• 한국재료학회지
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• 제16권3호
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• pp.193-197
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• 2006

The sodium/sulfur(Na/S) battery has many advantages such as high theoretical specific energy(760Wh/kg), and low material cost based on the abundance of electrode material in the earth. It has been reported that the electrochemical properties of sodium/sulfur cell above $300^{\circ}C$, utilized a solid ceramic electrolyte and liquid sodium and sulfur electrodes. A lot of researches have been performed in this field. Recently, Na/S battery system was applied for electricity storage system for load-leveling. One of severe problems of sodium/sulfur battery was high operating temperature above $300^{\circ}C$, which could induce the explosion and corrosion by molten sodium, sulfur and polysulfides. In order to develop sodium battery operated at low temperature, sodium ion battery has been studied using carbon anode, and sodium oxides cathodes. However, the energy densities of the sodium ion batteries were much lower than high temperature sodium/sulfur cell. In this study, the sodium/sulfur battery with 1M $NaCF_3SO_3$ is tested at room temperature. The charge-discharge mechanism was discussed based on XRD, DSC, SEM and EDS results.

• Ocean and Polar Research
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• 제27권4호
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• pp.451-461
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• 2005

The $CO_2$ storage in geologic and oceanic reservoirs is considered to be one of the carbon management strategies for responding to global climate change. Ocean carbon sequestration is purposeful storage acceleration into the ocean of large amounts of carbon that would accumulate in the atmosphere and naturally enter the ocean over a longer timespan. Some technologies for $CO_2$ ocean sequestrations have been developed as a nation project. However, $CO_2$ ocean sequestrations are attractive because they have the advantage of vast capacity sequestration far away from industrial areas, and offer easier monitoring whereas less economic advantage has been indicated as one of the key barriers compared with $CO_2$ geosphere sequestration, which is produced as a byproduct. In this paper, a conceptual design for $CO_2$ ocean sequestration is introduced, and the preliminary examination is described. As a result, the $CO_2$ price, US$ 24/t shows far away from the economics. The causes come from the expensive $CO_2$ recovery cost and the low $CO_2$ price. The expensive $CO_2$ recovery cost is because too much electricity and water are consumed. In order to look for an economic balance point for $CO_2$ ocean sequestration, NPV=0, it is increases the $CO_2$ price. Finally 60.4$ per ton is found to be the balance price.

• 한국조경학회지
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• 제45권5호
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• pp.97-104
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• 2017

적합한 조경식재를 통한 녹지 확충은 저탄소 사회를 구현하는데 필수적 역할이다. 본 연구는 주요 조경수종의 수령에 따른 줄기 직경 생장률, 지하부/지상부 생체량비 및 탄소흡수량의 변화를 분석하였다. 연구대상 수목은 중부지방에 식재된 11개 수종 및 112개체이었다. 줄기 직경 생장률과 지하부/지상부 생체량비는 근굴취를 포함한 직접수확법을 통해 측정한 자료를 바탕으로 분석하였다. 수령에 따른 탄소흡수량 변화는 유도한 계량모델을 적용하여 산정하였다. 연구대상 수목의 수령 30년에 걸친 연간 흉고직경 생장률은 낙엽수 평균 0.72cm/년 및 상록수 0.83cm/년이었다. 수령 전체의 지하부/지상부 생체량비는 낙엽수 평균 0.40 및 상록수 0.23으로서, 낙엽수의 뿌리 생체량은 상록수보다 약 1.7배 많았다. 수령별 그 생체량비는 수령 증가에 따라 감소한다는 기존 연구 결과와 상이하였다. 수령 25년까지의 누적 탄소흡수량은 느티나무가 198.3kg으로서 가장 많았고, 이어서 왕벚나무 121.7kg, 잣나무 117.5kg, 소나무 77.4kg 등의 순이었다. 느티나무의 누적 탄소흡수량은 동일 기간 가정용 전력소비에 따른 1인당 탄소배출량의 약 5%를 상쇄하는 셈이었다. 연구대상 조경수의 생장률과 탄소흡수능은 동일 수종의 산림수목보다 훨씬 양호하였다. 연구 결과에 근거하여, 수종 선정, 식재밀도, 생장지반 조성 등을 포함하여 탄소흡수를 증진하기 위한 조경식재 및 관리방안을 모색하였다. 본 연구는 수령에 따른 조경수의 생장 및 탄소흡수 변화를 구명하는 초석 연구로서 저탄소 도시녹지 조성에 유용하길 기대한다.

• 전기학회논문지
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• 제64권5호
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• pp.667-679
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• 2015

The bearer of the power sector's ETS compliance cost is power consumer for the following reasons. Firstly, power companies are constrained in establishing appropriate strategies to comply with ETS regulations due to the structural differences between the domestic power market and emission trading system. In other words, because power companies do not have a right to determine price and production of electricity, they have to compete with other companies under disadvantaged conditions in the emission trading market. Secondly, because ETS compliance cost is part of power production costs as it is also clearly written in the national greenhouse gas reduction road-map and the second energy supply plan, the cost should be included in power price following the power market operation rule. Thirdly, the most effective method to reduce carbon emissions in power sector is to reduce power demand, which is efficiently achieved through raising power price to a realistic level. Low power price in Korea is the major cause of rising power demand which is also the major cause of rising GHG emission. Therefore, power sector's ETS compliance cost should be included in power price to encourage power consumers' actions on reducing power consumption. Fourthly, when externality cost occurs in the process of delivering public services, usually beneficiary pay principle is applied to identify the cost bearer. Since electricity is one representative public good, the bearer of power sector's ETS compliance cost is power consumer.

