Electric Power Storage Research Articles

Design Principles for Covalent Organic Frameworks in Energy Storage Applications.

Covalent organic frameworks (COFs) are an exciting class of porous materials that have been explored as energy-storage materials for more than a decade. This review discusses efforts to develop these materials for applications in gas and electrical power storage. Some of the design strategies for developing the gas sorption properties of COFs and mechanistic studies on their formation are also discussed.

木炭EDLCを用いた1kWh級蓄電器

The activated carbon particles made of charcoal by using an alkaline activation method were applied to the EDLC electrodes. The EDLC cells were assembled with 34% KOH water electrolyte. The density of energy was approximately 2.7Wh/L in the EDLC cells. The EDLC units (12V-EDLC) were composed of the 12 pieces of charcoal EDLC cell in a series connection. An electric power storage (1kWh class EDLC) was composed from the 30 pieces of 12V-EDLC unit in a parallel connection. The electric power storage quantity of the 1kWh class EDLC was approximately the summation of the composed 12V-EDLCs of power storage on design. The internal resistance of the composed 1kWh class EDLC was only 13mΩ. From the obtained results, there is a possibility of the over 1kWh class EDLC with low internal resistance is also composed of charcoal EDLCs.

Повышение энергетической эффективности локомотивов с накопителями энергии

Objective: The development of hybrid technologies is an aspect that carries serious changes for the railway industry, its design and technological base. These changes provide the scientific and technological breakthroughs to a much greater extent than the implementation of any new projects in traditional forms. Methods: Of great interest is the solution to the problem of hybrid locomotives and related power supply interaction. In addition, there are problems of quality and reliability of the rolling stock. The relationship between the three sets of technology, as well as the problem of support quality of the latter, becomes essential for the successful implementation of hybrid locomotives with a combined power plant. Results: The primary problems of locomotive projects in question are: electric power storage, in-depth modernization of the traction drive, and implementation of an optimal motion control algorithms in different modes. Increasing energy density stored in the traction battery, while reducing vehicle mass, ensures competitive advantages of eco-friendly hybrid locomotives versus traditional. The cost of the traction battery tends to dominate over the relevant economic parameters of other components of the traction drive hybrid locomotives, therefore, projects with a high technological level are relevant, while ensuring lower total weight of the vehicle. However, in the last decade, due to the increasing importance of electronic components in the transportation industry, along with the objectives stated above, problems of management optimization of rolling stock systems and provision of an appropriate level of quality control take center stage. Issues of energy storage application in the hybrid locomotive and their advantages over the currently used energy sources are considered in the article. Practical importance: It is shown that the use of a hybrid energy storage system will significantly increase the efficiency and reliability of the locomotive.

Probing Lipid Bilayers under Ionic Imbalance

Biological membranes are normally under a resting transmembrane potential (TMP), which originates from the ionic imbalance between extracellular fluids and cytosols, and serves as electric power storage for cells. In cell electroporation, the ionic imbalance builds up a high TMP, resulting in the poration of cell membranes. However, the relationship between ionic imbalance and TMP is not clearly understood, and little is known about the effect of ionic imbalance on the structure and dynamics of biological membranes. In this study, we used coarse-grained molecular dynamics to characterize a dipalmitoylphosphatidylcholine bilayer system under ionic imbalances ranging from 0 to ∼0.06 e charges per lipid (e/Lip). We found that the TMP displayed three distinct regimes: 1) a linear regime between 0 and 0.045 e/Lip, where the TMP increased linearly with ionic imbalance; 2) a yielding regime between ∼0.045 and 0.060 e/Lip, where the TMP displayed a plateau; and 3) a poration regime above ∼0.060 e/Lip, where we observed pore formation within the sampling time (80 ns). We found no structural changes in the linear regime, apart from a nonlinear increase in the area per lipid, whereas in the yielding regime the bilayer exhibited substantial thinning, leading to an excess of water and Na+ within the bilayer, as well as significant misalignment of the lipid tails. In the poration regime, lipid molecules diffused slightly faster. We also found that the fluid-to-gel phase transition temperature of the bilayer dropped below the normal value with increased ionic imbalances. Our results show that a high ionic imbalance can substantially alter the essential properties of the bilayer, making the bilayer more fluid like, or conversely, depolarization of a cell could in principle lead to membrane stiffening.

