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Technology and Environment 1989. Pp. 9~113. Washington, DC: National Academy Press. Meeting the Near-Term Challenge for Power Plants RICHARD E. BALZHISER This volume frames a set of emerging multidimensional challenges to the science and technology of our energy economy and ecology. This chapter focuses on near-term challenges facing the utilibr industry and its engineers in accommodating to the realities of environmental, resource, and institutional constraints. It explores technological opportunities to maximize the value of past investments in meeting societal demands as well as the likelihood of finding new systems and synergies that can contribute to a healthy industry in the changing business climate in the years ahead. The challenges the industry faces need to be understood from several different perspectives. For convenience, these challenges can be considered as a matrix in which the elements interact. The matrix can be understood first by examining each element, or cell, and then considering their inter- actions. Near term Regional outlook Reasonably assured (less than 25 years) (city, state, part technology of country) Long term Global outlook Potential future (more than 25 years) (hemisphere, options continent, world) 95

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96 RICHARD E. BALZHISER The first pair of cells points out the different time frames of the challenges that must be addressed. In many aspects of energy technology, the time required for extensive penetration of a market, often characterized by a logistic curve (Ausubel and Lee, this volume), is 20 years or more, because large investments in facilities and infrastructure are involved. The utility industry is learning (with urgent need) to be able to effect some changes more quickly, even when this large fleet of facilities is involved. The long term opens up many more possibilities and options in technology, but also brings many tighter constraints with respect to air, water, land use, aesthetics, and resources. The industry must, therefore, anticipate and move to cope with the long-term considerations even in what is developed and applied in the near term. The next pair of elements in the matrix contrasts regional and global outlook Most of what is feasible and economical in energy is determined by what is practical and convenient in a given region, whether it be a city, a state, or a section of a country. The global view has received much theoretical attention for nearly a century, but the influence of transregional and transnational constraints on local decisions and choices has begun to take effect at a practical level only in the past decade. The third pair of matrix elements distinguishes between technology that has a reasonably firm base in knowledge and experience, and technology that may lead to potentially important applications but has either known or unexpected gaps in the knowledge and experience base. As the research arm of the U.S. electric utility industry, the Electric Power Research Institute (EPRI) carries out development work largely in the first two cells on the top row of the matrix, that is, near term and regional. In the third column EPRI aims at evolutionary refinements in known technologies, as well as developing the knowledge base for the most promising future options. However, there is ample scope for development even of "mature" technologies that are widely used and have long been in textbooks. These developments are often in response to the challenges discussed in this volume, namely, tighter environmental constraints, or economic incentives such as an opportunity for increased efflciengy or productivity in the production and use of energy and electricity. These challenges often reveal gaps in the technology base, and sometimes gaps in underlying science as well. Mere are two other driving forces for development, almost at opposite ends of the spectrum of technological maturity. At one end, as much as one-third of EPRI's development is still driven by inadequacies in the fundamental knowledge base of seemingly mature technologies. This is especially evident as economic incentives for extension of useful life of major equipment intensify. Extending the knowledge base to the prediction, detection, and control or remedy for various aging and wear-out phenomena

