101,921 research outputs found
Tools for Life Cycle Estimation of Energy Storage System for Primary Frequency Reserve
No full textBattery energy storage systems are widely recognized as viable means for providing frequency regulation in electrical systems characterized by the massive deployment of renewable resources. In this case, the estimation of the battery lifetime is very complex since its response depends strongly on the stochastic nature of various contingencies. By starting from the characterization of the power system frequency in terms of the stochastic process, in this paper, tools needed for the battery lifetime estimation are detailed. On the basis of a realistic dynamic model, the state of charge profile requested to a battery providing primary frequency regulation is derived, with the aim of characterizing statistically its degradation. In this way, it is expected to obtain an efficient battery lifetime estimation compared to the heuristic methods. Numerical simulations are carried out in the last part of the paper, illustrating a simulation tool for the estimation of the battery working cycle. © 2018 IEEE
Accelerated life tests of complete lithium-ion battery systems for battery life statistics assessment
No full textThe paper investigates the performances of automotive lithium-ion battery systems, which are considered as one of the most promising candidates for the use on electric and hybrid vehicles. Indeed, lithium batteries show technical properties and features particularly suitable for these applications in which high energy and power densities are required. In order to investigate lithium-ion battery major technical limitations, a set of experimental testing activities has been carried on battery packs and systems, whose behaviours are expected to be significantly different from the test results on single cells. One of the most crucial challenge is the problem of the battery lifetime. Many approaches have been proposed in the relevant literature, but a lot of difficulties persist, being related to the incidence of many factors which do not allow to derive a quite general model able to describe in an exhaustive way battery performances under different operating conditions. In the paper, a method is proposed which takes into account the randomness of the battery parameters, such as design maximum specific power and operating environment, in real operating condition, with reference to lithium ion batteries designed for a small electric bus (public transport service). Based on available experimental data, the lifetime probability distribution of these batteries has been estimated by means of a Weibull model. © 2016 IEEE
Accelerated life tests of complete lithium-ion battery systems
No full textA battery design method for lithium-ion batteries is discussed in the paper. The method takes into account the dependence of battery lifetime on different parameters, such as temperature, design maximum specific power, S.O.C., and relates it to the operating environment and economical aspect. The methods relies on a large set of experimental measurements, in particular accelerated life tests. The method allows to determine the optimal size, in terms of Life Cycle Cost, for a lithium ion battery designed for a small electric bus (public transport service)
Influence of Battery Aging on the Operation of a Charging Infrastructure
No full textThe increasingly widespread use of electric vehicles requires proper planning of the charging infrastructure. In addition to the correct identification of the optimal positions, this concerns the accurate sizing of the charging station with respect to energy needs and the management of power flows. In particular, if we consider the presence of a renewable energy source and a storage system, we can identify strategies to maximize the use of renewable energy, minimizing the purchase costs from the grid. This study uses real charging data for some public stations, which include “normal” chargers (3 kW and 7 kW) and “quick” ones (43 kW and 55 kW), for the optimal sizing of a photovoltaic system with stationary storage. Battery degradation due to use is included in the evaluation of the overall running costs of the station. In this study, two different cost models for battery degradation and their influence on energy flow management are compared, along with their impact on battery life
Comparing Charging Management Strategies for a Charging Station in a Parking Area in North Italy
No full textVia the analysis of a set of parking and journey information for vehicles traveling to the parking site at the University of Brescia (Italy), we evaluated the possibility of managing the electric recharging of these vehicles, which are hypothesized to be electric. The paper investigates charging optimization techniques that can limit the charge power peaks and distribute the energy demand throughout the day. A cost assessment for an auxiliary system consisting of a photovoltaic energy source (PV) and battery stationary storage (BSS) is also carried out. Optimal power management at the station with PV and BSS is introduced, and the performance of two feedback controllers based on the optimized results is compared with that of a real-time management algorithm in the presence of randomness in charging requests and insolation. The results show that the BSS degradation cost plays a primary role in determining the strategy to adopt to minimize the operating expenditure of a charging station
A demand-side approach to the optimal deployment of electric vehicle charging stations in metropolitan areas
