• Solar Energy
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• v.20 no.2
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• pp.75-84
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• 2000

Global wanning induced by greenhouse gases such as carbon dioxide is a serious problem for mankind. Carbon dioxide ocean disposal is one of the promising options to reduce carbon dioxide concentration in the atmosphere because the ocean has vast capacity for carbon dioxide sequestration. However, the dissolution rate of liquid carbon dioxide in seawater must be known in advance in order to estimate the amount of carbon dioxide sequestration in the ocean. Therefore, the solubility, the surface concentration, the droplet size and other factors of liquid carbon dioxide at various depths are calculated. The results show that liquid carbon dioxide changes to carbon dioxide bubble around 500 m in depth, and the droplet is completely dissolved below 500 m in depth if carbon dioxide droplet is released both at 1000 m in depth with the initial droplet diameter of 0.011 m or less and at 1500 m in depth with the diameter of 0.015 m or less. In addition, the hydrate film acts as a resistant layer for the dissolution of liquid carbon dioxide. The surface concentration of carbon dioxide droplet with the hydrate film is about 50% at 1500 m in depth and about 60% at 1000 m in depth of the carbon dioxide solubility. Also, the ambient carbon dioxide concentration in the plume is an another crucial parameter for complete dissolution at the intermediate ocean depth, and the injection of liquid carbon dioxide from a moving ship is more effective than that from a fixed pipeline.

• Journal of the Korea Institute of Building Construction
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• v.14 no.1
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• pp.68-75
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• 2014

In order to increase the integrity of the wellbore which is used to prevent the leakage of supercritical $CO_2$, it is necessary to develop a concrete that is strongly resistant to carbonation. In an environment where the concentration of $CO_2$ is exceptionally high, $Ca^{2+}$ ion concentration in pore solution of Portland cement concrete will drop significantly due to the rapid consumption of calcium hydroxide, which decreases the stability of the calcium silicate hydrate. In this research, calcium phosphates were used to modify Portland cement system in order to produce hydroxyapatite, a hydration product that is strongly resistant to carbonation under such an environment. According to the experimental results, calcium phosphates reacted with Portland cement to form hydroxyapatite. The formation of hydroxyapatite was verified using X-ray diffraction analyses with selective extraction techniques. When using dicalcium phosphate dihydrate and tricalcium phosphate, the 28-day compressive strength was lower than that of plain cement paste. However, the specimen with monocalcium phosphate monohydrate showed equivalent strength to that of plain cement paste.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.193-196
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• 2004

이산화탄소 저감 및 처리 기술개발 프로그램은 과학기술부에서 지원하고 있는 21세기 프론티어 사업 중 하나로, 2002년부터 2012년까지 연간 9백만 탄소 톤 상당의 이산화탄소 저감 및 처리기술개발과 개발기술의 상용화를 목표로 하고 있다. 동 프로그램의 주요 개발기술 분야는 고온순산소 연소기술, 반응분리 동시공정기술, 미활용에너지 이용기술, 이산화탄소 회수처리기술 등 4개 부문에 걸쳐 추진하고 있으며, 현재 1단계 2차년도 사업이 진행되고 있다. 동 프로그램의 목표는 단순한 기술개발에 머물지 않고 향후 실용화 가능성이 높은 과제를 선별하여 집중적인 투자와 함께 기술개발이 이루어지고 있으며 동 프로그램을 통해 이산화탄소 저감 기술 시장에서 우위를 확보하고 기술 이전 및 수출을 통해 연간 1.5조원의 경제적 효과와 함께 배출권 확보에 기여할 것으로 보고 있다. 본 논문에서는 기후변화에 관련된 온실가스 감축을 위해 추진되고 있는 이산화탄소 저감 및 처리기술의개발에 따른 성과제고를 위해 개발기술들을 대상으로 향후 발생될 여러 가지 영향요인(impact factor)을 발굴하고 이를토대로 결정론적 평가법 및 AHP기법을 이용한 분석평가를 수행하였다.

