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Showing papers on "Electricity generation published in 2003"


Journal ArticleDOI
TL;DR: In this paper, the simulation results of a grid-connected wind driven doubly fed induction machine (DFIM) together with some real machine performance results are presented for operating conditions below and above synchronous speed, which are actually achieved by a double-sided PWM converter joining the machine rotor to the grid.
Abstract: This paper presents the simulation results of a grid-connected wind driven doubly fed induction machine (DFIM) together with some real machine performance results. The modeling of the machine considers operating conditions below and above synchronous speed, which are actually achieved by means of a double-sided PWM converter joining the machine rotor to the grid. In order to decouple the active and reactive powers generated by the machine, stator-flux-oriented vector control is applied. The wind generator mathematical model developed in this paper is used to show how such a control strategy offers the possibility of controlling the power factor of the energy to be generated.

800 citations


Journal ArticleDOI
TL;DR: This research indicates that microbial electricity generation offers perspectives for optimization in relation to glucose dosage and five fold higher power output than reported thus far.
Abstract: A microbial fuel cell containing a mixed bacterial culture utilizing glucose as carbon source was enriched to investigate power output in relation to glucose dosage. Electron recovery in terms of electricity up to 89% occurred for glucose feeding rates in the range 0.5–3 g l−1 d−1, at powers up to 3.6 W m−2 of electrode surface, a five fold higher power output than reported thus far. This research indicates that microbial electricity generation offers perspectives for optimization.

786 citations


Proceedings ArticleDOI
13 Jul 2003
TL;DR: In this article, the authors present recommendations for dynamic modeling of the GE 1.5 and 3.6 MW WTG for use in system impact studies, including recommended model structure and data, as well the assumptions, capabilities and limitations of the resulting model.
Abstract: GE power systems has an ongoing effort dedicated to development of models of GE wind turbine generators (WTG) suitable for use in system impact studies. This paper documents the present recommendations for dynamic modeling of the GE 1.5 and 3.6 MW WTG for use in system impact studies. The paper includes recommended model structure and data, as well the assumptions, capabilities and limitations of the resulting model.

451 citations


Journal ArticleDOI
TL;DR: In this paper, the authors argue that a new electric power production industry is emerging, and that it will rely on a broad array of new technologies, such as internal combustion engine generators, fuel cells and microturbines.
Abstract: As the electric utility industry continues to restructure, driven both by rapidly evolving regulatory environments and by market forces, the emergence of a number of new generation technologies also profoundly influences the industry's outlook. While it is certainly true that government public policies and regulations have played a major role in the rapidly growing rate at which distributed generation is penetrating the market, it is also the case that a number of technologies have reached a development stage allowing for large-scale implementation within existing electric utility systems. At the onset of any discussion related to distributed generation, one question begs to be answered: is the fact that electric power producing facilities are distributed actually a new and revolutionary concept? Have power plants not always been located across broad expanses of land? The answer to these questions clearly is that electric power plants have always been sited all across the service territories of the utilities owning them. Hence, the opening question: as with many so-called innovations that have been put forward during the recent past, is the entire concept of distributed generation a simple semantic marketing hype or are we actually at the dawn of a new electric power generation era? We believe that a new electric power production industry is emerging, and that it will rely on a broad array of new technologies. This article sets the stage for distributed generation covering such topics as: the present power production situation; what distributed generation is; capability ratings and system interfaces; market penetration of internal combustion engine generators, fuel cells and microturbines; potential generation mix issues, network considerations including power quality, reactive power coordination, reliability and reserve margin, reliability, network redundancy, safety and accountability; public policy and regulatory impact; and standards.

342 citations


Journal ArticleDOI
TL;DR: In this article, a simulation model for analyzing the probability of power supply failure in hybrid photovoltaic-wind power generation systems incorporating a storage battery bank, and also analyzes the reliability of the systems.

