• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.2
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• pp.93-100
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• 2013

Many researches have been carried out to reduce and/or to capture the major global warming gases. Especially, the hydrate formation mechanisms were intensively investigated for carbon dioxide sequestration and storage process applications. In this study, the characteristics of film-type crystal growth mechanism of carbon dioxide hydrate were comprehensively examined. Carbon dioxide hydrate crystal was formed in semi-batch type stir reactor at various pressure conditions while the temperature was fixed to be constant to reduce and minimize the guest gas solubility effects. A supply gas composition was 99.999 % of Carbon dioxide, the observation data was collected by optical microscope adopted CCD camera (Nikon DS-5M/Fi1/2M-U2). This study revealed that the guest gas pressure changes significantly altered the crystal growth mechanism and film growth rate of carbon dioxide hydrate crystal. The critical pressure of the carbon dioxide hydrate of crystal growth mechanism change was found to be 2.0 MPa. The capillary force and gas concentration gradient also significantly changed the film-type crystal growth mechanism of carbon dioxide hydrate crystal.

• Journal of Environmental Impact Assessment
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• v.26 no.2
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• pp.93-104
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• 2017

CCS (Carbon Capture and Storage) is a technical process to capture $CO_2$ from industrial and energy-based sources, to transfer and sequestrate impressed $CO_2$ in geological formations, oceans, or mineral carbonates. However, potential $CO_2$ leakage exists and causes environmental problems. Thus, this study was conducted to analyze the spatial and temporal variations of $CO_2$ fluxes and concentrations after artificial $CO_2$ release. The Environmental Impact Evaluation Test Facility (EIT) was built in Eumseong, Korea in 2015. Approximately 34kg $CO_2$ /day/zone were injected at Zones 2, 3, and 4 among the total of 5 zones from October 26 to 30, 2015. $CO_2$ fluxes were measured every 30 minutes at the surface at 0m, 1.5m, 2.5m, and 10m from the $CO_2$ releasing well using LI-8100A until November 13, 2015, and $CO_2$ concentrations were measured once a day at 15cm, 30cm, and 60cm depths at every 0m, 1.5m, 2.5m, 5m, and 10m from the well using GA5000 until November 28, 2015. $CO_2$ flux at 0m from the well started increasing on the fifth day after $CO_2$ release started, and continued to increase until November 13 even though the artificial $CO_2$ release stopped. $CO_2$ fluxes measured at 2.5m, 5.0m, and 10m from the well were not significantly different with each other. On the other hand, soil $CO_2$ concentration was shown as 38.4% at 60cm depth at 0m from the well in Zone 3 on the next day after $CO_2$ release started. Soil $CO_2$ was horizontally spreaded overtime, and detected up to 5m away from the well in all zones until $CO_2$ release stopped. Also, soil $CO_2$ concentrations at 30cm and 60cm depths at 0m from the well were measured similarly as $50.6{\pm}25.4%$ and $55.3{\pm}25.6%$, respectively, followed by 30cm depth ($31.3{\pm}17.2%$) which was significantly lower than those measured at the other depths on the final day of $CO_2$ release period. Soil $CO_2$ concentrations at all depths in all zones were gradually decreased for about 1 month after $CO_2$ release stopped, but still higher than those of the first day after $CO_2$ release stared. In conclusion, the closer the distance from the well and the deeper the depth, the higher $CO_2$ fluxes and concentrations occurred. Also, long-term monitoring should be required because the leaked $CO_2$ gas can remains in the soil for a long time even if the leakage stopped.