• Journal of Soil and Groundwater Environment
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• v.24 no.3
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• pp.24-35
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• 2019

It is known that ${\delta}^{13}C_{DIC}$ (carbon-13 isotope of dissolved inorganic carbonate (DIC) ions) of water increases when dissolved $CO_2$ degases. However, ${\delta}^{13}C_{DIC}$ could decrease when the pH of water is lower than 5.5 at the early stage of degassing. Laboratory experiments were performed to observe the changes of ${\delta}^{13}C_{DIC}$ as $CO_2$ degassed from three different artificial $CO_2$-rich waters (ACWs) in which the initial pH was 4.9, 5.4, and 6.4, respectively. The pH, alkalinity and ${\delta}^{13}C_{DIC}$ were measured until 240 hours after degassing began and those data were compared with kinetic isotope fractionation calculations. Furthermore, same experiment was conducted with the natural $CO_2$-rich water (pH 4.9) from Daepyeong, Sejong City. As a result of experiments, we could observe the decrease of DIC and increase of pH as the degassing progressed. ACW with an initial pH of 6.4, ${\delta}^{13}C_{DIC}$ kept increasing but, in cases where the initial pH was lower than 5.5, ${\delta}^{13}C_{DIC}$ decreased until 6 hours. After 6 hours ${\delta}^{13}C_{DIC}$ increased within all cases because the $CO_2$ degassing caused pH increase and subsequently the ratio of $HCO_3{^-}$ in solution. In the early stage of $CO_2$ degassing, the laboratory measurements were well matched with the calculations, but after about 48 hours, the experiment results were deviated from the calculations, probably due to the equilibrium interaction with the atmosphere and precipitation of carbonates. The result of this study may be not applicable to all natural environments because the pressure and $CO_2$ concentration in headspace of reaction vessels was not maintained constant as well as the temperature. Nevertheless, this study provides fundamental knowledge on the ${\delta}^{13}C_{DIC}$ evolution during $CO_2$ degassing, and therefore it can be utilized in the studies about carbonated water with low pH and the monitoring of geologic carbon sequestration.

• Journal of the Korean Wood Science and Technology
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• v.46 no.2
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• pp.202-210
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• 2018

This study was carried out to quantify degree of contribution of harvested wood product (HWP) on mitigation of climate change by valuation of public benefits, environmentally and economically. The potential carbon dioxide emission reduction of HWP was estimated by accounting carbon storage effect and substitution effect. Based on 2014 statistics of Korea Forest Service, domestic HWPs were sorted by two categories, such as wood products produced domestically from domestic and imported roundwood. The wood products were divided into seven items; sawnwood, plywood, particle board, fiberboard (MDF), paper (including pulp), biomass (wood pellet) and other products. The carbon stock of wood products and substitution effects during manufacturing process was evaluated by items. Based on the relevant carbon emission factor and life cycle analysis, the amount of carbon dioxide emission per unit volume on HWP was quantified. The amounts of carbon stock of HWP produced from domestic and from imported roundwood were 3.8 million $tCO_{2eq}$., and 2.6 million $tCO_{2eq}$., respectively. Also, each reduction of carbon emission by substitution effect of HWP produced from domestic and imported roundwood was 3.1 million $tCO_{2eq}$. and 2.1 million $tCO_{2eq}$., respectively. The results of this study, the amount of carbon emission reduction of HWP, can be effectively used as a basic data for promotion of wood utilization to revise and establish new wood utilization promotion policy such as 'forest carbon offset scheme', and 'carbon storage labeling system of HWP'.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.36-43
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• 2013

In order to asses gas production behavior for $CO_2$ ECBM, the sorption charcteristics on coal are considered to be a key factor. In this study, we have investigated the change of the sorption rate of adsorbed gas as a function of pressure and temperature below the appropriate depth for $CO_2$-ECBM. The experiment were carried out under four different temperatures varying from $15^{\circ}C$ to $45^{\circ}C$, while the coal pressure was varied from atmosphere to 1,400 psi for every temperature. From this results, the sorption rate both $CO_2$ and $CH_4$ increased with increasing the coal pressure. Otherwise, the sorption rate both $CH_4$ and $CO_2$ decreased linearly as the coal temperature increased. From the sensitivity studies on pressure and temperature change, it was experimentally identified that $CO_2$ sequestration rate and $CH_4$ production rate are better at deeper depths below a depth of 800 m in coal seams. However, the results showed continued decline in the increasing ratio of ECBM with formation depth.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.421-430
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• 2014

