Showing papers on "Power station published in 2000"

Biomass cofiring: the technology, the experience, the combustion consequences

Abstract: Cofiring, the practice of supplementing a base fuel with a dissimilar fuel, is an extension of fuel blending practices common to the solid fuels community. Recently, there has been considerable emphasis on cofiring biomass opportunity fuels with coal in pulverized coal (PC) and cyclone boilers owned and operated by electricity generating utilities in order to address such issues as potential portfolio standards, voluntary actions to reduce fossil CO2 emissions, customer service, and the generation of green power within the context of deregulation. Biomass fuels considered for cofiring include wood waste, short rotation woody crops, short rotation herbaceous crops (e.g., switchgrass), alfalfa stems, various types of manure, landfill gas and wastewater treatment gas. Of these, the solid biofuels such as sawdust, urban wood waste and switchgrass have received the most attention. The Electric Power Research Institute (EPRI), along with the Tennessee Valley Authority (TVA), GPU Genco, Northern Indiana Public Service Company (NIPSCO), Central and South West Utilities (CS this agreement was extensively supported by the energy efficiency and renewable energy (EERE) element of USDOE. European cofiring programs also have been extensive and include gasification-based cofiring in Lahti, Finland and straw cofiring in Denmark. Three general techniques comprise the cofiring technology family: blending the biomass and coal in the fuel handling system and feeding that blend to the boiler; preparing the biomass fuel separately from coal, and injecting it into the boiler without impacting the conventional coal delivery system; and gasifying the biomass with subsequent combustion of the producer gas in either a boiler or a combined cycle combustion turbine (CCCT) generating plant. Commercialization has proceeded on the direct combustion approaches to cofiring, beginning with engineering and economic studies, parametric testing and the construction of demonstration projects. The direct combustion cofiring techniques are now ready for commercial deployment. This paper reviews the key projects, and details some of the influences of cofiring on the combustion process.

Solar Chimney cycle analysis with system loss and solar collector performance.

Abstract: An ideal air standard cycle analysis of the solar chimney power plant gives the limitingperformance, ideal efficiencies and relationships between main variables. The presentpaper includes chimney friction, system, turbine and exit kinetic energy losses in theanalysis. A simple model of the solar collector is used to include the coupling of the massflow and temperature rise in the solar collector. The method is used to predict the per-formance and operating range of a large-scale plant. The solar chimney model is verifiedby comparing the simulation of a small-scale plant with experimental data.@S0199-6231~00!00503-7#

Biomass cofiring: economics, policy and opportunities.

Abstract: The US Department of Energy (DOE), Electric Power Research Institute (EPRI) and utilities are evaluating, testing and applying technology that can give a new, and potentially profitable, mission to existing coal-fired power plants. The oldest of all fuels, wood, and the old original fuel of the industrial revolution, coal, are key to this move to a new mission. Technical issues that can lead to doubt about, or outright rejection of, wood (or biomass) cofiring are, in fact, being resolved through testing and experience. DOE, EPRI and utilities have joined to cosponsor tests in full-sized boilers and design/cost/supply studies related to these tests. Economic calculations, based on the measured performance and on cost estimates confirmed in purchases for the tests, are presented in this paper. The technical feasibility is proved. The constraints are identified. So far, the profits are in the future. Policy changes that produce stronger economic incentives could make profit possible today, and enable this low-cost form of renewable power to be deployed. But, without the policy, or market, change, the economic barrier is a strong one, when biomass cofiring must compete with low-cost coal at low fuel cost and with low-capital-cost gas turbine combined cycle power plants. The economics would not be a barrier at all if biomass cofiring were in competition against moderate-velocity wind power or solar PV power.

Cofiring coal and straw in a 150 MWe power boiler experiences

Abstract: In 1995 ELSAM/MIDTKRAFT equipped the 150 MW e pulverised coal-fired Studstrup power station, unit 1, for a technology demonstration cofiring of coal and straw. The conversion consisted of establishing a straw pre-processing plant and modifying the burner system. After plant commissioning in January 1996, a 2-year demonstration program was initiated. The objective of the program was to evaluate the influence of cofiring on boiler plant performance, combustion chemistry, heat surface deposits and corrosion, residue quality, emissions, and selective catalytic reduction (SCR) systems. This paper presents the plant conversion and results from the demonstration period.

Competitiveness of biomass-fueled electrical power plants.

Abstract: One way countries like the United States can comply with suggested rollbacks in greenhouse gas emissions is by employing power plants fueled with biomass. We examine the competitiveness of biomass‐based fuel for electrical power as opposed to coal using a mathematical programming structure. We consider fueling power plants from milling residues, whole trees, logging residues, switch grass, or short‐rotation woody crops. We do this using a combined model of the agricultural and forestry sectors. We find that the competitiveness of biomass depends in a key way upon the success of research in developing improved production methods for short‐rotation woody crops without great increases in costs.

