• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.534-538
• /
• 2001

Energy storage devices with high energy density as well as high power density are expected to be developed from the point of view of compensation of fluctuating load and generated power by distributed generations such as wind turbines, photovoltaic cells and so on. SMES (Superconducting Magnetic Energy Storage) has higher power density than other energy storage methods, and secondary batteries have higher energy density than SMES. The hybrid energy storage device using SMES and secondary batteries is proposed as the energy storage method with higher power and energy density, the sharing method of power reference value for each storage device, simulation and experimental results are presented.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.17 no.12
• /
• pp.1204-1209
• /
• 2005

In-situ measurement was made to evaluate chiller performance and thermal storage density of an ice thermal storage system. The system belonged to a big hotel and the measurement was conducted during late October. Owing to very small cooling load, the data logging was possible for a single thermal storage cycle. However, operation history of the chiller showed a relatively good spectrum of data for performance evaluation. COP and thermal storage density were calculated. The COP at full load was about 4.07, which was lower than $4.8\~6.4$ of new chillers. The measured storage density was about $10.9RT-h/m^3\;(=152MJ/m^3)$, which also was lower than a criterion of normal performance $(above\;13.0RT-h/m^3\;or\;181MJ/m^3)$. The study result provides technical basis for quantitative ESCO business scenario.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.422.2-422.2
• /
• 2016

스마트폰, 태블릿 등의 디바이스의 발전에 따라 휴대성이 매우 중요해졌다. 디바이스의 크기, 두께, 유연성에 관한 연구가 활발히 진행되고 있으며, 그 중에서도 energy storage device의 flexibility를 향상시키는 연구가 주목 받고 있다. Energy storage device의 성능 향상을 위해서는 power density를 높여야 하며 flexibility를 위해서는 전극판과 전극소재 간의 부착력을 증가시켜야 한다. 본 연구에서는, power density와 소재 간의 부착성을 개선시키기 위해 기존 graphene보다 표면적이 넓으며 power density가 좋고 전극판과의 부착성이 좋은 hybrid GNP-CNT를 사용하였다. 그리고 Ag NWs/CNT PET film 을 사용하여 전도성이 있는 flexible한 전극판을 사용하였다. SEM 측정을 통해 표면 분석을 하였고, sample에 패턴을 하고 Bending test를 하여 부착성을 확인하였다. 또한, CV curve를 측정하여 supercapacitor의 특성을 확인하였다. 향후, $MnO_2$ NWs를 hybrid GNP-CNT에 합성시킴으로 energy storage device의 energy density를 더욱 향상시키는 연구를 진행할 것이다.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.4
• /
• pp.39-45
• /
• 2006

The decrease in the summer peak electric load in our country is very important. The government has arranged and implemented a lot of support policies and statutes to decrease the peak electric load. And the ice thermal energy storage system is known as one of the alternatives. The purpose of this paper is to evaluate the efficiency and thermal characteristics of the closed ice thermal energy storage system using screw capsules. The measured thermal energy storage density is about 18.4 USRT-h/m3 (=232.9 MJ/m3), which is higher than 13.0 USRT-h/m3 (=164.6 MJ/m3), a low criterion of normal performance. And The efficiency of the discharging process and the total energy utilization is 96.2% and 2028.4 kcal/kWh respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.735-737
• /
• 2017

An Off grid or remote solar electric systems are an energy supply to our home or to our companies without the utility of Grid at all. Off grid solar systems are very important for those who live in remote locations especially for developing countries where getting the electric grid is extremely expensive, inconvenient or for those who doesn't need to pay a monthly bill with the electric bill in general. The main critical components of any solar power system or renewable energy harvesting systems are the energy storage systems and its charge controller system. Energy storage systems are the essential integral part of a solar energy harvesting system and in general for all renewable energy harvesting systems. To provide an optimal solution of both high power density and high energy density at the same time we have to use hybrid energy storage systems (HESS), that combine two or more energy storage technologies with complementary characteristics. In this present work, design and simulation we use two storage systems supercapacitor for high power density and lithium based battery for high energy density. Here the system incorporates fast-response supercapacitors to provide power to manage solar smoothing and uses a battery for load shifting. On this paper discuss that the total energy throughout of the battery is much reduced and the typical thermal stresses caused by high discharge rate responses are mitigated by integrating supercapacitors with the battery storage system. In addition of the above discussion the off grid solar electric energy harvesting presented in this research paper includes battery and supercapacitor management system, MPPT (maximum power point tracking) system and back/boost convertors. On this present work the entire model of off grid electric energy harvesting system and all other functional blocks of that system is implemented in MATLAB Simulink.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.37 no.2
• /
• pp.119-132
• /
• 2024

