Next Issue
Previous Issue

E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Table of Contents

Energies, Volume 4, Issue 4 (April 2011), Pages 563-716

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-9
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle Transport and Carbon Emissions in the United States: The Long View
Energies 2011, 4(4), 563-581; doi:10.3390/en4040563
Received: 31 January 2011 / Revised: 23 February 2011 / Accepted: 16 March 2011 / Published: 24 March 2011
Cited by 18 | PDF Full-text (420 KB) | HTML Full-text | XML Full-text
Abstract
The following analysis traces U.S. transport CO2 emissions in combustion by mode for 1960–2008. Changes in emissions are divided into components related to overall population and economic growth, transport mode shift, changes in the ratio of fuel used to passenger or tonne-km
[...] Read more.
The following analysis traces U.S. transport CO2 emissions in combustion by mode for 1960–2008. Changes in emissions are divided into components related to overall population and economic growth, transport mode shift, changes in the ratio of fuel used to passenger or tonne-km of activity, and changes in the CO2 content of fuels. Where data permit we show how changes in vehicle utilization affected CO2 emissions. We comment on factors causing the changes in components of emissions. A Log-Mean Divisia Index and Laspeyres decompositions of the 1960–2008 changes are calculated. From this decomposition we speculate to what extent the factors associated with the increases in CO2 emissions since 1960 would be important in the future, and what other factors could reduce emissions. This thorough decomposition is imperative for the crafting of transport policy that aims to address climate change. Full article
(This article belongs to the Special Issue Energy-Friendly Transportation)
Open AccessArticle Evaluation of Lithium-Ion Battery Equivalent Circuit Models for State of Charge Estimation by an Experimental Approach
Energies 2011, 4(4), 582-598; doi:10.3390/en4040582
Received: 24 January 2011 / Revised: 18 March 2011 / Accepted: 28 March 2011 / Published: 29 March 2011
Cited by 185 | PDF Full-text (517 KB) | HTML Full-text | XML Full-text
Abstract
To improve the use of lithium-ion batteries in electric vehicle (EV) applications, evaluations and comparisons of different equivalent circuit models are presented in this paper. Based on an analysis of the traditional lithium-ion battery equivalent circuit models such as the Rint, RC, Thevenin
[...] Read more.
To improve the use of lithium-ion batteries in electric vehicle (EV) applications, evaluations and comparisons of different equivalent circuit models are presented in this paper. Based on an analysis of the traditional lithium-ion battery equivalent circuit models such as the Rint, RC, Thevenin and PNGV models, an improved Thevenin model, named dual polarization (DP) model, is put forward by adding an extra RC to simulate the electrochemical polarization and concentration polarization separately. The model parameters are identified with a genetic algorithm, which is used to find the optimal time constant of the model, and the experimental data from a Hybrid Pulse Power Characterization (HPPC) test on a LiMn2O4 battery module. Evaluations on the five models are carried out from the point of view of the dynamic performance and the state of charge (SoC) estimation. The dynamic performances of the five models are obtained by conducting the Dynamic Stress Test (DST) and the accuracy of SoC estimation with the Robust Extended Kalman Filter (REKF) approach is determined by performing a Federal Urban Driving Schedules (FUDS) experiment. By comparison, the DP model has the best dynamic performance and provides the most accurate SoC estimation. Finally, sensitivity of the different SoC initial values is investigated based on the accuracy of SoC estimation with the REKF approach based on the DP model. It is clear that the errors resulting from the SoC initial value are significantly reduced and the true SoC is convergent within an acceptable error. Full article
(This article belongs to the Special Issue Electric and Hybrid Vehicles)
Open AccessArticle A Smart Online Over-Voltage Monitoring and Identification System
Energies 2011, 4(4), 599-615; doi:10.3390/en4040599
Received: 24 February 2011 / Revised: 6 April 2011 / Accepted: 15 April 2011 / Published: 18 April 2011
Cited by 12 | PDF Full-text (381 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a complete and effective smart over-voltage monitoring and identification system. In recent years, smart grids are of the greatest interest in power system research. One of the main features of smart grid is their self-healing, which can continuously carry out
[...] Read more.
This paper proposes a complete and effective smart over-voltage monitoring and identification system. In recent years, smart grids are of the greatest interest in power system research. One of the main features of smart grid is their self-healing, which can continuously carry out online self-evaluation, discover existing faults, and correct them immediately. The over-voltage smart monitoring-identification-suppression systems play a key role in the construction of self-healing grids. In this paper, eight kinds of common over-voltage are discussed and analyzed. The S-transform algorithm is used to extract features of over-voltage. Aiming at the main features of each kind of over-voltage, six different characteristic quantities are proposed. A well designed fuzzy expert system and a support vector machine are employed as the classifiers to build a two-step identification model. The accuracy of the identification system is verified by field records. Results show that this system is feasible and promising for real applications. Full article
(This article belongs to the Special Issue Future Grid)
Open AccessArticle Model for Predicting DC Flashover Voltage of Pre-Contaminated and Ice-Covered Long Insulator Strings under Low Air Pressure
Energies 2011, 4(4), 628-643; doi:10.3390/en4040628
Received: 28 February 2011 / Revised: 13 April 2011 / Accepted: 18 April 2011 / Published: 19 April 2011
Cited by 3 | PDF Full-text (301 KB) | HTML Full-text | XML Full-text
Abstract
In the current study, a multi-arc predicting model for DC critical flashover voltage of iced and pre-contaminated long insulator strings under low atmospheric pressure is developed. The model is composed of a series of different polarity surface arcs, icicle-icicle air gap arcs, and
[...] Read more.
In the current study, a multi-arc predicting model for DC critical flashover voltage of iced and pre-contaminated long insulator strings under low atmospheric pressure is developed. The model is composed of a series of different polarity surface arcs, icicle-icicle air gap arcs, and residual layer resistance. The calculation method of the residual resistance of the ice layer under DC multi-arc condition is established. To validate the model, 7-unit and 15-unit insulator strings were tested in a multi-function artificial climate chamber under the coexistent conditions of low air pressure, pollution, and icing. The test results showed that the values calculated by the model satisfactorily agreed with those experimentally measured, with the errors within the range of 10%, validating the rationality of the model. Full article
(This article belongs to the Special Issue Future Grid)
Open AccessArticle A Review of Current Issues in State-of-Art of Wind Farm Overvoltage Protection
Energies 2011, 4(4), 644-668; doi:10.3390/en4040644
Received: 17 January 2011 / Revised: 8 April 2011 / Accepted: 18 April 2011 / Published: 19 April 2011
