• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.99-108
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• 2004

Fundamental combustion characteristics, such as the combustion potential, burning velocity and flame stability, for the practical utilization of LFG(Landfill gas) and LFG-blended fuels were experimentally investigated. The combustion potentials(CP) of LFG-blended fuels calculated from the previously suggested formulae were compared with burning velocities obtained by present experiments. The results showed that the previous formulae fur CP of LFG-blended fuels were not agreed with the experimental burning velocity, and these formulae should be revised. To provide an useful information needed to design the combustion devices, a triangular diagram was suggested for the maximum burning velocity of the mixture of CH$_4$, LPG and LFG. From the investigation of the burning velocity and the flame stability in a practical combustor, it was noted that the LFG-blended fuels, of which heating values or Wobbe indices were adjusted to that of natural gas, could be used as an alternative fuel of natural gas.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.152.2-152.2
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• 2010

LFG는 매립된 폐기물 중 유기성분이 혐기성조건에서 미생물에 의해 분해가 되면서 발생하며, 이러한 매립지가스는 주변 지역의 자연 및 생활환경에 악영향을 미치기 때문에 소각 등의 방법으로 LFG를 처리하고 있다. 일반적으로 매립지로부터 발생하는 가스의 량은 폐기물 1톤 당 $150{\sim}250m^3$로서 매립 후 2~3년 후에 최대량이 발생하며 매립 후 20~30년 후까지 지속적으로 발생함으로 안정적인 LFG의 공급이 가능하며, 메탄함량이 50%인 경우 약 $5,000kcal/m^3$의 높은 발열량을 가지므로 대체에너지원으로 이용할 경우 환경적인 문제 해결 및 신재생에너지원으로 활용할 수 있다. LFG 자원화 할 경우 가장 안정적인 방안으로 발전 및 중질가스로 활용하는 것이나, 발전의 경우 최소 200만톤 이상의 매립용량을 갖추어야 경제적인 사업성을 확보할 수 있으며, 중질가스로 활용하는 경우 인근에 가스 수요처를 확보해야 하는 어려움이 있다. 만약 중 소규모의 매립장에서 발생하는 LFG를 안전하고 경제적인 조건으로 저장 및 수송할 수 있다면 중 소규모의 매립지에서 발생하는 LFG도 활용할 수 있을 것으로 기대되며, 안전하고 경제적인 저장과 수송기술을 통하여 발전이 아닌 중질가스로의 활용도 가능하게 될 것이다. 또한 여러 곳의 매립장에서 발생한 LFG를 한 곳으로 집중시켜 고질가스로 전환하는 설비비용을 절감할 수 있으며, 정제된 고질가스를 이용하여 발전보다 경제적인 자동차 연료나 도시가스로 활용할 수 있을 것이다. 본 연구에서는 LFG의 저장과 수송기술 중 GTS 기술을 통하여 저장과 수송에 제약이 크고 많은 비용이 소비되는 기체 상태의 에너지원을 하이드레이트화 시킴으로서 중 소규모 매립지에서 상대적으로 적은 비용으로 가스저장과 지상수송이 가능하게 할 수 있다. 본 연구의 결과로 LFG 에너지화 실증화 플랜트를 설계/제작 하였으며, 메탄+이산화탄소+물 하이드레이트 형성 실험 결과 4.56 Mpa, 277.2 K 조건에서 3시간을 한 사이클로 하는 공정운전을 가지는 것을 확인하였다. 이때 생성된 슬러리상의 하이드레이트를 고압으로 배출하여 펠릿으로 형성시켰으며, 형성된 하이드레이트 펠릿의 경우 92.27%의 메탄을 포함하는 것을 확인하였다.

• Food Science of Animal Resources
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• v.33 no.6
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• pp.787-795
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• 2013

