to 6,727MWh/day. It could be confirmed that energy recovery using $CH_{4}$ gas was possible. Above these results, food waste containing organic matters of high concentration could be treated in HRT 30 days under an anaerobic condition, using the hybrid anaerobic reactor and reuse of $CH_{4}$ gas was possible.

• Asian-Australasian Journal of Animal Sciences
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• 제12권4호
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• pp.642-650
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• 1999

Options available for utilization of animal wastes include sources of plant nutrients, feed ingredients for farm animals, substrate for methane generation, and substrate for microbial and insect protein synthesis. The wastes have the most economic value for use as animal feed. Performance of animals fed diets containing animal wastes is similar to that of animals fed conventional diets. Processing of animal wastes to be used as animal feed is necessary for destruction of pathogens, improvement of handling and storage characteristics, and maintenance or enhancement of palatability. Feeding of animal waste has not adversely affected the quality and taste of animal products. In the USA copper toxicity has been reported in sheep fed high-copper poultry litter, but this is not a serious problem with cattle. Potential pathogenic microorganisms in animal wastes are destroyed by processing such as heat treatment, ensiling and deep stacking. Incidents of botulism, caused by Clostridium botulinum, have been reported in cattle in some countries, and this problem was caused by the presence of poultry carcasses in litter. This problem has not occurred in the USA. With appropriate withdrawal, heavy metal, pesticide or medicinal drug accumulation in edible tissues of animals fed animal wastes is not a problem. Feeding of animal wastes is regulated by individual states in the USA. The practice is regulated in Canada, also. With good management, animal wastes can be used safely as animal feed.

• Transactions of the Korean hydrogen and new energy society
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• 제34권3호
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• pp.267-273
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• 2023

As the impacts of global climate change become increasingly apparent, the reduction of carbon emissions has emerged as a critical subject of discussion. Nuclear power has garnered attention as a potential carbon-free energy source; however, the rapidity of load following in nuclear power generation poses challenges in comparison to fossil-fueled methods. Consequently, power-to-gas systems, which integrate nuclear power and hydrogen, have attracted growing interest. This study presents a preliminary design of a very high temperature reactor (VHTR) integrated blue hydrogen production process utilizing DWSIM, an open-source process simulator. The blue hydrogen production process is estimated to supply the necessary calorific value for carbon capture through tail gas combustion heat. Moreover, a thermodynamic assessment of the main recuperator is performed as a function of the helium flow rate from the VHTR system to the blue hydrogen production system.

• Korean Chemical Engineering Research
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• 제56권4호
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• pp.496-523
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• 2018

The objective of this study is to evaluate the economic feasibility of two fast pyrolysis and biooil upgrading (FPBU) plants including feed drying, fast pyrolysis by fluidized-bed, biooil recovery, hydro-processing for biooil upgrading, electricity generation, and wastewater treatment. The two FPBU plants are Case 1 of an FPBU plant with steam methane reforming (SMR) for $H_2$ generation (FPBU-HG, 20% yield), and Case 2 of an FPBU with external $H_2$ supply (FPBUEH, 25% yield). The process flow diagrams (PFDs) for the two plants were constructed, and the mass and energy balances were calculated, using a commercial process simulator (ASPEN Plus). A four-level economic potential approach (4-level EP) was used for techno-economic analysis (TEA) under the assumption of sawdust 100 t//d containing 40% water, 30% equity, capital expenditure equal to the equity, $H_2$ price of $1050/ton, and hydrocarbon yield from dried sawdust equal to 20 and 25 % for Case 1 and 2, respectively. TCI (total capital investment), TPC (total production cost), ASR (annual sales revenue), and MFSP (minimum fuel selling price) of Case 1 were $22.2 million, $3.98 million/yr, $4.64 million/yr, and $1.56/l, respectively. Those of Case 2 were $16.1 million, $5.20 million/yr, $5.55 million/yr, and $1.18/l, respectively. Both ROI (return on investment) and PBP (payback period) of Case 1(FPBU-HG) and Case 2(FPBU-EH) were the almost same. If the plant capacity increases into 1,500 t/d for Case 1 and Case 2, ROI would be improved into 15%/yr.

