Economics of electric energy storage for energy arbitrage and regulation in New York

Unlike markets for storable commodities, electricity markets depend on the real-time balance of supply and demand. Although much of the present-day grid operates effectively without storage, cost-effective ways of storing electrical energy can help make the grid more efficient and reliable. We investigate the economics of two emerging electric energy storage (EES) technologies: sodium sulfur batteries and flywheel energy storage systems in New York state's electricity market. The analysis indicates that there is a strong economic case for EES installations in the New York City region for applications such as energy arbitrage, and that significant opportunities exist throughout New York state for regulation services. Benefits from deferral of system upgrades may be important in the decision to deploy EES. Market barriers currently make it difficult for energy-limited EES such as flywheels to receive revenue for voltage regulation. Charging efficiency is more important to the economics of EES in a competitive electricity market than has generally been recognized.     

Research progress on fre protection technology of LFP lithium-ion battery used in energy storage power station

随着电化学储能市场的蓬勃发展,电化学储能电池本身的安全性越来越受到关注,如何最大程度地降低储能电池组火灾风险是电化学储能大规模应用时亟需解决的问题。本文综述目前国内外针对锂离子电池热失控已有的研究成果,包括磷酸铁锂电池的燃烧特性、火灾危险等级以及在储能电站预警系统中应用的锂离子电池热失控及热扩散参数;梳理不同灭火剂对电池火灾的灭火效率;同时总结电化学储能电站的灭火系统选择,为电网储能工程应用提供参考,有效支持锂离子储能电池的大规模工程需求。     

Application and prospect of zinc nickel battery in energy storage technology

本文介绍了近几年电力储能在全球储能领域的现况及电力储能在现有储能系统中的应用规模。针对目前较成熟的电化学储能电池进行了分析,着重分析了锌镍电池的特点,首先对锌镍电池的低温放电性能、寿命、大电流充放等性能进行了阐述,模拟储能系统充放电实验的结果表明锌镍电池具有循环寿命长和充放电效率高等特点。其次对单液流锌镍电池的工作原理进行了介绍,就目前单液流锌镍电池的各个型号的中试产品以及50 kW·h储能系统进行了总结和讨论,分析表明锌镍电池作为一种新型的蓄电池,其循环寿命长、安全性能好、制造和维护成本较低,随着近几年新材料的发展,锰正极的锌基电池实验成功,促进了锌空气电池、锌铁电池等系列锌基电池的研发,锌镍电池未来在储能市场将会大放异彩。     

Operation conditions of batteries in PV applications

For a continuous energy supply of photovoltaic operated and off-grid loads, the storage of the solar generated electrical energy is necessary. About 60% of all over the world manufactured solar cells are used for such stand alone systems. In case of photovoltaic systems, mainly electrochemical battery storage systems are used.

The paper describes the requirements for batteries in solar systems. The most important storage systems, such as lead–acid, NiMH and Li-ion batteries are described in detail and further developing trends are discussed.

As it is well known that the operation conditions strongly influence the battery lifetime, this paper reviews photovoltaic operation conditions and experience in performance and lifetime in photovoltaic systems.     

Challenges for rechargeable batteries

Strategies for Li-ion batteries that are based on lithium-insertion compounds as cathodes are limited by the capacities of the cathode materials and by the safe charging rates for Li transport across a passivating SEI layer on a carbon-based anode. With these strategies, it is difficult to meet the commercial constraints on Li-ion batteries for plug-in-hybrid and all-electric vehicles as well as those for stationary electrical energy storage (EES) in a grid.Existing alternative strategies include a gaseous O₂ electrode in a Li/air battery and a solid sulfur (S₈) cathode in a Li/S battery. We compare the projected energy densities and EES efficiencies of these cells with those of a third alternative, a Li/Fe(III)/Fe(II) cell containing a redox couple in an aqueous solution as the cathode. Preliminary measurements indicate proof of concept, but implementation of this strategy requires identification of a suitable Li⁺-ion electrolyte.     

Fundamental scientific aspects of lithium batteries(I)--Thermodynamic calculations of theoretical energy densities of chemical energy storage systems

本文主要讨论电池的能量密度.基于热力学数据,根据能斯特方程,可以计算不同电化学反应体系的理论能量储存密度,从而了解化学储能体系理论能量密度的上限,了解哪些体系能够实现更高的能量密度,哪些材料具有更高的电压.     

