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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] 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 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: ► 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] 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.
[en] Inductive energy storage systems is now used in electromagnetic lauch technology A high-power-density inductor is the key assembly. This paper described a new design in construction of brooks coil used as a high-power-density inductor. Experimental result was used to improve the design. (authors)
[en] We give a detailed description of the energy balance equation for a stand-alone hybrid solar–wind power generating system. The dimensions of the power generator and the energy capacity of a buffer battery (used as an energy storage system) are chosen to suit a known consumer's profile. Future applications of the mathematical model developed and analogies with a similar hydrodynamic problem are discussed. (paper)
[en] Highlights: • A review of power converter interfaces for electrochemical energy storage (EES) system is presented. • EES devices and their specificities regarding to integration with the electrical systems are also described. • Power converters are divided into standard, multilevel and multiport technology. • The smart storage concept and the interface requirements to integrate the EES devices are also reviewed. - Abstract: Energy storage concept that supports important technologies for electrical systems is well established and widely recognized. Several energy storage techniques are available, including an electrochemical energy storage system used to support electrical systems. These storage systems require interfaces based on power electronic converters for interconnection with an electrical system. This paper reviews the literature covering the various types of interfaces developed for electrochemical energy storage systems. Different electrochemical energy storage devices and their specificities regarding to integration with the electrical systems are described. . The various power converter interfaces that can be used for electrochemical energy storage systems are presented. These interfaces have been divided into standard, multilevel and multiport technology. The main characteristics and specificity of each topology considering its application to electrochemical energy storage systems are presented. The review also covers the smart storage concept and the requirements of the interface to integrate the electrochemical energy storage devices upon this concept
[en] Highlights: • An optimal planning model for DESSs in SOP-based active distribution networks is proposed. • The power flow controllability of SOP is modeled and optimally coordinated with DESS operation. • Inverter-based DG reactive power capability and short-term network reconfiguration at the hourly timescale are incorporated in the planning. • The proposed DESS planning model is formulated as a computationally efficient MISOCP problem. - Abstract: The integration of high-penetration distributed generators (DGs) with smart inverters and the emerging power electronics technology of soft open points provide increased controllability and flexibility to the operation of active distribution networks. Existing works on distributed energy storage planning have not fully considered the coordinated operation of these new power electronic devices with distributed energy storage systems, leading to less economic investment decisions. This paper proposes an optimal planning model of distributed energy storage systems in active distribution networks incorporating soft open points and reactive power capability of DGs. The reactive power capability of DG inverters and on load tap changers are considered in the Volt/VAR control. Moreover, soft open points are modeled to provide flexible active and reactive power control on the associated feeders. Hourly network reconfiguration is conducted to optimize the power flow by changing the network topology. A mixed-integer second-order cone programming model is formulated to optimally determine the locations and energy/power capacities of distributed energy storage systems. Finally, the effectiveness of the proposed model is validated on a modified IEEE 33-node distribution network. Considering soft open points, DG reactive power capability, and network reconfiguration, the results demonstrate the optimal distributed energy storage systems planning obtained by the proposed model achieves better economic solution.