• Journal of Ocean Engineering and Technology
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• v.25 no.4
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• pp.54-58
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• 2011

The need and importance of developing and utilizing the oceans, not only as sources of renewable energy and mineral resources, but also as countermeasures to global warming such as for CCS (carbon capture and storage), have continued to increase, especially in countries with limited land areas and resources. Therefore, it is necessary to assess the sustainability of an ocean utilization technology or system not only from an economic point of view but also from an ecological one. For this purpose, it might be effective to develop a comprehensive evaluation method and/or index, by which the assessment of and decisions about a technology and system can be made more objectively. It would also be useful to have an environmental simulation model, which was developed and reported in a previous research. The aim of this study was to modify a reasonable and quantitative index, with which a comprehensive evaluation system can be established, to assess environmental sustainability and risk.

• Journal of the Korean Society of Combustion
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• v.15 no.2
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• pp.1-11
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• 2010

Power generation systems based on the oxy-coal combustion with carbon dioxide capture and storage (CCS) capability are being proposed and discussed lately. Although a large number of lab scale studies for oxy-coal power plant have been made, studies of pilot scale or commercial scale power plant are not enough. Only a few demonstration projects for oxy-coal power plant are publicized recently. The proposed systems are evolving and various alternatives are to be comparatively evaluated. This paper presents a proposed approach for performance evaluation of a commercial 100 MWe class power plant, which is currently being considered for 'retrofitting' for the demonstration of the concept. The system is configurated based on design and operating conditions with proper assumptions. System components to be included in the discussion are listed. Evaluation criteria in terms of performance are summarized based on the system heat and mass balance and simple performance parameters, such as the fuel to power efficiency and brief introduction of the second law analysis. Also, gas composition is identified for additional analysis to impurities in the system including the purity of oxygen and unwanted gaseous components of nitrogen, argon and oxygen in air separation unit and $CO_2$ processing unit.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.499-506
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• 2015

Recently the Korean government announced its decision to select the $3^{rd}$ proposal, which targets reducing $CO_2$ by 37% of the BAU level by 2030, for the Intended Nationally Determined Contribution (INDC). According to this proposal, natural gas (or equivalent gas) combined cycle (NGCC) are suggested as alternatives for conventional pulverized coal (PC). In this study, we analyzed the environmental, economic, and energy mixing aspects of synthetic natural gas combined cycle(SNGCC) using NETL material (2011~2012 version) and other domestic materials (2014 version). We found the following conclusions: 1) Considering carbon capture and storage (CCS) integration, $CO_2$ emission factors of SNGCC and supercritical PC are the same. However, 60% of $CO_2$ from SNGCC is produced as high pressure and high purity (99%) gas, making it highly suitable for CCS, which is now strongly supported by the government. 2) Based on the economic analysis for SNGCC using domestic materials and comparison with NGCC, it was found that the settlement price of SNGCC was 30% lower than that of NGCC.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2940-2945
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• 2008

The scale of 2.4 MW MCFC was taken to construct a high-efficiency and economical power generation system without CO2 emission into the atmosphere for utilizing its exhaust gas. The conventional steam turbine power generation system (STGS) was evaluated and the net generated power (NGP) was estimated to be only 133 kW and the STGS is not economically feasible. A CO2-caputuring repowering system was proposed, where low temperature steam (LTS) produced at HRSG by using exhaust gas from MCFC is utilized as a main working fluid of a gas turbine, and the temperature of LTS was raised by combusting fuel in a combustor by using pure oxygen, not the air. It has been shown that NGP of the proposed system is 264 kW, and CO2 reduction amount is 608 t-CO2/y, compared to 306 t-CO2/y of STGS. The CO2 reduction cost was estimated to be negligible small, even when the costs of oxygen production and CO2 liquefaction facilities etc. were taken into account.