A review of electrical energy storage technologies for renewable power generation and smart grids

储能技术是突破可再生能源大规模开发利用瓶颈的关键技术,是智能电网的必要组成部分.在储能市场商业化雏形阶段,系统性的比较分析各类储能技术的性能特点,为未来市场发展提供筛选技术路线的框架基础至关重要.本文阐述了储能技术在可再生能源发电和智能电网中的作用,对物理储能(抽水蓄能,压缩空气储能,飞轮储能),电化学储能(二次电池,液流电池),其它化学储能(氢能,合成天然气)等储能技术进行了系统的比较与分析,最后提出储能技术的发展趋势.     

Research progress on capacitive lithium-ion battery

锂离子电池具有高的能量密度,而超级电容器则以高功率密度和长循环寿命为突出优势。电容型锂离子电池是在锂离子电池的正极中加入部分电容炭材料,在不显著降低能量密度的情况下,大幅度改善锂离子电池的功率特性和循环寿命,从而实现电容与电池技术的融合。本文综述了国内外近年来在电容型锂离子电池领域的最新研究进展,介绍了主要的电容型锂离子电池体系及其性能特点,并对其未来发展方向进行了展望。     

Introducing the energy efficiency map of lithium‐ion batteries

The charge, discharge, and total energy efficiencies of lithium‐ion batteries (LIBs) are formulated based on the irreversible heat generated in LIBs, and the basics of the energy efficiency map of these batteries are established. This map consists of several constant energy efficiency curves in a graph, where the x‐axis is the battery capacity and the y‐axis is the battery charge/discharge rate (C‐rate). In order to introduce the energy efficiency map, the efficiency maps of typical LIB families with graphite/LiCoO₂, graphite/LiFePO₄, and graphite/LiMn₂O₄ anode/cathode are generated and illustrated in this paper. The methods of usage and applications of the developed efficiency map are also described. To show the application of the efficiency map, the effects of fast charging, nominal capacity, and chemistry of typical LIB families on their energy efficiency are studied using the generated maps. It is shown how energy saving can be achieved via energy efficiency maps. Overall, the energy efficiency map is introduced as a useful tool for engineers and researchers to choose LIBs with higher energy efficiency for any targeted applications. The developed map can be also used by energy systems designers to obtain accurate efficiency of LIBs when they incorporate these batteries into their energy systems.     

Lead carbon ultrabatteries for energy storage

储能技术在太阳能、风能等可再生能源发电、智能电网/微网建设等方面有着广阔的应用前景。铅酸电池具有价格低、较高电压、性能稳定、宽工作温度范围等优势,占据着固定储能市场的主导地位。但在智能电网、混合动力车的实际应用中,电池必须在不同的充电状态下操作,特别是在高倍率部分荷电模式。在这种操作模式下,硫酸盐沉积物积聚在电极表面,限制了铅酸电池的容量和循环寿命。铅碳电池是由铅酸电池和超级电容器组合形成的新型储能装置,它抑制了放电过程中负极板表面硫酸盐的不均匀分布和充电时较早的析氢现象,具有铅酸电池高能量和超级电容器高功率的优点,在部分荷电态大功率充放电状态具有较高的循环寿命,适合高倍率循环和瞬间脉冲放电等工作状态。本文介绍了铅碳电池的基本概念及原理,并对铅碳电池储能技术的发展历程和现状进行了总结。     

Redox flow batteries—Concepts and chemistries for cost-effective energy storage

Electrochemical energy storage is one of the few options to store the energy from intermittent renewable energy sources like wind and solar. Redox flow batteries (RFBs) are such an energy storage system, which has favorable features over other battery technologies, e.g. solid state batteries, due to their inherent safety and the independent scaling of energy and power content. However, because of their low energy-density, low power-density, and the cost of components such as redox species and membranes, commercialised RFB systems like the all-vanadium chemistry cannot make full use of the inherent advantages over other systems. In principle, there are three pathways to improve RFBs and to make them viable for large scale application: First, to employ electrolytes with higher energy density. This goal can be achieved by increasing the concentration of redox species, employing redox species that store more than one electron or by increasing the cell voltage. Second, to enhance the power output of the battery cells by using high kinetic redox species, increasing the cell voltage, implementing novel cell designs or membranes with lower resistance. The first two means reduce the electrode surface area needed to supply a certain power output, thereby bringing down costs for expensive components such as membranes. Third, to reduce the costs of single or multiple components such as redox species or membranes. To achieve these objectives it is necessary to develop new battery chemistries and cell configurations. In this review, a comparison of promising cell chemistries is focused on, be they all-liquid, slurries or hybrids combining liquid, gas and solid phases. The aim is to elucidate which redox-system is most favorable in terms of energy-density, power-density and capital cost. Besides, the choice of solvent and the selection of an inorganic or organic redox couples with the entailing consequences are discussed.     

