Energy Storage System Requirements Research Articles

Impact of Multiple Module Collectors on the Cell Current Distribution within the Battery Pack

Lithium-ion batteries are usually connected in series and parallel to form a pack for meeting the voltage and capacity requirements of energy storage systems. However, different pack configurations and battery module collector positions result in different equivalent connected resistances, leading to pack current inhomogeneity, which seriously reduces the lifetime and safety of the pack. Therefore, in order to quantitatively analyze the influence of the connected resistance on the current distribution, this study researched the initial cell current distribution of the parallel module by developing mathematical models of different configurations. Then, this study explored the influence of multiple module collector positions on the current inhomogeneity of the pack under the dynamic current condition. The results show that the inhomogeneity of cell current and discharge capacity in the pack with parallel modules connected in series can be improved by keeping each cell in a parallel module with the same distance to its module collector. Furthermore, the current homogeneity of the edge parallel modules in the pack is seriously affected by the position of the single module collector. Therefore, this study innovatively proposes the symmetrical multiple module collectors of the pack, which can greatly improve the current homogeneity of the edge parallel modules, thereby improving the lifetime and safety of the pack.

Fiscal- and Space-Constrained Energy Optimization Model for Hybrid Grid-Tied Solar Nanogrids

Due to rising fossil fuel costs, electricity tariffs are also increasing. This is motivating users to install nanogrid systems to reduce their electricity bills using solar power. However, the two main constraints for a solar system installation are the initial financial investment cost and the availability of space for the installation of solar panels. Achieving greater electricity savings requires more panels and a larger energy storage system (ESS). However, a larger ESS also increases the electricity bill and reduces the available solar power due to higher charging power requirements. The increase in solar power leads to the need for more space for solar panel installation. Therefore, achieving the maximum electricity savings for a consumer unit requires an optimized number of solar panels and ESS size within the available financial budget and the available physical space. Thus, this study presents a fiscal- and space-constrained mixed-integer linear programming-based nanogrid system model (FS-MILP) designed to compute the optimal number of solar panels and ESS requirements, and the daily electricity unit consumption and savings. The proposed model is also validated through an OMNET++-based simulation using real-time solar irradiance and residential load values of one year for the city of Karachi, Pakistan. The investigation results show that a maximum of 1050 electricity units can be saved and exported to the main power grid within the maximum financial budget of PKR 1,000,000/-.

Redox‐Active Polymer Integrated with MXene for Ultra‐Stable and Fast Aqueous Proton Storage

AbstractProton is a charge carrier with the smallest ionic size and quickest kinetics, making aqueous proton batteries (APBs), a promising technology for safe and profitable energy storage systems. Despite being potential electrode materials, organic compounds have not yet been fully investigated in terms of proton storage properties and APB applications due to their low capacity and unstable cycle life in aqueous electrolytes. Herein, a novel redox‐active polymer (PDPZ) with diquinoxalino‐phenazine as the structural unit has been designed, which is further integrated with MXene nanosheets to construct a flexible PDPZ@MXene electrode material with a rapid and ultra‐stable proton storage behavior. In‐operando monitoring techniques, i.e., in situ Raman and in situ FTIR, demonstrate the highly reversible redox reaction between CN and CN/NH bonds in electro‐active PDPZ molecule with the strong proton absorption ability. Theoretical calculation further proves the electron transfer from MXene to PDPZ promotes the redox reaction of the PDPZ@MXene electrode. As a result, a flexible APB device is developed with a considerable energy density (64.3 mWh cm−3), a supercapacitor‐level power density (6000 mW cm−3), and a record lifespan with ≈98.2% capacity retention over 10 000 cycles, revealing its potential applications in satisfying the various requirements of energy storage systems.

Battery-type Ni-Co-Se hollow microspheres cathode materials enabled by bifunctional N-doped carbon quantum dots with ultrafast electrochemical kinetics for hybrid supercapacitors

Hybrid supercapacitors (HSCs) with large energy and power density have received increasing concern for their great potential in satisfying the requirements of energy storage systems. Nonetheless, the imbalanced kinetics between the sluggish battery-type cathode and the rapid capacitor-type anode make it difficult for HSCs to achieve high energy density at high power density. Herein, a novel N-doped carbon quantum dots/Ni-Co-Se (N-CQDs/Ni-Co-Se) hollow microspheres composite is synthesized via a facile hydrothermal approach using bifunctional CQDs as size regulators and conductive agents for the first time. Thanks to the synergism of highly conductive N-CQDs with rapid electron transfer and reduced-size hollow micro-/nanostructures contributing to the enhanced ion transport, the as-prepared battery-type N-CQDs/Ni-Co-Se hollow microspheres composite cathode exhibits admirable rate property. In-depth electrochemical kinetic analyses and density functional theory (DFT) calculations are utilized to elucidate the preeminent kinetic properties. Furthermore, a novel HSC is fabricated based on the N-CQDs/Ni-Co-Se hollow microspheres composite cathode with ultrafast electrochemical kinetics, displaying a high energy density of 23.1 Wh kg−1 at a superb power density of 38.3 kW kg−1. This encouraging work provides a good strategy to construct ultrahigh rate battery-type electrode materials with tunable size and component for simultaneously obtaining high energy/power density HSCs.

