Tennessee Valley Authority Research Articles

RIVERWARE: A GENERALIZED TOOL FOR COMPLEX RESERVOIR SYSTEM MODELING1

ABSTRACT: Water management agencies seek the next generation of modeling tools for planning and operating river basins. Previous site‐specific models such as U.S. Bureau of Reclamation's (USBR) Colorado River Simulation System and Tennessee Valley Authority's (TVA) Daily Scheduling Model have become obsolete; however, new models are difficult and expensive to develop and maintain. Previous generalized river basin modeling tools are limited in their ability to represent diverse physical system and operating policy details for a wide range of applications. RiverWare(tm), a new generalized river basin modeling tool, provides a construction kit for developing and running detailed, site‐specific models without the need to develop or maintain the supporting software within the water management agency. It includes an extensible library of modeling algorithms, several solvers, and a rich “language” for the expression of operating policy. Its point‐and‐click graphical interface facilitates model construction and execution, and communication of policies, assumptions and results to others. Applications developed and used by the TVA and the USBR demonstrate that a wide range of operational and planning problems on widely varying basins can be solved using this tool.

Comparison of operational design criteria for subsurface flow constructed wetlands for wastewater treatment

Many communities are investigating the use of constructed wetlands as a simple, viable alternative to poorly operating on-site wastewater treatment. Currently, the most popular design models in the U.S.A. for subsurface flow units are the US Environmental Protection Agency (EPA) and the Tennessee Valley Authority (TVA) methods. However, there has been limited data verifying if the operating performance is up to design standards. In order to address this problem, this paper documents the performance of such treatment systems over a broad range of conditions in North Alabama. The operational data is used to determine a best-fit value of reaction rate constant and proposes improved input parameters for both design models. According to this data, the average plug-flow reaction rate constant was calculated to be 0.70 d-1 for the EPA method, while the recommended organic loading criterion is 11.4 m2/kg BOD5 per day into the wetland for the TVA method.

Indicators of sustainable development for catchment management in South Africa - Review of indicators from around the world

Indicators are the ideal means by which progress towards sustainable development can be measured. However, most indicator initiatives throughout the world have been aimed at state-of-the-environment reporting, with relatively few aimed at developing sectoral indicators. This paper provides the results of a review to establish trends in the development of indicators that assist in integrated water resource management. Twenty-one organisations from around the world were approached with regard to whether they had developed indicators of sustainable development for catchment management. Of these, only five organisations had developed, or were in the process of developing, indicator sets that were available for review. These included the Fraser Basin Council (Canada), the Murray-Darling Basin Commission (Australia), the Tennessee Valley Authority (USA), the United States Environmental Protection Agency and the World Resources Institute. All of these indicator sets were developed using an issuesbased approach. Each indicator set was unique, reflecting the policy, both national and organisational, upon which it had been based. An analysis of these five indicator sets revealed that the most important themes that required information for water resource management at a catchment level, were biodiversity and ecosystem integrity, land-use change, water quality, waste production, water availability and resource use. Common indicators included population growth; community involvement; water availability; water use; water quality trends; soil contamination; non-compliance; species at risk; key species assessment; change in vegetation; agricultural impact; access to recreational opportunities, and ecosystem health. The identification of these themes and common indicators will be useful for the development of indicators for catchment management in South Africa. More importantly, policy frameworks and the physical characteristics of catchment systems in the country need to be taken into account. Additionally, it is recognised that no effective indicator set can be developed without the input of stakeholders. WaterSA Vol.27(4) 2001: 539-550

Goal Programming Decision Support System for Multiobjective Operation of Reservoir Systems

Many authors have documented the minimal use of optimization in practical day-to-day multipurpose reservoir operations. The RiverWare decision support system is a flexible general river basin modeling tool that allows water resources engineers to both simulate and optimize the management of multipurpose reservoir systems for daily operations. This paper describes RiverWare's optimization capabilities and its use by Tennessee Valley Authority operations schedulers. Input data requirements include (1) physical and economic characteristics of the system; (2) prioritized policy goals; and (3) parameters for automatic linearization. RiverWare automatically generates and efficiently solves a multiobjective, preemptive linear goal programming formulation of a reservoir system. An advanced feature of RiverWare is that both the physical model of the river basin and the operating policy are defined and easily modified by the modeler through an interactive graphical user interface. Any modifications are automaticall...