A method for determining the generators' share in a consumer load

Abstract: In the paper, a new method for determining the generators' contribution to a particular load is presented, The method uses the nodal generation distribution factors (NGDF-s). It features a search algorithm, capable of handling the active and reactive powers. The method has been tested on the IEEE 118 and on the Slovenian 275 bus systems. The results demonstrate that electrical energy flows from a producer to a customer based on physical rather than on economical rules. By means of the new method, it can be shown that in general, the customer does not obtain the full power from the selected power plant according to the contract but also from other power plants. The method of the NGDF-s can be used for transmission service pricing, for congestion management and for reactive power management.

Liquid Gallium: Potential Uses as a Heat-Transfer Agent

Abstract: This paper deals with potential uses of gallium, as well as the most important gallium-based alloys, as energy carriers in high-safety nuclear power plants. Experimental data are given on the thermophysical, electrophysical, chemical, acoustic, and other properties of gallium and its alloys.

Evaluation of energy storage method using liquid air

Abstract: An energy storage system using liquid air for high storage efficiency is studied Liquid air is produced by off-peak power and can be stored at atmospheric pressure in a large tank When on-peak power is needed, the stored liquid air is pumped to high pressure and fed to the combustor of a gas turbine Then, power generation is more than doubled from that of a system with an ordinary air compressor Furthermore, energy storage efficiency of this system is significantly increased above that of a pumping-up power plant when low-temperature liquid air is used to produce new liquid air © 2000 Scripta Technica, Heat Trans Asian Res, 29(5): 347–357, 2000

Exergy Analysis of Modern Fossil-Fuel Power Plants

Abstract: The definition of open cycle rational efficiency is unequivocally based on the ratio of the actual shaft work output from a power plant to the maximum work that could be obtained in a reversible process between prescribed inlet and outlet states. However, different constraints may be applied to such an ideal reversible process, and the maximum work obtainable will then vary, as will the value of the rational efficiency. Attention has been drawn to this issue before in the literature and it is discussed further here. In particular the consequences of defining the outlet state for the ideal process are critical. A furthe complication occurs when water or steam is injected into a gas turbine plant. Three definitions of rational efficiency are discussed here and some illustrative calculations presented. There are small but significant differences between the values of the three derived efficiencies.

Valuation of Power Generation Assets: A Real Options Approach

Abstract: Real options theory is an increasingly popular tool for valuing physical assets such as power generation plants. In this paper, we describe a model for power plant valuation that accounts for such important operating characteristics as minimum on- and off-times, ramp time, nonconstant heat rates, response rate and minimum electricity dispatch level. The power plant values and optimal operating policies are obtained by employing stochastic dynamic programming. Sample numerical results, using electricity price data from the New England power pool, show that operating constraints can have a significant impact on power plant values and optimal operating policies.

A coal shipping and blending problem for an electric utility company

Abstract: In this paper, we address the issues of coal supply and blending pertaining to an electric utility company in Taiwan. Since the fuel used by coal-fired power plants are mainly imported in bulk from overseas sources, the planning of coal shipping and blending is of great economic importance. This operation involves the consideration of (1) each contract's coal supply, quality and price, (2) each power plant's demand, environmental constraints and limit on the maximum number of different coal sources that can supply it, (3) installation of blending facilities and (4) the transient seaport's shipload capacity. A mixed-integer zero–one programming model is presented for finding optimal shipping and blending decisions of coal fuel from each overseas contract to each power plant. A solution procedure is developed that employs heuristic rules in conjunction with branch-and-bound methods, and is illustrated using real-world data collected from the electric power company. Results reveal the benefits of the proposed approach, which has proven to be very practical and convincing for the top management of the company.

Gas power generation in Norway: Good or bad for the climate? Revised version

Abstract: Norway has abundant gas resources in the North Sea. The Norwegian gas production accounts for 2 percent of the world production and 17 percent of the European gas production. Despite huge gas production and resources, gas is not used for electricity generation in Norway. Excess capacity, cheap hydropower, low electricity prices and political restrictions have prevented gas based power generation in Norway. Lately, import of electric power from neighboring countries with fossil fuel based power systems has led industry spokesmen and various politicians to propose building of several gas power plants in Norway. Electric self-sufficiency, domestic natural gas utilization and environmental benefits through reduced coal power generation abroad are used as arguments to support construction of gas power plants in Norway. Several industrial groups have applied for concession to build natural gas fired power stations. Initially, the Norwegian Pollution Control Authority (SFT) denied emissions concession referring to Norwegian obligations under the Kyoto protocol. In March 2000, however, a majority in parliament voted against the SFT-decision and advised the Government to issue concession. The core argument from both sides was the environmental impacts from gas power generation in Norway. SFT argued that increased power generation would lead to lower energy prices and thereby higher energy consumption and more pollution. The view of the majority of Parliament was that Norwegian gas power will replace coal power generation in Denmark and Germany and thus give lower total climate gas emissions since coal based power results in much higher emissions per unit of energy than gas power does. The Nordic electricity system and market is very complex and therefore energy policy measures may result in numerous different impacts and repercussions. Therefore, we carry out a number of model simulations to analyze the impacts from introduction of Norwegian gas power generation into this market. We apply an equilibrium model for the Nordic electricity market. In order to describe important intra-year supply-side technology and fuel substitution, the Normod-T model has a detailed time-resolution. Our calculations show that none of the two views are completely right. The aggregate effect on climate emissions from producing gas power in Norway may be positive or negative, and depends heavily on the assumptions made. Keywords: Electricity market, Gas power, Climate policy, Electricity trade