Multi-Objective Optimization-Based Real-Time Control Strategy for Battery/Ultracapacitor Hybrid Energy Management Systems

Battery and ultracapacitor (UC) have complementary advantages, which meet the requirements of energy storage systems (ESSs) for plug-in electric vehicles (PEVs). In this paper, a novel control strategy is proposed to manage the power distribution between the battery and UC for a hybrid energy management system (HEMS) in PEVs. This control strategy aims at realizing less power loss, longer battery lifecycle, as well as UC's stable terminal voltage and ability of quick charge/discharge. Based on these three optimization targets, we define three sets of loss functions and formulate a multi-objective optimization (MOO) problem. In particular, two different methods, weighted method and no-preference method, are implemented to transform the MOO problem into a uni-objective convex optimization problem. The final problem is solved using the Karush-Kuhn-Tucker conditions. Simulation is conducted to verify the proposed control strategy, while a battery-only ESS and a HEMS utilizing rule-based control strategy are implemented as a comparative study. A scaled-down laboratory prototype is built to validate the theoretical analysis and simulation results. The results indicate that the proposed control strategy brings the benefits of minimized battery current magnitudes and ripples, enhanced system efficiency, stabilized dc-link voltage, and improved dynamic response. Moreover, this strategy exhibits fast computation speed and requires no pre-information of future load demand. Therefore, it can be easily deployed in real-time.

Nanocellulose for Energy Storage Systems: Beyond the Limits of Synthetic Materials.

The ongoing surge in demand for high-performance energy storage systems inspires the relentless pursuit of advanced materials and structures. Components of energy storage systems are generally based on inorganic/metal compounds, carbonaceous substances, and petroleum-derived hydrocarbon chemicals. These traditional materials, however, may have difficulties fulfilling the ever-increasing requirements of energy storage systems. Recently, nanocellulose has garnered considerable attention as an exceptional 1D element due to its natural abundance, environmental friendliness, recyclability, structural uniqueness, facile modification, and dimensional stability. Recent advances and future outlooks of nanocellulose as a green material for energy storage systems are described, with a focus on its application in supercapacitors, lithium-ion batteries (LIBs), and post-LIBs. Nanocellulose is typically classified as cellulose nanofibril (CNF), cellulose nanocrystal (CNC), and bacterial cellulose (BC). The unusual 1D structure and chemical functionalities of nanocellulose bring unprecedented benefits to the fabrication and performance of energy storage materials and systems, which lie far beyond those achievable with conventional synthetic materials. It is believed that this progress report can stimulate research interests in nanocellulose as a promising material, eventually widening material horizons for the development of next-generation energy storage systems, that will lead us closer to so-called Battery-of-Things (BoT) era.

Overcoming Solar PV Intermittency using Demand Response Management in Buildings

Singapore’s National Climate Change Policy is aimed to make energy usage in Singapore more efficient, reduce pollution and expand the nation’s green spaces. Part of the plan is to promote the integration of solar photovoltaics (PVs) on rooftops of high-rise HDB residential and commercial buildings. This initiative contributed to the significant growth in the integration of solar PV systems in the last few years. However, large-scale integration of solar PVs will put at risk the reliability and stability of Singapore’s power system due to its intermittent nature. The intermittency problem of solar PV, typically in the range of minutes, will become very significant in Singapore as the installations of PV systems continue to increase. Conventionally, large energy storage systems are deployed as an energy buffer to compensate for the deficit or surplus of power supplied by solar PV systems. However, the high capital and maintenance costs as well as large space requirement for energy storage systems makes this an unfavorable option for building owners. This paper proposes a solution that utilizes the centrifugal fans in building air conditioning and mechanical ventilation (ACMV) system to dynamically compensate for the deficit or surplus of power supplied by solar PVs. For example, the developed solution will reduce the load demand of fans in the ACMV system equal to the drop of solar generation by controlling the speed of the fan. This will ensure that the amount of power supplied by the grid to the building will remain the same (as before the drop of solar generation) and thus no impact on the grid stability. However, since ACMV system is directly linked to building occupant comfort/health, the proposed solution will also include battery management and priority-based load shedding programs to provide support when room temperature (air conditioning) or CO level (ventilation) is above regulatory limit.