• Journal of the Korean Ceramic Society
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• v.49 no.2
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• pp.185-190
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• 2012

The purpose of this study was to examine a possibility that fly ash could be used as raw material for carbonation by conducting the experiment on magnetic separation and hydration of fly ash that contained a large amount of CaO composite. Wet magnetic separation experiment was performed to remove the component of magnetic substance that contained fly ash, which aimed at increasing the content of CaO in the non-magnetic domain. The selected fly ash was used for hydration experiment before the TG-DTA, XRF and XRD analyses were made to confirm the Ca component that could be carbonated. Then, the fly ash was turned to a hydrate that was favorable to dissociation of $Ca^{2+}$ ion. As a result, the magnetic separation enabled detecting the content of CaO component by up to 61 wt% in the non-magnetic domain. Since the hydrate was confirmed, it is believed that the fly ash can be used as raw material for carbonation.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.69-76
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• 2021

This study is to identify the mineralogical properties of caprock samples from drilling cores of the Pohang basin, which is the research area for the demonstration-scale CO2 storage project in Korea. The interaction of water-rock-gas that can occur due to CO2 injection was identified using geochemical modeling. Results of mineralogical studies, together with petrographic data of caprock and data on the physicochemical parameters of pore water were used for geochemical modeling. Modelling was carried out using the The Geochemist's Workbench 14.0.1 geochemical simulator. Two steps of modeling enabled prediction of immediate changes in the caprocks impacted by the first stage of CO2 injection and the assessment of long-term effects of sequestration. Results of minerlaogical analysis showed that the caprock samples are mainly composed of quartz, K-feldspar, plagioclase and a small amount of pyrite, calcite, kaolinite and montmollonite. After the injection of carbon dioxide, the porosity of the caprock increased due to the dissolution of calcite, and dawsonite and chalcedony were precipitated as a result of the dissolution of albite and k-feldspar. In the second step after the injection was completed, the precipitation of dawsonite and chalcedony occurred as a result of dissolution of calcite and albite, and the pH was increased due to this reaction. Results of these studies are expected to be used as data to quantitatively evaluate the efficiency of mineral trapping capture in long-term storage of carbon dioxide.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.226-233
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• 2023

In this study, two phases were conducted to investigate the direct injection of gaseous CO₂ into cement mortar. The aim was to advance carbon capture, utilization, and storage (CCUS) technology by harnessing industrial waste CO₂ from the domestic ready-mixed concrete industry. In the first phase, the factors influencing the physical properties of cement mortar when using gaseous CO₂ were identified. This included a review of materials to achieve physical properties comparable to a reference formulation. As a result of this phase, it was confirmed that traditional approaches, such as adjusting the water-to-cement ratio, had limitations in achieving the desired physical properties. Consequently, the second phase focused on the optimization of CO₂-injected mortar. This involved studying the CO₂ application and mixing method for cement mortar. Changes in properties were observed when gaseous CO₂ was injected into the mortar. The optimal injection quantity and time to enhance the compressive strength of mortar were determinded. As a result, this study indicated that an extra mixing time exceeding 120 seconds was necessary, compared to conventional mortar. The optimal CO₂ injection rate was identified as 0.1 to 0.2 % by weight of cement, taking both flowability and compressive strength performance into account. Increasing the CO₂ injection time did not further enhance strength. For this approach to be employed as a CCUS technology, additional studies are required, including a microstructural analysis evaluating the amount of immobilized CO₂.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.121-127
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• 2010

The in-furnace desulfurization technique is applied to the $O_2/CO_2$ combustion system for the carbon capture and storage (CCS) process because this combustion system does not need an additional chamber for the desulfurization. $CaCO_3$ sorbent particles, which have a wide range in size from a few nanometers to several tens of micrometers, are used for this process. In this study, an experimental system which can simulate the $O_2/CO_2$ combustion system was developed. $CaCO_3$ sorbent particles were exposed to the high temperature reactor at $1200^{\circ}C$ with various residence times (0.33-1.46 s) in air and $CO_2$ atmospheric conditions, respectively. The sorbent particles were then sampled at the inlet and outlet of the reactor and analyzed qualitatively/quantitatively using SMPS, XRD, TGA, and SEM. The results showed that the residence time and atmospheric condition in a high temperature reactor can affect the characteristics of the $CaCO_3$ sorbent particles used in the in-furnace desulfurization technique, such as the calcination rate and reaction mechanism.