압축공기에너지저장 : 지질학적 저장 방식과 소요 체적

류동우 한국자원공학회 2023 한국자원공학회지 Vol.60 No.2

In recent years, climate change and nationally determined contribution (NDC) policies worldwide have accelerated the transition from fossil energy sources to renewable energy. Consequently, the energy storage system (ESS) sector has emerged as an area of increasing importance in this industry. In particular, compressed air energy storage (CAES), which has a long history of commercialization, is reappraised as a competitive ESS technology with the potential for long-duration and utility-scale storage. The second part of the comprehensive overview aims to provide valuable insights into the planning, design, and construction stages of the CAES system. It describes various geological storage methods for CAES, such as rock salt, aquifers, and depleted gas fields, as well as the potential issues that need to be addressed when deploying each method. Furthermore, it elucidated the isochoric and isobaric storage types and introduced an analytical model for calculating the storage energy density of CAES based on each storage type with sample configurations. 최근 들어 기후 변화와 전 세계 각국의 NDC 정책은 화석 에너지에서 재생에너지로의 전환을 가속화시키고 있다. 이에 따라 에너지저장시스템(ESS) 분야는 산업계에서 점점 더 중요성이 커지는 분야로 부상하고 있다. 특히 상용화의 역사가 오래된 압축공기에너지저장(CAES)은 장시간 및 유틸리티 규모의 저장이 가능한 경쟁력 있는 ESS 기술로 재평가되고 있다. CAES 시스템의 계획, 설계및 건설 단계에서 통찰력을 제공하기 위해 준비한 CAES 관련 두 번째 총설이다. 본 총설에서는 암염 공동, 대수층, 폐가스전과 같은 지질학적 저장 방식을 소개하고, 이와 관련한 주요 현안들을 설명하였다. 또한, 저장공동의 압력 변화에 따라 정압저장과 정적저장에 대한 설명과 각 저장 방식별 저장에너지 밀도를 계산하는 모델을 예시 사례와 함께 소개하였다

용액 저장 탱크가 결합된 태양열 구동 흡수식 칠러의 건물 냉방부하별 성능 특성 분석

최형원(Hyung Won Cho),정재희(Jaehui Jeong),강용태(Yong Tae Kang) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

The solar-assisted absorption chiller is integrated with the thermal energy storage tanks to implement elongated operation with solar energy as well as to complement the incompatibility of the time gap between the cooling load of the building and the supply of renewable energy source. In this research, the thermal energy storage capacity and the operating characteristics of the system merging a single-effect absorption chiller employing water-lithium bromide as a working fluid and three thermal energy storage tanks were investigated. This system transforms the solar thermal energy into the chemical potential of water-lithium bromide solution to store the thermal energy and has the advantage of not requiring insulation of the thermal energy storage tank. Numerical investigation has been conducted to analyse the ratio between the mass flow rate of refrigerant to absorption chiller and that of thermal energy storage tank, which has been set as a key parameter to optimize the system performance. Based on the data of the cooling load of the residential building in July, which requests the largest cooling load, the feasibility study of energy management plan is conducted to establish the optimization of system performance. The regenerated water vapor is condensed to be supplied to absorption chiller for producing the cooling effect during the daytime and the rest is stored in the refrigerant storage tank to response to the cooling load during the night. This supply ratio of refrigerant is the significant parameter to optimize the operation of the system according to the specific cooling load of the building. Based on a hotel with cooling area of 30 m2, the optimized thermal energy storage density is estimated of 106.7 kWh/m3. The optimal cooling capacity of the evaporator of the absorption chiller is 2.2 kW at the ratio of thermal energy storage of 0.53, which means 53% generated refrigerant should be stored to effectively relieve the cooling load without solar energy. Simultaneously, the maximum thermal energy storage density is estimated of 216.4 kWh/m3, and that of the cooling capacity of the evaporator of absorption chiller is 4.46 kW.