Fouling in a 160 MWe FBC boiler firing coal and petroleum coke

The 160 MWe fluidized bed combustor (FBC) boiler owned and operated by the Tennessee Valley Authority (TVA) has recently been co-fired with coal and petroleum coke (up to 50%). However, it has suffered some fouling problems. On examination of the deposits it became clear that, in only a few cases could the fouling be partially attributed to alkali metals, and even in those cases the primarily limestone-derived materials were almost quantitatively sulphated to a level which was sufficient to cause strength development by itself. In other cases, it appeared that the fouling mechanism was carbonation of the free lime component of the deposit followed by sulphation. Finally, in a few deposits which were less sulphated than bed materials and fly ash, strength development appeared to have occurred by conversion of the free lime in the deposits to Ca(OH) 2, followed by carbonation. This type of agglomeration has not been reported previously in a FBC.

The Effects of Ash Deposits on High-Temperature Corrosion of Alloys in a Fluidized Bed Combustion System

Abstract Five 1,000-h combustion tests firing 5 different coals were conducted in a 0.1-MWth fluidized bed combustion (FBC) facility at Western Kentucky University (WKU) with the operating conditions simulating those of the FBC unit at the Tennessee Valley Authority's (TVA) Shawnee Power Station. Five coals were selected with various S and Cl contents ranging from high S (4.48%) and high Cl (0.47%) to low S (0.97%) and low Cl (0.012%). Three types of uncooled steel coupons (Types 304 [UNS S30400], 309 [UNS S30900], and 347 [UNS S34700] stainless steel [SS]) were prepared and installed, based on the advice of TVA, to simulate the evaporator tubes in the superheater region (550°C to 600°C [1,020°F to 1,100°F]). Metal wastage of each coupon was determined by measuring the thickness before and after each combustion test. In order to study the relationship between metal corrosion and ash deposits, a total of 170 ash deposits were collected from the test coupon surfaces during the 5,000-h testing and analyzed. ...

The Contemporary Presidency: The Presidential “Hundred Days”: An Overview

The “Hundred Days” of 1933, when Franklin D. Roosevelt at the onset of his first term got sixteen major bills through Congress, is a poor guide to what contemporary presidents can plan or hope to do in their first three months. For one thing, under the Twentieth Amendment, Congress is already in regular session when they arrive, and three months takes one only to the Easter recess of the first session. For another thing, presidential “honeymoons” with the public, hence with Congress, rarely last until summer, while the crucial months for controversial bids usually come later. Third, brand‐new presidents and their associates in both the cabinet and White House tend to be too ignorant of Congress and of one another to take full advantage of the opportunities their first months bring.

Comparison of heavy metal accumulation in a natural wetland and constructed wetlands receiving acid mine drainage

Metal accumulations in sediments and plants of constructed and natural wetlands were compared in two wetlands constructed by the Tennessee Valley Authority (TVA) for the treatment of acid mine drainage and a natural wetland. Load rates and removal efficiencies of most metals were generally greater in the constructed wetlands than in the natural wetland. There were similar sediment and plant metal concentrations between one constructed wetland and the natural wetland and greater metal concentrations in the sediments and plants in the other constructed wetland compared to the natural wetland. Data indicate that Mn, Zn, Cu, Ni, B, and Cr are being accumulated in the plants at all three wetlands, although accumulation of metals by these plants accounts for only a small percentage of the removal of the annual metal load supplied to each wetland.

ReCip Constructed Wetlands for Wastewater Treatment: Treatability Study I.