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NE4R-1~RA! CHAI~NGE FOR POWER PUS 97 is now a major goal of research and development. (Industries concerned with aircraft, oil supply, and much of our basic infrastructure of dams, bridges, telecommunications, and buildings also see the needs, and large economic incentives, for safely extending useful lifetimes.) At the other end of the technology maturity spectrum, EPRI supports exploratory research, not necessarily tied to any existing industnal-scale technology. This seeks to extend the knowledge base of potential future technology or methods for the production, storage, transport, or use of energy. These projects range from seeking new types of exotic composite materials, through modeling and mathematics for configuration and control of large complex computer programs, to theoretical aspects of nonneutronic fusion processes. All of these activities include implicit judgments about the nature of the challenges for the utility industry, and for the national economy and the environmental, legislative, and administrative context in which it functions. A key point, also made by other authors in this volume, is the need to be skeptical of forecasts. For the energy industry, skepticism means that even reasonably stable trends or widely believed forecasts need to be used in conjunction with contingency plans and options. For example, conventional wisdom is that electricity demand growth will be between 1.5 and 2.5 percent per year for the next decade at least. But 1987 and 1988 saw growth rates roughly twice this high. As another example, natural gas is generally agreed to be the most convenient fuel of choice for capacity additions over the next decade. It is clean, available, and minimizes financial risk in investment. It is convenient to install in relatively small increments for either utility or nonutility generation and for cogeneration. It continues to show attractive technical advances in lifetime and efficiency of turbines and in combined gas-steam cycle systems. Nevertheless, it would be less than prudent to neglect the possibility of price increases or supply limitations as the use of gas increases. The enormous resource base of domestic coal can provide a vital insurance policy for energy resources supply. It is the nation's mainstay at present and is likely to continue as such, provided industry can effectively explore and demonstrate ways to make it environmentally more benign. This environmental issue for coal divides into two parts. One is to get the most useful lifetime out of the large national investment in existing coal capacity; the other is to find the next generation of technology that exploits a fundamentally different systems approach to clean coal combustion. One development that looks especially promising involves the marriage of coal and gas technologies. This comes about from the development of efficient coal gasifiers that can feed a system using a gas turbine and a combined steam cycle. Such a system can make a technically and eco- nomically practical transition from a low-efficiency gas turbine cycle to a

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98 RICHARD E. IRALZHISER

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NEAR-TERA! CHALLENGE FOR POOR PITS 99 achieved without significantly compromising economic well-being. For the utilities, the energy/environment dilemma is especially confounding because electricity is itself such an important means to reconciliation of societal ex- pectations, including environmental ones. THE ROLE OF ELEc@1KICITY IN ECONOMIC GROWTH AND PRODUCTIVITY Over the centuries, auxiliary sources of energy have enabled man to leverage the economic benefits deliverable from human inputs of capital, and mental or physical labor. In the last century, electricity has amplified the economic productivity of society, initially through widespread use of motors as the muscle of our increasingly sophisticated factories. In recent years, the computer revolution has built on the versatility of electricity to move us into the electronic era, in which both man and machine work smarter and faster, achieving still higher productivity levels. This versatility reflects the "form value" of electrici~the ease of moving it and of turning it on or off (Schmidt, 1986~. The form value accounts for the remarkably rapid growth of its use, despite limited thermodynamic efficiency of the Carnot cycle (cycle efficiencies of about 5 percent were common for the first decade or two) and losses in transmission. Figure 1 shows the contrasting changes in energy and electricity inten- sity of our economy over the past 35 years. The use of electricity per unit of gross national product (GNP) increased until about 1975, after which it leveled off. The use of electricity has grown over the past decade at about the same rate as the economy but has been trending slightly upward again relative to GNP since 1985. Meanwhile, the intensity of energy use in our economy has declined sharply over this period since 1973. In the post-OPEC (Organization of Petroleum Exporting Countries) period, the sharp decline comes from improved use efficiencies, in the Industrial and transportation sectors especially, and increasing conversion to electricity generally. The use of electricity has also reached higher efficiencies in many conventional applications. However, there are a continuing stream of new industrial applications for electricity and a continued growth in the commercial sectors that have maintained the electricipr-GNP ratio, even though the ratio of ener~v to, GNP has been falling (National Research --A V Council, 1986~. Among the most important attributes of electrician emphasized by events of the past two decades is He ability to produce it from a wide range of resources, varying from geothermal sources and garbage on one end of the spectrum to the atom and sunlight on the other. This flexibility is central to the optimistic outlook for the increasing role of electricity in meeting our energy, environmental, and economic needs.