용액 저장 탱크가 결합된 태양열 구동 흡수식 칠러의 건물 냉방부하별 성능 특성 분석

최형원(Hyung Won Cho),정재희(Jaehui Jeong),강용태(Yong Tae Kang) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

The solar-assisted absorption chiller is integrated with the thermal energy storage tanks to implement elongated operation with solar energy as well as to complement the incompatibility of the time gap between the cooling load of the building and the supply of renewable energy source. In this research, the thermal energy storage capacity and the operating characteristics of the system merging a single-effect absorption chiller employing water-lithium bromide as a working fluid and three thermal energy storage tanks were investigated. This system transforms the solar thermal energy into the chemical potential of water-lithium bromide solution to store the thermal energy and has the advantage of not requiring insulation of the thermal energy storage tank. Numerical investigation has been conducted to analyse the ratio between the mass flow rate of refrigerant to absorption chiller and that of thermal energy storage tank, which has been set as a key parameter to optimize the system performance. Based on the data of the cooling load of the residential building in July, which requests the largest cooling load, the feasibility study of energy management plan is conducted to establish the optimization of system performance. The regenerated water vapor is condensed to be supplied to absorption chiller for producing the cooling effect during the daytime and the rest is stored in the refrigerant storage tank to response to the cooling load during the night. This supply ratio of refrigerant is the significant parameter to optimize the operation of the system according to the specific cooling load of the building. Based on a hotel with cooling area of 30 m2, the optimized thermal energy storage density is estimated of 106.7 kWh/m3. The optimal cooling capacity of the evaporator of the absorption chiller is 2.2 kW at the ratio of thermal energy storage of 0.53, which means 53% generated refrigerant should be stored to effectively relieve the cooling load without solar energy. Simultaneously, the maximum thermal energy storage density is estimated of 216.4 kWh/m3, and that of the cooling capacity of the evaporator of absorption chiller is 4.46 kW.

PDFF 기법을 적용한 플라이휠 에너지 저장장치용 PWM 인버터 시스템 제어

최규하,정병환,박종찬,최해용 전력전자학회 2007 전력전자학회 논문지 Vol.12 No.3

본 논문은 현재 청정에너지의 개념으로 대두되고 있는 에너지원 가운데 기계적인 에너지로 저장하여 필요 시 꺼내어 사용할 수 있는 플라이휠 에너지 저장장치에 대한 에너지 입, 출력 모델링 및 PWM 인버터 시스템의 해석 및 제어에 관한 논문으로서, 플라이휠 저장장치 특성 및 시스템 모델링에 관해 논의한다. 재질에 따른 플라이휠의 특성과 플라이휠 에너지 저장장치의 속도 특성에 따른 전압과 전류의 변화량을 수식으로 간략화하여 분석하고, 시뮬레이션을 통하여 플라이휠의 에너지 저장상태를 분석하였다. 또한, 부하측 전원의 이상유무에 관계없이 에너지를 공급할 수 있는 Online UPS로 사용하기 위해 PDFF 제어기법을 이용 하여 전압제어 및 전류제어의 이중루프 제어로 구성된 단상 PWM방식의 인버터 시스템 제작 하였으며, 실험을 통하여 실제로 0.1[p.u], 1[p.u]에서의 제어되는 전압, 전류제어파형 및 THD 특성에 관하여 평가한다. This paper presents about energy input and output modeling for a flywheel energy storage system that can store and supply mechanical energy, which is emerging as one of clean energy sources, and the analysis and control of a PWM inverter system.Moreover, this paper describes flywheel's characteristics related to variations of mechanical and electrical parameters like as voltage and current versus speed characteristics formed as numerical formula and thus simulate behaviour-status of flywheel energy. Also for comparison and analysis between PI control and PDFF control, the modeling, design and analysis to the single-phase full bridge inverter with double loop feedback control is accomplished through numerical description and simulation. Finally, under load condition 0.1[pu], 1[pu]. it is validated that harmonic characteristics for voltage and current wave is controlled within 5% below even dynamics condition.

중저온 열원을 활용한 열화학 에너지저장 선행연구

박문용(Moon Yong Park),이우수(Woo Su Lee),이승수(Seung Soo Lee),Xuan Quang Duong,정재동(Jae Dong Chung) 대한설비공학회 2021 설비공학 논문집 Vol.33 No.6

Various methods are being studied to meet the demand for heat energy for cooling and heating. Energy utilization methods using adsorption and desorption have the advantage of being eco-friendly and have been actively studied recently. In particular, they have a higher energy density than storage system using sensible heat or phase change of water. In addition, research is being conducted regarding energy storage with small energy loss, despite long-term storage. However, driving conditions and performances are different depending on the adsorption pair and necessitate further investigation before commercialization. Although studies on the components and shapes of adsorption beds have been actively conducted worldwide, research focusing on the outlet temperature of hot water discharged from the storage system is still insufficient. Therefore, in this study, we identified how various driving conditions of the system affect the effective energy density and outlet temperature of the bed. Our findings revealed that the effective energy density and outlet temperature of the bed were higher since the evaporator temperature and inlet temperature were higher and the flow rate was lower. In addition, in case of same flow rate, the results in series conditions were better than in parallel.

