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[en] Phase change material (PCM) can store large amount of thermal energy at phase change temperature. Determination of thermophysical properties of PCM plays an important role in estimation of energy stored or released in storage device. Properties of PCM are key factors for designing a latent heat thermal energy storage system. This paper deals with the study of effect of heating/cooling rate on thermophysical properties, especially on melting temperature and latent heat of fusion /solidification. Results indicate that latent heat of fusion has more dependence on heating/cooling rate than onset, peak and end temperature. (author)
[en] This paper presents a real-time simulation and hardware-based approach for systematic integration of Distributed Energy Resources (DERs) in advanced distribution grids with a special focus on resilience. Advanced distribution grids are considered to be functionally more sophisticated than traditional ones. The desirable advanced functionalities include – reconfiguration, real-time sensing, DERs, self-healing, etc. Some of these functionalities are currently being realized by microgrids as well. However, it is not feasible to convert each section of a distribution grid into a microgrid, but can be instituted with functionalities by design and controls at relatively lower costs. Interconnection of DERs, including energy storage to improve reliability and resilience is presented in details. Resilience of distribution grids is gaining greater importance and research towards enhancing it utilizing DERs is a key area. A real-time resilience framework with Analytical Hierarchical Processes (AHP) is developed that adapts to changing configurations, DERs, switching operations, grid conditions, etc. to provide an accurate and adoptable composite resilience metric. This framework and the composite resilience metric can play a unique role in operational and design decisions for operating future distribution grids. Advanced functionalities such as scenario-based reconfiguration in distribution grids are considered, with resilience metrics as performance criteria for choosing a preferred combination. Simulations are performed using Digital Real-Time Simulator (DRTS) and characterized response of flow battery validated against actual flow battery hardware is imposed to provide realistic results. Reconfiguration program is interfaced with DRTS for bi-directional real-time communication. Key contributions include enhancement of resilience of distribution grids using energy storage system under dynamic operating conditions.
[en] Highlights: • A single energy storage can always be split into two hybrid energy storages. • These hybrid storages have the same total energy and power as the single storage. • The potential for storage hybridisation depends on the shape of the power profile. • A higher potential allows a higher spread of the power/energy-ratios of the storages. • Automobile and pulsed power applications are well suited for storage hybridisation. - Abstract: Aim of a storage hybridisation is a beneficial usage or combination of different storage technologies with various characteristics to downsize the overall system, decrease the costs or to increase the lifetime, system efficiency or performance. In this paper, the point of interest is a different ratio of power to energy (specific power) of two storages to create a hybrid energy storage system (HESS) with a resulting specific power that better matches the requirements of the application. The approach enables a downsizing of the overall system compared to a single storage system and consequently decreases costs. The paper presents a theoretical and analytical benchmark calculation that determines the maximum achievable hybridisation, i.e. possible spread in specific power, while retaining the original total energy and power capacities of an equivalent single storage system. The theory is independent from technology, topology, control strategy, and application and provides a unified view on hybrid energy storage systems. It serves as a pre-dimensioning tool and first step within a larger design process. Furthermore, it presents a general approach to choose storage combinations and to characterize the potential of an application for hybridisation. In this context, a Hybridisation Diagram is proposed and integral Hybridisation Parameters are introduced.