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100 28 24 of CO 20 Cal 0 tin SO - m co A 12 8 4 o 1950 1955 1960 1965 1970 1975 1980 1985 _ -_' Total Energy Intensity ~ _~ /ctricity Intensity I I , , RIC~4RD E. BALZHISER 0.8 0.7 0.6 0~5 c`` oo 0.4 0.3 0.2 0.1 O Year FIGURE 1 Changes in intensity of energy use in the U.S. economy, 195~1985. Intensity is shown as the ratio of energy use, in thousands of British thermal units (Btu) and in kilowatt-hours (kWh), to U.S. gross national product (GNP) in 1982 dollars. IMPACIS OF REGULATIONS The dramatic size of the political and legislative response to environ- mental concerns is shown in Figure 2, which chronicles laws and regulations aimed at controlling the effects of energy-related activity on air, water, and land use (Yeager and Baruch, 1987~. The early challenges were the most visible and aesthetically disturbing forms of pollution, such as smoke and strip mining wastage. Pollution of the waterways, by both chemical and thermal pollutants, received attention as civic and recreational interests became affected. Finally, concerns began to focus on invisible traces of chemical constituents in gas, liquid, and solid effluents. The sensitivity of routine measurements has unproved from parts per million, through parts per billion, to parts per trillion with a little more effort. These capabilities and associated concerns led to proliferation of legislation that began in the mid-1960s and continues virtually unabated today. The overall result is an enormous, uncoordinated patchwork of control requirements for smoke, air and water pollution, solid wastes, noise, and aesthetics. The Clean Air Act (CAA), which was originally focused on human health effects much more than environmental considerations, required a seemingly simple unit operation, flue gas scrubbing, to remove sulfur dioxide (SO:) from most coal plants built after 1971. These scrubbers introduced utilities to the world of chemical or process engineering and, for many companies, things have not been quite the same since (see Figure 3~. Today, the nation's power plants include 62,000 megawatts of capacity with

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NEAR-TERM CHALLENGE FOR POWER PLANTS 50 DO 25 o ._ o SARA NWpA EPM CWA ALA FLPMA ~RCRA ESECA ~TSCA ESA ~ SDWA CZMA NEPA ~ OSHA NHPA ~ CM cwna ~ WSRA WL RA - RHA ~ IA ~~r~ WRA ~ WRPA _~ FWCA Aft _w row TGA _ _ ~I I ~ 1895 1915 1935 1955 1975 1995 Year 101 1973 - Endangered Species Act (ESA) 1974 - Deepwater Port Act (DPA) 1974 - Safe Drinking Water Act (SDWA) 1974 - Energy Supply and Environmental Coordination Act (ESECA) 1976 - Toxic Substances Control Act (TSCA) 1976 - Federal Land Policy and Management Act (PUMA) 1976 - Resource Conservation and Recovery Act (RCRA) 1977 - Clean Air Act Amendments (CAAA) 1977 - Clean Water Act (CWA) 1977- Surface Mining Control and Reclamation Act (SMCRA) 1977 - Soil and Water Resources Conservation Act (SWRCA) 1978 - Endangered Species Act Amendments (ESM) 1978- Environmental Education Act (EEA) 1980- Comprehensive Environmental Response Compensation and Uability Act (CERCLA) 1899 - River and Harbors Act (RHA) 1902 - Reclamation Act (RA) 1910 - Insecticide Act (IA) 191 1 - Weeks Law (WL) 1934 - Taylor Graring Act (TGA) 1937 - Flood Control Act (FCA) 1937 - Wildlife Restoration Act (WRA) 1958 - Fish and Wildlife Coordination Act (FWCA) 1964 - Wilderness Act DIVA) 1965 - Solid Waste Disposal Act (SWDA) 1965 - Water Resources Planning Act (WRPA) 1966 - National Historic Preservation Act (NHPA) 1968 - Wild and Scenic Rivers Act (VVSRA) 1969 - National Environmental Policy Act (NEPA) 1970 - Clean Air Act (CM) 1970 - Occupational Safety and Health Act (OSHA) 1972 - Water Pollution Control Act (NPCA) 1972- Marine Protection, Research and Sanctuaries Act (MPRSA) 1982 - Nuclear Waste Policy Act (NWPA) 1972 - Coastal Zone Management Act (CZMA) 1984 - Resource Conservation and Recovery Act 1972- Home Control Act (HCA) Amendments (RCRAA) 19?2 - Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) 1972 - Parks and Waterways Safety Act (PWSA) 1972 - Marine Mammal Protection Act (MMPA) 1984 - Environmental Programs and Assistance Act (EPM) 1986 - Safe Drinking Water Act Amendments (SDWM) 1986 - Superfund Amendments and Reorganization Act (SARA) FIGURE 2 Growth in the number of U.S. environmental laws. scrubbers operating and 27,000 megawatts of scrubber capacity planned and under construction. Congress has amended the original CAA to require a scrubber on essentially every new coal plant and is now contemplating a retrofit re- quirement for old coal plants to reduce acid deposition in the eastern half of the United States. Stiff emission standards are being considered for oxides of nitrogen (NO=) as well, posing further challenges for coal-fired plants. Selective catalytic reduction is already commonly used on fossil stations in Japan to achieve very low NOR emissions. Its operation on U.S.