Dielectric ceramic capacitors present high output power density due to the fast energy charge and discharge nature of dielectric polarization. By forming dense ceramic films with nano-grains through the Aerosol Deposition (AD) process, dielectric ceramic capacitors can have high dielectric breakdown strength, high energy storage density, and leading to high power density. Dielectric capacitors fabricated by AD process are expected to meet the increasing demand in applications that require not only high energy density but also high power output in a short time. This article reviews the recent progress on the dielectric ceramic capacitors with improved energy storage properties through AD process, including energy storage capacitors based on both leadbased and lead-free dielectric ceramics.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.29 no.8
• /
• pp.429-436
• /
• 2017

There are three main methods to store heat energy; sensible heat storage, latent heat storage, and thermochemical heat storage. Thermochemical heat storage has the highest storage density among the three methods, so this study focused on the thermochemical heat storage method. Experiments were conducted in this study with Zeolite 13x as thermochemical material in a large-scale reactor with 8 kg of Zeolite 13x. Experiments analyzed storage density of Zeolite 13x with respect to four different heating temperatures ($50^{\circ}C$, $100^{\circ}C$, $150^{\circ}C$, $200^{\circ}C$) in heat storage process. As a result, they showed 40~50 percent of storage efficiency in the experiment. Experiments also revealed that reactions between Zeolite 13x and water vapor were reversible and stable, but efficiency of the system was low, compared with sensible heat storage systems or latent heat storage systems.

• Journal of Powder Materials
• /
• v.30 no.6
• /
• pp.509-515
• /
• 2023

Lead-free perovskite ceramics, which have excellent energy storage capabilities, are attracting attention owing to their high power density and rapid charge-discharge speed. Given that the energy-storage properties of perovskite ceramic capacitors are significantly improved by doping with various elements, modifying their chemical compositions is a fundamental strategy. This study investigated the effect of Zn doping on the microstructure and energy storage performance of potassium sodium niobate (KNN)-based ceramics. Two types of powders and their corresponding ceramics with compositions of (1-x)(K,Na)NbO₃-xBi(Ni_2/3Ta_1/3)O₃ (KNN-BNT) and (1-x)(K,Na)NbO₃-xBi(Ni_1/3Zn_1/3Ta_1/3)O₃ (KNN-BNZT) were prepared via solid-state reactions. The results indicate that Zn doping retards grain growth, resulting in smaller grain sizes in Zn-doped KNN-BNZT than in KNN-BNT ceramics. Moreover, the Zn-doped KNN-BNZT ceramics exhibited superior energy storage density and efficiency across all x values. Notably, 0.9KNN-0.1BNZT ceramics demonstrate an energy storage density and efficiency of 0.24 J/cm³ and 96%, respectively. These ceramics also exhibited excellent temperature and frequency stability. This study provides valuable insights into the design of KNN-based ceramic capacitors with enhanced energy storage capabilities through doping strategies.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.1
• /
• pp.64-70
• /
• 2008

This paper briefly discusses the main sources of errors and their solutions for measuring hydrogen uptake from gas phase by the Sieverts technique. Correction of volumetric errors of apparatus, density of hydrogen storage material, estimation of temperature gradient are investigated. Systematic errors and the change of density of the host material according to the pressure have been the subject of much controversy in recent years. We considered the standard ball calibration, temperature gradient distribution, pretreatment of hydrogen storage materials to minimize errors. We could lessen the miscalculations after applying those methods to Equilibrium pressure-composition isotherm data.

• Journal of the Korean Ceramic Society
• /
• v.56 no.1
• /
• pp.1-23
• /
• 2019

Dielectric materials with inherently high power densities and fast discharge rates are particularly suitable for pulsed power capacitors. The ongoing multifaceted efforts on developing these capacitors are focused on improving their energy density and storage efficiency, as well as ensuring their reliable operation over long periods, including under harsh environments. This review article summarizes the studies that have been conducted to date on the development of high-performance dielectric ceramics for employment in pulsed power capacitors. The energy storage characteristics of various lead-based and lead-free ceramics belonging to linear and nonlinear dielectrics are discussed. Various strategies such as mechanical confinement, self-confinement, core-shell structuring, glass incorporation, chemical modifications, and special sintering routes have been adopted to tailor the electrical properties and energy storage performances of dielectric ceramics. In addition, this review article highlights the challenges and opportunities associated with the development of pulsed power capacitors.