Direct Charge and Discharge Using the Glycolic Acid/Oxalic Acid Redox Couple for the Carbon-Neutral Energy Circulation

The major impact of increasing CO2 concentration on climate change has been recognised. Thus, efficient utilisation of renewable electricity is of increasing significant importance and development of various manner of its operation is required for our energetic and environmental sustainability. Recently, electric power storage in high-energy chemicals, called “energy carriers”, has received much attention for the efficient storage and on-demand supply of renewable electricity. Here, we demonstrate direct power charge using an alcohol/carboxylic acid redox couple. Highly transportable glycolic acid, an alcoholic compound, was successfully produced by electroreduction of oxalic acid, a dicarboxylic acid, on ubiquitous TiO2 catalysts with high efficiency and selectivity (70-95% Faradaic efficiency and >98% selectivity) under mild conditions in the potential region of -0.5 to -0.7 V vs. the RHE at 50 ºC. The most desirable characteristic of this electroreduction is the suppression of hydrogen evolution even in acidic aqueous media (Faradaic efficiency of 70–95%, pH 2.1). The detailed observation of TiO2 catalysts using scanning TEM and eels techniques provided a mechanistic insight into the highly selective catalysis. Recently, we coud demonstrate glycolic acid synthesis using an electrochemical cell consisting of the TiO2catalyst and a polymer electrolyte, i.e., a polymer electrolyte alcohol synthesis cell. Furthermore, we succeeded in electric power generation via the selective electrooxidation of glycolic acid to oxalic acid without CO2emission—specifically, carbon-neutral power generation. These results are the first experimental proof of concept for a carbon-neutral energy circulation system based on charging/discharging electric power using an alcohol/carboxylic acid redox couple[1, 2] as shown in Fig. 1. Reference [1] R. Watanabe, M. Yamauchi, M. Sadakiyo, R. Abe, T. Takeguchi, “CO2-free electric power circulation via direct charge and discharge using the glycolic acid/oxalic acid redox couple", Energy Environ. Sci. , 8, 1456-1462 (2015).[2] T. Matsumoto, M. Sadakiyo, M.L.Ooi, S.Kitano, T.Yamamoto, S.Matsumura, K. Kato, T. Takeguchi, and M. Yamauchi, “CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media” , Sci. Rep. , 4,5620(2014). Figure 1

Change of Average and Local Structures for 0.5Li2MnO3-0.5LiMn1/3Ni1/3Co1/3O2 in First Charge Process of Different Rate