Cited by 13 | PDF Full-text (846 KB) | HTML Full-text | XML Full-text
Abstract
This paper elaborates on several important outstanding issues in the state-of-art of overvoltage protection selection for modern wind farms. The lack of experience with this still-new technology, together with the inherent complexity of wind farm electrical systems, entails several unresolved issues pertinent to
[...] Read more.
This paper elaborates on several important outstanding issues in the state-of-art of overvoltage protection selection for modern wind farms. The lack of experience with this still-new technology, together with the inherent complexity of wind farm electrical systems, entails several unresolved issues pertinent to the topic of overvoltage protection, particularly in relation to lightning-initiated surges. Firstly, several aspects of the wind turbine lightning incidence, along with the issues related to the selection of lightning current parameters (pertinent to the wind farm overvoltage protection), are addressed in this paper. Secondly, several issues in the state-of-art models of the wind farm electrical systems—for the lightning surge analysis—are addressed and discussed. Here, a well-known ElectroMagnetic Transients Program (EMTP) software package is often employed, with all of its benefits and some limitations. Thirdly, the metal-oxide surge arrester energy capability and the issues related to the selection of the surge arrester rated energy—in relation to the direct lightning strikes to wind turbines—is addressed. Finally, some general considerations concerning the overvoltage protection selection for wind farm projects, particularly regarding the installation of the metal-oxide surge arresters, are provided as well. Full article
(This article belongs to the Special Issue Wind Energy 2011)
Open AccessArticle Selective Preparation of Furfural from Xylose over Sulfonic Acid Functionalized Mesoporous Sba-15 Materials
Energies 2011, 4(4), 669-684; doi:10.3390/en4040669
Received: 25 March 2011 / Revised: 11 April 2011 / Accepted: 18 April 2011 / Published: 20 April 2011
Cited by 54 | PDF Full-text (276 KB) | HTML Full-text | XML Full-text
Abstract
Sulfonic acid functionalized mesoporous SBA-15 materials were prepared using the co-condensation and grafting methods, respectively, and their catalytic performance in the dehydration of xylose to furfural was examined. SBA-15-SO3H(C) prepared by the co-condensation method showed 92–95% xylose conversion and 74% furfural
[...] Read more.
Sulfonic acid functionalized mesoporous SBA-15 materials were prepared using the co-condensation and grafting methods, respectively, and their catalytic performance in the dehydration of xylose to furfural was examined. SBA-15-SO3H(C) prepared by the co-condensation method showed 92–95% xylose conversion and 74% furfural selectivity, and 68–70% furfural yield under the given reaction conditions. The deactivation and regeneration of the SBA-15-SO3H(C) catalyst for the dehydration of xylose was also investigated. The results indicate that the used and regeneration catalysts retained the SBA-15 mesoporous structure, and the S content of SBA-15-SO3H(C) almost did not change. The deactivation of the catalysts is proposed to be associated with the accumulation of byproducts, which is caused by the loss reaction of furfural. After regeneration by H2O2, the catalytic activity of the catalyst almost recovered. Full article
(This article belongs to the Special Issue Biomass and Biofuels)
Open AccessArticle Impacts of Urban Transportation Mode Split on CO2 Emissions in Jinan, China
Energies 2011, 4(4), 685-699; doi:10.3390/en4040685
Received: 11 February 2011 / Revised: 7 April 2011 / Accepted: 11 April 2011 / Published: 21 April 2011
Cited by 8 | PDF Full-text (222 KB) | HTML Full-text | XML Full-text
Abstract
As the world’s largest developing country, China currently is undergoing rapid urbanization and motorization, which will result in far-reaching impacts on energy and the environment. According to estimates, energy use and carbon emissions in the transportation sector will comprise roughly 30% of total
[...] Read more.
As the world’s largest developing country, China currently is undergoing rapid urbanization and motorization, which will result in far-reaching impacts on energy and the environment. According to estimates, energy use and carbon emissions in the transportation sector will comprise roughly 30% of total emissions by 2030. Since the late 1990s, transportation-related issues such as energy, consumption, and carbon emissions have become a policy focus in China. To date, most research and policies have centered on vehicle technologies that promote vehicle efficiency and reduced emissions. Limited research exists on the control of greenhouse gases through mode shifts in urban transportation—in particular, through the promotion of public transit. The purpose of this study is to establish a methodology to analyze carbon emissions from the urban transportation sector at the Chinese city level. By using Jinan, the capital of China’s Shandong Province, as an example, we have developed an analytical model to simulate energy consumption and carbon emissions based on the number of trips, the transportation mode split, and the trip distance. This model has enabled us to assess the impacts of the transportation mode split on energy consumption and carbon emissions. Furthermore, this paper reviews a set of methods for data collection, estimation, and processing for situations where statistical data are scarce in China. This paper also describes the simulation of three transportation system development scenarios. The results of this study illustrate that if no policy intervention is implemented for the transportation mode split (the business-as-usual (BAU) case), then emissions from Chinese urban transportation systems will quadruple by 2030. However, a dense, mixed land-use pattern, as well as transportation policies that encourage public transportation, would result in the elimination of 1.93 million tons of carbon emissions—approximately 50% of the BAU scenario emissions. Full article
(This article belongs to the Special Issue Energy-Friendly Transportation)
Open AccessArticle Multiple Objective Compromised Method for Power Management in Virtual Power Plants
Energies 2011, 4(4), 700-716; doi:10.3390/en4040700
Received: 22 February 2011 / Revised: 6 April 2011 / Accepted: 18 April 2011 / Published: 21 April 2011
Cited by 4 | PDF Full-text (304 KB) | HTML Full-text | XML Full-text
Abstract
In practical optimization, a priority requirement for different objectives of multiple objective optimization problems should be considered. In this paper, the distributed power management of a Virtual Power Plant (VPP) with priority requirement is optimized by the compromised method. The operation optimization model
[...] Read more.
In practical optimization, a priority requirement for different objectives of multiple objective optimization problems should be considered. In this paper, the distributed power management of a Virtual Power Plant (VPP) with priority requirement is optimized by the compromised method. The operation optimization model of VPP is formulated as a fuzzy multiple objective optimization problem considering the satisfaction of customers and suppliers, the system stability, the power quality, and costs with operation limitations. The multiple objective optimization algorithm with the compromise of the satisfactory degree and the priority of objectives is studied based on the principle of two-step interactive satisfactory optimization. This method is also applied in a test system. Full article
(This article belongs to the Special Issue Future Grid)

