High-capacity Energy Storage System Research Articles

Nickel-iron layered double hydroxides and reduced graphene oxide composite with robust lithium ion adsorption ability for high-capacity energy storage systems

Rationally designed electrode materials with high capacity, excellent stability, and good rate capability are essential for high-performance energy storage systems. This study reported the design of nickel-iron layered double hydroxides nanosheets and reduced graphene oxide composites (NiFe-LDHs/rGO composites) for high-capacity LIB electrode. The NiFe-LDHs/rGO composites were prepared by adsorption of Ni2+ and Fe3+ ions onto the graphene oxide (GO) surface, co-deposition of NiFe-LDHs nanosheets from the adsorbed ions in alkaline solution, and reduction of GO into rGO. In the composites, a large interlayer spacing of 7.55 Å and proper adsorption energy for Li+ ion (−4.36 eV) in NiFe-LDHs nanosheets greatly facilitate the reversible transport and storage of abundant Li+ ions. Meanwhile, the outer rGO wrappings offer a highly conductive matrix as efficient electron pathways. With these advantages, the NiFe-LDHs/rGO composites demonstrated a good cyclic stability with 602.8 mAh g−1 capacity remained over 80 charge/discharge cycles at a current density of 500 mA g−1. Thus, our studies offer a low-cost NiFe-LDHs/rGO material for high-performance LIBs.

Numerical study of the Martelange mine to be used as underground reservoir for constructing an Underground Pumped Storage Hydropower plant

Abstract. Underground Pumped Storage Hydropower (UPSH) using abandoned mines has been considered as a potential high capacity Energy Storage Systems. In UPSH plants, the excess of electricity is stored in the form of potential energy by pumping water from an underground reservoir (abandoned mine in this paper) to a surface reservoir, while electricity is produced (when the demand increases) discharging water from the surface into the underground reservoir. The main concerns may arise from the water exchanges occurring between the underground reservoir and the surrounding medium, which are relevant in terms of environmental impact and UPSH efficiency. Although the role of the water exchanges has been previously addressed, most studies are based on synthetic models. This work focuses on a real abandoned slate mine located in Martelange (Belgium). The effects of different rehabilitation works to prepare the mine as an underground reservoir are assessed in terms of groundwater exchanges and their associated consequences.

Real-Time Dynamic Simulation of Korean Power Grid for Frequency Regulation Control by MW Battery Energy Storage System

The aim of this study was to develop a real-time dynamic simulator of a power grid with power plant and battery model. The simulator was used to investigate the frequency control characteristics of a megawatt-scale high-capacity energy storage system connected to the electric power grid. In this study, a lithium-ion secondary battery was chosen as one of the batteries for a grid-connected model. The dynamics of the model was analysed in both steady and transient states. The frequency control system of the battery model plays a role in regulating the grid frequency by controlling the power of energy storage systems according to process variables and grid frequencies. The power grid model based on the current power network of South Korea, included power plants, substations and power demands. The power supply is classified by the type of turbine generator as thermal, nuclear, hydro power, pumped power storage, combined power plants and batteries, including high-capacity energy storage systems rated for a maximum of 500 MW. This study deals with an installed capacity of 87.17 GW and peak load of 77.30 GW in the Korean power grid. For 24 hours of operation, the maximum and minimum power outputs were simulated as 61.59 GW and 46.32 GW, respectively. The commercialized real-time dynamic simulation software ProTRAX was used. The simulation was conducted to observe the operation characteristics of the frequency control system during a breakdown of power plants, as well as under governor-free operation, auto generation control operation, and with the battery energy storage system connected. The results show that the model is valid for each power plant breakdown simulation. They also confirm that the output power and frequency controls of the battery operated well during simulations.

Frame-filling structural nanoporous carbon from amphiphilic carbonaceous mixture comprising graphite oxide

Among all of the requirements for carbon materials used in electric double-layer capacitors (EDLCs), specific surface area (SSA) and electrical conductivity is a pair of mutual competing demands. In this paper, a series of frame-filling structural nanoporous carbons were prepared using an amphiphilic mixture of graphite oxide and a coal tar pitch-based carbonaceous material as precursor ensuring a high carbon yield. In the final porous composites, the few-layer graphene microsheets derived from graphite oxide contribute to the conductive frame construction by randomly cross-stacking during exfoliation and thermal reduction, while nanoparticles derived from coal tar pitch-based carbonaceous material fill into the frame and chemically bind on the surface of graphene microsheets of about 2 nm in thickness. The SSA is up to 2441 m2 g−1 and the electrical conductivity is 179 S/m. It has energy storage superiorities over an ordinary nanoporous carbon, rendering a shortened relaxation time constant (5.34 s), improved gravimetric capacitance (115.4 F/g) as well as cyclic stability in 10,000 cycles with 87.8% capacity retention in 1 M TEABF4/PC electrolyte. The frame-filling structural nanoporous carbon shows great potential for blocks or high-capacity energy storage system by complex serial-parallel.

Stabilizing the surface of lithium metal

Abstract

Integration of fuel cells and supercapacitors in electrical microgrids: Analysis, modelling and experimental validation

This article examines a hybrid storage system comprising fuel cells (FC) and supercapacitors (SC) for an electrical microgrid located in the Renewable Energies Laboratory at the Public University of Navarre. Firstly, the hybrid storage system size was determined based on an energy and frequency analysis of real data for the electrical power generated and consumed in the microgrid over the course of a year in operation. This was followed by the experimental characterisation of the electrical behaviour of the FCs and SCs, in steady-state and dynamic modes of operation. Furthermore, an electrical model was developed for the FCs and another for the SCs, both of which gave satisfactory results in the experimental validations. Finally, a study was made of the storage system, comprising four 1.2 kW proton exchange membrane fuel cells (PEMFC) and three SCs of 83.3 F and 48.6 V each, in a real microgrid operating environment. Specifically, a comparison was made between the storage system solely comprising FCs and the hybrid storage system formed by a combination of FCs and SCs. The hybridisation of the FCs and SCs resulted in a complete, high-capacity energy storage system, to guarantee supply even in those months with low renewable energy resources and, in turn, able to provide the fast dynamic responses regularly required by supply and demand in the microgrid.

Smart Operation of Smart Grid: Risk-Limiting Dispatch

The drastic reduction of carbon emission to combat global climate change cannot be realized without a significant contribution from the electricity sector. Renewable energy resources must take a bigger share in the generation mix, effective demand response must be widely implemented, and high-capacity energy storage systems must be developed. A smart grid is necessary to manage and control the increasingly complex future grid. Certain smart grid elements-renewables, storage, microgrid, consumer choice, and smart appliances-increase uncertainty in both supply and demand of electric power. Other smart gird elements-sensors, smart meters, demand response, and communications-provide more accurate information about the power system and more refined means of control. Simply building hardware for renewable generators and the smart grid, but still using the same operating paradigm of the grid, will not realize the full potential for overall system efficiency and carbon reduction. In this paper, a new operating paradigm, called risk-limiting dispatch, is proposed. It treats generation as a heterogeneous commodity of intermittent or stochastic power and uses information and control to design hedging techniques to manage the risk of uncertainty.