Showing papers on "Electricity generation published in 1990"

Voltage stability condition in a power transmission system calculated by sensitivity methods

Abstract: A new method for determining the voltage stability condition in a power system is presented. The method is based on sensitivity techniques, taking into account the limits on reactive power generation capacities. A distance to voltage collapse in terms of MVAr is defined as a measure of system security. Results from calculations on a 480-bus network with 140 generators are presented. The method can be efficiently used for reactive power security evaluation in both system planning and operation. >

Power generation from lng

Abstract: LNG (9) is pumped to high pressure (13) vaporized (19), further heated (21) and then expanded to create rotary power (29) that is used to generate electrical power (31). A reservoir of carbon dioxide at about its triple point (41) is created in an insulated vessel to store energy in the form of refrigeration recovered from the evaporated LNG. During peak electrical power periods, liquid carbon dioxide is withdrawn therefrom, pumped to a high pressure (45), vaporized (47, 75) further heated (55), and expanded to create rotary power (57) which generates additional electrical power (59). The exhaust from a fuel-fired combustion turbine (61), connected to an electrical power generator (63), heats the high pressure carbon dioxide vapor. The discharge stream from the CO2 expander is cooled (53) and at least partially returned to the vessel (41) where vapor condenses by melting stored solid carbon dioxide. During off-peak periods, CO2 vapor is withdrawn from the reservoir and condensed to liquid by vaporizing LNG, so that use is always efficiently made of the available refrigeration from the vaporizing LNG, and valuable peak electrical power is available when needed by using the stored energy in the CO2 reservoir (41).

Limits on the performance of the three-phase self-excited induction generators

Abstract: Dependency of the output voltage and frequency of the isolated self-excited induction generator on the speed, load, and terminal capacitance causes certain limitations on its performance. In this study, the performance of the induction generator under a wide range of operating conditions is examined. It is found that the machine operates only in certain element ranges and that all generated currents and voltages are bounded. It is also shown that a combination of these elements exists that is optimal for maximum power generation. >

Method and apparatus for converting low temperature heat to electric power

Abstract: A method and apparatus for implementing a thermodynamic cycle which may be used to convert low temperature heat to electric power.

Electrical power storage apparatus

Abstract: A rechargeable, electrical power storage system employing an electrical power storage medium in the form of a slurry containing active metal particles and an electrolyte solution, which system includes one or more metal-air cells, each including outer electrode apparatus including air electrode apparatus and being configured to define a liquid permeable housing; a volume of the active metal particles arranged within the housing so as to define a static bed which is saturated with the electrolyte solution; inner electrode apparatus arranged within the housing so as to be surrounded by the static bed. The system also includes apparatus for circulating an electrolyte solution through the static bed so as to dissolve discharge products that form therein as the slurry becomes electrically discharged, and apparatus for removing the dissolved discharge products from the circulating electrolyte. The electrical power storage system may be used for powering an electric vehicle. An electrical energy system includes an electric utility having electricity generation apparatus and distribution lines, and rechargeable electrical power storage apparatus which provides energy to the electric utility, when required. The rechargeable electrical power storage apparatus may optionally also be used for the regeneration of slurry for replacement of electrically discharged slurry in the electrical power storage system of an electric vehicle.

Interfuel substitution in OECD‐European electricity production

Abstract: This is the author-created final postprint peer-reviewed version of the article. The original publication is available at www.interscience.wiley.com.

Electrical energy system

Abstract: An electrical energy system including an electric utility having an electricity generating apparatus and distribution lines, a plurality of electric vehicles and electric power storage apparatus receiving electrical power from the electric utility and supplying electrical power to the plurality of electric vehicles and to the electric utility when required.

Energy from Nuclear Power

Abstract: Nuclear power should play a pivotal and expanded role in supplying world energy, the authors says Risks must be minimized by designing a new generation of safe reactors Atomic energy's vast potential can be harnessed only if issues of safety, waste and nuclear-weapon proliferation are addressed by a globally administered institution The current situation in nuclear power is described before addressing its future

Maximum power point tracking: a cost saving necessity in solar energy systems

Abstract: It is argued that a well-engineered renewable remote energy system utilizing the principal of maximum power point tracking (MPPT) can be cost effective, has a high reliability, and can improve the quality of life in remote areas. A highly efficient power electronic converter for converting the output voltage of a solar panel or wind generator to the required DC battery bus voltage has been realized. The converter is controlled to track the maximum power point of the nput source under varying input and output parameters. MPPT for relatively small systems is achieved by maximization of the output current in a battery charging regulator, using an optimized hill-climbing, inexpensive microprocessor-based algorithm. Through field measurements it is shown that a minimum input source saving of 15% on 3-5 kWh/day systems can easily be achieved. >

Emission Impacts of Electric Vehicles

Abstract: Alternative vehicular fuels are proposed as a strategy to reduce urban air pollution. In this paper, we analyze the emission impacts of electric vehicles in California for two target years, 1995 and 2010. We consider a range of assumptions regarding electricity consumption of electric vehicles, emission control technologies for power plants, and the mix of primary energy sources for electricity generation. We find that, relative to continued use of gasoline-powered vehicles, the use of electric vehicles would dramatically and unequivocally reduce carbon monoxide and hydrocarbons. Under most conditions, nitrogen oxide emissions would decrease moderately. Sulfur oxide and particulate emissions would increase or slightly decrease. Because other areas of the United States tend to use more coal in electricity generation and have less stringent emission controls on power plants, electric vehicles may have less emission reduction benefits outside California.