296 citations


Proceedings ArticleDOI
07 Sep 2003
TL;DR: In this article, a combined natural gas and electric optimal power flow (GEOPF) problem is presented, where the authors show fundamental modeling of the natural gas network to be used for the GEOPF, and describes the equality constraints, which describe the energy transformation between gas and electricity networks at combined nodes (i.e., generators).
Abstract: In this paper, the combined natural gas and electric optimal power flow (GEOPF) problem is presented. It shows fundamental modeling of the natural gas network to be used for the GEOPF, and describes the equality constraints, which describe the energy transformation between gas and electric networks at combined nodes (i.e., generators). We also present the formulation of the natural gas load flow problem, which includes the amount of gas consumed in compressor stations. Case studies are presented to show the sensitivity of the real power generation to wellhead gas prices. Results from the simulation demonstrate that the GEOPF can provide social welfare maximizing solutions considering both gas and electric networks.

293 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe the production of emulsions from biomass fast pyrolysis liquid and diesel fuel for utilisation in diesel engines and test the emulsion on different diesel engines.
Abstract: The current method of utilising biomass derived fast liquid (bio-crude oil or bio-oil) in a diesel engine requires three fuels and a complex start-up and shut down procedure. For more rapid and successful commercialisation of this renewable liquid fuel, a more convenient and cheaper method of utilisation is needed that provides a single fuel that is stable and readily ignites in a compression engine. This paper describes the production of emulsions from biomass fast pyrolysis liquid and diesel fuel for utilisation in diesel engines. The objective is to allow unmodified diesel engines to run on fast pyrolysis liquid derived from biomass without the cost and complexity of a dual fuel system. The immediate application is in stationary engines for power generation, but there are longer term opportunities for use as a transport fuel. This paper describes the production of the emulsions that have been tested in different diesel engines (tests in engines is reported in a separate paper).

275 citations


Proceedings ArticleDOI
15 Jun 2003
TL;DR: In this paper, a new control method and proportional PWM modulation of the cascaded H-bridge multilevel converter for grid-connected photovoltaic systems is introduced.
Abstract: This paper introduces a new control method and proportional PWM modulation of the cascaded H-bridge multilevel converter for grid-connected photovoltaic systems. This control makes each H-bridge module supply different power levels, allowing therefore for each module an independent maximum power point tracking of the corresponding photovoltaic array.

270 citations


Journal ArticleDOI
TL;DR: In this article, the authors present an overview of the current state-of-the-art of photovoltaic electricity technology, and address its potential for cost reductions over the first few decades of the 21st century.