In this study, a series of autoclave experiments were conducted in order to investigate the geochemical and mineralogical effects of carbon dioxide on deep subsurface environments. High pressure and temperature conditions of $50^{\circ}C$ and 100 bar, which are representative environments for geological $CO_2$ sequestration, were created in stainless-steel autoclaves for simulating the interactions in the $scCO_2$-groundwater-mineral reaction system. Zeolite, a widespread mineral in Pohang Basin where many researches have been focused as a candidate for geological $CO_2$ sequestration, and groundwater sampled from an 800 m depth aquifer were applied in the experiments. Geochemical and mineralogical alterations after 30 days of $scCO_2$-groundwater-zeolite sample reactions were quantitatively examined by XRD, XRF, and ICP-OES investigations. The results suggested that dissolution of zeolite sample was enhanced under the acidic condition induced by dissolution of $scCO_2$. As the cation concentrations released from zeolite sample increase, $H^+$ in groundwater was consumed and pH increases up to 10.35 after 10 days of reaction. While cation concentrations showed increasing trends in groundwater due to dissolution of the zeolite sample, Si concentrations decreased due to precipitation of amorphous silicate, and Ca concentrations decreased due to cation exchange and re-precipitation of calcite. Through the reaction experiments, it was observed that introduction of $CO_2$ could make alterations in dissolution characteristics of minerals, chemical compositions and properties of groundwater, and mineral compositions of aquifer materials. Results also showed that geochemical reactions such as cation exchange or dissolution/precipitation of minerals could play an important role to affect physical and chemical characteristics of geologic formations and groundwater.

• Journal of the Mineralogical Society of Korea
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• v.28 no.1
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• pp.39-49
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• 2015

Recently, carbon capture and storage (CCS) techniques have been globally studied. This study was conducted to use waste cement powder as an efficient raw material of mineral carbonation for $CO_2$ sequestration. Direct aqueous carbonation experiment was conducted with injecting pure $CO_2$ gas (99.9%) to a reactor containing $200m{\ell}$ reacting solution and the pulverized cement paste (W:C = 6:4) having particle size less than 0.15 mm. The effects of two additives (NaCl, $MgCl_2$) in carbonation were analyzed. The characteristics of carbonate minerals and carbonation process according to the type of additives and pH change were carefully evaluated. pH of reacting solution was gradually decreased with injecting $CO_2$ gas. $Ca^{2+}$ ion concentration in $MgCl_2$ containing solution was continuously decreased. In none $MgCl_2$ solution, however, $Ca^{2+}$ ion concentration was increased again as pH decreased. This is probably due to the dissolution of newly formed carbonate mineral in low pH solution. XRD analysis indicates that calcite is dominant carbonate mineral in none $MgCl_2$ solution whereas aragonite is dominant in $MgCl_2$ containing solution. Unstable vaterite formed in early stage of experiment was transformed to well crystallized calcite with decreasing pH in the absence of $MgCl_2$ additives. In the presence of $MgCl_2$ additives, the content of aragonite was increased with decreasing pH whereas the content of calite was decreased.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.723-726
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• 2009

As a preliminary study of cost estimates for nuclear hydrogen systems, the hydrogen production costs of the nuclear energy sources benchmarking GT-MHR are estimated in the necessary input data on a Korean specific basis. G4-ECONS developed by EMWG of GIF in 2008 was appropriately modified to calculate the cost for hydrogen production of SI process with VHTR as a thermal energy source rather than the LUEC. The estimated costs presented in this paper show that hydrogen production by the VHTR could be competitive with current techniques of hydrogen production from fossil fuels if $CO_2$ capture and sequestration is required. Nuclear production of hydrogen would allow large-scale production of hydrogen at economic prices while avoiding the release of $CO_2$. Nuclear production of hydrogen could thus become the enabling technology for the hydrogen economy. The major factors that would affect the cost of hydrogen were also discussed.

• International Journal of Concrete Structures and Materials
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• v.10 no.1
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• pp.15-28
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• 2016

With the aim to reduce the atmospheric $CO_2$, utilization of the carbonated lime produced from the aqueous carbonation reaction for the synthesis of a cementitious material would be a promising approach. The present investigation deals with the aqueous carbonation of slaked lime, followed by hydrothermal synthesis of a cementitious material utilizing the carbonated lime, silica fume, and hydrated alumina. In this study, the aqueous carbonation reaction was performed under four different conditions. The TGA, FESEM, and XRD analysis of the carbonated product obtained from the four different reaction conditions was performed to evaluate the efficacy of the reaction conditions used for the production of the carbonated lime. Additionally, the performance of the cementitious material was verified analyzing the physical characteristics, mechanical property and setting time. Based on the results, it is demonstrated that the material produced by the hydrothermal method possesses the cementing ability. Additionally, it is revealed that the mortar prepared using the alternative cementitious material yields $33.8{\pm}1.3MPa$ compressive strength. Finally, a plausible reaction scheme has been proposed to explain the overall performances of the aqueous carbonation as well as the hydrothermal synthesis of the cementitious material.