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NEAR-TERM CHALLENGE FOR POWER PI-ANTS 103 coal plants poses much more serious engineering and operating challenges because c)f the lower grades of coals Epically used. Combustion modifica- tion options can provide substantial NOR reductions at a fraction of the cost of catalytic reduction. The key point with respect to further environmental legislation aimed at air quality is the growing disparity between the price to the U.S. economy through higher electricity costs and the marginal air quality benefits attainable this way. Environmental demands are not the only challenges to which utilities must adjust. Large uncertainties in long-term fuel prices and availability continue. Legislative and regulatory changes are reshaping the business of electricity supply and the obligation-to-serve concept. Meanwhile, electrical load growth continues (in some regions at phenomenal rates in 1988) and existing capacity ages. Given the growing reluctance of utilities and their regulators to add generating capacity, the need to sustain the performance of existing plants is more important than ever. The present and planned generation mix by resource is shown in Figure 4. Coal continues to be the backbone of the current mix, representing 44 percent of the capacity and supplying 55 percent of the kilowatt-hours in 1987, much of it in the nation's heartland. A surprisingly large fraction of U.S. electricity generating capacity nationwide uses oil or gas. Because many of these units were built in days of very low oil and gas prices, much of this capacity is in peaking gas turbines that are relatively inefficient and typically lack flexibility to use alternative fuels. ~day, given the higher efficiencies available with more modern combustion turbines and combined cycles, coupled with current low oil and gas prices, much of the planned generating capacity for the next decade will fall into this category. It is more difficult to anticipate and track closely, because many decisions are being put off as long as possible. The role of independent producers that are less subject to regulation can bridge important gaps where demand growth is foreseen to outpace capacitor. However, this capacity is without the obligation to serve, so a new balance may have to be struck between reliability of services and costs, as independent generation becomes a noticeable percentage of capacity in any given region. In Figure 4, the hydroelectric component remains relatively stable, and nuclear capacity growth ends with completion of the few remaining plants the pipeline. In the current public and regulatory climate, no chief executive officer of a public utilibr will even consider another nuclear plant in his remaining tenure, nor are significant additions to U.S. hydroelectric power likely. Yet, along with intensified conservation, these are among the most desirable options with respect to air quality or global warming concerns. Figure 5 shows the requirements for new power generating capacity implied by today's demand as well as 1, 2, and 3 percent compounded growth until