211 citations


ReportDOI
01 Jun 2003
TL;DR: In this paper, the authors presented a three-year project to find an economically feasible process for the production of hydrogen, by nuclear means, using an advanced high-temperature nuclear reactor as the primary energy source.
Abstract: OAK B202 HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER. Combustion of fossil fuels, used to power transportation, generate electricity, heat homes and fuel industry provides 86% of the world's energy. Drawbacks to fossil fuel utilization include limited supply, pollution, and carbon dioxide emissions. Carbon dioxide emissions, thought to be responsible for global warming, are now the subject of international treaties. Together, these drawbacks argue for the replacement of fossil fuels with a less-polluting potentially renewable primary energy such as nuclear energy. Conventional nuclear plants readily generate electric power but fossil fuels are firmly entrenched in the transportation sector. Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. Hydrogen will be particularly advantageous when coupled with fuel cells. Fuel cells have higher efficiency than conventional battery/internal combustion engine combinations and do not produce nitrogen oxides during low-temperature operation. Contemporary hydrogen production is primarily based on fossil fuels and most specifically on natural gas. When hydrogen is produced using energy derived from fossil fuels, there is little or no environmental advantage. There is currently no large scale, cost-effective, environmentally attractive hydrogen production process available for commercialization, nor has such a process been identified. The objective of this work is to find an economically feasible process for the production of hydrogen, by nuclear means, using an advanced high-temperature nuclear reactor as the primary energy source. Hydrogen production by thermochemical water-splitting (Appendix A), a chemical process that accomplishes the decomposition of water into hydrogen and oxygen using only heat or, in the case of a hybrid thermochemical process, by a combination of heat and electrolysis, could meet these goals. Hydrogen produced from fossil fuels has trace contaminants (primarily carbon monoxide) that are detrimental to precious metal catalyzed fuel cells, as is now recognized by many of the world's largest automobile companies. Thermochemical hydrogen will not contain carbon monoxide as an impurity at any level. Electrolysis, the alternative process for producing hydrogen using nuclear energy, suffers from thermodynamic inefficiencies in both the production of electricity and in electrolytic parts of the process. The efficiency of electrolysis (electricity to hydrogen) is currently about 80%. Electric power generation efficiency would have to exceed 65% (thermal to electrical) for the combined efficiency to exceed the 52% (thermal to hydrogen) calculated for one thermochemical cycle. Thermochemical water-splitting cycles have been studied, at various levels of effort, for the past 35 years. They were extensively studied in the late 70s and early 80s but have received little attention in the past 10 years, particularly in the U.S. While there is no question about the technical feasibility and the potential for high efficiency, cycles with proven low cost and high efficiency have yet to be developed commercially. Over 100 cycles have been proposed, but substantial research has been executed on only a few. This report describes work accomplished during a three-year project whose objective is to ''define an economically feasible concept for production of hydrogen, by nuclear means, using an advanced high temperature nuclear reactor as the energy source.'' The emphasis of the first phase was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen from water in which the primary energy input is high temperature heat from an advanced nuclear reactor and to select one (or, at most three) for further detailed consideration. During Phase 1, an exhaustive literature search was performed to locate all cycles previously proposed. The cycles located were screened using objective criteria to determine which could benefit, in terms of efficiency and cost, from the high-temperature capabilities of advanced nuclear reactors. The more promising cycles were then analyzed in depth as to their adaptability to advanced high-temperature nuclear reactors. As a result, the Sulfur-Iodine (S-I) cycle was selected for integration into the advanced nuclear reactor system. In Phases 2 and 3, alternative flowsheets were developed and compared. This effort entailed a considerable effort into developing the solution thermodynamics pertinent to the S-I cycle.

194 citations


ReportDOI
01 Dec 2003
TL;DR: In this paper, a study of power plants and their respective water consumption was completed to effectively analyze evaporative cooling systems, and a technical paper will aid the High Performance Buildings Research Program by providing a metric in determining water efficiency in building cooling systems.
Abstract: A study of power plants and their respective water consumption was completed to effectively analyze evaporative cooling systems. This technical paper will aid the High Performance Buildings Research Program by providing a metric in determining water efficiency in building cooling systems. Further analysis is planned to determine the overall water efficiency of evaporative cooling systems compared to conventional direct expansion systems and chiller systems with cooling towers.

Journal ArticleDOI
TL;DR: This work model the hourly CHP operation as an LP problem with a special structure and presents the specialised Power Simplex algorithm that utilises this structure efficiently and performs from 21 to 190 times faster than the tabular Simplex.

Journal ArticleDOI
TL;DR: In this article, the main scientific results of the DISS project are presented, which aims at the investigation and demonstration of the Direct Steam Generation (DSG) process in parabolic troughs under real solar conditions.

Journal ArticleDOI
TL;DR: In this paper, the authors presented a preliminary analysis of the process economics and operational regimes necessary in the UK Electrical Supply Industry to accommodate the methanol plant, and four different designs were assessed, all based on a supply of renewable energy limited to 16 h / day when demand is off-peak.

