Organic rechargeable batteries have attracted extensive attention as a potential alternative for the current lithium-ion batteries. However, most of the reports are limited to organic macromolecules or modified small organic molecules which exhibit low reversible capacity, poor rate capability, and very limited cycle life. Herein, a small organic compound, maleic acid, is adopted as the anode for lithium ion batteries without any modification. It exhibits an ultrahigh reversible capacity of ca. 1500 mAh g–1 at 46.2 mA g–1 current density. Even at a high current density of 46.2 A g–1, the electrode still delivers a capacity of 570.8 mAh g–1. When cycled at 2.31 A g–1, a capacity retention of 98.1% is obtained after 500 cycles. The excellent performance of the maleic acid organic anode is ascribed to its small volume effect and unique lithium-ion storage mechanisms. This new type of organic anode material may have a great opportunity for large-scale energy-storage systems with high-power properties.

Ultrahigh-Capacity Organic Anode with High-Rate Capability and Long Cycle Life for Lithium-Ion Batteries

This study is focused on the topical issue of increasing the energy efficiency in DC railway systems, in the context of global concerns for reducing the CO2 emissions by minimizing the energy consumption and energy loss. The main achievements in this complex issue are synthesized and discussed in a comprehensive review, emphasizing the implementation and application of the existing solutions on concrete case studies. Thus, all specific subtopics related to the energy efficiency are covered, starting with power quality conditioning and continuing with the recovery of braking energy, of which a large part is lost in the classic DC-traction substations. The solutions of onboard and wayside storage systems for the braking energy are discussed and compared, and practical examples are given. Then, the achievements in transforming the existing DC-traction substations in reversible substations with capabilities of power quality improvement are systematically reviewed by illustrating the main results of recent research on this topic. They include the equipment available on the market and solutions validated through implementations on experimental models. Through the results of this extensive review, useful reference and support are provided for the research and development focused on energy efficient traction systems.

A Review of the Energy Efficiency Improvement in DC Railway Systems

This paper describes the development of a bilateral dc/dc converter rated at 1500 V with a peak power of 500 kW for battery energy storage systems supporting railway dc feeder systems. The dc/dc converter converts regenerated power from a braking train and charges the batteries. The dc/dc converter discharges the stored energy to feed the train during powering. The converter main circuit and the control system are described, and successful test results obtained at the factory are reported. For the main circuit test, a special test method was applied. For the control system test, a real-time digital simulator was used for hardware-in-loop tests. In addition to the converter tests, the results from dc feeder system tests with an actual rectifier and battery bank are also presented.

Development of DC/DC Converter for Battery Energy Storage Supporting Railway DC Feeder Systems

The application of a stationary ultra-capacitor energy storage system (ESS) in urban rail transit allows for the recuperation of vehicle braking energy for increasing energy savings as well as for a better vehicle voltage profile. This paper aims to obtain the best energy savings and voltage profile by optimizing the location and size of ultra-capacitors. This paper firstly raises the optimization objective functions from the perspectives of energy savings, regenerative braking cancellation and installation cost, respectively. Then, proper mathematical models of the DC (direct current) traction power supply system are established to simulate the electrical load-flow of the traction supply network, and the optimization objections are evaluated in the example of a Chinese metro line. Ultimately, a methodology for optimal ultra-capacitor energy storage system locating and sizing is put forward based on the improved genetic algorithm. The optimized result shows that certain preferable and compromised schemes of ESSs’ location and size can be obtained, acting as a compromise between satisfying better energy savings, voltage profile and lower installation cost.

https://www.mdpi.com/1996-1073/7/10/6434/pdf

An Improved Genetic Algorithm for Optimal Stationary Energy Storage System Locating and Sizing

As a large energy consumer, the railway systems in many countries have been electrified gradually for the purposes of performance improvement and emission reduction With the widespread utilization of energy-saving technologies such as regenerative braking techniques, and in support of the full electrification of railway systems in a wide range of application conditions, energy storage systems (ESSes) have come to play an essential role In this paper, some recent developments in railway ESSes are reviewed and a comprehensive comparison is presented for various ESS technologies The foremost functionalities of the railway ESSes are presented together with possible solutions proposed from the academic arena and current practice in the railway industry In addition, the challenges and future trends of ESSes in the railway industry are briefly discussed

Energy Storage Devices in Electrified Railway Systems - A Review

In 2006, the first Li-ion battery was installed in traction power supply system by West Japan Railway Company and now more than 20 energy storage systems have already installed in traction power supply system in Japan. In this article, the recent trend for regenerative energy utilization is summarized not only in d.c. railway but also a.c. railway. We, East Japan Railway Company, have installed 3 energy storage systems for d.c. railway and one railway static power conditioner for a.c. railway for regenerative energy utilization. The effects of these systems are also shown quantitatively in this paper.

Review of regenerative energy utilization in traction power supply system in Japan: Applications of energy storage systems in d.c. traction power supply system

Railway is widely recognized as eco-friendly transportation method. For example, in Japan, CO2 emission per person per 1km by railway is about 18g while it is 164g for car and 108g for air plane. On the other hand, the total amount of energy consumption for railway operation is not small and it is important to improve efficiency of energy utilization in traction power supply system more. As one of the most possible solutions to improve energy efficiency in traction power supply system, a regenerative utilization is expected and some energy storage systems have realized in d.c. traction power supply system in Japan. In this paper, some methods to make use of regenerative energy are compared not only in the effect but also in the cost. Other existing choices for eco-friendly energy utilization such as energy saving at station and renewable energy utilization are also compared. In conclusion, regenerative energy utilization by energy storage system has a large potential and will be a practical choice even from the viewpoint of return on investment in the near future.

Comparative study of investment and efficiency to reduce energy consumption in traction power supply: A present situation of regenerative energy utilization by energy storage system

In this paper, some application examples of energy saving measures in two representative Japanese railway companies, mainly in d.c. electric traction power supply system, are introduced. The effect of electric energy storage systems installed to substations is mentioned especially. In addition, it is also described about the potential of regenerative braking energy, which will be able to be utilized by installation of energy storage systems or other measures.

Application examples of energy saving measures in Japanese DC feeding system

In this paper, concerned with an energy storage system (ESS) with Li-ion battery for DC traction power system, a study about planning of introducing ESS and the performances of two examples in actual operation are described. Through this study, a suitable condition for introducing ESS with respect to headway of trains was obtained and confirmed by analysis measurements. Further, the effects of adjusting threshold voltages of charge and discharge on the practical use of ESS are also described.

/pdf/introduction-and-practical-use-of-energy-storage-system-with-5bj9jn5oxp.pdf

Takashi Yamanoi

Papers

Review of regenerative energy utilization in traction power supply system in Japan: Applications of energy storage systems in d.c. traction power supply system

Comparative study of investment and efficiency to reduce energy consumption in traction power supply: A present situation of regenerative energy utilization by energy storage system

Application examples of energy saving measures in Japanese DC feeding system

Introduction and Practical Use of Energy Storage System with Lithium-ion Battery for DC Traction Power Supply System