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104 1 000 cO :' E - i' co co 200 o RICI14RD E. 84LZHISER ~Oil: ~ & Gas 1985 1990 1995 2000 2005 2010 Year FIGURE 4 Current and projected electric power generating capacity of U.S. utilities, by fuel. Power generating construction by U.S. utilities is reaching completion with undefined commitments to meet future customer load growth. SOURCES: Utility Data Institute (19883; Federal Energy Regulatory Commission (l988~. the year 2010. Clearly, the United States is in trouble if demand parallels economic growth as it has historically. However, the real concern and more serious near-term challenge to utilities is whether they can even afford to keep some of the existing generation operating. The shaded region in Figure 5 is a reminder that, historically, a capacity margin of at least 17 percent has been required to service users reliably at times of peak demand. Even if that performance might be improved somewhat in the future with added transmission, additional capacity will still be required. If the aging of this capacity is considered, as shown in Figure 6, the challenges become clear. All components of the mix will be well advanced in age by the turn of the century. Like much of the aging national infrastructure, it is taken for granted as we live comfortably for the moment on the investments of the past The operating licenses of about one-third of U.S. nuclear capacity will have expired by 2010. More than half of fossil capacity will be more than 30 years of age by 2000. Up to a third of U.S. hydroelectric capacity faces relicensing and, in some cases, serious questions of safety between now and 2010. The challenges keep coming. The productivity and reliability of aging plants are increasingly difficult to sustain, given typical original design lifetimes of 30 years (themselves often optimistic) and the cyclic operation many units have experienced. The cost of providing for modest growth is substantial, let alone having to

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106 RIC~4RD E. RA1ZHISER replace large portions of the existing mu. Given the fuel, environmental, and institutional uncertainties existing today, most decisions are being deferred until absolutely necessary. Short-term factors will likely dominate, which means some unattractive long-term prices may be payable in lowered reliability of service and high replacement costs. Given the popularity of prudency reviews and major disallowances of investments after the fact by public utility commissions, there is an obvious reluctance to invest in scrubbers on aging coal plants when these could soon be made obsolete by still further requirements for the reduction of emissions. Moreover, concerns about global warming could do to coal what unlimited intervention has done to nuclear power. The investment risk of both options far exceeds that of oil and gas, and environmental intervention can drive up costs unpredictably. Commitments for new generation are logically moving to combustion turbines and combined cycles where these exposures are minimized. If U.S. gas reserves and the ability to produce and transport gas are as abundant as the utility industry projects, that is a reasonable path, provided it is possible to keep robust systems with some diversity and contingency options. Developing technology opportunities can help deal with this concern. TRENDS IN EFFICIENCY An important track record of engineering achievement is shown in Figure 7, which illustrates a sustained improvement in thermal efficiency accompanied by a continuing decline in the cost of electricity over most of the last century. The reversal in both efficiency and cost coincide with imposition of more stringent emission controls for particulates and SO2, as well as for thermal discharges. Energy requirements and losses associated with these control devices more than offset continued engineering improve- ments in both gas and steam cycle conversion technology that had pushed actual power plant thermal efficiencies above 40 percent. The new challenge to which the industry is now responding is to reverse the negative pressures on thermal efficiency and, at the same time, improve environmental controls. Holistic approaches to past and future environmental concerns have been pursued doggedly over the past 15 years, recently with amazing success. CLEAN POWER FROM COAL Leo basic technologies have been adapted for producing clean power from coal: fluidized-bed combustion (FBC) and integrated gasification combined cycle (IGCC). Both technologies avoid the need for scrubbers