Review

Jump to: Research

Open AccessReview Evaluation of Various Solid Biomass Fuels Using Thermal Analysis and Gas Emission Tests
Energies 2011, 4(4), 616-627; doi:10.3390/en4040616
Received: 21 February 2011 / Revised: 28 March 2011 / Accepted: 15 April 2011 / Published: 18 April 2011
Cited by 12 | PDF Full-text (574 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Various recently proposed biomass fuels are reviewed from the point of view of their safety. Many biomass materials are proposed for use as fuels, such as refuse derived fuel (RDF), wood chips, coal-wood mixtures, etc. However, these fuels have high energy potentials
[...] Read more.
Various recently proposed biomass fuels are reviewed from the point of view of their safety. Many biomass materials are proposed for use as fuels, such as refuse derived fuel (RDF), wood chips, coal-wood mixtures, etc. However, these fuels have high energy potentials and can cause fires and explosions. We have experienced many such incidents. It is very difficult to extinguish fires in huge piles of biomass fuel or storage facilities. Here current studies on heat generation for these materials and proposed evaluation methods for these new developing materials in Japan are introduced, which are consistent with measurements using highly sensitive calorimeters such as C80, or TAM, and gas emission tests. The highly sensitive calorimeters can detect small heat generation between room temperature and 80 °C, due to fermentation or other causes. This heat generation sometimes initiates real fires, and also produces combustible gases which can explode if fuel is stored in silos or indoor storage facilities. Full article
(This article belongs to the Special Issue Coal, Biomass & Solid Refuse Combustion)

Journal Contact

MDPI AG
Energies Editorial Office
St. Alban-Anlage 66, 4052 Basel, Switzerland
energies@mdpi.com
Tel. +41 61 683 77 34
Fax: +41 61 302 89 18
Editorial Board
Contact Details Submit to Energies
Back to Top