• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.871-877
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• 2018

Storing the surplus energy from renewable energy resource is one of the challenges related to intermittent and fluctuating nature of renewable energy electricity production. $CO_2$ methanation is well known reaction that as a renewable energy storage system. $CO_2$ methanation requires a catalyst to be active at relatively low temperatures ($250-500^{\circ}C$) and selectivity towards methane. In this study, the catalytic performance test was conducted using a pressurized bubbling fluidized bed reactor (Diameter: 0.025 m and Height: 0.35 m) with $Ni/{\gamma}-Al_2O_3$ (Ni70%, and ${\gamma}-Al_2O_3$30%) catalyst. The range of the reaction conditions were $H_2/CO_2$ mole ratio range of 4.0-6.0, temperature of $300-420^{\circ}C$, pressure of 1-9 bar, and gas velocity ($U_0/U_{mf}$) of 1-5. As the $H_2/CO_2$ mole ratio, temperature and pressure increased, $CO_2$ conversion increases at the experimental temperature range. However, $CO_2$ conversion decreases with increasing gas velocity due to poor mixing characteristics in the fluidized bed. The maximum $CO_2$ conversion of 99.6% was obtained with the operating condition as follows; $H_2/CO_2$ ratio of 5, temperature of $400^{\circ}C$, pressure of 9 bar, and $U_0/U_{mf}$ of 1.4-3.

• Journal of Navigation and Port Research
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• v.37 no.1
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• pp.79-84
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• 2013

For the diversity of energy supply system and the improvement in the habitants' living environments of the islands, it is possible and necessary to use the natural energy as resources of the electric power generation system. In this study, the characteristics of wind and solar radiation on 4 islands offshore Namhae-Tongyoung of Korea were measured for one year from November 2010 to October 2011 and analyzed in relation to energy resources survey. As a result of measurement and analysis, the respective wind rose diagrams of 4 islands were made, and showed that the frequencies of wind directions were quite different from among the islands. The Rayleigh probability distribution of wind velocity showed that the wind speeds of KR and SS were mainly 2~5m/s, and the respective quantities of electric power generation of 4 islands were shown to be different. The variation of solar radiations and potential quantity of those uses were measured to be similar to each other among 4 islands.

• Environmental and Resource Economics Review
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• v.31 no.4
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• pp.645-668
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• 2022

Hydrogen energy is emerging as an important means of carbon neutrality in the various sectors including power, transportation, storage, and industrial processes. Fuel cell power plants are the fastest spreading in the hydrogen ecosystem and are one of the key power sources among means of implementing carbon neutrality in 2050. However, high volatility in system marginal price (SMP) and renewable energy certificate (REC) prices, which affect the profits of fuel cell power plants, delay the investment timing and deployment. This study applied the real option methodology to analyze how the dual uncertainties in both SMP and REC prices affect the investment trigger price level in the irreversible investment decision of fuel cell power plants. The analysis is summarized into the following three. First, under the current Renewable Portfolio Standard (RPS), dual price uncertainties passed on to plant owners has significantly increased the investment trigger price relative to one under the deterministic price case. Second, reducing the volatility of REC price by half of the current level caused a significant drop in investment trigger prices and its investment trigger price is similar to one caused by offering one additional REC multiplier. Third, investment trigger price based on gray hydrogen and green hydrogen were analyzed along with the existing byproduct hydrogen-based fuel cells, and in the case of gray hydrogen, economic feasibility were narrowed significantly with green hydrogen when carbon costs were applied. The results of this study suggest that the current RPS system works as an obstacle to the deployment of fuel cell power plants, and policy that provides more stable revenue to plants is needed to build a more cost-effective and stable hydrogen ecosystem.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1353-1362
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• 2014

In recent years, numerous environmental problems associated with the excessive use of fossil fuel are taking place. For an alternative energy resource, the importance of renewable energy and the demands of facilities to generate renewable energy are continuously rising. To satisfy such demands, a large number of photovoltaic energy generation structures are constructed and planned with large scale. However, because these facility zones are mostly constructed on land, some troubles are occurred such as rising of construction cost due to the cost of land use, environmental devastation, etc. To solve such problems, the floating type photovoltaic energy generation system using FRP members have been developed in Korea. FRP members are recently available in civil engineering applications due to many advantages such as high strength, corrosion resistance, light weight, etc. and they are suitable to fabricate the floating structures because of their material properties. In this study, the analytical and experimental investigations to evaluate the structural performance of floating PV generation structure and SMC FRP vertical member which is used to fabricate the structure were conducted. The static and dynamic performances of floating PV generation structure are evaluated through the FE analysis and the experiment, respectively. Moreover, the structural safety evaluation and buckling analysis of SMC FRP vertical compression member are also conducted by the FE analysis, and the structural behavior of SMC FRP member under compression and pullout is investigated by the experiments. From this study, it was found that the structural system composed of pultruded FRP and SMC FRP members are safe enough to resist externally applied loads.

• Clean Technology
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• v.26 no.4
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• pp.239-250
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• 2020

Biomass is an abundant renewable energy resource that can replace fossil fuels for the reduction of greenhouse gas (GHG). Indonesia has a large number of cheap biomass feedstocks, such as reforestation (waste wood) and palm residues (empty fruit bunch or EFB). In general, raw biomass contains more than 20% moisture and lacks calorific value, energy density, grindability, and combustion efficiency. Those properties are not acceptable fuel attributes as the conditions currently stand. Recently, torrefaction facilities, especially in European countries, have been built to upgrade raw biomass to solid fuel with high quality. In Korea, there is no significant market for torrefied solid fuel (co-firing) made of biomass residues, and only the wood pellet market presently thrives (~ 2 million ton yr-1). However, increasing demand for an upgraded solid fuel exists. In Indonesia, torrefied woody residues as co-firing fuel are economically feasible under the governmental promotion of renewable energy such as in feed-in-tariff (FIT). EFB, one of the chief palm residues, could replace coal in cement kiln when the emission trading system (ETS) and clean development mechanism (CDM) system are implemented. However, technical issues such as slagging (alkali metal) and corrosion (chlorine) should be addressed to utilize torrefied EFB at a pulverized coal boiler.

• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.439-449
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• 2014

RPS (Renewable Portfolio Standard) has increased wood pellet demand dramatically in recent years in Korea where self-supply rate of wood pellet is not more than 10%. However global production capacity of wood pellet is prospected to be unable to meet the global demand after 2020. Therefore it is urgently needed to develop new sustainable biomass energy resources which can replace wood pellet at lower cost. As a result of this study EFB (empty fruit bunch) and MF (mesocarp fiber), the representative solid palm biomass, are estimated to be generated at the rate of 20 and 28 million tons per year (based on 10% moisture content) in Malaysia and Indonesia, respectively in 2012. Total annual generation rate of EFB and MF is estimated as 48 million tons per year only in Malaysia and Indonesia in 2012. With calorific value of over 90% of wood pellet EFB is expected to be a excellent biomass energy resource which can replace wood pellet. EFB can be utilized as fuel for power generation or industrial purpose. However EFB may not be a proper fuel for domestic and greenhouse heating because of its high ash content.

• Journal of the Korean Solar Energy Society
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• v.23 no.2
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• pp.21-34
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• 2003

This study aims to present the applicability of wind turbine generator system to urban buildings for the utilization of clean renewable energy. The results are as follows; According to the wind resource analysis, it has been found that small sized wind power system can be viable for buildings application due to the amplification of wind velocity around buildings or building clusters, in spite of low mean velocity of 2-3m/s in Seoul and Kyunggi urban areas. But planners must perform micrositing analysis around building so that wind turbine can be located at high velocity zones. The system must be designed to avoid obstacles preventing prevailing wind in buildings. It should be recognized that wind speeds are changing depending on the height and length from buildings. The wind power system can be used as a symbol of landmark which shows a sustainable architecture from the scenary Itself A case study for apartment building in urban showed that wind power systems can be applicable in two kinds of place, rooftops and ground levels. Especially, the wind power systems must be carefully positioned so that wind resources do not decrease when it is installed at ground levels. and according to life cycle cost analysis, adaption of new small win4 power systems to buildings were proved to produce a profit if it is considered the expense of environment improvement and the wind speed increasing according to rise of building height. This research will ultimately achieve green architecture that preserves nature and at the same time provides pleasant environment to humans, and will play a great role in establishing the environment-preserving sustainable architecture of the 21th century.

• Journal of Climate Change Research
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• v.4 no.3
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• pp.279-290
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• 2013

This study aims to suggest the direction of urban planning for coping with climate change focusing on urban metabolism. The study consists of two main parts: literature review and case study. The cases are selected for mixed-use housing estate in Europe, which established the plans for energy saving and efficient use of resources and waste. The case study was carried out in accordance with the framework, which had four aspects that are 'to minimize energy input,' 'to use renewable energy sources,' 'to recycle waste,' and 'to reuse natural resources.' As a result, in all the cases, analysis showed that the circular metabolism system was built for energy, waste and water resources and that the plan satisfying all the aspects of the framework was established. Moreover, main planning elements are different reflecting resource conditions for each case. In conclusion, in order to achieve urban metabolism, it will be necessary to analyze various conditions including the surrounding environment of the region and to introduce planning elements that can maximize the regional potential.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.69-72
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• 2022

This paper actually investigates the load on major large-scale buildings in the downtown area, examines the economic feasibility of installing PV and ESS in a microgrid target building, and evaluates whether an electric vehicle capable of V2G through two buildings is effective as an economical analysis program (HOMER) was analyzed using. It is economical to install a mixture of ESS rather than using the whole PV, and it is shown that if there is an electric vehicle using the V2G function of EV, there is an economic effect to replace the PV. So that Incentives and policies are needed to replace a large area of PV and utilize the existing parking lot to lead EV as a resource of the microgrid. Currently, P2X technology that stores power as ESS or converts it to other energy to control when surplus renewable energy occurs in large-capacity solar power plants and wind farms, etc. This is being applied, and efforts are being made to maintain the stability of the system through the management of surplus power, such as replacing thermal energy through a heat pump. Due to the increase in electric vehicles, which were recognized only as a means of transportation, technologies for using electric vehicles are developing. Accordingly, existing gas stations do not only supply traditional chemical fuels, but electricity, and super stations that also produce electricity have appeared. Super Station is a new concept power plant that can produce and store electricity using solar power, ESS, V2G, and P2G. To take advantage of this, research on an urban microgrid that forms an independent system by tying a large building and several buildings together and supplies power through a super station around the microgrid is in full swing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.401-408
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• 2021

Supplies of wood chips for fuel tend to increase owing to energy decentralization and new renewable energy policies. This study suggests a technical method that is necessary in order to supply heating energy to rural regions by using wood chips for fuel. Therefore, this study investigates the effects of natural drying methods for eight months by installing a drying facility with natural ventilation capable of loading 10 tons of wood chips, and which derive a natural drying method based on this to meet the quality standards of wood chips for fuel. The study results confirm that it is possible to produce wood chips for high-quality fuel with water content at 20% or less after around 90 days of drying, provided that a drying facility with natural ventilation is equipped with materials that can be procured easily in rural regions. It is also possible to block the proliferation and fermentation of molds that affect the quality of wood chips, provided that intake and exhaust systems adhering to standards are equipped.