一种退役动力电池梯次利用储能系统安全评估方法

以梯次利用于储能系统的退役动力电池为研究对象,提出一种梯次利用电池组合安全评估方法,采用梯次利用电池厂家、种类、测试等多维数据,通过熵权-TOPSIS法及层次分析法对梯次利用电池安全性能进行综合评估与算例分析。研究结果表明：对拟采用不同厂家、批次、种类退役动力电池构建的储能系统,该方法可对其中的梯次电池进行有效安全评估,有助于选用安全性更高的梯次电池来构建储能系统,进一步提升系统安全性,符合梯次利用储能系统大规模推广建设的现实需要。     

A hierarchical management system for energy storage batteries

现有的储能电池管理系统大都是从电动汽车电池管理系统直接引用过来的,其管理的电池容量小,功能单一,实时性较差.兆瓦级储能系统由大容量电池串联,对电池系统管理效率提出了新要求.为解决这一问题,提出了一种3层分层式储能电池管理系统.对底层BMU,中层BCMS和顶层BAMS从硬件和软件设计两方面做了详细地介绍.分层式储能电池管理系统具有检测与计算,电池单体均衡管理,高压管理,统计存储,充放电管理,报警功能和通信.     

Electrode and electrolyte materials for electrochemical capacitors

Among different electric energy storage technologies electrochemical capacitors are used for energy storage applications when high power delivery or uptake is needed. Their energy and power densities, durability and efficiency are influenced by electrode and electrolyte materials however due to a high cost/performance ratio; their widespread use in energy storage systems has not been attained yet.Thanks to their properties such as high surface area, controllable pore size, low electrical resistance, good polarizability and inertness; activated carbons derived from polymeric precursors are the most used electrode materials in electrochemical capacitors at present. Other electrode materials such as shaped nano-carbons or metal oxides are also investigated as electrode materials in electrochemical capacitors, but only as useful research tools.Most commercially used electrochemical capacitors employ organic electrolytes when offering concomitant high energy and high power densities. The use of aqueous based electrolytes in electrochemical capacitor applications is mainly limited to research purposes as a result of their narrow operating voltage. Recent studies on room temperature ionic liquids to be employed as electrolyte for electrochemical capacitor applications are focused on fine tuning their physical and transport properties in order to bring the energy density of the device closer to that of batteries without compromising the power densities.In this paper a performance analysis, recent progress and the direction of future developments of various types of materials used in the fabrication of electrodes for electrochemical capacitors are presented. The influence of different types of electrolytes on the performance of electrochemical capacitors such as their output voltage and energy/power densities is also discussed.     

Electric energy storage systems in a market-based economy: Comparison of emerging and traditional technologies

Unlike markets for storable commodities, electricity markets depend on the real-time balance of supply and demand. Although much of the present-day grid operate effectively without storage technologies, cost-effective ways of storing electrical energy can make the grid more efficient and reliable. This work addresses an economic comparison between emerging and traditional Electric Energy Storage (EES) technologies in a competitive electricity market. In order to achieve this goal, an appropriate Self-Scheduling (SS) approach must first be developed for each of them to determine their maximum potential of expected profit among multi-markets such as energy and ancillary service markets. Then, these technologies are economically analyzed using Internal Rate of Return (IRR) index. Finally, the amounts of needed financial supports are determined for choosing the emerging technologies when an investor would like to invest on EES technologies. Among available EES technologies, we consider NaS battery (Natrium Sulfur battery) and pumped-storage plants as emerging and traditional technologies, respectively.     