In recent years, there is an increasing demand for lithium ion batteries. It was used in small devices such as mobile phones. Recently, the expansion of the intended use of electric vehicles and power storage equipment has been expected. However, it is necessary to improve high energy density. The solid solution material Li2MnO3 –Li（Mn,Ni,Co）O2 have attracted attention because they deliver high discharge capacity. On the other hand, it was reported such a problem that this material shows large irreversible capacity in the first cycle and discharge capacity greatly decreased at the high rate. It has been considered that irreversible capacity is due to oxygen removal to take place during the initial charge process above 4.5 V. But the mechanism of the discharge capacity fade is not clear. To commercialize the solid solution materials, it is necessary to solve the problem. We focused on the above problem. Our previous report described a transition metal rearrangement that occurs between 4.6 and 3.3 V during the initial discharge process at low rate [1]. In this study, we focused on the change of average and local structures of 0.5Li2MnO3 -0.5LiMn1/3Ni1/3Co1/3O2, layered solid solution material, during the initial charge process to clarify the arrangements of formation at the different rates. First, the change of average structures of 0.5Li2MnO3 -0.5LiMn1/3Ni1/3Co1/3O2, layered solid solution material during the initial charge process was clarified the arrangements of formation at different rates using Synchrotron X-ray [BL02B2, SPring-8, Japan] and neutron diffractions [iMATERIA, J-PARC, Japan}. The refined site occupancy in the charging process showed different results from before charge. The Mn occupancy localized to 4g site after charge at 1C rate whearas that moved from 4g site to 2b site at 3C rate. Although the both 4g and 2b sites were occupied by Co in the charging process at 1C rate, the only 4g site was occupied by Co in the charge at 3C rate. It was revealed that the differentiation of charge rate induced the atomic arrangement in the transition metal layer. Second, to clarify the mechanism local atomic arrangement change, we carried out PDF analysis using powder neutron diffraction measurements and synchrotron X-ray total scattering measurement [BL04B2, SPring-8, Japan]. In addition, first-principle calculation (VASP-code) used to determine the initial structure when performing PDF analysis. The λ and σ2 of optimal model was calculated after PDF analysis, in order to investigate the distortion of the crystal structure of the charging process of different rates.In the pristine, distortion of MnO6 octahedra is small compared to NiO6 and CoO6 octahedra. Comparing MnO6 and CoO6 octahedra distortion in the initial charging process at 1C rate, MnO6 octahedra showed an increasing trend. At 3C rate, CoO6 octahedra showed an increasing trend. In λ and σ2 of NiO6 octahedra entered the Li layer by cation mixing in the charging process at 3C rate increased . This was related to the trend of localization of Mn and Co of average structure. Perhaps, MO6 octahedra to localize tend to distorted in the charging process and localized element is different by the charging rate. Acknowledgement This work was supported in part by JSPS KAKENHI Grant Number 25420718. [1] Y. Idemoto et al, Electrochimica Acta, , 153, 399(2015).

Surface Modifications of LiMn2O4 electrode for Aqueous Lithium Ion Batteries

1. Introduction The rechargeable lithium-ion batteries (LIBs) have been considered as the power sources for the various applications from portable devices to high power applications such as electric vehicles and power storage for renewable energy [1]. However, their safety concerns and high cost are issues restricting their field for large scale energy storage system because the conventional LIBs contain the large energy and dangerous carbonate electrolyte. In this regards of safety and cost, the aqueous electrolyte can be the best candidate [2]. However, its practical application was limited due to its decreasing cycle life from poor electrochemical stability window. Here, we have shown that surface modifications of LiMn2O4 showed highly improved rate and cycle life in aqueous electrolyte. 2. Results and discussion The effect of the surface coating on the electrochemical properties of LiMn2O4 cathode in aqueous electrolyte solution was investigated by systematic electrochemical and instrumental analyses. The electrochemical performance of pristine LiMn2O4 and coated LiMn2O4 is presented. Despite the high ionic conductivity of the aqueous electrolyte (1 M Li2SO4 in water), the pristine LiMn2O4 did not show the high rate capabilities. In detail, the pristine and coated LiMn2O4 by 1,2, and 3wt.% AlF3 in aqueous electrolyte deliver the initial discharge capacity of 109.7, 106.6, 103.4 and 99.0 mAh g−1 at 1 C, respectively. The AlF3 coating has a dual role of surface stabilizer and resistance for lithium transportation. Based on these results, it is confirmed that the resistance from the surface failure mode of LiMn2O4 could be a main hurdle for cycle decaying especially in the aqueous electrolyte. After the surface modification of the electrochemically stable inorganic species, the rate capability and the cycle life are further improved. This coating enhance the surface stability to the aqueous solution and presents very promising cycle and rate capabilities for the development of ARLBs. Furthermore, they are investigated in detail by using XPS, SEM and TEM analyses. Acknowledgments This research was supported by the Post-Doctor Research Program (2014-2015) through the Incheon National University (INU) and the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT & Future Planning (NRF-2014R1A1A1038248). Reference [1] M.R. Palacin, Recent advances in rechargeable battery materials: a chemist’s perspective, Chem. Soc. Rev. 38 (2009) 2565-2575. [2] W. Li, J.R. Dahn, D.S. Wainwright, Rechargeable Lithium Batteries with Aqueous Electrolytes, Science 264 (1994) 1115-1118.