No full textDespite all the acknowledged advantages in terms of environmental impact reduction, energy efficiency and noise reduction, the electric mobility market is below expectations. In fact, electric vehicles have limitations that pose several important challenges for achieving a sustainable mobility system: among them, the availability of an adequate charging infrastructure is recognized as a fundamental requirement and appropriate approaches to optimize public and private investments in this field are to be delineated. In this paper we consider actual data on conventional private vehicle usage in the urban area of Rome to carry out a strategy for the optimal allocation of charging infrastructures into portions (subareas) of the urban area, based on an analysis of a driver sample under the assumption of a complete switch to an equivalent fleet of electric vehicles. Moreover, the energy requirement for each one of the subareas is estimated in terms of the electric energy used by the equivalent fleet of electric vehicles to reach their destination. The model can be easily generalized to other problems regarding facility allocation based on user demand. © 2016 Elsevier Lt
The role of transposable elements activity in aging and their possible involvement in laminopathic diseases
No full textEukaryotic genomes contain a large number of transposable elements, part of which are still active and able to transpose in the host genome. Mobile element activation is repressed to avoid deleterious effects, such as gene mutations or chromosome rearrangements. Control of transposable elements includes a variety of mechanisms comprising silencing pathways, which are based on the production of small non-coding RNAs. Silencing can occur either through transposable element RNA degradation or through the targeting of DNA sequences by heterochromatin formation and consequent transcriptional inhibition. Since the important role of the heterochromatin silencing, the gradual loss of heterochromatin marks in constitutive heterochromatin regions during the aging process promotes derepression of transposable elements, which is considered a cause of the progressive increase in genomic instability and of the activation of inflammatory responses. This review provides an overview of the effects of heterochromatin loss on the activity of transposable elements during the aging process and the possible impact on genome function. In this context, we discuss the possible role of the nuclear lamina, a major player in heterochromatin dynamics, in the regulation of transposable element activity and potential implications in laminopathic diseases
Accelerated life tests of complete lithium-ion battery systems for Battery Life Statistics assessment
No full textThe paper investigates the performances of automotive lithium-ion battery systems, which are considered as one of the most promising candidates for the use on electric and hybrid vehicles. Indeed, lithium batteries show technical properties and features particularly suitable for these applications in which high energy and power densities are required. In order to investigate lithium-ion battery major technical limitations, a set of experimental testing activities has been carried on battery packs and systems, whose behaviours are expected to be significantly different from the test results on single cells. One of the most crucial challenge is the problem of the battery lifetime. Many approaches have been proposed in the relevant literature, but a lot of difficulties persist, being related to the incidence of many factors which do not allow to derive a quite general model able to describe in an exhaustive way battery performances under different operating conditions. In the paper, a method is proposed which takes into account the randomness of the battery parameters, such as design maximum specific power and operating environment, in real operating condition, with reference to lithium ion batteries designed for a small electric bus (public transport service). Based on available experimental data, the lifetime probability distribution of these batteries has been estimated by means of a Weibull model
Flexible Charging to Energy Saving—Strategies Assessment with Big Data Analysis for PHEVs Private Cars
No full textIn road transport, most vehicles today still rely on internal combustion engines. However, these engines have lower efficiency and generate higher pollution levels compared to electric motors. Consequently, there is a growing interest in the transition from conventional vehicles to electric ones. However, the transition to an electrified road transport system is not without challenges. Among these, the impact that electric vehicle charging will have on the electricity grid is of particular concern. This paper analyzes different charging scenarios for plug-in hybrid electric vehicles (PHEVs) and proposes charging strategies to minimize their impact on the electricity grid. The analysis is based on a large dataset of trips in urban areas in Italy. The study shows that smart charging of PHEVs can be implemented to minimize the impact on the electricity grid. The implementation of optimized charging strategies can contribute to making PHEVs a valid, eco-sustainable alternative to conventional vehicles while also promoting the stability and efficiency of the electricity grid. The study aims to verify the effectiveness and efficiency of the flexible charging strategy by comparing the common charging operation (first in–first out) with other, less impactful charging schemes
Spatial activation and repression of the drosophila vitelline membrane gene VM32E are switched by a complex cis-regulatory system
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