More Efficient Gas Plants and Improved Gas Alternatives Needed

Issue 10 and Volume 107.

By: Steve Blankinship, Associate Editor

There will be no shortage of energy issues to discuss at POWER-GEN International, December 9-11 in Las Vegas. But uncertainties surrounding the price and supply of natural gas — for more than a decade the fuel of choice for nearly 90 percent of all new U.S. power capacity – will be at center stage.

Although capacity margins are currently healthy in most regions, a looming economic rebound could close the gap sooner rather than later. To make matters worse, much of the margin consists of generation fueled by natural gas, a resource whose increasing prices and dwindling domestic supplies have spurred government and industry to fear an impending energy crisis.

As a result, there is an intensified urgency for advances in gas-fired generation efficiency, less conventional gas-fired options, new coal and nuclear alternatives, and accelerated interest in renewables and distributed generation.

At least one session will take direct aim at the gas price/supply crisis and potential alternatives to address it. Gas Price Volatility — Is Fuel Diversification the Answer? will explore the practicality of alternative fuels being used to meet this economic challenge. The session will detail the viability of alternative fuel and generation supply options, including liquefied natural gas, nuclear and coal.

The session will include a paper presented by Nancy Mohn, director of utility boilers marketing strategy for ALSTOM, entitled Is There a Role for Coal in the Future US Energy Mix? “The U.S. power industry has a somewhat schizophrenic view of coal-fired generation,” she says. “Installed base of coal units has continued to generate over 50 percent of our electricity with increasing hours of operation every year since 1991. All of that has been during a time when more stringent environmental regulations have driven reductions in emissions from these same units. The availability/reliability of these units has also been excellent, despite their aging. Yet during the last three-year boom cycle, 99 percent of these orders have been for natural gas-fired turbines.”

Gas price volatility, and questions on short-term supply, have again focused on the role of operating coal units to meet near-term power needs economically and reliably. The ALSTOM paper will examine the outlook for new coal-fired generation and what will be required for new coal plants to compete with gas turbine plants.

Florida Municipal Power Agency is one utility studying the potential development of more coal-fired generation. Roger Fontes, the agency’s general manager and CEO, Richard Casey, planning and contracts manager, and David Gardner of POWER Engineers Inc. will detail how several Florida consumer community-owned utilities are considering the joint development of a 500 MW to 1,000 MW coal-fired generation project. The paper will describe engineering and financial studies, comparing coal-firing technology alternatives such as pulverized coal, circulating fluidized bed and integrated gasified combined cycle, supercritical steam conditions and innovative use of gas turbine feedwater heating. It will also address technologies for NOx, SOx and mercury control as well as integration of biomass energy with the primary coal-fired operation.

Regulatory uncertainty and inconsistency, combined with the formidable economic costs and lead-time requirements associated with environmental control equipment, have historically made planning difficult and risky in the power industry.

Among the sessions addressing environmental policy and the possibility that it might eventually stabilize will be Changes and Developments in Environmental Regulations. The session will cover recent developments in the application and interpretation of environmental regulations that affect operations at most power plants. Effects on air emissions, water intake/discharge and plant compliance will be included.

Jim McConnach of Castle Hill Engineering will address emissions trading in a paper entitled Status Report on Standards and Protocols for the Quantification of Greenhouse Gas Emission Credits. The paper summarizes various initiatives in place or under development at the national and international levels for greenhouse gas trading quantification standards and the main principles being adopted. Also included will be a progress report on the IEEE Standards Association Project P1595 to develop an international standard for the quantification of CO2 emission credits in the electricity sector.

Dr. Ravi Agrawal of Entropy Technology and Environmental Consultants will present a paper — Strategies to Profit from the New Cap and Trade Regulations — detailing how new cap and trade regulations already in place or soon to be implemented by the EPA provide flexibility in controlling emissions.

“The new rules allow NOx reduction beyond the state or federal limits to be banked as emission credits,” he says. “Sources not meeting the new limits will need to reduce NOx emissions, or can purchase NOx emission credits annually. In the past, shortage of yearly NOx emission credits have caused NOx credits to be traded as high as $100,000 per ton; however, under normal conditions, credits are expected to trade in the $4,000-$50,000/ton range. If the cost of NOx control technology is less than the cost of emission credits, it will be economical to install NOx control technology.” Agrawal says the easiest way to generate emission credits is by installing cost-effective combustion control technology as soon as possible.