• New & Renewable Energy
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• 제7권3호
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• pp.17-28
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• 2011

Biogas production and utilization are an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy sectors such as space heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded that is mainly the removal of carbon dioxide to increase the methane content up to more than 95 ~ 97 vol% in some cases, similar to the composition of fossil-based natural gas. Usage of Biogas as a fuel of vehicles have an effect of reducing $CO_2$ emission compared to fossil fuels. Biomethane which is produced by upgrading of biogas is regarded as a good alternative energy and usage of clean energy is encouraged to deal with air pollution and waste management as well as production of clean energy. Recently, biogas projects for vehicle fuel are newly being launched and Korea government have also announced a plan for investment to develop biogas as a transport fuel. In this study, it is aimed to examine the potential feasibility of biomethane as a transport fuel. As a results, the status of biomethane, quality standard, quality characteristics, and upgrading technology of biogas were investigated to evaluate of biogas as a vehicle fuel of transportation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.50-53
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• 2006

Regional geophysical surveys and geological cal studies on natural gas hydrate (NGH) in the East Sea were carried out by the Korea Institute of Geoscience and Mineral Resources (KIGAM) from 2000 to 2004. 16 piston cores, 2270 L-km of multi-channel reflection seismic (MCRS) data and 730 L-km of 3.5kHz Chirp data obtained from the southwestern part of the deep-water Ulleung Basin were analyzed in this study. In piston cores, cracks generally developed parallel to bedding suggest significant gas content. The core analyses showed high total organic carbon (TOC) content, sedimentation rate and heat flow of sediments. These are in favor of the general ion of substantial biogenic methane, which can form the NGH within the stability zone of the near seafloor sediments in the study area. The cores generally show also high residual hydrocarbon gas concentrations for the formation of natural gas hydrates The geophysical indicators of the presence of gas and/or NGH such as bottom simulating reflectors (BSRs), seismic blank Bones, pockmarks and gas seeping features were well defined on the MCRS and Chirp data.

• Journal of Microbiology and Biotechnology
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• 제20권7호
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• pp.1092-1100
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• 2010

Bacteria, fungi, and protozoa inhabiting the rumen, the largest chamber of the ruminants' stomach, release large quantities of hydrogen during the fermentation of carbohydrates. The hydrogen is used by coexisting methanogens to produce methane in energy-yielding processes. This work shows, for the first time, a fundamental possibility of using a hydrogen-rich fermentation gas produced by selected rumen ciliates to feed a low-temperature hydrogen fuel cell. A biohydrogen fuel cell (BHFC) was constructed consisting of (i) a bioreactor, in which a hydrogen-rich gas was produced from glucose by rumen ciliates, mainly of the Isotrichidae family, deprived of intra- and extracellular bacteria, methanogens, and fungi; and (ii) a chemical fuel cell of the polymer-electrolyte type (PEFC). The fuel cell was used as a tester of the technical applicability of the fermentation gas produced by the rumen ciliates for power generation. The average estimated hydrogen yield was ca. 1.15 mol $H_2$ per mole of fermented glucose. The BHFC performance was equal to the performance of the PEFC running on pure hydrogen. No fuel cell poisoning effects were detected. A maximum power density of $1.66\;kW/m^2$ (PEFC geometric area) was obtained at room temperature. The maximum volumetric power density was $128\;W/m^3$ but the coulombic efficiency was only ca. 3.8%. The configuration of the bioreactor limited the continuous operation time of this BHFC to ca. 14 h.

• Applied Chemistry for Engineering
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• 제19권1호
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• pp.17-26
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• 2008

With the effectuation of Kyoto Protocol on the United Nations Framework Convention on the Climate Change, the emission reduction of greenhouse gases became an urgent issue and has been competitively secured among countries as the form of certificates through clean development mechanism (CDM) or joint implementation (JI). Nitrous oxide ($N_2O$) is one of the major greenhouse gases along with carbon dioxide ($CO_2$) and methane ($CH_4$) having warming potential 310 times that of carbon dioxide and chemically very stable in the atmosphere to give a life time of more than 120 years so that it reaches to the stratosphere to act as an ozone depleting substance. $N_2O$ hardly decomposes and thus, besides to the adoption of thermal decomposition at high temperature, selective catalytic reduction methods are usually used at temperatures over $400^{\circ}C$ in which the presence of NOx acts as a major impeding material in the decomposition process. In this article, the sources of various $N_2O$ generation, catalytic reduction processes and the status and trends of emission trade with CDM projects for greenhouse gas reduction are summarized and discussed on a condensed basis.