Fuel Cell Handbook, Fifth Edition

Abstract: Progress continues in fuel cell technology since the previous edition of the Fuel Cell Handbook was published in November 1998. Uppermost, polymer electrolyte fuel cells, molten carbonate fuel cells, and solid oxide fuel cells have been demonstrated at commercial size in power plants. The previously demonstrated phosphoric acid fuel cells have entered the marketplace with more than 220 power plants delivered. Highlighting this commercial entry, the phosphoric acid power plant fleet has demonstrated 95+% availability and several units have passed 40,000 hours of operation. One unit has operated over 49,000 hours. Early expectations of very low emissions and relatively high efficiencies have been met in power plants with each type of fuel cell. Fuel flexibility has been demonstrated using natural gas, propane, landfill gas, anaerobic digester gas, military logistic fuels, and coal gas, greatly expanding market opportunities. Transportation markets worldwide have shown remarkable interest in fuel cells; nearly every major vehicle manufacturer in the U.S., Europe, and the Far East is supporting development. This Handbook provides a foundation in fuel cells for persons wanting a better understanding of the technology, its benefits, and the systems issues that influence its application. Trends in technology are discussed, including next-generation concepts that promise ultrahigh efficiency and low cost, while providing exceptionally clean power plant systems. Section 1 summarizes fuel cell progress since the last edition and includes existing power plant nameplate data. Section 2 addresses the thermodynamics of fuel cells to provide an understanding of fuel cell operation at two levels (basic and advanced). Sections 3 through 8 describe the six major fuel cell types and their performance based on cell operating conditions. Alkaline and intermediate solid state fuel cells were added to this edition of the Handbook. New information indicates that manufacturers have stayed with proven cell designs, focusing instead on advancing the system surrounding the fuel cell to lower life cycle costs. Section 9, Fuel Cell Systems, has been significantly revised to characterize near-term and next-generation fuel cell power plant systems at a conceptual level of detail. Section 10 provides examples of practical fuel cell system calculations. A list of fuel cell URLs is included in the Appendix. A new index assists the reader in locating specific information quickly.

Cofiring multiple opportunity fuels with coal at Bailly Generating Station

Abstract: Northern Indiana Public Service Company (NIPSCO) has developed a long-term demonstration firing biomass and petroleum coke with coal at its Bailly Generating Station boiler #7, a 160 MW e (net) cyclone boiler. This demonstration, funded by the US Department of Energy (USDOE) Office of Energy Efficiency and Renewable Energy (EERE) and the USDOE National Energy Technology Laboratory (NETL), has been developed as part of the Electric Power Research Institute (EPRI) biomass cofiring demonstration program. The NIPSCO demonstration program — the triburn program — has involved designing and constructing a fuel preparation and blending facility. It then involved extensive testing of firing clean urban wood waste — biomass — with coal, firing petroleum coke with coal, and firing various blends of urban wood waste and petroleum coke with coal. Results of the extensive testing program have shown that the triburn blends of biomass and petroleum coke with coal have accomplished the following: (1) increased boiler efficiency, (2) reduced fuel costs; and (3) reduced emissions of oxides of nitrogen (NOx), mercury, and fossil carbon dioxide (CO2). At the same time, the triburn program has not increased other emissions. This paper summarizes the results of testing at Bailly Generating Station, discusses the impacts of petroleum coke and wood waste, discusses the synergies between these two opportunity fuels, and considers the implications of the demonstration.

A model of fossil fueled plant with once-through boiler for power system frequency simulation studies

Abstract: A model of a fossil fueled generating power plant with a once-through boiler for power system frequency simulation studies is presented. In the model, the plant control system is modeled to represent the fundamental response of the coordinated boiler-turbine control in the large-size supercritical plants under changes in the system frequency. The model is based on a survey of configurations of the plant control systems used in the major units commercially operated in Japan. The values of the parameters in the model are described through the comparisons with plant responses in a field test and with simulation results from a detailed model of the plant manufacturer. Sample simulation results from the model are presented for demonstrating the fundamental response of the once-through plants under change in system frequency.