전류밀도에 따른 바나듐 레독스 흐름 전지의 효율 변화

최호상,인대민,송영준,유철휘,황갑진 한국수소및신에너지학회 2017 한국수소 및 신에너지학회논문집 Vol.28 No.5

The performance of all-vanadium redox flow battery (VRFB) was tested with an increase of the current density. APS membrane (anion exchange membrane) and GF050CH (cabon felt) were used as a separator and electrode, respectively. An average energy efficiency of the VRFB was 79.5%, 68.1%, and 62.8% for the current density of 60 mA/cm2, 120 mA/cm2, and 160 mA/cm2, respectively. It was confirmed that VRFB can be used as a energy storage system at the higher current density even if the energy efficiency was deceased about 21%.

재생에너지 수용률 확보 조건에서 연 단위의 BESS 경제적 운영전략

김문겸,류한석,이지원,강현준 대한전기학회 2022 전기학회논문지 Vol.71 No.8

The increase in Renewable Energy causes a problem of stability of the power system due to its intermittent characteristics. Renewable Energy depends on natural conditions such as wind speed and solar irradiation, which has characteristics of uncertainty and variability. An ESS(Energy Storage System) is being used as one of the flexible resources to cope with these variables. This paper proposed the economical BESS(Battery Energy Storage System) operation strategy under the precondition of accommodating Renewable Energy maximally, considering both BESS and Renewable Energy. The BESS operation strategy was established from the viewpoint of maximizing efficiency of BESS in consideration of battery degradation conditions and initial SoC(State Of Charge). The operation strategy establishment procedure was conducted in the order of analyzing the actual power demand data, grouping the load characteristics, calculating amount of the Renewable Energy, and deriving BESS charge/discharge scheduling. After removing outliers from the resulting values derived through a series of processes, we finally propose a continuous and consistent annual operation strategy for BESS.

Effect of SiO2 additives on the microstructure and energy storage density of SrTiO3 ceramics

Guanghui Zhao,Yiqiu Li,Hanxing Liu,Jing Xu,Hua Hao,Minghe Cao,Zhiyong Yu 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3

The compositions of (1-x) SrTiO3-x SiO2 were prepared by a solid-state reaction. The crystalline structure, microstructure and energy storage performance were studied for the purpose of a potential application in high energy density capacitors. Fine grains with an average size of about 400 nm were obtained by adding SiO2 to SrTiO3 ceramics, which leads to a great enhancement in the breakdown performance of the samples. For SiO2-added samples, the notable increase in breakdown strength makes an obvious increase in energy storage density. With 15 vol.% addition, the sample exhibited an average breakdown strength of 36.1 kV/mm, and an energy storage density of 1.155 J/cm3.

DC-Link Active Power Filter for High-Power Single-Phase PWM Converters

Hongbo Li,Kai Zhang,Hui Zhao 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.3

Single phase converters suffer from ripple power pulsating at twice the line frequency. The ripple power is usually absorbed by a bulky capacitor bank and/or a dedicative LC resonant link, resulting in a low power density and a high cost. An alternative solution is using a dc link active power filter (APF) to direct the pulsating power into another energy-storage component. The main dc link filter capacitor can then be reduced substantially. Based on a mainstream dc APF topology, this paper proposed a new control strategy incorporating both dual-loop control and repetitive control. The circuit parameter design is also re-examined from a control point of view. The proposed APF scheme has better control performance, and is more suited for high power applications since it works in CCM and with a low switching frequency.

DC-Link Active Power Filter for High-Power Single-Phase PWM Converters

Li, Hongbo,Zhang, Kai,Zhao, Hui The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.3

Single phase converters suffer from ripple power pulsating at twice the line frequency. The ripple power is usually absorbed by a bulky capacitor bank and/or a dedicative LC resonant link, resulting in a low power density and a high cost. An alternative solution is using a dc link active power filter (APF) to direct the pulsating power into another energy-storage component. The main dc link filter capacitor can then be reduced substantially. Based on a mainstream dc APF topology, this paper proposed a new control strategy incorporating both dual-loop control and repetitive control. The circuit parameter design is also re-examined from a control point of view. The proposed APF scheme has better control performance, and is more suited for high power applications since it works in CCM and with a low switching frequency.