Proceedings ArticleDOI
13 Jul 2003
TL;DR: In this article, the authors investigated the impact of the critical clearing time (CCT) of the wind power-based embedded generators (WPBEGs) on the stability of wind farms.
Abstract: Summary form only given. Generation of electricity using wind power has received considerable attention worldwide in recent years. In order to investigate the impacts of the integration of wind farm into utilities' network various windmill models is developed. One such impact is related to the critical clearing time (CCT) of the wind power based embedded generators (WPBEGs). The work in this paper shows that oversimplification of the modelling of windmill mechanical drive train could introduce significant error in the value of the CCT that defines the stability limit of an integrated wind farm. This paper also reports investigation into the factors that influence the dynamic behaviour of the WPBEGs following network fault conditions. It is shown that wind farm CCT can be affected by various factors contributed by the host network. Results obtained from several case studies are presented and discussed. This investigation is conducted on a simulated grid-connected wind farm using EMTP.

Journal ArticleDOI
01 May 2003-Energy
TL;DR: In this article, a simultaneous optimization of the design and operation of a district heating, cooling and power generation plant supplying a small stock of residential buildings has been undertaken with regards to cost and CO?2 emissions.

Proceedings ArticleDOI
23 Jun 2003
TL;DR: In this article, aggregated models for wind parks equipped with either constant or variable speed wind turbines are presented, and results obtained with an aggregated model and with a detailed model show a high degree of correspondence, both for normal operation and for disturbances.
Abstract: Increasing numbers of wind turbines are connected to electrical power systems, in order to reduce the adverse environmental impact of conventional electrical power generation. A tendency can be observed to erect these turbines in wind parks, connected to the high voltage transmission grid. These parks effect the dynamic behaviour of power systems, because in wind turbines generator types that are different from the conventional synchronous generator are used. To investigate the impact of a wind park on the dynamics of the power system to which it is connected, an adequate model is required. In order to avoid the necessity of developing a detailed model of a wind park with tens or hundreds of wind turbines and their interconnections and to calculate the wind speed signal for each individual turbine, aggregated wind park models are needed. In the paper, aggregated models for wind parks equipped with either constant or variable speed wind turbines are presented. It is shown that results obtained with an aggregated model and with a detailed model show a high degree of correspondence, both for normal operation and for disturbances.

Journal ArticleDOI
TL;DR: The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piez Zoelectric layers.
Abstract: The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piezoelectric layers. One of these layers models the driving transducer for generating acoustic wave, and the other layer models the receiving transducer for converting the acoustic energy into electric energy to power a load circuit. The output voltage, the output power, and the efficiency of this system are expressed as explicit functions of the system parameters. A numerical example is included to illustrate the dependence of the system performance upon the physical and geometrical parameters.

Journal ArticleDOI
TL;DR: In this paper, the tradeoff between CO 2 emissions and total cost of technologies is analyzed so that the most cost-effective technology can be determined for different CO2 emissions constraints. And the position of supercritical water gasification in various technologies of energy conversion is examined by modeling an overall energy system.
Abstract: Efficiency and CO 2 emissions between various methods of biomass energy conversion are compared from the viewpoint of life-cycle evaluation. As for electricity generation, efficient processes are thermal gasification combined cycle, supercritical water gasification combined cycle, and direct combustion in order of efficiency for low moisture content biomass. Supercritical water gasification combined cycle is the most efficient for high moisture content biomass. Battery electric vehicle, gasoline hybrid electric vehicle, and gas full cell vehicle (FCV) show high efficiency in automobiles. Biomass FCV shows high efficiency in the vehicles utilizing biomass. Biogas combustion is the most efficient for heat utilization. Then, the position of supercritical water gasification in various technologies of energy conversion is examined by modeling an overall energy system. The tradeoff between CO 2 emissions and total cost of technologies is analyzed so that the most cost-effective technology can be determined for different CO 2 emissions constraints. Computed results show that biomass is mainly consumed for electricity and heat generation so as to utilize finite biomass resources efficiently. Transportation fuels are generally made from fossil fuels. Cost-effective processes for CO 2 reduction are thermal gasification and reforming when the present efficiency and prices are assumed. Supercritical water gasification is also one of the optimal processes when the relative cost to fuel cell decreases. Improving heat exchange efficiency also contributes toward enhancing the position of supercritical water gasification in biomass technologies.