ReCip Constructed Wetlands for Wastewater Treatment: Treatability Study I.Scientists at the Tennessee Valley Authority (TVA), in collaboration with the U.S. Environmental Protection Agency (EPA), have developed an innovative wastewater treatment system based on reciprocating subsurface-flow constructed wetlands. Reciprocation relates to patented improvements in the design and operation of paired subsurface-flow constructed wetlands in which contiguous wetland cells are...Author(s)L.L. BehrendsL. HoukeE. BaileyP. JansenD. BrownSourceProceedings of the Water Environment FederationSubjectSession 71 - Small and Natural Systems and Water Reuse: Natural Soil Based SystemsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2001ISSN1938-6478SICI1938-6478(20010101)2001:9L.73;1-DOI10.2175/193864701790861361Volume / Issue2001 / 9Content sourceWEFTECFirst / last page(s)73 - 73Copyright2001Word count139

Power at the Top

A discussion of Miguel Angel Centeno, Democracy within Reason: Technocratic Revolution in Mexico, University Park: Pennsylvania State University Press, 1997. Richard A. Colignon, Power Plays. Critical Events in the Institutionalization of the Tennessee Valley Authority, Albany: State University of New York Press, 1997. John Gaventa, Power and Powerlessness. Quiescence and Rebellion in an Appalachian Valley, Urbana: University of Illinois Press, 1980.

Effect of Increased Truck Traffic from Chickamauga Lock Closure

The lock at Chickamauga Dam on the Tennessee River may have to close for various periods for major repair work. Such scheduled or unscheduled closures will disrupt the barge traffic serving many industries located upstream of the dam. Some of the commodities moving on barges will be diverted to trucks, depending on the nature of the closures, and the new truck traffic may result in a variety of effects, or externalities. A method is presented to estimate the effects of increased truck traffic. Delays from traffic congestion and incidents, pavement damage, truck-related accidents, and air pollution are examined. The study was performed for the Tennessee Valley Authority.

Cofiring from the TVA public power perspective

The Tennessee Valley Authority (TVA), created by Act of Congress in 1933, has responsibility for generating electricity, providing flood control, and promoting agricultural and industrial development for the Tennessee Valley. In the generation of electricity, TVA initially developed extensive hydroelectric facilities throughout the valley and, subsequently, extensive fossil and nuclear facilities. In the changing regulatory and economic environment associated with electricity generation, TVA has created the Public Power Institute (PPI). The PPI has responsibility for advancing energy generation and pollution reduction; it has responsibility for renewable energy development. In carrying out its renewable energy commitment, the PPI extends the leadership in biomass cofiring started in 1992, with studies and testing performed in cooperation with the Electric Power Research Institute at such locations as the Kingston Fossil Plant and the Allen Fossil Plant. It extends the activities associated with using tire-derived fuel at the Allen Fossil Plant. Through the PPI, TVA will continue to take a leadership role in the development of biomass systems.

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

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 CO 2 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 (C&SW), Southern Company, Madison Gas & Electric (MG&E), New York State Electric and Gas (NYSEG) and others developed a concerted effort to commercialize direct combustion cofiring of biomass with coal. The USDOE joined the program with a cooperative agreement between the Federal Energy Technology Center (FETC) — now the National Energy Technology Laboratory (NETL) and EPRI; 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.

Sport Fishing Index (SFI)

Abstract A team of biologists, including representatives from the Tennessee Valley Authority (TVA) and state fishery resource agencies in the Tennessee River Valley, developed an index to quantify sport fishing quality for individual sport fish species. The objective of the Sport Fishing Index (SFI) is to provide the fishing public with information that will assist them in selecting locations that have the best potential for a successful fishing experience for the species they prefer. Additionally, the index provides biologists with a reference point measure of the quality of that fishery. Comparison of population sampling parameters and creel results for a particular sport fish species with expectations of these parameters from a high quality fishery (reference conditions) allows determination of fishing quality. To date, indices developed include largemouth, smallmouth, and spotted bass; crappies (black and white combined); walleye; sauger; and channel catfish. Each SFI relies on measurements of quantity and quality aspects of angler success and fish population characteristics. Comparison of index results among reservoirs and between years from the Tennessee and Cumberland River reservoirs from 1996 to 1998 indicated that differences in fishing quality for a particular species were measurable.

