Technology and Environment (1989) / Chapter Skim
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Pages 95-158
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From page 95... ...
(city, state, part technology of country) Long term Global outlook Potential future (more than 25 years)
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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.
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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.
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NEAR-TERA! CHALLENGE FOR POOR PITS 99 achieved without significantly compromising economic well-being.
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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:)
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1976 - Resource Conservation and Recovery Act (RCRA) 1977 - Clean Air Act Amendments (CAAA)
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~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.
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utilities is reaching completion with undefined commitments to meet future customer load growth. SOURCES: Utility Data Institute (19883; Federal Energy Regulatory Commission (l988~.
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sheaf Sl 1noqe ~ aald" O1 u!
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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.
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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~.
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From page 108... ...
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~.
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From page 109... ...
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.
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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.
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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.
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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.
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Demonstration of a dean and efficient new coal technology. Science 232(May 2~:609 61~ Utility Data Institute.
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Whereas the size of the fossil fuel resource base was the overriding concern of the 1970s, today the formidable challenge is how to use energy sources in ways that support social and economic development and protect the environments ~ develop a strategic perspective on how to meet this challenge in the long term, it will be necessary to explore some of the misconceptions of the past that led to costly errors in energy planning. Such a review, in retrospect and prospect, will help answer the question: What happens after the fossil age?
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By the early 1960s, coal had been displaced by crude oil as the dominant fuel on the primary market, both in market shares
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Nonetheless, around 1980 crude oil peaked on the world primary market, both in terms of shares and on an absolute basis, and began to decline thereafter. As Figure 1 also shows, natural gas and nuclear energy have been steadily gaining market shares against crude oil: natural gas since the 1920s, and nuclear energy since 1970.
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, forbidding the use of natural gas for electricity generation, was modified in 1987. There is ample evidence to indicate that the consumption trend will reverse.
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Examining energy technology in this context suggests that gas technology is still young. For years, natural gas was a by-product of oil exploration.
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Perhaps the most convincing dynamic technological advance for this case is the conversion efficiency of combined-cycle systems using natural gas. In a gas turbine combined-cycle (GTCC)
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LEE 1o2 101 10° 10 1 10-2 =~_ . _ V Natural Gas I I I ~I I 0.99 0.90 rat ,~ ~1 1 1 960 0.50 -° lL 0.10 I .
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32~. 1o2 1o1 10° 1 10 10-2 1 ~ I I 0.99 b Wood Natural G:s .,~'C ~ Oil 0.90 0.10 't ~ ~ 0.01 1800 1850 1900 1950 2000 Year to FIGURE 7 Energy substitution in the United States; gas from nonassociated wells is shown separately as gas technology.
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system. With a set of reasonable assumptions, the study concluded that natural gas-fired combined-cycle systems with efficiency already in hand contributed to the optimal-capacity mix.
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This occurred after Japan, in an effort to diversify energy sources, ordered several gigawatts of combined-cycle systems from the General Electric Company. Results of the analysis done by El-Masri are shown in Figure 11, in which the combined-pycle system efficiency is plotted as a function of pressure ratios at various peak temperatures (measured by H
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The results of a 1986 workshop on these topics were recently published in a book entitled The Methane Age Wee et al., 1988~. Much remains to be done in engineering research and practice if methane is to become a bridge to the era beyond fossil fuels.
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ADVANCED FOSSIL FZJEL SYSTEMS AND BEYOND 65 _ - o of ° 60 ._ ._ a)
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. The fact that the deep oceans are huge sinks for CO2 instills hope that increases in the atmospheric concentration of CO2 may be brought to zero without cutting the emission from fossil fuel combustion to zero.
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are the right things to do. More penetration by natural gas into the primary energy market is a step in that direction.
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'' Wood H/C = 0.1 Coal H/C = 1 Oil H/C = 2 Gas H/C = 4 , ~1 1 1 1 ~ 1700 1800 1900 2000 2100 Year 0.10 0.01 o ._ FIGURE 14 Evolution of the hydrogen-to carbon ratio in pama~y energy sources, 185(~ 2100. SOURCE: Marchetti (1985~.
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Societies are continually developing and seeking to meet new demands, be they in areas of safety or environmental quality. The responsibility of the technical community is to anticipate societal challenges and be ready with technological solutions.
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131 r 0' ~ - O ~ Q if C - ~IS___ ~ 1 OC on C _ ~ on ~ en 0= _ C _ ~ O I O Cot o Q In _ ~ C O ( C/)
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Crude oil, liquefied petroleum gases, natural gas, and other industrial gases are the primary materials used by the complex, but each is used for many purposes. For example, natural gas is used as fuel in heaters, as a feedstock, or as fuel for the unit making hydrogen.
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The simplest integrated energy system, the cogeneration system using natural gas, for example, can be traced from gas to combined cycle to electricity and process heat and steam. Other systems can be constructed by selecting the appropriate options, as shown in Figure 16.