Coaxial multi-turbine generator

Abstract: Turbines are suspended coaxially between a hub structure and a pivot. The hub acts to stabilize the coaxial turbine system and it acts as the power take off. The pivot acts to stabilize the other end of the coaxial turbine system. A coaxial assembly of unique flexible turbines convert wind energy into rotational mechanical energy. Driver lines attached to the extremities of the turbines transmit this energy to the extremities of the hub structure. The hub imparts torque to a drive shaft at its center thorough a moment arm and the drive shaft supplies power to a useful application, such as generating electricity. The coaxial turbine system is suspended from tower to tower between existing power transmission lines. Electricity generated by this system is fed directly into the existing power distribution system. This coaxial generator system utilizes a variety of turbine configurations and can be suspended in the wind in a number of ways.

Performance evaluation of selected combustion gas turbine cogeneration systems based on first and second-law analysis

Abstract: The thermodynamic performance of selected combustion gas turbine cogeneration systems has been studied based on first-law as well as second-law analysis. The effects of the pinch point used in the design of the heat recovery steam generator, and pressure of process steam on fuel-utilization efficiency (first-law efficiency), power-to-heat ratio, and second-law efficiency, are examined. Results for these systems using state-of-the-art industrial gas turbines show clearly that performance evaluation based on first-law efficiency alone is inadequate. Decision makers should find the methodology contained in this paper useful in the comparison and selection of cogeneration systems.

Economic, safety and environmental prospects of fusion reactors

Abstract: Controlled fusion energy is one of the long term, non-fossil energy sources available to mankind. It has the potential of significant advantages over fission nuclear power in that the consequences of severe accidents are predicted to be less and the radioactive waste burden is calculated to be smaller. Fusion can be an important ingredient in the future world energy mix and can be part of an 'insurance policy' energy strategy to develop new sources as a hedge against environmental, supply or political difficulties connected with the use of fossil fuel and present-day nuclear power. Progress in fusion reactor technology and design is described for both magnetic and inertial fusion energy systems. The projected economic prospects show that fusion will be capital intensive, and the historical trend is towards greater mass utilization efficiency and more competitive costs. Recent studies emphasizing safety and environmental advantages show that the competitive potential of fusion can be further enhanced by specific choices of materials and design. The safety and environmental prospects of fusion appear to exceed substantially those of advanced fission and coal. For example, the level of radioactivity in a low activation fusion reactor at 1 year and at 100 years after shutdown is calculated to be about one-millionth of the radioactivity in a fission reactor of the same power. Likewise, the maximum plausible dose predicted at the site boundary in the case of a low activation fusion reactor is estimated to be between 100 and 500 times smaller than that estimated for a fission power plant. Clearly, a significant and directed technology effort is necessary to achieve these advantages. Typical parameters have been established for magnetic fusion energy reactors, and a tokamak at moderately high magnetic field (about 7 T on axis) in the first regime of MHD stability (β ≤ 3.5 I/aB) is closest to present experimental achievement. Further improvements of the economic and technological performance of the tokamak are possible through the following achievements: higher magnetic fields to lower the required plasma current and reactor size; higher values of the plasma beta, including reaching the second stable MHD regime, to lower the requirements on field and plasma current; and more efficient techniques to drive the plasma current. In addition, alternative, non-tokamak magnetic fusion approaches may offer substantive economic and operational benefits, although at present these concepts must be projected from a less developed physics base. For inertial fusion energy, reactor studies are at an earlier stage, but the essential requirements are a high efficiency (≥ 10%) repetitively pulsed pellet driver capable of delivering up to 10 MJ of energy on target, targets capable of an energy gain (ratio of energy produced to energy on target) of about 100, reactor chambers capable of absorbing the energy released per shot at conditions consistent with power generation, and effective means of isolating the target chamber and driver system.

Emission impacts of electric vehicles

Abstract: Alternative vehicular fuels are proposed as a strategy to reduce urban air pollution. In this paper, we analyze the emission impacts of electric vehicles in California for two target years, 1995 and 2010. We consider a range of assumptions regarding electricity consumption of electric vehicles, emission control technologies for power plants, and the mix of primary energy sources for electricity generation. We find that, relative to continued use of gasoline-powered vehicles, the use of electric vehicles would dramatically and unequivocally reduce carbon monoxide and hydrocarbons. Under most conditions, nitrogen oxide emissions would decrease moderately. Sulfur oxide and particulate emissions would increase or slightly decrease. Because other areas of the United States tend to use more coal in electricity generation and have less stringent emission controls on power plants, electric vehicles may have less emission reduction benefits outside California.