Chemical Composition of Fine Particles in the Tennessee Valley Region

ABSTRACT Fine particles in the atmosphere have elicited new national ambient air quality standards (NAAQS) because of their potential role in health effects and visibility-reducing haze. Since April 1997, Tennessee Valley Authority (TVA) has measured fine particles (PM2.5) in the Tennessee Valley region using prototype Federal Reference Method (FRM) samplers, and results indicate that the new NAAQS annual standard will be difficult to meet in this region. The composition of many of these fine particle samples has been determined using analytical methods for elements, soluble ions, and organic and elemental carbon. The results indicate that about one-third of the measured mass is SO4 -2, one-third is organic aerosol, and the remainder is other materials. The fraction of SO4 -2 is highest at rural sites and during summer conditions, with greater proportions of organic aerosol in urban areas throughout the year. Additional measurements of fine particle mass and composition have been made to obtain the short-term variability of fine mass as it pertains to human exposure. Measurements to account for semi-volatile constituents of fine mass (nitrates, semi-volatile organics) indicate that the FRM may significantly under-measure organic constituents. The potentially controllable anthropogenic fraction of organic aerosols is still largely unknown.

Quantitative Precipitation Forecasting for the Tennessee and Cumberland River Watersheds Using the NCEP Regional Spectral Model

Abstract A limited-area spectral model—the Regional Spectral Model—developed at the National Centers for Environmental Prediction is used to prepare daily quantitative precipitation forecasts out to 48 h for the Tennessee and Cumberland River basins in the southeastern United States. One year of these forecasts is evaluated against data from a network of 243 rain gauges and against traditional man–machine forecasts provided under contract to Tennessee Valley Authority river system managers. The intent of this study was to determine whether the model forecasts, made at greater spatial resolution than those typically available from other sources, offered any advantages to water resource managers responsible for making critical day-to-day decisions affecting flood control, navigation, and hydropower production. The model’s performance, determined using a variety of statistical measures, was found to be more accurate than the traditional forecasts. In particular, the model had less bias and lower root-mean-sq...

Wintering Waterbird Use of Two Aquatic Plant Habitats in a Southern Reservoir

Increasing use of grass carp (Ctenopharyngodou idella) to control aquatie plants in large reservoirs has been a concern of waterbird managers because grass carp reduce biomass and diversity of native aquatic macrophytes and potentially lower habitat quality for birds. Native macrophytes were virtually climinated from Guntersville Reservoir. Alabama after the Tennessee Valley Authority (TVA) released grass carp, but Eurasian: watermilfoil (Myriophyllum spicatum) was unaffected. We revegetated 0.1-ha areas at Guntersville Reservol with native plants, and compared waterbird use and activity in native plant and miltoil habitats during October January to better evaluate effects of these habitat chauges on migrating and wintering waterbirds. We also determined the relative availability of these 2 plant types during fall and early winter. Milfoil and native plant habitats were used predominately by dabbling ducks and American coot (Fulica americana). Waterbirds were absent more often from native vegetation plots (36%) than from milfoil plots (1%) Density of waterbirds was high in native plant habitats in October, but was greater in milfoil habitats from November to January as native plant biomass declined and milfoil remained relatively abundant. Feeding was the predominant activity in most months, and time spent foraging did not differ between plant habitats in 1994-95. In 1993-94, waterfowl loraged more in native plant habitats in October and November, but foraging was greater in milfoil habitats in December and Jamiary. Submersed native plants and milfoil both were important to ducks and coot using Guntersville Reservoir Results suggest that maintaining a diverse aquatic plant community at southern reservoirs is beneficial to migrating and wintering waterbirds.