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NEAR-TERM CHALLENGE FOR POWER PLANTS 107 Y A <1, 1 0~ ._ ~ oh 10~ 106 ~ - 1 05 ~ a) ._ :$: a) 2 s 10 10 50 40 30 20 10 107 600 - Pulverize~ Coal \~. First ~ / Station _ ~ - - - Combined Cycle - Supercritical l Boiler \ `_ _ 1 - O _ , , , ,IO_ 18~30 1900 1920 1940 19601990 Year 500 400 300 0 200 100 FIGURE 7 Power plant evolution. As the thermal efficiency of coal-fired steam electric generation increased from about 5 percent in the late 1800s to 35~0 percent in the late 196Os, fuel Consumption per kilowatt of power produced decreased by 85 percent. Dunng the same period, boiler size increased from 50 kilowatts to 1,2~ megawatts. As a result, the cost of new generating capacity dropped from $350 per kilowatt in 1920 to $130 per kilowatt in 1967 (constant 1967 dollars), and average residential service cost dropped from $0.25 to $0.02 per kilowatt-hour. This pattern of improved efficiency and lower energy costs ended in the late 196Qs, which suggests that existing power plants had approached limits set by thermodynamics, available materials, and economics. Moreover, it coincided with the increasing priority on controlling environmental pollutants. by internalizing means for control of emissions in the combustion process. Waste products are more manageable and even salable. Fluidized-bed combustion captures sulfur from burning coal in a bed of huidized limestone; NOR formation is suppressed by virtue of lower temperatures in the combustor (see Figure 8~. Ninetr percent of SO2 removal is achievable, and NOR levels are Epically between 200 and 300 parts per million (ppm), or well below (about half) of today's new source performance standards. These lower and more uniform combustion temperatures also permit increased fuel flexibility, because combustion temperatures remain below the temperature at which the ash melts and becomes slag. Adaptability to a wide range of fuels is a major advantage for FBC. It helps to ensure competitive fuel costs as prices trend upward. These advantages are being demonstrated at a scale of approximately 80 to 160 megawatts in several key projects. Early results at Northern States Power in Minneapolis (130 megawatts), Montana-Dakota (80 megawatts), and Colorado-Ute (110 megawatts) have been extremely instructive and encouraging. Projects at TVA/Duke and American Electric Power will

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108 Superheaterlreheater _ 41 ~ 1 Fluidized bed of particles surround in-bed boiler tubes RICHARD E. BALZHISER High pressure steam to turbine Convection Water in _ ~ pass , ~ | flue gas ecycle , ~ ~ Cool system < <, flue gas 14.. ~ ~r Solids , ~ recycle J system Hc'` flue aa~ FIGURE 8 Fluidized-bed combustion (IBM) of coal. Modern FBC boilers can burn even high-sulfur coal cleanb, meeting emissions standards without scrubbed for flue gas. Forced air suspends a mixture of coal, limestone, ash, and sand, maintaining a turbulent, fluidlike bed in which some of the boiler tubes are immersed. Sulfur released by the burning coal is captured as solid calcium compounds by reaction with the limestone panicles in the fluidized bed. The excellent heat transfer within the bed limits the combustion temperature, which avoids the formation of NOR and the melting of ash into slag that could block the furnace. With low-sulfur fuels, a bed of mainly coal ash or sand captures most of the residual sulfur. explore the operational regimes of FBC pressurized to higher than atmo- spheric pressures. The FBC projects have been making important but evolutionary ad- vances in combustion technology. Meanwhile, the IGCC has made what can be considered a quantum jump forward. Successful operation of large demonstration plants at Southern California Edison's Cool Water site in California and, more recently, at Dow Chemical's Plaquemine, Louisiana, plant provide the basis for clean use of coal for the next century. The Cool Water plant has operated with high- and low-sulfur coals over the past five years, producing a plume comparable to that of the natural gas fired combined-cycle plant adjacent to it Emissions of SO2, NO=, and particulates are all below federal and state requirements as shown in Table 1 (Spencer, 1986~. The vitrified solids leaving the gasified are virtually inert, passing tough California leaching tests for contamination of drinking

