• Title/Summary/Keyword: energy storage

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Thermal Energy Balance Analysis of a Packed Bed for Rock Cavern Thermal Energy Storage (충전층을 이용한 암반공동 열에너지저장시스템의 열에너지 수지 분석)

  • Park, Jung-Wook;Ryu, Dongwoo;Park, Dohyun;Choi, Byung-Hee;Synn, Joong-Ho;Sunwoo, Choon
    • Tunnel and Underground Space
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    • v.23 no.3
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    • pp.241-259
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    • 2013
  • A packed bed thermal energy storage (TES) consisting of solid storage medium of rock or concrete through which the heat transfer fluid is circulated is considered as an attractive alternative for high temperature sensible heat storage, because of the economical viability and chemical stability of storage medium and the simplicity of operation. This study introduces the technologies of packed bed thermal energy storage, and presents a numerical model to analyze the thermal energy balance and the performance efficiency of the storage system. In this model, one dimensional transient heat transfer problem in the storage tank is solved using finite difference method, and temperature distribution in a storage tank and thermal energy loss from the tank wall can be calculated during the repeated thermal charging and discharging modes. In this study, a high temperature thermal energy storage connected with AA-CAES (advanced adiabatic compressed air energy storage) was modeled and analyzed for the temperature and the energy balance in the storage tank. Rock cavern type TES and above-ground type TES were both simulated and their results were compared in terms of the discharging efficiency and heat loss ratio.

Hybridization of the Energy Generator and Storage Device for Self-Powered Electronics (자가구동형 전자소자 구현을 위한 에너지 발전/저장 소자 융합 기술 동향)

  • Lee, Ju-Hyuck
    • Journal of the Korean Electrochemical Society
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    • v.21 no.4
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    • pp.68-79
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    • 2018
  • Currently, hybridization of energy generator and storage devices is considered to be one of the most important energy-related technologies due to the possibility of replacing batteries or extending the lifetime of a batteries in accordance with increasing battery demand. This review aims to describe current progress on the mechanical energy generator and hybridization of energy generator and energy storage devices for self-powered electronics. First, the research trends related to energy generation devices using piezoelectric and triboelectric effect that convert physical energy into electric energy is introduced. In addition, integration of energy generators and energy storage devices is introduced. In particular, self-charging energy cells provide an innovative approach to the direct conversion of mechanical energy into electrochemical energy to decrease energy conversion loss.

Hybrid thermal seasonal storage and solar assisted geothermal heat pump systems for greenhouses

  • Ataei, Abtin;Hemmatabady, Hoofar;Nobakht, Seyed Yahya
    • Advances in Energy Research
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    • v.4 no.1
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    • pp.87-106
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    • 2016
  • In this research, optimum design of the combined solar collector, geothermal heat pump and thermal seasonal storage system for heating and cooling a sample greenhouse is studied. In order to optimize the system from technical point of view some new control strategies and functions resulting from important TRNSYS output diagrams are presented. Temperatures of ground, rock bed storage, outlet ground heat exchanger fluid and entering fluid to the evaporator specify our strategies. Optimal heat storage is done with maximum efficiency and minimum loss. Mean seasonal heating and cooling COPs of 4.92 and 7.14 are achieved in series mode as there is no need to start the heat pump sometimes. Furthermore, optimal parallel operation of the storage and the heat pump is studied by applying the same control strategies. Although the aforementioned system has higher mean seasonal heating and cooling COPs (4.96 and 7.18 respectively) and lower initial cost, it requires higher amounts of auxiliary energy either. Soil temperature around ground heat exchanger will also increase up to $1.5^{\circ}C$ after 2 years of operation as a result of seasonal storage. At the end, the optimum combined system is chosen by trade-off between technical and economic issues.