Index to Russell’s Authority and the Individual

Index to Russell’s Authority and the Individual

Historic PM2.5/PM10 Concentrations in the Southeastern United States—Potential Implications of the Revised Particulate Matter Standard

ABSTRACT This report summarizes a PM2.5/PM10 particulate matter data set consisting of 861 PM2.5/PM10 sample pairs collected with dichotomous samplers by the Tennessee Valley Authority (TVA) from 1982 to 1991. Eight monitoring stations, ranging from urban-industrial to rural-background, were operated across three east-central U.S. states. Annual average PM2.5 concentrations ranged from 12.6 to 21.3 micrograms per cubic meter (μg/m3), with an overall mean of 15.7 μg/m3. Likewise, annual average PM10 concentrations ranged from 17.8 to 33.7 μg/m3, with an overall mean of 23.7 μg/m3. High summer-low winter seasonality was evident, particularly for PM2.5, with the highest monthly PM2.5 and PM10 concentrations in August (26.4 and 37.5 μg/m3, respectively) and the lowest in February (9.9 and 15.3 μg/m3, respectively). A strong association (r2 = 0.84) was found between PM and PM mass with PM mass contributing, on average, 67% of PM10 mass. Applying TVA's PM2 5/PM10 ratio to recent (1993-1995) regional high-volume PM10 Aerometric Information Retrieval System (AIRS) data for the east-central United States suggests that as many as 80% of monitored counties would have equaled or exceeded the level of the new annual PM2.5 metric of 15 μg/m3. A decline in average PM2.5 mass on the order of 3-5 μg/m3 from 1982 through 1991 is also suggested. Daily PM2 5 mass appears to be reasonably well associated (r = 0.47) with maximum hourly ozone during the warmer months (spring through fall). Sulfate compounds comprise a major portion of the measured PM2 5 mass, with that fraction being highest in the summer months. Viewed collectively, these data suggest that although compliance with the annual and 24-hr PM and 24-hr PM metrics should prove readily attainable, the annual PM2.5 metric will present a major regulatory management challenge for much of the east-central United States.

99/03385 Impacts from a fossil fuel power plant on ozone levels in Memphis, Tennessee

The Tennessee Valley Authority (TVA) Allen power plant is located on the Mississippi River in the southwest corner of Memphis, Tennessee. Allen has three coal-fired cyclone boilers with a rated capacity of 272 MW each. It is a Phase 2 plant under Title IV of the Clean Air Act and is the largest single source of NO{sub x} in the Memphis area. TVA plans to reduce Allen NOx emissions through a combination of burning low-sulfur coal (which has the benefit of reducing NO{sub x} emissions while also reducing SO{sub 2} emissions) and installing gas re-burn technology. A modeling study using the SAI, Inc., UAM-V photochemical model was conducted to examine the potential impacts of NO{sub x} reductions on ozone levels in the Memphis area. A series of four model simulations were made in which different Allen emissions scenarios were examined. The focus period of the photochemical modeling was 11--14 July 1995 when measurements in and near Memphis indicated peak hourly ozone levels of 135--140 ppb. This analysis primarily examined computed impacts within 50 km of Memphis. Allen was computed to contribute as much as 20--30 ppb to ground ozone levels 20-50 km downwind using its NO{sub x} emission rate beforemore » Title IV compliance. After compliance it was computed to contribute only about 10--20 ppb. At the same time, maximum daily ozone reductions due to Allen NO{sub x} titration of ozone were between 30 and 60 ppb. These benefits will be reduced by 30--50% after Title IV compliance, and are expected to occur within 30 km of the plant. More model grid cells indicated dis-benefits (net ground-level ozone increases) than benefits on three of the four episode days using the Title IV compliance emission rate. Significant ozone dis-benefits were expected because of the well-documented NO titration of ozone within plumes having a high ratio of NO to volatile organic compounds.« less