This study was carried out to investigate the characteristics of goat and cow milk yogurts containing high-exopolysaccharide fermented by Streptoccous thermophilus LFG isolated from kefir. The pH of cow milk yogurt was higher than that of goat milk yogurt. The contents of lactic acid was greater in goat milk yogurt (743.9-1043.8 mg/100 g) than in cow milk yogurt (441.6-709.9 mg/100 g). The numbers of survival lactic acid bacteria were the greatest in goat milk yogurt fermented by Str. thermophilus LFG. Viscosity was greater in cow and goat milk yogurts cultured by Str. thermophilus LFG than in yogurts by Str. thermophilus TH3. Syneresis of yogurt fermented by Str. thermophilus LFG was 9.6-16.1% and 28.2-31.8% in yogurt fermented by Str. thermophilus TH3 after 10 d storage at $4^{\circ}C$. Flavor compounds identified from goat milk were acetone, ethylbutanoate, ethyl-3-methylbutyrate, ethyl-2-butenoate and ethylhexanoate, and those from cow milk were ethylbutanoate, acetone, 2-heptanone and acetoin. Flavor compounds detected from goat milk and cow milk yogurts were acetic acid, butanoic acid, butanol, diethylcarbinol, acetone, diacetyl, decane, 2-methyl-3-pentanone, hexanal, 2-heptanone, acetoin, benzaldehyde, dimethyldisulfide, and dimethyltrisulfide. In sensory evaluation, overall preference and texture values were higher in goat milk yogurt fermented by Str. thermophilus LFG than in cow milk yogurts and the yogurt fermented by mixed culture resulted in the highest score.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.553-553
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• 2009

LFG는 약 4,500kcal/$m^3$의 높은 발열량을 가지는 에너지원으로 활용이 가능한 동시에 GWP가 21인 $CH_4$를 제거함으로써 탄소배출권(CERs) 확보를 통해 CDM 또는 ET 시장에서 유리한 위치를 선점할 수 있다. LFG의 활용기술에는 발전과 중질가스 및 고질가스 형태의 연료로 생산하는 방식이 있다. 하지만 기존의 기술은 LFG의 발생량이 일정규모 이상인 매립지에서 경제성을 가지기 때문에 국내에서는 14곳의 대형 매립지에서만 에너지원으로 활용하고 있다. 그 외 중소규모 매립지에서는 대기중으로 방출하거나 소각하여 처리하므로 가용한 에너지원이 버려지고 있을 뿐만 아니라 지구온난화에 영향을 미친다. 본 연구에서는 중소규모 매립지에서 발생하는 LFG를 경제성을 가지는 에너지원으로 활용하기 위하여 하이드레이트화를 이용한 $CH_4$ 분리, 정제, 수송 연구를 진행하였으며, 이러한 연구의 일환으로 pure $CH_4$를 대상으로 하이드레이트 형성 시 구동력(driving force)에 따른 induction time, growth rate, gas consumption 측정을 통하여 LFG를 이용한 가스 하이드레이트 생산을 위한 운전조건 선정을 위한 기본 자료로 사용하고자 한다.

• Food Science of Animal Resources
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• v.28 no.1
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• pp.82-90
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• 2008

Two strains of pure lactic acid bacteria capable of forming both acid and slime were isolated from the kefir made of goat milk. The isolated strains observed by morphological and physiological properties, and their 16S rDNA partial sequence were identified as Streptococcus salivarius subsp. thermophilus(LFG-1) and Lactococcus lactis subsp. lacits(LFG-2) with over 99% homology. The optimum temperature of Str. salivarius subs. thermophilus LFG-1 for growth was $40-45^{\circ}C$, and its generation time was 40.6 minutes. The final pH of cultured broth by Str. salivarius subsp. thermophilus LFG-1 and the commercial strain Str. thermophilus Body-1 for 24hr at $37^{\circ}C$ were 4.30 and 4.55, respectively. The coagulative activity of Str. salivarius subsp. thermophilus LFG-1 was almost as strong as that of commercial strain Str. thermophilus Body-1. However, the LFG-2 strain showed lower coagulative activity than Str. thermophilus Body-1. The survival rate of lactic acid bacteria were between 22-29% in 0.3% bile extract. At pH 1.0 all of the bacteria were killed, and most of lactic acid bacteria died against pH 3.0. However, all lactic acid bacteria survived well at pH 4.5.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.77-85
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• 2004

