• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.1
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• pp.57-63
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• 2011

Development of alternative energy is needed as the fossil is started to be exhausted. This alternative energy should be environmental friendly and renewable. Currently, the alternative energy which gets the most attraction is hydrogen. Hydrogen can be produced by a number of different processes. Among those methods, hydrogen production in biological way is considered as the most environmental friendly method. However, productivity of biological hydrogen production is not good enough to be commercialized yet. Thus, many researchers are trying to improve productivity and yield of biohydrogen production. Here, progress in the diverse developmental approaches on biological hydrogen production, is reviewed.

• Journal of Forest and Environmental Science
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• v.36 no.4
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• pp.298-310
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• 2020

Fuel management can play enormous role in fire management in tropical dry forests. However, unlike the temperate forests, knowledge on implications of different fuel management methods in tropical forests is often inadequate. In this study, the implications of prescribed burning and hand thinning treatments on implementation cost, fuel loading and post-treatment fire behaviour were tested and compared in degraded forests and teak plantations in two forest reserves of different levels of dryness in Ghana. The study found that prescribed burning was less expensive (62.02 US Dollars ha-1) than hand thinning (95.37 US Dollars ha-1). The study also indicated that the two fuel management methods were able to reduce fuel loading in degraded forests and teak plantations. However, prescribed burning was more effective in reducing fuel loading than hand thinning. While the relative change of fuel reduction was 13% higher in prescribed burning than the hand thinning in degraded forest, it was 41% higher in prescribed burning than hand thinning in teak plantations. The fire behaviour of post-treatment experimental fire was also lower in prescribed burning than the hand thinning and control plots. Fuel management, therefore, has a great potential in fire management in degraded forests and teak plantations in Ghana.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.151-151
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• 2021

The alarming climate change impacts are demanding the use of renewable energy sources like never before. Hydropower is one of the most cost-effective and environmental friendly energy technology recognized in the world. Big hydropower projects come up with the requirements of huge investment costs along with environmental impacts, whereas small hydropower(SHP) are considered a best solution for the economical source of energy. SHP, basically Run-of-River (RoR) type plants can be sustainable renewable energy sources and given the nature of perennial rivers flowing from steep gradient and rugged topography, feasibility of such plants is equally high in Nepal. The objective of this study is to determine the primary potential sites for the development of RoR type SHP sites using Geo-spatial Information System(GSIS). The use of GSIS enables precise survey of large area within a short period of time. This study has focused on the determination of locations by establishing defined criterions and methodologies and hence have located multiple locations rather than selecting one best location. The approach is applicable for the rapid initial screening of potential locations and results can facilitate detail feasibility study for the technical and economic analysis of SHP in the basin.

• New & Renewable Energy
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• v.19 no.4
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• pp.2-10
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• 2023

The current mandatory domestic biodiesel blending ratio is 3.5%, which is planned to be gradually increased to achieve carbon neutrality by 2050. The aim of this study was to improve domestic self-sufficiency in biodiesel raw oil by conducting a technical review on the possibility of utilizing waste oils, such as soup oil, chicken oil, and leather oil, as biodiesel feedstocks. These waste oils have an acid value that is too high to be converted directly into biodiesel. Therefore, a pretreatment to reduce the acid value is necessary. The neutralization process was examined as a potential technology for reducing the acid value. The oil recovery rate of the soup oil after neutralization was significantly low at 37.6 wt%. The oil recovery rates of leather oil and chicken oil were 66.49 wt% and 79.08 wt%, respectively. Based on biodiesel conversion experiment using waste oil with a reduced acid value, the conversions were analyzed as 89 wt%, 91.1 wt%, and 90.5 wt% for soup oil, leather oil, and chicken oil, respectively. Thus, it is technically possible to use soup oil, leather oil, and chicken oil as raw materials for producing biodiesel.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.3
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• pp.231-257
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• 2016

Several efforts to replace the use of existing fossil energy resources have already been made around the world. As a result, a new industry of renewable energy has been created, and efficient energy distribution and storage has been promoted intensively. Among the newly explored renewable energy sources, the most widely used one is solar energy generation, which has a high market potential. An energy storage system (ESS) is a system as required. In this paper, the design and implementation of an ESS for the efficient use of power in stand-alone street lights is presented. In current ESS applied to stand-alone street lights, either 12V~24V DC (from solar power) or 110V~220V AC (from commercial power) is used to recharge power in systems with lithium batteries. In this study, an ESS that can support both solar power and commercial power was designed and implemented; it can also perform emergency recharge of portable devices from solar powered street lights. This system can maximize the scalability of ESSes using lithium batteries with efficient energy conversion, with the advantage of being an eco-friendly technology. In a ripple effect, it can also be applied to smart grids, electric vehicles, and new, renewable storage markets where energy storage technology is required.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.463-466
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• 2005