In a paper from Duke/Flour Daniel —Testing and Monitoring Requirements: The Forgotten Aspect of Environmental Permitting — Bart Vince will present examples of commonly-encountered permit conditions related to emission testing and monitoring that can result in significant cost, schedule, or compliance impacts to both gas-turbine and coal-fired power plant projects. The paper will present solutions and outline a generic approach to identifying and correcting troublesome permit requirements related to testing and monitoring.

Bryan Hansen of Burns & McDonnell will present a paper entitled NPDES Compliance: Analyzing the Possibilities to Meet Changing Regulations. “Keeping plants in compliance with National Pollutants Discharge Elimination System (NPDES) permit requirements is becoming increasingly more difficult as a result of regulatory changes,” he says. Environmental concerns continue to tighten the allowable discharge limitations for many water quality constituents including chlorides, sulfates, total dissolved solids, and many metals.

The Burns & McDonnell paper explores options available for utilities to meet the changing NPDES permit regulations and water quality discharge limitations. Options evaluated include water treatment; wastewater treatment; discharge to alternative streams, rivers or lakes; deep well injection; how to obtain better makeup water to help improve discharge quality; optimization of existing plant wastes; rerouting of existing plant drains; modifications to existing plant systems; and modifications to existing operating practices.

Squeezing More Performance From Gas

Higher prices and tighter supplies of natural gas will certainly intensify interest in improved performance and efficiency in both the existing gas-fired fleet and in new gas-fired capacity. Several sessions will focus on gas generation technology improvements.

Obtaining additional power output and efficiency from combustion turbines is often more cost effective and timely than installing new generation. The session Combustion Turbine Power Augmentation will compare current and future power enhancement techniques for combustion turbines. The session is designed to incorporate technical and economic information from users, suppliers, consultants and OEMs.

Included in the session will be a presentation by Sanjeev Jolly and Scott Cloyd of Caldwell Energy & Environmental and Alberto Zabaleta of Soluziona Servicios Profesionales on Performance Enhancement of GT24 with Wet Compression. The paper will compare the performance effects of applying wet compression to the Alstom GT24 with the performance of older combustion turbine frames that have been operated with wet compression systems for many years. The paper will also address the relative changes in compressor and turbine operating conditions and how these affect component life.

“Wet compression is not just spraying water into the compressor inlet; one must realize there is an expensive and high precision turbine downstream,” says Jolly. “The system must be properly integrated with the turbine controls and any issues or concerns with wet compression must be thoroughly evaluated and addressed.”

The session will also feature a paper on Gas Turbine Inlet Air Cooling Techniques: An Overview of Current Technologies, presented by Craig Cortes and Daniel Willems of Siemens Westinghouse. The paper compares cooling techniques and systems employed for gas turbine inlet air applications, contrasting fogging with wet pad evaporative cooling and chilling (refrigeration cycle) in various inlet ambient conditions, and describing each system and its effect upon a 185 MW industrial gas turbine. “Free water has the potential of causing erosion and other damage to inlet compressor blades and hence is to be avoided in today’s high efficiency compressors,” notes Cortes. “Control systems have been developed and implemented to address the problem and we will be describing them.”

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POWER-GEN’s Technology Enhancement session will address a number of methods for improving the applicability of gas turbines, including advances in materials, frequency conversions, hot climate modifications, combustor design upgrades for reduced emissions, and control of combustor oscillations. Featured papers will include one on the Conversion of a GE 7FA from 60 Cycle to 50 Cycle Generation, presented by Cummins & Barnard. The purpose for such a conversion is allow the 7FA to compete with the 13E2, V94.2A and the other units in this class. “There are three apparent forms of conversion of this size of unit to 50-cycle operation,” says Andy Sutherland, who will present the paper [see table]. “We’ll also address some related issues such as situations where conversion is feasible, black-start, auxiliary power and controls and touch on alternatives for economic use of these gas turbines in other markets.”

Michael Greenberg of Pratt & Whitney Power Systems will present one of the other papers in this session — Improving Performance of Gas Turbines in Hot Climates. Hot climates represent a challenge to operators of gas turbines. As the temperature rises, the performance of a gas turbine declines. The need for water to cool and control emissions adds to the complexity. The paper compares the performance of gas turbines in high temperature climates, highlighting aeroderivative gas turbines.

“We will show how aeroderivatives can sustain constant power output over a wider range of operating temperatures,” says Greenberg. “It will also discuss the ability of aeroderivatives to run ‘dry,’ a particular advantage in areas where water is an issue, and highlight benefits and drawbacks of adding cooling technology such as chillers and foggers.”