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134 o ._ a, iii 0 .
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Residential, commercial, and industrial consumers would welcome energy forms with greatly reduced environmental concerns. Implementation of integrated energy systems requires major changes in industrial infrastructure.
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1986. Natural gas fired combined cycle generators: Dominant solutions in capacity planning.
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Protecting the Ozone Layer: A Perspective from Industry JOSEPH P GLAS Protection of the ozone layer is a model of the way science, technology, and public polio y can work together to achieve global agreement and action.
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published an article proposing that the ultimate fate of CFCs was ultraviolet photodecomposition in the stratosphere with the release of chlorine atoms. Through a series of rapid chemical reactions, these chlorine atoms might cause a reduction in the total amount of stratospheric ozone Figure 1~.
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probably be required well in advance of any identifiable damage to the biosphere. Second, the science involved is incredibly complex, with relevant new chemical reactions being discovered regularly, and in key respects is un proven.
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commits Du Pont to "determine that each product can be made, used, handled and disposed of safely and consistent with appropriate safety, health and environmental quality criteria." In fact, in 1975, Chairman of the Board Irving Shapiro stated publicly that if there were credible scientific evidence of harm to human health or the environment, Du Pont would cease manufacture of fully halogenated CFCs. About once a year, dating back to the mid-l97Os, Du Pont formally reviewed its position.
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Long-term projections of stratospheric ozone change, based on constant emission rates, provide an example of how complex, poorly understood processes can significantly affect the predictions of a mathematical model of man-made environmental changes. This graph shows stratospheric ozone change estimates from a series of models developed to predict the effects in the next century of steady-state emissions of both CFCs and nitrogen oxides from a hypothetical fleet of SSIt.
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Idtal world consumption was 2,510 million pounds. SOURCE: Du Pant Company estimates.
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The expressed purpose of the Alliance is to advocate that policies be based on the best science and that only a global approach to controls would be effective in protecting the ozone layer. In October 1980, reacting to model calculations that ozone depletion might reach 15-20 percent at the end of the next century, the Environmental Protection Agency (EPA)
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FIGURE 5 Worldwide production and consumption of CFCs Above, estimated worldwide total production of CFCs for both aerosol and nonaerosol use from 1960 to 1988, below, differences in consumption by application in 1774 and 1988. Although the United States banned the use of CFCh as aerosol propellants for most applications in 19~78, many countries did not SOURCE: Du Pant Company.
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From page 145... ...
Completed in late 1985, the study concluded that there was no evidence of global ozone depletion and forecast no depletion based on limited growth in CFC usage (WMO-NASA, 19863. However, model calculations that assumed sustained growth in CFC emissions did predict depletion in ozone (see Figure 6~.
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These growth forecasts, coupled with computer model predictions of ozone depletion if there were sustained growth in CFC emissions, once again increased concerns (see Figure 6~. With the body of information
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Du Pont was an active participant throughout, as was the Alliance for Responsible CFC Policy. With some initial reluctance, other leading CFC producers also offered their support for an international agreement.
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This acceptance contributed to the development of the international process and helped government negotiators to focus on the issues necessary to gain a consensus. Ensuing negotiations in the late spring and early summer of 1987 led to signing of the Montreal Protocol in mid-September (UNEP, 1987~.
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Halon-1211, 1301, and 2402 would be frozen at 1986 consumption levels in 1992, or three years after the protocol became effective. The Montreal Protocol required ratification by nations representing at least two-thirds of total world consumption of CFCs and haloes.
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From page 150... ...
The company also reiterated support for the Montreal agreement as the only effective means of addressing the issue on a global basis and called for a strengthening of the protocol to consider further global limitations on the emissions of CFCs. Since the announcement, CFC producers such as Penowalt Corporation, Allied-Signal, and Imperial Chemical Industries, as well as the Alliance for Responsible CFC Policy, the Food Service and Packaging Institute, the American Refrigeration Institute, and several CFC users have either taken steps to reduce the use of CFCs or urged more stringent controls through the international process.
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. By October the total ozone over Antarctica had been reduced by more than 50 percent of its 1979 value.
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CONCLUSION A lot has been learned about the science of stratospheric ozone in the nearly 20 years since Lovelock's early work in his basement laboratory. More important, through efforts to address the ozone depletion issue, we appear finally to have found a way to behave as a global community and
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From page 153... ...
in which CFC emissions are not decreased by more than the 50 percent reduction required by the Montreal Protocol. The effect of moving forward each reduction step by one control period is minimal (B)
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Concern for the protective ozone layer around the world stems from the fact that this layer, primarily 1~20 kilometem above the earth, screens out most of the biologically damaging ultraviolet radiation emitted by the sun Laugh, 19803. REFERENCES Bloomfield, P., G
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Montreal Protocol on Substances lbat Deplete the Ozone Layer. Montreal: UNEP.
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Social and Institutional Aspects
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Key Terms
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