Evaluation of distributed building thermal energy storage in conjunction with wind and solar electric power generation

Energy storage is often seen as necessary for the electric utility systems with large amounts of solar or wind power generation to compensate for the inability to schedule these facilities to match power demand. This study looks at the potential to use building thermal energy storage as a load shifting technology rather than traditional electric energy storage. Analyses are conducted using hourly electric load, temperature, wind speed, and solar radiation data for a 5-state central U.S. region in conjunction with simple computer simulations and economic models to evaluate the economic benefit of distributed building thermal energy storage (TES). The value of the TES is investigated as wind and solar power generation penetration increases. In addition, building side and smart grid enabled utility side storage management strategies are explored and compared. For a relative point of comparison, batteries are simulated and compared to TES. It is found that cooling TES value remains approximately constant as wind penetration increases, but generally decreases with increasing solar penetration. It is also clearly shown that the storage management strategy is vitally important to the economic value of TES; utility side operating methods perform with at least 75% greater value as compared to building side management strategies. In addition, TES compares fairly well against batteries, obtaining nearly 90% of the battery value in the base case; this result is significant considering TES can only impact building thermal loads, whereas batteries can impact any electrical load. Surprisingly, the value of energy storage does not increase substantially with increased wind and solar penetration and in some cases it decreases. This result is true for both TES and batteries and suggests that the tie between load shifting energy storage and renewable electric power generation may not be nearly as strong as typically thought.     

Renewable energy integration through optimal unit commitment and electricity storage in weak power networks

In this work, the impact of intermittent renewable energy sources on total production cost is evaluated, using annual data regarding the isolated power system of the island of Cyprus. Once electrical energy storage (EES) is identified as an approach enhancing flexibility and reliability, the selected EES facilities are modelled and evaluated via a life-cycle cost analysis, based on the most realistic characteristics and cost metrics found in the literature. The results derived from the uncertainty analysis performed, show that vanadium-redox flow battery provides the highest net present value (NPV). However, sodium-sulfur battery system offers the most secure investment in terms of uncertainty range and mean value, followed by lead-acid battery system. Lithium-ion battery system exhibits expensive capital cost which still governs its overall cost performance achieving a negative mean NPV far below zero.     

Dynamic evaluation of two configurations for a hybrid DFIG‐based wind turbine integrating battery energy storage system

Hybrid systems comprising battery energy storage systems (BESSs) and wind power generation entail considerable advances on the grid integration of renewable energy. Doubly fed induction generators (DFIGs) stand out among different wind turbine (WT) technologies. On the other hand, electrochemical batteries have proved to be valid for these purposes. In this paper, a comparative analysis is carried out between two alternative configurations for hybrid WT‐BESS systems, where the BESS is connected either outside or inside the DFIG. The modeling of these two configurations and the control systems applied for achieving the coordinate operation of the energy sources (DFIG and batteries) are illustrated. The hybrid systems under study are evaluated by simulation under normal operation (wind speed fluctuations and grid demand changes) and grid faults. Simulation results show that both configurations improve the grid integration capability of the WT, although the configuration with external BESS presents better results since it can provide additional active/reactive power injection. Copyright © 2014 John Wiley & Sons, Ltd.     

All year power supply with off-grid photovoltaic system and clean seasonal power storage

The objective of the project is an all-year secure supply of alternating current based on a solar energy island grid consisting of serial components and seasonal energy storage. Photovoltaic modules, inverters, electrolysers, batteries, hydrogen stores and fuel cells form the basis of the independent power supply system. For this, selected load profiles were analysed and evaluated in theory and practice.The analysis is based on the results of the test runs of the system and the simulations, in which the combined hydrogen-battery-system is compared to the battery system.It was revealed that it is sensible to complement an island grid operating on lead batteries for shortterm energy supply with hydrogen as a long-term store. This ensures a year-round supply security based on solar energy and the extension of the life span of the batteries required for hydrogen-based power stores. The systems based purely on batteries can not provide perfect supply security during long periods of low solar radiation since they do not possess energy stores which allow long-term energy storage.Hence a seasonal energy store, such as hydrogen, is required to guarantee reliable power supply for every day of the year.Autonomous power supply systems with long-term energy stores operate independently from the public grid system and can be implemented without elaborate intelligent energy management. For this, however, the costs of the serial components must be reduced and the efficiency of the system must be improved.     

Recent progress in the application of carbon materials to supercapacitors and lead-carbon batteries

新型炭材料是电化学储能领域中非常重要的一类储能材料,目前广泛应用于各种电化学储能器件.本文综述了具有电容特性的高比表面积炭材料在超级电容器与铅炭电池中的应用.采用不同的方法合成具有高比表面积的新型炭材料作为超级电容器电极材料,能够得到较高的比容量.适量高比表面积的炭材料应用于铅酸电池负极,形成铅炭电池,极大地提高了电池的储能特性.论文最后探讨了新型炭材料在超电容以及铅炭电池中应用的发展方向.