Synthesis and Electrochemical Properties of Li2MnO3 Li4Mn5O12 Binary System As Positive Electrode Materials for Lithium Ion Battery

Synthesis and Electrochemical Properties of Li2MnO3―Li4Mn5O12 Binary System as Positive Electrode Materials for Lithium Ion Battery Masaki Okada and Yuya Sakaguchi Inorganic Materials Research Laboratory, TOSOH CORPORATION Lithium ion batteries are their high energy density compared with other batteries, progressed recently applied to applications requiring large capacity like for electric power storage system and electric vehicle. The positive electrode materials for a lithium ion battery, lithium metal oxide containing a large amount of rare metallic element such as cobalt or nickel are mainly investigated. Positive electrode material containing a large amount of these rare elements is very difficult to achieve both high energy density and low cost. As a positive electrode material that does not contain a rare metallic element, it is being studied of Li2MnO3 with a layered rock-salt structure. Li2MnO3 shows a large discharge capacity of more than 250mAh/g in the first cycle, but the capacity decreases with charge and discharge cycles. [1-3] In this work, we studied the Li2MnO3―Li4Mn5O12 binary system (Li4/3-4X/5Mn2/3O2-2X/5, 0<X<1) of the positive electrode materials based on Li2MnO3. Li4/3-4X/5Mn2/3O2-2X/5 can be suppressed capacity fading as compared with the conventional Li2MnO3. It may be able to achieve both low cost and high energy density. Li4/3-4X/5Mn2/3O2-2X/5 was prepared by reacting of mixture of MnCO3･0.5H2O and LiOH･H2O as raw material. The mixture was fired at 400～600ºC for 32h in air stream. Crystal structure and multilayered particle structure were investigated through TEM and N2adsorption-desorption isotherm analysis, respectively. The electrochemical characterization of positive electrode material was performed on CR2032 coin type cells. From the TEM images of the prepared samples, the presence of two crystal phases was observed. In addition, the electron diffraction pattern is attributed to the rock salt and the spinel phase, the possibility of a two-phase coexistence structure of Li2MnO3 and Li4Mn5O12 having a twin structure has been suggested. The initial charge and discharge capacity of Li4/3-4X/5Mn2/3O2-2X/5 was reduced as compared with Li2MnO3, but cycle stability was improved (X=0.36, 170mAh/g@50th, 50mA/g, RT). In additionally, capacity fading is suppressed by magnesium substitution of a part of manganese, the substituted sample showed stable cycling at about 200mAh/g (X=0.36, Mg 8mol %). In the viewpoint of the crystal structure and multilayered particle structure, the effect of the characters on capacity and cycle ability will be discussed. [1] Denis Y.W. Yu et.al., J. Electrochem. Soc. 2009 156(6) A417-A424 [2] Denis Y.W. Yu et.al. J. Electrochem. Soc. 2010 157(11) A1177-A1182 [3] Denis Y.W. Yu et.al., J. Electrochem. Soc. 2011 158(9) A1015-A1022

A Study on the Power System Security under Future Uncertainties

SUMMARYIn this paper, we propose three applications to quantitatively evaluate N‐1 security with increased uncertainties. By using a robust dynamic security region (RDS), which is based on the concept of robust power system security (RS), the key region for judging the security and a new evaluation index for quantitative analysis, we can evaluate power system security as follows. (1) The calculation of the RDS at the time of yearly peak load demand can be recognized as the benchmark for the N‐1 security at present, and this method can be applied to the future power system with increased renewable energy resources (RES) such as PV. (2) We show the yearly declining trend for N‐1 security resulting from increased PV deployment year by year. (3) We calculate the necessary amount of additional power supply capacity, including conventional electric power generators or storage batteries, needed for maintaining the N‐1 security at the present level. The effectiveness of the proposed method is demonstrated through simulations using a model system with three machines.