Levelized cost of electricity generation technologies

Abstract: The levelized cost of electricity is estimated for more than 70 electricity production technologies and for two facility ownership sectors. The analysis uses a Lotus 1–2-3 spreadsheet for a consistent approach. The cost effectiveness of several alternative technologies is compared with that of conventional technologies. A variety of owners could build and operate facilities made from these conventional and alternative technologies.

Thermal energy storage

Abstract: This paper discusses how thermal energy storage (TES) can aid in the efficient use and provision of thermal energy, wherever there is a mismatch between energy generation and use. Three fundamental types of thermal energy storage processes (sensible, latent, and thermochemical) can be used, and many different media are available within each type. Various subsets of these processes are being researched and developed to accelerate TES implementation, focusing on applications in building heating and cooling, industrial energy efficiency, and utility and space power systems. TES can contribute significantly to meeting society's needs for more efficient, environmentally benign energy use in these and other sectors.

Solar energy system for generating electricity

Abstract: A solar energy system for generating electricity. The system tracks the sun during the day to produce a concentrated beam of light which is focused through a fixed opening in a heat storage chamber. The beam of light pressurizes the chamber and seals the fixed opening to prevent depressurization of the chamber. A closed circuit fluid heat transfer system collects heat from the heat storage chamber and powers a turbine. Heat powers the closed circuit system. A pump is not used in the closed circuit system. The turbine powers an electrical generator.

Wind energy and electricity production

Abstract: The benefits of the use of wind energy in terms of the economic value of electricity that is produced by grid-connected wind turbines is examined. To calculate the costs that are avoided when wind power is installed as part of the electric power generating system, one has to analyze the wind regime at the location and at the hub height of wind turbines to gain information about the amount of electricity that can be produced by wind turbines. New models to calculate the wind speed in the lower part of the surface boundary layer over sea and in coastal regions are discussed. With those models and appropriate measured wind speed data one can calculate the wind speed at any given location and height in the Netherlands. These calculated wind speed data form the basis for an analysis of the power production of wind turbines. A model is developed to simulate the hourly power produced by large numbers of wind turbines. The model incorporates detailed information about the siting of wind turbines, the power performance of these turbines, the wind speed measured at meteorological stations, and meteorological methods to transform and scale these measured wind speed data to wind speed data at the location and hub height of each wind turbine. The capacity credit of wind turbines is investigated. An analysis is made of the influence of the penetration level of wind turbines on the capacity credit and of the possible influence of geographical dispersal of wind turbines over the Netherlands. Finally, the economic value of using wind energy is evaluated by analyzing the impact on investment in conventional capacity, on operation and maintenance costs and on the use of fuels. The analysis includes the extra costs of advanced techniques to reduce the emission of NO{sub x}, SO{sub 2} and CO{sub 2}. The method of calculating the avoided costs is described. These costs are calculated over the lifetime of wind turbines. (Abstract Truncated)

Reliability survey of 600 to 1800 kW diesel and gas-turbine generating units

Abstract: A study of the reliability, availability, and maintainability (RAM) characteristics of diesel and gas-turbine power systems producing less than 2 MW is discussed. The study included collection and examination of source data for power systems at commercial and military facilities operating in continuous or standby service. A database of system, subsystem, and component RAM data was established. These data will be useful in the design of primary and standby power systems for military or commercial facilities. >

Measurement of transformer power losses and efficiency in real working conditions

Abstract: A method for measuring power losses in transformers under actual working conditions is presented. The technique is based on an unusual correlation between input and output electric quantities and yields uncertainties lower than those obtainable by evaluating these quantities as the difference between input and output powers. The analysis is carried out for both single-phase and polyphase transformers, whether with sinusoidal or any other periodic waveforms. >

Simplify heat recovery steam generator evaluation

Abstract: Heat recovery steam generators (HRSGs) are widely used in process and power plants, refineries and in several cogeneration/combined cycle systems. They are usually designed for a set of gas and steam conditions but often operate under different parameters due to plant constraints, steam demand, different ambient conditions (which affect the gas flow and exhaust gas temperature in a gas turbine plant), etc. As a result, the gas and steam temperature profiles in the HRSG, steam production and the steam temperature differ from the design conditions, affecting the entire plant performance and economics. Also, consultants and process engineers who are involved in evaluating the performance of the steam system as a whole, often would like to simulate the performance of an HRSG under different gas flows, inlet gas temperature and analysis, steam pressure and feed water temperature to optimize the entire steam system and select proper auxiliaries such as steam turbines, condensers, deaerators, etc.

Power generation and the environment

Abstract: This book reviews environmental aspects of large-scale power generation. It includes historic background of present-generation patterns and a discussion of fossil fuel, nuclear energy, and renewable technologies.