[en] The significance of nuclear energy is increasing because it has the potential to solve a number of problems concerned with shortages of fuels and environmental degradation in the 21st century. Therefore the uses of nuclear power should be widened so that it can be used as a source of heat energy as well as just being used for electrical generation. A concept for utilizing nuclear energy effectively has been studied for an electric power company. A new electric energy storage system has been proposed which stores power by producing a synthetic fuel, methanol. The methanol is made from coal gas and hydrogen which is produced by excess off-peak electricity and high temperature heat from a HTGR. The system is not only technically feasible, but is also cost-competitive with other storage systems. (author)
[en] The application of lightweight reliable capacitors in a mobile energy store is discussed. The relationship of system design parameters to capacitor size and life is displayed. Electric fields and weights of a 21 J/lb and a 77 J/lb pulse discharge capacitor design are given. Estimates of future near-tern development are made
[en] Highlights: ► PV systems with sun tracking and concentrators (CPVS) can reduce the cost of energy per kWh produced. ► The V-trough low-concentration system solution is compatible with flat PV module technologies. ► Optical, thermal and electrical models are needed to forecast real power production. ► The description of a PV grid connected system with batteries, a one-axis tracker and CPV photovoltaic system is presented. ► Outdoor measurements of the generating system are provided and discussed. - Abstract: Photovoltaic systems (PVSs) combined with either some form of storage, such as a battery energy storage system (BESS), or direct load control, can play a crucial role in achieving a more economical operation of the electric utility system while enhancing its reliability with additional energy sources. At the same time, it is also important to use cost-effective PV solutions. In this context, a low-concentration PVS (CPVS) is analysed as a feasible alternative. This paper, present a case study of a complex PVS, composed of two PVSs, a storage system (BEES) and an inverter that allows the system to operate in both the island and grid-connected modes. The first PVS, is a 2.76-kWp single-axis tracking system (azimuth) with modules facing south and tilted 30°, while the second PVS is a dual-axis tracking system, rated 860 Wp, consisting of a concentrator at the flat mirrors (DoubleSun® Four). The system is installed on the roof of the main building of the “ITIS Marconi” school (Italy). A detailed description of the system is provided, and preliminary operating data are presented and discussed. The efficiencies of the PV systems are calculated and measured to evaluate the cost effectiveness of a low-concentration system.
[en] A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. Many aspects of the quasi-static behavior of flywheel rotors still need to be studied closely, and the rotors require a stable and highly efficient supporting system such as high temperature superconductor (HTS) bearings, which offer dynamic stability without the use of active control. Quasi-static properties of HTS bearings in the radial direction provide data to solve problems which may occur in a running system. Since stiffness in countering rotor vibration is the main parameter for designing an HTS bearing system, we investigated the quasi-static properties of the magnetic force between permanent magnets(PMs) and HTS bulks in the radial direction. We measured radial stiffness, and discovered that bearing stiffness varied greatly depending on the number of active HTS bulks. This is valuable data for predicting the change in stiffness during partial HTS bearing failure. The quasi-static test results are used for optimal design and performance prediction for the 100 kWh class superconductor bearing.
[en] The IEA GHG Weyburn Midale CO2 monitoring and Storage Project was undertaken in Southwestern Saskatchewan in 2000 in an effort to study geological CO2 storage. Under this project, a geological storage system was tested along with technologies to measure and monitor the effective long term storage of CO2. A recent study performed by Petro-Find Geochem Ltd. concluded that CO2 injected as part of this project migrated to the surface; the aim of this paper is to respond to this study. The Petroleum Technology Research Center points out that the CO2 was monitored by over 30 research organizations and that the results of the scientific research do not support the CO2 migration statement. In addition, the Petro-Find report stated that the injected CO2 was the source of high concentrations of CO2 in soils of the Kerr property, however, the Petroleum Technology Research Center did not find any substantial evidence of this in the report.
[en] Highlights: ► Super-capacitors are used to store regenerative braking energy in a metro network. ► A novel approach is proposed to model easily and accurately the metro network. ► An efficient approach is proposed to calculate the required super-capacitors. ► Maximum energy saving is around 44% at off-peak period and 42% at peak period. ► Benefit/cost analyses are performed for the suggested ESS. - Abstract: In this paper, the stationary super-capacitors are used to store a metro network regenerative braking energy. In order to estimate the required energy storage systems (ESSs), line 3 of Tehran metro network is modeled through a novel approach, in peak and off-peak conditions based on the real data obtained from Tehran metro office. A useful method is proposed to predict the maximum instantaneous regenerative energy which is delivered to each station before applying ESS and based on that the ESS configuration for each station is determined. Finally, the effectiveness of the proposed ESS is confirmed by economic evaluations and benefit/cost analyses on line 3 of Tehran metro network.