Surface Modifications of LiFePO4 Electrode for Aqueous Lithium Ion Batteries

1. Introduction The rechargeable lithium-ion batteries (LIBs) with organic electrolytes have become the alternative energy supply for portable equipments, consumer electronic devices and high power applications such as electric vehicles and power storage for renewable energy [1]. However, their safety issue and high cost limit their application for large scale energy storage because LIBs use the flammable and expensive organic electrolytes. An aqueous rechargeable lithium battery (ARLB) was first reported by Dahn et al., which has advantages such as safety and low cost [2]. However, its practical application was hindered due to its poor cycling and not good rate capability. Here, we have shown that surface modifications of LiFePO4 showed a much better rate capability in aqueous electrolyte than pristine LiFePO4. 2. Results and discussion The influence of the surface coating on the electrochemical properties of LiFePO4 cathode in aqueous electrolyte solution was investigated by systematic electrochemical and instrumental analyses. The electrochemical performance of pristine LiFePO4 and coated LiFePO4 is presented in Fig. 1. Despite the high ionic conductivity of the aqueous electrolyte (1 M Li2SO4 in water), the pristine LiFePO4 did not show the high rate capabilities. In detail, the pristine LiFePO4 and coated LiFePO4 in aqueous electrolyte, which can deliver the initial discharge capacity of 127.5 and 132.1 mAh g−1 at 1 C, respectively. The pristine LiFePO4 and coated LiFePO4 have still the discharge capacity of 108.9 and 122.7 mAh g−1 after 100 cycles. Based on these results, it is confirmed that the resistance from the surface failure mode of LiFePO4 could be a main hurdle for cycle decaying especially in the aqueous electrolyte. After the surface modification of the electrochemically stable inorganic species, the rate capability and the cycle life are further improved. This coating enhance the surface stability to the aqueous solution and presents very promising cycle and rate capabilities for the development of ARLBs. Furthermore, they are investigated in detail by using XPS, SEM and TEM analyses. Acknowledgments This research was supported by the Post-Doctor Research Program (2014-2015) through the Incheon National University (INU) and the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT & Future Planning (NRF-2014R1A1A1038248). Reference [1] M.R. Palacin, Recent advances in rechargeable battery materials: a chemist’s perspective, Chem. Soc. Rev. 38 (2009) 2565-2575. [2] W. Li, J.R. Dahn, D.S. Wainwright, Rechargeable Lithium Batteries with Aqueous Electrolytes, Science 264 (1994) 1115-1118. Fig. 1. The cycling performance of pristine LiFePO4 and coated LiFePO4 in aqueous solution. Figure 1

Soft, thin skin-mounted power management systems and their use in wireless thermography

Power supply represents a critical challenge in the development of body-integrated electronic technologies. Although recent research establishes an impressive variety of options in energy storage (batteries and supercapacitors) and generation (triboelectric, piezoelectric, thermoelectric, and photovoltaic devices), the modest electrical performance and/or the absence of soft, biocompatible mechanical properties limit their practical use. The results presented here form the basis of soft, skin-compatible means for efficient photovoltaic generation and high-capacity storage of electrical power using dual-junction, compound semiconductor solar cells and chip-scale, rechargeable lithium-ion batteries, respectively. Miniaturized components, deformable interconnects, optimized array layouts, and dual-composition elastomer substrates, superstrates, and encapsulation layers represent key features. Systematic studies of the materials and mechanics identify optimized designs, including unusual configurations that exploit a folded, multilayer construct to improve the functional density without adversely affecting the soft, stretchable characteristics. System-level examples exploit such technologies in fully wireless sensors for precision skin thermography, with capabilities in continuous data logging and local processing, validated through demonstrations on volunteer subjects in various realistic scenarios.