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This new generation technology is linked to a large number of factors like economics and performance, safety and reliability, market regulations, environmental issues, or grid connection constrains. KEPOD (Korea Electric Power Corporation) is performing the project to develope the Distributed Micro Gas Turbine (MGT) technologies by using Swine BID-ENERGY. This paper describes the plans and strategies for the renewable energy of MGT on actual grid-connection under Korean situations. KEPOD also, has a research plan on bio-gas pretreatment system applicable to our domestic swine renewable resources and is performing concept design of pilot plant to test grid operation. In addition, this testing will be conducted in order to respond to a wide variety of needs for application and economic evaluation in the field of On-site generation.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.678-683
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• 2005

Korea is utilizing geothermal resources mainly in the bathing and swimming facilities with very few applications for industrial processes or space heating. It is estimated that geothermal capacity and annual utilization are 36.2MWt and 761TJ/year as compared to global capacity and annual utilization of 15,145MWt and 190,699 TJ/year. RETScreen software is a user's friendly tool for analyzing the technical and financial pre-feasibility of potential Renewable Energy (RE) projects that promotes the use of RE applications through the capacity building of planners, decision-makers and industries for successful implementation of RE projects. Strong ties between Canada and Korean organizations such as Korean Solar Energy Society (KSES) and the Korea Institute of Energy Research (KIER) exist for knowledge transfer about RETScreen. In this paper, an overview of RETScreen and its ground source heat pump (GSHP) model with a practical example of an existing project of a community hall in Canada are described to illustrate effectiveness of RETScreenin the implementation of RE technologies. The same community hall project is then evaluated hypothetically considering its location at Kangnyng, Korea. The main objective is to demonstrate how RETScreen GSHP model can also be utilized effectively for GSHP applications in Korea.

• New & Renewable Energy
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• v.6 no.1
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• pp.20-28
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• 2010

Developing the offshore wind farm is essential to meet the national target of the renewable energy and to achieve the green growth in Korea. In this context, KEPRI is now carrying the feasibility study for introducing the offshore wind fam in Korea. Accordingly, it is required to formulate an appropriate strategy, this paper mainly discuss, for this goal. First of all, several preliminary sites for the offshore wind farm are selected based on the evaluation criteria presented herein. In addition, the domestic sub-technological level of key technology sectors associated with the offshore wind power is analyzed. It includes the industries related to wind turbine, grid integration, structural design and construction. Integrating these results, we propose a strategy in order to successfully develop the first offshore wind farm more than 100-MW class in the south-western sea area of Korea.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.479-491
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• 2005

지구환경문제와 에너지 수급관계를 감안할 때, 청정 및 대체에너지 연구개발은 불가피하며, 그 중에서도 태양에너지는 대표적인 대안의 하나로 인식된다. 따라서 태양에너지의 적극적인 활용에 필요한 기초자료의 마련은 필수적이다. 태양에너지의 이용 및 관련 절약 기술에 필요한 태양에너지 자원(기상)에 대한 기술자료는 최소한 30년간의 측정 자료를 필요로 한다. 이들 자료에는 시간별 수평면전 일사량, 법선면 직달일사량 및 수평면 산란일사량은 물론 시간별 평균치로 운량, 기온, 습도 등이 포함된다. 이들 자료로부터 자료의 분포, 평균 및 최고, 최저값 등과 같은 기초자료들을 선별하여 관련 시스템 설계에서 요구하는 기준을 충족하여야 하는 것이다. 그러나 우리나라의 경우, 태양에너지 자원에 대한 정밀한 측정은 1982년 이후 수평면 전일사량, 1990년 이후에서나 법선면 직달일사량에 대하여 본격적으로 이루어진 실정으로, 자료의 표준화 및 신뢰성 확보에는 여전히 상당한 시간과 노력이 요구되는 실정이다. 지속적인 측정과 더불어 요구되는 것으로 측정자료의 가공기술을 들 수 있다. 즉, 측정자료의 품질평가 및 관리 기술, 미측정 또는 불량자료의 복원 기술 및 측정 지역외 자료의 추정을 위한 보간기술 등이다. 이와 같은 기초자료 및 기술에 관한 연구개발은 보다 구체적인 적용에 앞서 필수적으로 이루어져야 할 과제이다.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.231-237
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• 2016

Recently, the interest in DC systems to achieve more efficient connection with renewable energy sources, energy storage systems, and DC loads has been growing extensively. DC systems are more advantageous than AC systems because of their low conversion losses. However, the DC-link voltage is variable during operation because of different random effects. This study focuses on DC voltage stabilization applied in stand-alone DC microgrids by means of voltage ranges, power management, and coordination scheme. The quality and stability of the entire system are improved by keeping the voltage within acceptable limits. In terms of optimized control, the maximum power should be tracked from renewable resources during different operating modes of the system. The ESS and VSDG cover the power shortage after all available renewable energy is consumed. Keeping the state of charge of the ESS within the allowed bands is the key role of the control system. Load shedding or power generation curtailment should automatically occur if the maximum tolerable voltage variation is exceeded. PSIM-based simulation results are presented to evaluate the performance of the proposed control measures.