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Energies, Volume 3, Issue 9 (September 2010), Pages 1529-1638

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Research

Jump to: Review

Open AccessArticle A Study on the Hydrotreating of Coal Hydroliquefaction Residue and its Kinetics
Energies 2010, 3(9), 1576-1585; doi:10.3390/en3091576
Received: 19 August 2010 / Revised: 26 August 2010 / Accepted: 30 August 2010 / Published: 9 September 2010
Cited by 5 | PDF Full-text (208 KB) | HTML Full-text | XML Full-text
Abstract
Hydro-conversion of coal hydroliquefaction residue obtained from a 6t/day pilot plant of Shenhua Group in Shanghai was carried out under the hydrotreating condition. The coal hydroliquefaction residue and its product were extracted in sequence with n-hexane, toluene and tetrahydrofuran in a [...] Read more.
Hydro-conversion of coal hydroliquefaction residue obtained from a 6t/day pilot plant of Shenhua Group in Shanghai was carried out under the hydrotreating condition. The coal hydroliquefaction residue and its product were extracted in sequence with n-hexane, toluene and tetrahydrofuran in a Soxhlet apparatus. The n-hexane soluble fractions increased with the increase of reaction temperature and time. Its amount increased from 14.14% to a maximum of 40.86% under the conditions of 470 °C and 30 min, which meant that moderate extension of coal residence time in the coal hydroliquefaction reactor is beneficial to the increase of oil yield. A 4-lumped kinetic model of coal hydroliquefaction residue hydro-conversion was performed using solubility-based lumped fractions. In the model, the tetrahydrofuran insoluble fractions were classified into two parts: easily reactive part and unreactive part. The kinetic parameters were estimated by a fourth-order Runge-Kutta method and a nonlinear least squares method, and the apparent activation energies were calculated according to the Arrhenius Equation. A large quantity of total catalyst consisting of remained liquefaction catalyst, part of the mineral from raw coal and additive Fe-based catalyst could considerably reduce the apparent activation energy of hydro-conversion for the toluene insoluble/tetrahydrofuran insoluble fractions to 36.79 kJ•mol-1. The calculated values of the model coincided well with the experimental values. Full article
(This article belongs to the Special Issue Coal, Biomass & Solid Refuse Combustion)
Open AccessArticle Estimation of State of Charge of a Lithium-Ion Battery Pack for Electric Vehicles Using an Adaptive Luenberger Observer
Energies 2010, 3(9), 1586-1603; doi:10.3390/en3091586
Received: 29 July 2010 / Accepted: 23 August 2010 / Published: 9 September 2010
Cited by 63 | PDF Full-text (294 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
In order to safely and efficiently use the power as well as to extend the lifetime of the traction battery pack, accurate estimation of State of Charge (SoC) is very important and necessary. This paper presents an adaptive observer-based technique for estimating [...] Read more.
In order to safely and efficiently use the power as well as to extend the lifetime of the traction battery pack, accurate estimation of State of Charge (SoC) is very important and necessary. This paper presents an adaptive observer-based technique for estimating SoC of a lithium-ion battery pack used in an electric vehicle (EV). The RC equivalent circuit model in ADVISOR is applied to simulate the lithium-ion battery pack. The parameters of the battery model as a function of SoC, are identified and optimized using the numerically nonlinear least squares algorithm, based on an experimental data set. By means of the optimized model, an adaptive Luenberger observer is built to estimate online the SoC of the lithium-ion battery pack. The observer gain is adaptively adjusted using a stochastic gradient approach so as to reduce the error between the estimated battery output voltage and the filtered battery terminal voltage measurement. Validation results show that the proposed technique can accurately estimate SoC of the lithium-ion battery pack without a heavy computational load. Full article
(This article belongs to the Special Issue Hybrid Vehicles)
Open AccessArticle Evaluating the Use of an Integrated Approach to Support Energy and Climate Policy Formulation and Evaluation
Energies 2010, 3(9), 1604-1621; doi:10.3390/en3091604
Received: 18 August 2010 / Accepted: 8 September 2010 / Published: 10 September 2010
Cited by 6 | PDF Full-text (262 KB) | HTML Full-text | XML Full-text
Abstract