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HE4R-1~RM CHAI1NGE FOR POWER PLANTS TABLE 1 Cool Water Program Heat Recovery Steam Generator Stack Emissions (Utah Coal) Emissions Parts per Pounds per Million, Pounds Million Effluent volume per Hour Btu Permit requirement (lO)a 35b 0033 Actual test result 9 33 0.033 NOx Permit requirement (27)a 140 0.06S Actual test result 23 61 0.061 Particulates Permit requirement Actual test result - 1 0.001 bNominal translation from pounds per hour at typical conditions. Environmental Protection Agency permit requirements for Utah (SUFCO) design coal correspond to 95% sulfur removal. Permit requirement (and expected SO2 emissions) for Illinois No. 6 coal test is 175 pounds per hour, corresponding to 97% sulfur removal. 109 water. Requirements for cooling water are less stringent in these plants than in conventional coal plants using scrubbers. Even more impressive has been the high level of availability (70 percent) realized in 1987 by this first-of-a-kind plant. If carbon dioxide (CO2) must eventually be removed from plant effluents, IGCC technology can probably best accommodate this requirement-not without cost, but at costs below other coal-based alternatives. With today's gas prices and system base load capacity, simple gas turbines for peaking are often the option of choice for most utilities. With proper planning and siting, these units can be upgraded in several stages, first from a simple cycle to a combined gas-and-steam cycle with an increase in output and in thermal efficiency. Where coal becomes the fuel of choice, an integrated gasifies can be added. This phased growth adaptability of IGCC makes it particularly attractive to utilities at the present time. The Fl3C and IGCC options also have application in repowering some existing fossil units. Repowering by using either option, where feasible, achieves SOc and NON control in addition to improving overall plant productivity a much preferred alternative to scrubbers. The application of FBC to the Black Dog unit of Northern States Power gained 25 megawatts of capacity and 25 years of useful life.

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110 40 s 3 30 - - O 20 a) N - a) > 10 Commercial Technology Advanced Technology-Retrofit Plants Advanced Technology-New Plants o _ W Linings 0 10 20 30 40 50 60 70 80 90 100 :.:..::. Advanced Coal Cleaning...:.. ::.: ' and Dry Scrubbing : :.. ,~,~ a] a- ~e ~e te ~ ~ RlC~4RD E. BALZHISER it, ,~ Wet ^~ Scrubbing - \\\\\\\\\w Percent SO2 or NOX Emission Reduction FIGURE 9 Control options for SO2 and NO=. Advanced coal cleaning and dry scrubbing retrofit options (B) offer oost'ffective emission reductions at levels between present physical coal cleaning capabilities (A1) and wet flue gas snubbing (A2) for existing commercial power plants. Improved coal use technologies both for retrofitting (B) and for new plant applications (C3 can combine high levels of emission and effluent control with reduced costs and improved thermal efficiency. Levelized cost represents the present value of the lifestyle capital, operation, and maintenance costs normalized to a uniform annual cost. NOTE: 1 mill = 0.001 dollar. Figure 9 shows the control options for SO2 and NOR. Options for retrofitting existing plants win advanced technology to SO2 typically have lower removal potential, but also lower capital costs than wet flue gas scrubbers. In the case of NOR, similar retrofit controls now under develop- ment in this country offer appreciable NOR reduction at lower capital and operating costs than current commercial scrubbers. The essence of clean coal programs is to provide long-term holistic solutions to coal's environmental impacts, such as FBC and IGCC, and better retrofit technology. The latter is essential to mitigate legitimate environmental problems without forcing premature retirement of aging units, which are still a major part of U.S. base load capacitor. As extended lifetime performance becomes an increasingly important objective for older fossil and nuclear units, it is necessary to look for better indicators of declining safety margins or incipient failures of equipment. Ideally such deficiencies or degradation effects are detected early enough to permit the scheduling of repair work It is also preferable to detect such conditions so as to get plants off Be line in time to avoid damaging failures. One of the keys to maintaining performance is much broader