Frequency response services designed for energy storage

Energy Storage Systems (ESS) are expected to play a significant role in regulating the frequency of future electric power systems. Increased penetration of renewable generation, and reduction in the inertia provided by large synchronous generators, are likely to increase the severity and regularity of frequency events in synchronous AC power systems. By supplying or absorbing power in response to deviations from the nominal frequency and imbalances between supply and demand, the rapid response of ESS will provide a form of stability which cannot be matched by conventional network assets. However, the increased complexity of ESS operational requirements and design specifications introduces challenges when it comes to the realisation of their full potential through existing frequency response service markets: new service markets will need to be designed to take advantage of the capabilities of ESS. This paper provides new methods to analyse and assessing the performance of ESS within existing service frameworks, using real-time network simulation and power hardware in the loop. These methods can be used to introduce improvements in existing services and potentially create new ones. Novel statistical techniques have been devised to quantify the design and operational requirements of ESS providing frequency regulation services. These new techniques are demonstrated via an illustrative service design and high-resolution frequency data from the Great Britain transmission system.

A hybrid three-dimensionally structured electrode for lithium-ion batteries via 3D printing

New hybrid 3D structure electrodes with a high aspect ratio are fabricated through extrusion-based additive manufacturing to achieve high mass loading. This new 3D printed battery exhibits both high areal and specific capacity, thus overcoming the trade-off between the two of the conventional laminated batteries. This excellent battery performance is achieved by introducing a hybrid 3D structure that utilizes the benefits of the existing laminated structure and three-dimensional interdigitated structure. In addition, conventional battery paste components are used optimally to fit the 3D printing process, which eliminates the need for a complicated solvent preparation process required for a typical 3D printing process for battery applications. Using the CR2032 coin cell, the general assembly problem that occurs at the 3D structured electrodes is solved, which means that the proposed hybrid 3D structure can easily be added to the existing lamination structure. This innovative design and fabrication process demonstrates the high areal energy and power density, which is a critical requirement for energy storage systems in transportation and stationary applications.

Modelling of full electric and hybrid electric fuel cells buses

Future road transports will increasingly move towards zero emissions. Although electric bus technology is available today, low energy density of lithium-ion (li-ion) batteries is a major drawback, leading to higher vehicle mass and range limitations. Hybrid buses, with more energy dense storage, appear as an easier transition from fossil fuels towards zero local emissions. Main objective of the research is drive systems’ modelling and calculating energy consumption for public buses. Simulations were conducted in MATLAB/Simulink by modelling fuel cells and li-ion batteries where power consumption is driven by the instantaneous power demand of a bus on a given route. The simulation output includes the output power, energy consumption, efficiency, energy storage system requirements and refuelling times. The model can iterate energy storage options, to determine effects on system efficiency. Simulation results show that hybrid fuel cells buses offer up to 75% mass reduction, up to 43% volume reduction, with faster refuelling time, over battery only systems. This study provides a tool that allows comparison of multiple bus configuration for any route, on the path of viable, efficient and environmentally friendly transport system.

Metal hydride based thermal energy storage system requirements for high performance concentrating solar power plants

High temperature concentrating solar power plants require suitable thermal energy storage systems to produce electric power efficiently. Thermochemical energy storage based on metal hydrides represents a very appealing prospect for low cost and high efficient solar storage systems. The objective of the paper is to assess the properties required by the metal hydride systems to achieve the U.S. Department of Energy's SunShot techno-economic targets. A simplified model has been developed to evaluate the cost and the exergetic efficiency of hydride-based storage systems. Results demonstrate that metal hydride materials, operating at temperatures higher than 650 °C, with reaction enthalpy on the order of 95–110 kJ/molH2, raw material cost on the order of 1.4–2 $/kg, weight capacities on the order of 3–4% and operating pressures on the order of tens of bars have the potential to closely approach the targets. Selected sensitivity analyses have also been carried out showing that the raw material cost, the material weight capacity and the metal hydride reaction enthalpy are the properties that strongly affect the performance of the storage system.

Evaluation of Energy Storage System Requirements for Hybrid Mining Loaders

The objective of this paper is to evaluate technical requirements for electrochemical energy storage systems (ESSs) in hybrid mining loaders. These requirements take into account power and energy capacity, costs, life cycle, and safety-related requirements. The evaluation of the requirements is based on the characteristics of the current energy storage technology and vehicle simulation results. The evaluation shows that lithium-based batteries offer sufficient power and energy capacity; meanwhile, the requirements for cost and cycle life durability are dependent on the operating strategy and configuration of the loader. In particular, the power-intensive duty cycle of a mining loader can be challenging for batteries in terms of cycle life and thermal management.