A Study on Optimal Operation Strategy for Mild Hybrid Electric Vehicle Based on Hybrid Energy Storage System

  • Bae, SunHo;Park, Jung-Wook
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.631-636
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    • 2018
  • This paper proposed an optimal operation strategy for a hybrid energy storage system (HESS) with a lithium-ion battery and lead-acid battery for mild hybrid electric vehicles (mild HEVs). The proposed mild HEV system is targeted to mount the electric motor and the battery to a conventional internal combustion engine vehicle. Because the proposed mild HEV includes the motor and energy storage device of small capacity, the system focuses on low system cost and small size. To overcome these limitations, it is necessary to use a lead acid battery which is used for a vehicle. Thus, it is possible to use more energy using HESS with a lithium battery and a lead storage battery. The HESS, which combines the lithium-ion battery and the secondary battery in parallel, can achieve better performance by using the two types of energy storage systems with different characteristics. However, the system requires an operation strategy because accurate and selective control of the batteries for each situation is necessary. In this paper, an optimal operation strategy is proposed considering characteristics of each energy storage system, state-of-charge (SOC), bidirectional converters, the desired output power, and driving conditions in the mild HEV system. The performance of the proposed system is evaluated through several case studies with respect to energy capacity, SOC, battery characteristic, and system efficiency.

Recent Research Trend of Zinc-ion Secondary Battery Materials for Next Generation Batterie (차세대 이차전지용 아연 이온 이차전지 소재 연구 개발 동향)

  • Jo, Jeonggeun;Kim, Jaekook
    • Ceramist
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    • v.21 no.4
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    • pp.312-330
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    • 2018
  • Energy storage/conversion has become crucial not only to meet the present energy demand but also more importantly to sustain the modern society. Particularly, electrical energy storage is critical not only to support electronic, vehicular and load-levelling applications but also to efficiently commercialize renewable energy resources such as solar and wind. While Li-ion batteries are being intensely researched for electric vehicle applications, there is a pressing need to seek for new battery chemistries aimed at stationary storage systems. In this aspect, Zn-ion batteries offer a viable option to be utilized for high energy and power density applications since every intercalated Zn-ion yields a concurrent charge transfer of two electrons and thereby high theoretical capacities can be realized. Furthermore, the simplicity of fabrication under open-air conditions combined with the abundant and less toxic zinc element makes aqueous Zn-ion batteries one of the most economical, safe and green energy storage technologies with prospective use for stationary grid storage applications. Also, Zn-ion batteries are very safe for next-generation technologies based on flexible, roll-up, wearable implantable devices the portable electronics market. Following this advantages, a wide range of approaches and materials, namely, cathodes, anodes and electrolytes have been investigated for Zn-ion batteries applications to date. Herein, we review the progresses and major advancements related to aqueous. Zn-ion batteries, facilitating energy storage/conversion via $Zn^{2+}$ (de)intercalation mechanism.

Study on Heat Storage and Transportation System for Recovering Non-using Low-temperature Heat (폐열회수 증대를 위한 열운송 축열 시스템 특성 연구)

  • Oh, Changyong;Im, Hongseop;Kim, Insu
    • New & Renewable Energy
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    • v.10 no.4
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    • pp.29-35
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    • 2014
  • Non-used waste heat has recently been paid special attention due to several global warming regulation and energy cost rising. In this study, therefore, thermal energy storage system which uses a solid type heat media has been investigated about the possibility of heat accumulation and heat release for thermal energy storage system. 35kWh of bench-scale thermal storage system was used to investigate the characteristics of the solid type heat media. From the result, it is shown that a solid type heat media should be divided to supply constant heat to the customers' side. It is also shown the flow direction should be considered to reduce temperature difference between top and bottom sides in the thermal storage system.

Electrical Modeling of Renewable Energy Sources and Energy Storage Devices

  • Williamson, Sheldon S.;Rimmalapudi, S.Chowdary;Emadi, Ali
    • Journal of Power Electronics
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    • v.4 no.2
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    • pp.117-126
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    • 2004
  • This paper focuses on the electrical modeling techniques of renewable energy sources and storage devices such as batteries, fuel cells (FCs), photovoltaic (PVs) arrays, ultra-capacitors (UCs), and flywheel energy storage systems (FESS). All of these devices are being investigated recently for their typical storage and supply capabilities for various industrial applications. Hence, these devices must be modeled precisely taking into account the concerned practical issues. An obvious advantage of electrically modeling these renewable energy sources and storage devices is the fact that they can easily be simulated in real-time in any CAD simulation program. This paper reviews several types of suitable models for each of the above-mentioned devices and the most appropriate model amongst them is presented. Furthermore, a few important applications of these devices shall also be highlighted.