Book
01 Jan 2003
TL;DR: A brief review of power generation thermodynamics is given in this article, where the gas turbine as a cogeneration plant and the combined cycle gas turbine (CCGT) is considered.
Abstract: A brief review of power generation thermodynamics. Reversibility and Availability. Basic gas turbine cycles. Cycle effeciency with turbine cooling. Full calculations of plant effeciency. Wet gas turbine plants. The combined cycle gas turbine (CCGT). Novel gas turbine cycles. The gas turbine as a cogeneration plant.

Patent
10 Dec 2003
TL;DR: In this paper, a solar-powered power generation system and an associated method are provided, which includes at least one trough solar absorption device for heating a heat transfer fluid to a first temperature, and at least two tower solar absorption devices for further heating the transfer fluids to a second temperature.
Abstract: A solar-powered power generation system and an associated method are provided. The system includes at least one trough solar absorption device for heating a heat transfer fluid to a first temperature, and at least one tower solar absorption device for further heating the transfer fluid to a second temperature. Thus, the generation system can efficiently heat the transfer fluid to high temperatures. Subsequently, the heated fluid can be used, e.g., to generate steam and/or electricity.

Journal ArticleDOI
TL;DR: In this article, the authors discuss and analyze different national strategies for solving the problem of "surplus production" in Denmark, where the electricity production exceeds the demand during certain periods and creates a problem of surplus production.

Proceedings ArticleDOI
23 Jun 2003
TL;DR: In this article, the authors presented a model to compute the maximum amount of power that can be supplied by the combined-cycle power plants in a system, and the effect of compressors to enlarge the transmission capacity of the network is included.
Abstract: The growth of power generation in Spain and several other countries is mainly based on the construction of combined-cycle power plants. As the number of this type of plants increases, the gas and electricity systems are linked together. Therefore, power system reliability studies should consider the gas supply reliability. As a consequence, the new generation of reliability models should take into account the joint operation of electrical and gas systems. This paper presents a model to compute the maximum amount of power that can be supplied by the combined-cycle power plants in a system. The gas network is modeled. The effect of compressors to enlarge the transmission capacity of the network is included. The developed model will be integrated into a higher level model that analyzes the joint reliability of the electrical and gas systems. A case study based on the Belgian high-calorific gas network is analyzed.

Journal ArticleDOI
Saifur Rahman1
TL;DR: In this article, the authors discuss the market potential for renewable resources, green power in the mainstream electric utilities, and the following renewable resources: hydroelectric power, wind power; biomass; solar thermal power; solar photovoltaics; and geothermal power.
Abstract: The interest in commercial green power in the developed world is about 25 years old, starting in the mid-1970s after the first oil shock. Electricity derived from any renewable energy source is considered "green" because of the negligible impact on greenhouse gas emissions. In terms of commercial energy, this list currently includes hydro, wind, biomass, geothermal, and solar. In the 1970s and 1980s, the interest in green power was driven by the goal of replacing fossil fuels to minimize the dependence on oil. Now there is a broader goal: to minimize the emission of CO/sub 2/ (the most common global warming gas) that results from the burning of fossil fuels. This article discusses the market potential for renewable resources, green power in the mainstream electric utilities, and the following renewable resources: hydroelectric power, wind power; biomass; solar thermal power; solar photovoltaics; and geothermal power.

Journal ArticleDOI
TL;DR: In this paper, the authors present a quantitative analysis of air pollution impacts on human health, damages from greenhouse gas emissions, and the avoided health costs from electrification, as well as discussing other impacts qualitatively.