Methanol for Renewable Energy Storage and Utilization

AbstractToday’s efforts to substitute fossil energy carriers by renewable energy sources suffer from fluctuations of wind and sunlight for which there is a lack of appropriate energy storage technologies, in particular for electricity. A promising method in this direction is chemical energy storage, as the energy density of the chemical bond is unrivaled. At present, there are chiefly two alternatives under discussion: power‐to‐gas (PtG) producing methane (synthetic natural gas, SNG) and power‐to‐liquid, which stores electric power in the form of methanol. However, the pros and cons of either technology are typically discussed without regarding the process economy and the overall efficiencies, and the material use of the target compounds has also been neglected. Detailed analyses of operational experiences from existing methane and methanol plants by AirLiquide (formerly Lurgi) revealed significant differences between both approaches, among which methanol has emerged to have the best overall efficiency (44.9 %). In addition, methanol has the additional advantage of being a universal chemical and fuel feedstock, thus representing the ideal candidate for not only chemical energy storage, but also for substituting fossil raw materials.

Integrated chemisorption cycles for ultra-low grade heat recovery and thermo-electric energy storage and exploitation

The integrated chemisorption technology driven by ultra-low grade heat for simultaneous electrical power and thermal energy storage has been investigated in this work. A resorption cycle employing low and high temperature salts, with the coupling between manganese chloride (MnCl2), calcium chloride (CaCl2) and sodium bromide (NaBr), was evaluated and compared in the proposed integrated system for a heat source temperature of between 30°C and 100°C. During the energy charging process, working fluid compression was introduced to convert mechanical power or electricity into chemical energy so that it could be stored during the adsorption process at the same time as utilising low temperature heat energy. During the energy discharging process, mechanical power could be generated via the expansion of the desorbed high pressure working vapour from the low temperature salt reactor, there is also a by-product potential of the cooling energy which can be extracted from the cold expansion exhaust. In addition to the power generation and the potential cold energy, upgraded heat could also be provided by the exothermic adsorption process in the high temperature salt reactor. The performance of this integrated cycle in terms of energy and exergy efficiency and energy density have been discussed. With the help of ultra-low grade heat, a 100% round-trip electricity storage efficiency of the proposed system has been found to be achievable using CaCl2–NaBr and MnCl2–CaCl2 pairs when the heat source temperature was higher than 50°C and 60°C, respectively. Also a temperature lift of the heat by 15–33°C and 22–68°C respectively was possible using these two adsorbent pairs.

Anti-Ferroelectric Ceramics for High Energy Density Capacitors.

With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE) display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

Performance of a 10-kJ SMES model cooled by liquid hydrogen thermo-siphon flow for ASPCS study

We propose a new electrical power storage and stabilization system, called an Advanced Superconducting Power Conditioning System (ASPCS), which consists of superconducting magnetic energy storage (SMES) and hydrogen energy storage, converged on a liquid hydrogen station for fuel cell vehicles. A small 10- kJ SMES system, in which a BSCCO coil cooled by liquid hydrogen was installed, was developed to create an experimental model of an ASPCS. The SMES coil is conductively cooled by liquid hydrogen flow through a thermo-siphon line under a liquid hydrogen buffer tank. After fabrication of the system, cooldown tests were carried out using liquid hydrogen. The SMES coil was successfully charged up to a nominal current of 200 A. An eddy current loss, which was mainly induced in pure aluminum plates pasted onto each pancake coils for conduction cooling, was also measured.

A Comparative Analysis of Technologies for Covering Peak Loads in the Power System

One of the key and so far completely unsolved problem of modern power engineering is minimizing the cost of compensating for the imbalance between the generated and consumed powers in power systems. In addition to traditional regulation methods using hydroelectric and thermal power plants, the possibilities of storing power in different forms, including stationary electrochemical storage systems, are being more and more widely used at present. It is planned in future to use the on-board storage batteries of electric vehicles (V2G technology) for this purpose. Traditional and promising future technologies for compensating load fluctuations in electric power systems have their own niche applications and costs under different operating conditions. In this paper we provide comparative estimates of the specific costs when compensating load fluctuations of different duration using traditional technologies, which use flexible power units and peak power plants, and also technologies based on the use of electrochemical electric power storage. The costs for 1 kW h of peak electric power and the costs in theory per 1 kW of peak power are estimated. As follows from the results of the calculations, the use of electrochemical storage is economically useful for continuous operating times of less than 1 h. To cover longer electric consumption fluctuations, the most suitable technologies remain flexible gas turbine systems and simple-cycle and gas-piston equipment under peak conditions.

THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING

The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with profile-steel bearing and cylindrical-Wall bearing have similar values in Mises stress, but the steel silo with profile-steel bearing has a smaller radial displacement and a better capability of buckling resistance. Meanwhile, the total steel volumes reduced 8.0% comparing to the steel silo with cylindrical-wall bearing. Therefore, steel soil with profile-steel bearing not only has a less steel volumes but also a good stability.

Evaluation of La2NiO4 as Anode Material for Solid Oxide Electrolyser Cells

Rising capacities in renewable energy production pose major challenges resulting from the decoupling between supply and demand, which requires long-range distribution and storage of electrical power. Electrolysis of water is considered a promising method for converting, storing and distributing surplus electrical energy in chemical form. Stimulated by the large-scale installation of wind parks, interest in high temperature steam electrolysis as a highly efficient means for hydrogen production is reviving. This technology appears to be especially favourable if external heat sources from power plants or industrial facilities can be utilised to assist in sustaining operating temperatures above 600°C.High temperature electrolysis is based on solid oxide electrolyser cells (SOEC) which adopt design concepts and materials developed for solid oxide fuel cells (SOFC). In this work the promising SOFC cathode material La2NiO4+δ is investigated with respect to its suitability as anode for SOEC application. Important material properties characterising electrical conductivity and oxygen transport kinetics are determined on densely sintered samples of La2NiO4+δ. In addition, its performance as air electrode is investigated on asymmetric cells under anodic polarisation at current densities of up to -410 mAcm-2 by means of impedance analysis and I-V measurements. Electrochemical characterisation is conducted at 800°C and 0.2 bar oxygen partial pressure and the long-term stability is studied over several thousand hours. Special emphasis is put on the effect of Cr-poisoning on the oxygen exchange kinetics and SOEC anode performance in dry and humid atmospheres. Results from post-test examination of porous electrode structures as well as dense samples of La2NiO4+δ by microstructural analysis with SEM-EDX and AFM are presented.

Experimental Research on Compensation for Power Fluctuation of the Renewable Energy Using the SMES Under the State-of-Current Feedback Control

Power generation by renewable resources that are environment friendly has been attractive lately. However, it is a big problem that the output fluctuation from the renewable energy sources causes instability to the power network when they are directly connected to the utility grid. Although a power storage system is effective for compensating for the output fluctuation, this electric power storage system must have large capacity and quick response. We proposed an advanced superconducting power conditioning system (ASPCS) composed of two kinds of power storage systems. In this paper, we experimentally verified the validity of the compensating system for fluctuating output power using a superconducting magnetic energy storage and an electronic load instead of an electrolyzer. It was demonstrated that the ASPCS was effective for compensating for the output fluctuation of the renewable energy.

Design of a subframe to integrate an electric drivetrain in existing vehicles

The global efforts on CO2 emission reduction reflect the importance of a change in personal mobility. Nowadays there is a need in the automotive sector to focus more and more on ecological energy sources. One key to approach this intention is to transfer the modular manufacturing, as known in the conventional car design, to the design of electric powered vehicles. Taking into account that renewable energy sources, for example hydrogen, green electric power or fuel produced out of plants, are able to be combined with an electrical drivetrain, which is able to handle all of them in once. The impressive opportunity is that all those energy sources have a commonality. All of them can be used to produce electrical power onboard. The easiest way seems to be the storage of electrical power in rechargeable batteries; however there are various different options. Hydrogen can be utilized in a fuel cell to produce electrical power and every hydrocarbon fuel can also be used to power a fuel cell in combination with a previous steam reformation. Considering hydrocarbon fuel, there is further the alternative to burn it in combustion engines and to combine it with a generator. The perspective of this short excursus is that it does not depend on the chosen energy resource, because there is always the option to use the energy, to power an electrical drivetrain.This assumption leads to the encouragement to develop a modular and scalable electric driven axle, which is easily adaptable to ensure a compatibility with a brought field of vehicles.