• 자원ㆍ환경경제연구
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• 제31권3호
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• pp.393-417
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• 2022

전력시장 도매가격인 전력계통한계가격(System Marginal Price, SMP)의 급등락은 발전 사업자들의 재생에너지 및 기존 신규 발전설비에 대한 투자 결정을 변경하거나 지연시켜 에너지 정책 실현에 부정적인 영향을 미칠 수 있다. 이 연구는 2016~2020년 시간별 데이터를 활용하여 우리나라 SMP 주간 실현 변동성을 측정하고 결정요인을 파악함으로써 SMP 급등락 현상에 대한 정보 제공을 목적으로 한다. 국면전환(regime-switching)을 베이지안 변수선택(Bayesian stochastic selection) 모형에 적용하여 추정한 결과, SMP 고변동·저변동 국면 모두에서 기저 발전인 석탄 및 원자력 발전과 재생에너지인 태양광 발전의 증가는 SMP 변동성을 심화시키고, 가스발전량과 LNG 가격 변화는 고변동 국면에서만 SMP 변동성을 감소시키는 것으로 나타났다. 이러한 결과는 탄소 중립이나 에너지 전환 정책에 따른 재생에너지의 점진적인 확대가 SMP 변동성을 확대할 수 있지만, 재생에너지의 간헐성을 보완하기 위한 가스발전의 증가나 탄소 중립을 위한 석탄발전 감축은 SMP 변동성 증가를 상쇄시키는 역할을 할 수 있음을 시사한다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.227-234
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• 2004

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.

• 디지털융복합연구
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• 제11권4호
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• pp.279-284
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• 2013

지구환경 개선을 위한 저탄소 배출 및 그린에너지에 관심이 높아지고 있으며, 이를 이루기 위한 기존의 전력망에 IT기술을 결합하여 보다 효율적이고 친환경적인 지능형 전력망을 이루는 스마트 그리드 사업이 전 세계적으로 활발히 전개되고 있다. 스마트 그리드는 양방향 디지털 기술을 사용하여 공급 업체와 소비자 사이에 전기를 제공하며, 소비자 집에 있는 지능형 가전이나, 에너지 절약 비용을 절감하고 안정성, 효율성 및 투명성을 높이기 위해 필요하며, 앞으로 지속적으로 발전될 것을 예상한다. 하지만, 스마트 그리드를 구축하기 위해서 반드시 선행되어야 하는 사항인 보안 모델을 구축하여 지능형 전력망을 안전하고 효율적으로 사용되도록 구축하는 방안을 제시하는 연구이다.

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.350-358
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• 2017

Recently, owing to increased interest in low-carbon energy supplies, renewable energy sources such as photovoltaics and wind turbines in distribution networks have received considerable attention for generating clean and unlimited energy. The presence of energy storage systems (ESSs) in the promising field of active distribution networks (ADNs) would have direct impact on power system problems such as encountered in probabilistic distributed generation (DG) model studies. Hence, the optimal procedure is offered herein, in which the simultaneous placement of an ESS, photovoltaic-based DG, and wind turbine-based DG in an ADN is taken into account. The main goal of this paper is to maximize the net present value of the loss reduction benefit by considering the price of electricity for each load state. The proposed framework consists of a scenario tree method for covering the existing uncertainties in the distribution network's load demand as well as DG. The collected results verify the considerable effect of concurrent installation of probabilistic DG models and an ESS in defining the optimum site of DG and the ESS and they demonstrate that the optimum operation of an ESS in the ADN is consequently related to the highest value of the loss reduction benefit in long-term planning as well. The results obtained are encouraging.

• 한국분무공학회지
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• 제15권4호
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• pp.195-201
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• 2010

Due to its carbon-neutral nature, biogas generated from anaerobic digestion or fermentation of biodegradable wastes is one of the important renewable energy sources to reduce global warming. It is mainly composed of methane and various inert gases such as $CO_2$ and $N_2$, and the actual composition of biogas significantly varies depending on the origin of anaerobic digestion process. Therefore, in order to effectively utilize this fuel as an energy source for electricity, it is important to develop power generation engines which can successfully apply biogas with significant composition variations. In this study, efforts have been made to develop a diesel-biogas duel fuel engine as a way to achieve such a stable power generation. The effects of diesel fuel injection quantity and pressure on stable combustion and engine performance were investigated, and an impact of diesel fuel atomization was discussed. The engine test results show that there exists a 2 stage combustion which consists of diesel pilot fuel burning and premixed biogas/air mixture burning in dual fuel engine operation and optimum diesel injection parameters were suggested for biogases with various compositions and heating values.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.458-458
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• 2022

It is essential to reduce global carbon emissions, mainly from energy use. The water supply and distribution sector is a vital part of human society and is one of the primary energy consumers. The procurement and distribution of water require electricity to operate the pump to deliver water to users with sufficient pressure. As the water users are spatially distributed over a wide area, the energy required to deliver water to each user differs depending on the corresponding supplying element (reservoir, tank, pipe, pump, and valve). This difference in energy required for each user also comes with a difference in pressure availability which affects the level of service for individual users and the whole network. Typically, there is a disproportion where users close to the source experience excessively high pressure with low energy consumption. In contrast, remote users need more energy to get the minimum pressure. This study proposes the Energy Return Index (ERI) to quantify the pressure return from particular energy consumption to supply water to each node. The disproportionality can be quantified and identified in the network using the proposed ERI. The index can be applied to optimize the network elements such as pump operation and tank location/size to reach a balanced energy consumption with the appropriate level of service.