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NE4R-TERM CHALLENGE FOR POWER PLANTS in ._ {5) o o Cat a) a) Q c 111 Chimney Vibration T G TOFS;On Flame Flicker T-G Vibration Tube Leaks O Bearing Rubs Ultrasonic NDE Arcing _ Creep NDE ~ Coal Moisture Meter ..... 10 103 105 1O1O 1015 1o2o 1025 Electromagnetic Spectrum (Frequency, hertz) FIGURE 10 Technologies for monitoring and inspection of power generation equipment in operation. Low-ffequency devices monitor or detect low-f~quengy phenomena, such as turbogenerator (T-G) torsion and vibration; higher frequencies are used for nondestructive evaluation (NDE), among other purposes. coverage of equipment with on-line diagnostics, an emerging technology of great potential value to utilities. This involves both new sensor technologies and computer-assisted discrimination and diagnostic tools, including expert systems and artificial intelligence applications. Figure 10 shows the general kinds of devices and signals that can serve to monitor equipment while it operates. Devices use a wide spectrum of frequencies to detect, for example, incipient failures in turbine rotors or hot spots in a generator or combustion turbine. Avoidance of forced outage takes on added importance as equipment is operated beyond original design lifetimes. CARBON DIOXIDE AND GLOBAL WARMING Much effort has been expended over the past 15 years to deal with the mandate to make cleaner use of coat The engineering accomplishments on this need-by many individuals and organi7~tion~have been impressive (Conference Report, 1987; Simbeck et aL, 1983~. Exploiting the foregoing technology opportunities addresses all but the most recent environmental concern-global warming. If minimization of CO2 emissions becomes a serious objective, the United States will most certainly want to revisit the

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112 RICHARD E. BALZHISER nuclear option as well as redouble its efforts on solar energy, electric trans- portation, and improved efficiency in the generation and use of electricity. The United States can both engineer and afford these options. Many emerging countries can do neither and will likely continue to rely largely on coal and oil. CONCLUSION Power plants are becoming more oriented to chemical processes and, therefore, more adaptable to environmental goals. Coal gasification not only produces a clean fuel for combustion turbines or fuel cells but also the building blocks for methanol and many other petrochemicals. One should recognize that coal gasification represents the core of a coal refinery with electricity as only one of many products available. Who will most successfully commercialize this technology in the future? The opportunities for adding value are large. Given that coal can eventually be relied on for feedstock purposes, it appears that the United States can safely turn increasingly to gas for near- term energy needs. At current prices and with available combustion turbine and combined-cycle technology, it is the option of economic choice not only for peaking, but also for middle-range and some base load applications. It can be added quickly; it operates cleanly and emits less CO2 per kilowatt- hour than any other fossil option. It permits time to understand the issue of global warming better without imposing costs or ineffectual CO2 removal requirements. Finally, when gas prices rise, installation of coal gasifiers permits adaptation and continued productive use of the power generation investment. The electric power industry now has a technological tool kit that can meet most of the environmental challenges identified to date. Most important, the industry and the nation have an engineering capability that will continue to adapt to changes ahead. REFERENCES Balzhiser, R. E., and K E. Yeager. 1987. Coal-fired power plants for the future. Scientific American 257(September):100 107. Conference Report. 1987. Proceedings of Sixth Annual Conference on Coal Gasification, Electric Power Research Institute Report AP-5343-SR, October 1987. Palo Alto, Calif. Federal Energy Regulatory Commission. 1988. Data base maintained by R. Congo, Office of Hydropower Incensing, Washington, D.C National Research Council, Energy Engineenng Board. 1986. Electricity in Economic Growth. Washington, D.C.: National Academy Press Schmidt, P. 1986. Form Value of Electacibr. Pp. 199 227 in Electncity Use, Productive Efficiency and Economic Growth, S. Schu~r and S. Sonenblum, eds Palo Alto, Calif.: Electric Power Research Institute.

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NEAR-TERM CHAI~NGE FOR POWER PI-ANTS 113 Simbeck, D. R., R L Dickenson, and E. D. Oliver. 1983. Guide to coal gasification systems. Electric Power Research Institute Report AP-3109, June 1983. Palo Alto, Cali Spencer, D. F., S. B. Alpert, and H. H. Oilman. 1986. Cool Water. Demonstration of a dean and efficient new coal technology. Science 232(May 2~:609 61~ Utility Data Institute. 1988. Edison Electric Institute power statistics data base. Washington, D.C. Yeager, K E., and S. B. Baruch. 1987. Environmental issues affecting coal technology: A perspective on U.S. trends Pp. 471-502 in Annual Reviews of Energy, Vol. 12. Palo Alto, Calif.: Annual Reviews, Inc.