In this study, the concentrations of reduced S compounds (including hydrogen sulfide (H$_2$S); methyl mercaptan ($CH_3$SH); dimethyl sulfide (($CH_3$)$_2$S); carbon disulfide (CS$_2$); and dimethyl disulfide (($CH_3$)$_2$S$_2$) were determined from landfill gas (LFG) in three municipal landfill sites in the two cities of Gwang Ju (GJ) and Jeju (JJ), Korea. The S gas concentrations measured in these landfill sites were found to be dominated by H$_2$S with its mean concentration of 850 ppm from 10 LFG samples. Both absolute and relative dominance of H$_2$S was seen to be significant in most LFG samples, except those collected from very old and inactive landfills. Unlike the pattern of H$_2$S, other S gases were typically observed at much reduced concentration levels (a few ppm or less) as follows: DMS (3.5); $CH_3$SH (1.3); CS$_2$(1.2); and DMDS (0.02 ppm). If compared equally in mass concentration unit (mg m$^{-3}$ ), H$_2$S generally explained far above 90% of all S gas masses determined concurrently. Moreover, as its mass concentration commonly exceeds those of the major aromatic VOC components in LFG (like benzene and toluene), it appeared to be one of the most dominant gaseous components emitted as LFG in a quantitative sense.

• Journal of Environmental Impact Assessment
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• v.14 no.6
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• pp.365-375
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• 2005

For managing and utilizing a closed municipal solid waste landfill site in environmentally secure conditions, it is necessary to verify the stabilization level of landfill gas(LFG) and waste. For assessing LFG and waste stabilization of an open-dumping municipal solid waste landfill (Salmi Landfill) which is located at the vicinity of Chungju Reservoir which flows into Paldang Reservoir that has been used for Seoul Metropolitan water supplies, the history and the surrounding characteristics of the landfill site were surveyed. In this study, waste and LFG samples obtained from landfill site were physically and chemically analyzed, and then the analysis results were evaluated on the basis of 'The Criteria of Landfill Waste Stabilization(CLWS)' that were promulgated by Korean Ministry of Environment. Based on LFG composition of Salmi landfill, $CH_4$ was as high as 68%. In CLWS regulation, the stabilization criteria of $CH_4$ should be lower than 5%, and the criteria of C/N ratio should also be lower than 1/10. The result showed that C/N ratio of landfilled waste ranged 17.4~24.7. From this results, it was concluded that the LFG and C/N ratio stabilization level of this landfill based on the CLWS were still actively proceeding.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.25-31
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• 2023

The purpose of this study is to increase the thermal efficiency of a landfill gas (LFG) power generation engine by capturing carbon dioxide (CO₂) from landfill gas (LFG) using monoethanolamine (MEA), which is widely used in the chemical CO₂ absorption process. Since the use of LFG as an energy source can be a means of reducing greenhouse gas emissions, MEA can be used to reduce CO₂ in LFG and increase the concentration of CH₄ to improve the efficiency of power generation. In this study, experiments were conducted to measure the solubility of CO₂ and CH₄ in MEA solution, increase the solubility under different conditions, and analyse the dissolution characteristics. It was found that the CO₂ absorption rate increased as the ratio of MEA to reaction gas increased. There is an optimum MEA concentration to maximise CO₂ solubility, and even if the concentration is increased above this concentration, the solubility does not improve significantly. This study provided fundamental work to develop a more practical fuel by capturing CO₂ from LFG and increasing the concentration of CH₄ while reducing greenhouse gas emissions.

• New & Renewable Energy
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• v.5 no.2
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• pp.15-24
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• 2009

As new small scale LFG (landfill gas) energy project model which can improve economic feasibility limited due to the economy of scale, LFG-Microturbine combined heat and power system with $CO_2$ fertilization into greenhouses was proposed and investigated including basic design process prior to the system installation at Gwang-ju metro sanitary landfill. The system features $CH_4$ enrichment for stable microturbine operation, reduction of compressor power consumption and low CO emission, and $CO_2$ supplement into greenhouse for enhancement plant growth. From many other researches, high $CO_2$ concentration was found to enhance $CO_2$ assimilation (also known as photosynthesis reaction) which converts $CO_2$ and $H_2O$ to sugar using light energy. For small scale landfills which produce LFG under $3\;m^3$/min, among currently available prime movers, microturbine is the most suitable power generation system and its low electric efficiency can be improved with heat recovery. Besides, since its exhaust gas contains very low level of harmful contaminants to plant growth such as NOx, CO and SOx, microturbine exhaust gas is a suitable and economically advantageous $CO_2$ source for $CO_2$ fertilization in greenhouse. The LFG-Microturbine combined heat and power generation system with $CO_2$ fertilization into greenhouse gas to enhance plant growth is technologically and economically feasible and improves economical feasibility compared to other small scale LFG energy project model.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.11a
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• pp.33-38
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• 2003