An Economic Evaluation under Thailand Feed in Tariff of Residential Roof Top Photovoltaic Grid Connected System with Energy Storage for Voltage Stability Improving

  • Treephak, Kasem;Saelao, Jerawan;Patcharaprakiti, Nopporn
    • International Journal of Advanced Culture Technology
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    • v.3 no.1
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    • pp.120-128
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    • 2015
  • In this paper, Residential roof top photovoltaic system with 9.9 kW design is proposed. The system composed of 200 Watts solar array 33 panels connecting in series 10 strings and parallels 3 strings which have maximum voltage and current are 350 V and 23.8 A. The 10 kW sinusoidal grid-connected inverter with window voltage about 270-350 is selected to convert and transfer DC Power to AC Power at PCC (Point of Common Coupling) of power system following to utility standard. However the impact of fluctuation and uncertainty of weather condition of PV may decrease the voltage stability and voltage collapse of power system. In order to solve this problem the energy storage such 120 V 1200 Ah battery bank and 30 kVAR capacitor are designed for voltage stability control. The other expensed for installing the system such battery charger, cable, accessories and maintenance cost are concerned. The economic analysis by using investment from money loan with interest about 7% and use own money which loss income of deposit about 3% are calculated as 671,844 and 547,044 for PV system with energy storage and non energy storage respectively. The solar energy from PV is about 101,616 Bath per year which evaluated by using the value of $5kWh/m^2/day$ from average peak sun hour (PSH) of the Thailand and 6.96 Bath/kWh of Feed in Tariff Incentive. The payback periods of four scenarios are proposed follow as i) PV system with energy storage and use loan money is 15 years ii) PV system with no energy storage and use loan money is 10 years iii) PV system with energy storage and use deposit money is 9 years iv) PV system with energy storage and use deposit money is 7 years. In addition, the other scenarios of economic analysis such no FIT support and other type of economic analysis such NPV and IRR are proposed in this paper.

Effective modelling of borehole solar thermal energy storage systems in high latitudes

  • Janiszewski, Mateusz;Siren, Topias;Uotinen, Lauri;Oosterbaan, Harm;Rinne, Mikael
    • Geomechanics and Engineering
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    • v.16 no.5
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    • pp.503-512
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    • 2018
  • Globally there is an increasing need to reduce the greenhouse gas emissions and increase the use of renewable sources of energy. The storage of solar thermal energy is a crucial aspect for implementing the solar energy for space heating in high latitudes, where solar insolation is high in summer and almost negligible in winter when the domestic heating demand is high. To use the solar heating during winter thermal energy storage is required. In this paper, equations representing the single U-tube heat exchanger are implemented in weak form edge elements in COMSOL Multiphysics(R) to speed up the calculation process for modelling of a borehole storage layout. Multiple borehole seasonal solar thermal energy storage scenarios are successfully simulated. After 5 years of operation, the most efficient simulated borehole pattern containing 168 borehole heat exchangers recovers 69% of the stored seasonal thermal energy and provides 971 MWh of thermal energy for heating in winter.

A Study on On-Board Energy Storage System for Urban Transit System (전기철도 차량 탑재용 회생 에너지저장시스템에 관한 연구)

  • Lee, Han-Min;Lee, Chang-Mu;Oh, Seh-Chan;Kim, Gil-Dong;Park, Hyun-June
    • Proceedings of the KIEE Conference
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    • 2008.11a
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    • pp.144-146
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    • 2008
  • The energy storage system is considered to be one of the useful devices for energy storing and recycling. Also the energy storage system can stabilize the system voltage. This paper proposes the type of on-board energy storage system.

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