Proceedings ArticleDOI
01 Jun 2003
TL;DR: In this article, the authors show the possible application of a particular motion system, the joint system, JS, in a simplified HEV model and demonstrate the suitability for the control of HEVs.
Abstract: Coupled with the accelerated search of "clean generation" of electric energy is the growing need for alternative energy source in urban transportation that can reduce the overall impact on air pollution. Hybrid electric vehicles, HEV, are offering the best possibility for the use of new energy sources, because electricity can result from a transformation with high efficiency in a system with electric drives and components. In this paper the authors pretend to show the possible application of a particular motion system, the joint system, JS, in a simplified HEV model. A special energy management strategy must be applied in order to take into account the operation modes of the JS and the particular constraints linked to the structure and configuration of an HEV. An application-oriented overview of a rule-based control is presented and is demonstrated the suitability for the control of HEVs.

Patent
24 Feb 2003
TL;DR: In this paper, a closed-cycle charged refrigerant loop is used to recover electric power from low-grade waste heat/solar energy, comprising a reverse-plumbed gas compressor.
Abstract: Recovery of electric power from low-grade waste heat/solar energy, comprising a closed-cycle charged refrigerant loop. Pressurized refrigerant fluid is pumped at ambient temperature through a heat exchanger connected to a waste heat/solar source to extract heat energy during conversion to a high pressure gas. Heated/pressurized refrigerant gas is inlet into an expander to power an output shaft during the expansion of the fluid to a cooled gas at approximately 0 psig. Cooled gaseous refrigerant is condensed to a liquid at low pressure and ambient temperature, and recycled under pressure to the heat exchanger. The expander is a reverse-plumbed gas compressor; the pressurized, hot refrigerant gas is inlet at what is ordinarily its outlet, and the normal inlet becomes the expander end. The refrigerant gas mass flow pressure/temperature drop spins the expander shaft for direct mechanical power take-off, or coupling to a synchronous or inductive generator to produce electricity.

Proceedings ArticleDOI
25 Jul 2003
TL;DR: In this article, two types of piezoelectric materials were experimentally investigated for use as power harvesting devices, i.e., monolithic PZT and Macro Fiber Composites, which were recently developed at the NASA Langley Center.
Abstract: Piezoelectric materials can be used as mechanisms to transfer ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, Piezoelectric power generation can provide a conventional alternative to traditional power sources used to operate certain types of sensors/actuators, telemetry, and MEMS devices. In this paper, two types of piezoelectric materials were experimentally investigated for use as power harvesting devices. The two types being the commonly used monolithic piezoelectric (PZT) and Macro Fiber Composites (MFC), which were recently developed at the NASA Langley Center. Our experimental results estimate the efficiency of these devices and identify the feasibility of their use in real world applications. In general the power produced by the vibration of a piezoelectric device is on the order of a few milliwatts which is far too little to power for most applications. Therefore, each the transducer is used to charge nickel metal hydride batteries of varying sizes to compare their performance and ability of to store electrical power. The results presented in this paper show the potential of piezoelectric materials for use in power harvesting applications.

Proceedings ArticleDOI
02 Jul 2003
TL;DR: It is shown that with simple scheduling techniques, overall leakage energy can be reduced by an order of magnitude.
Abstract: Modern embedded systems are often severely resource-constrained. In current research, the reduction of dynamic power has been the focus. However, with increased chip speed and density in submicron scale, the static (leakage) power consumption has become an increasingly significant fraction of the total. Indeed, a five-fold increase in leakage power per technology generation has been observed. At this pace, leakage power could soon equal dynamic power. In this paper, we investigate scheduling policies to reduce leakage power in real-time systems. We show that with simple scheduling techniques, overall leakage energy can be reduced by an order of magnitude.

Journal ArticleDOI
TL;DR: In this article, a solar chimney power plant, which is expected to provide electric power for remote villages in northwestern China, has been analyzed in three counties in Ning Xia Hui Autonomous region, namely, Yinchuan, Pingluo and Helan, where solar radiation is better than other regions of China, were selected as pilot locations to construct solar power plant.