With the adoption of the Kyoto Protocol in 1997 national leaders have started investigating options for reducing carbon emissions within national borders [1]. Despite confronting similar energy issues, every country that adopted the Kyoto Protocol has a unique energy strategy [1,2] -being [...] Read more.
With the adoption of the Kyoto Protocol in 1997 national leaders have started investigating options for reducing carbon emissions within national borders [1]. Despite confronting similar energy issues, every country that adopted the Kyoto Protocol has a unique energy strategy [1,2] -being characterized by a different context, social, economic or environmental that influences the way different nations deal with climate change and other energy-related issues. Finding that currently available energy models are often too detailed or narrowly focused to inform longer-term policy formulation and evaluation holistically [3], the present study proposes the utilization of an integrated cross-sectoral medium to longer-term research and modeling approach, incorporating various methodologies to minimize exogenous assumptions and endogenously represent the key drivers of the system analyzed. The framework proposed includes feedback, delays and non-linearity and focuses on structure, scenarios and policies, requires a profound customization of the model that goes beyond a new parameterization. The inclusion of social and environmental factors, in addition to economic ones, all unique to the geographical area analyzed, allows for a wider analysis of the implication of policies by identifying potential side effect or longer-term bottlenecks for socio-economic development and environmental preservation arising from cross-sectoral relations. Full article
(This article belongs to the Special Issue Energy-sustainable Development)
Open AccessArticle Hierarchical MAS Based Control Strategy for Microgrid
Energies 2010, 3(9), 1622-1638; doi:10.3390/en3091622
Received: 11 August 2010 / Accepted: 8 September 2010 / Published: 10 September 2010
Cited by 26 | PDF Full-text (801 KB) | HTML Full-text | XML Full-text
Abstract
Microgrids have become a hot topic driven by the dual pressures of environmental protection concerns and the energy crisis. In this paper, a challenge for the distributed control of a modern electric grid incorporating clusters of residential microgrids is elaborated and a [...] Read more.
Microgrids have become a hot topic driven by the dual pressures of environmental protection concerns and the energy crisis. In this paper, a challenge for the distributed control of a modern electric grid incorporating clusters of residential microgrids is elaborated and a hierarchical multi-agent system (MAS) is proposed as a solution. The issues of how to realize the hierarchical MAS and how to improve coordination and control strategies are discussed. Based on MATLAB and ZEUS platforms, bilateral switching between grid-connected mode and island mode is performed under control of the proposed MAS to enhance and support its effectiveness. Full article
(This article belongs to the Special Issue Future Grid)

Review

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Open AccessReview Enhanced Oil Recovery: An Update Review
Energies 2010, 3(9), 1529-1575; doi:10.3390/en3091529
Received: 27 June 2010 / Accepted: 10 August 2010 / Published: 27 August 2010
Cited by 115 | PDF Full-text (339 KB) | HTML Full-text | XML Full-text
Abstract
With the decline in oil discoveries during the last decades it is believed that EOR technologies will play a key role to meet the energy demand in years to come. This paper presents a comprehensive review of EOR status and opportunities to [...] Read more.
With the decline in oil discoveries during the last decades it is believed that EOR technologies will play a key role to meet the energy demand in years to come. This paper presents a comprehensive review of EOR status and opportunities to increase final recovery factors in reservoirs ranging from extra heavy oil to gas condensate. Specifically, the paper discusses EOR status and opportunities organized by reservoir lithology (sandstone and carbonates formations and turbiditic reservoirs to a lesser extent) and offshore and onshore fields. Risk and rewards of EOR methods including growing trends in recent years such as CO2 injection, high pressure air injection (HPAI) and chemical flooding are addressed including a brief overview of CO2-EOR project economics. Full article
(This article belongs to the Special Issue Oil Recovery)
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