Air Quality and Stationary Source Emission Control (1975) / Chapter Skim
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Part Two in Brief: Strategies for Controlling Sulfur-Related Power Plant Emissions
Part Two in Brief: Strategies for Controlling Sulfur-Related Power Plant Emissions
Pages 193-232
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From page 193... ...
After emission, sulfur dioxide mixes with he ambient air by alffusing both vertically and horizontally, and is transported {generally eastwards or northeastwards} by the wind. Some of the sulfur dioxide is oxidized to form sulfates, which may in turn form aerosols and travel long distances with~the wind (see Chapter 6)
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From page 194... ...
Because sulfur dioxide is absorbed fairly rapidly by the ground, emissions from stacks are probably more important than low level emissions as a source of sulfate aerosols downwind {see Chapters 6, 7} . ~ For the same reason, ambient concentrations of sulfur dioxide measured at ground level are determined primarily by sources nearby and a short distance upwind; in contrast, ambient concentrations of sulfates are determined by sources further upwind {see Chapter 6~.
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From page 195... ...
at: I: :: 1 I;!
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From page 196... ...
Between 1960 and 1970 total emissions of sulfur oxides in the United States increased by about 4 5 percent, primarily due to a neardoubling in emissions from electric power plants (see Table 6-2} . However, as a result of limitat ions imposed on the amount of sulf ur permitted in fuels, sulfur oxide emissions in urban areas were reduced substantially during that decade (while those in non-urban areas increased disproportionately: see Table 6-2~.
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From page 197... ...
T-1 i '' i L:~: is: a: ' a:, ~ i : ;: ~ i: ~ : I: r.r ~~ ~— 4.!
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From page 198... ...
But the only measure of marginal Cost that has any economic signif icance is current costs, or, as one sets rates for the future, the cost that will be incurred or saved during the period when those rates are in effect. In times of rapid inflation, those marginal costs tend, naturally, to rise relative to average company revenue requirements, when the latter are based heavily on historic costs.
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From page 199... ...
for reducing sulfur dioxide emissions. it is by no- means the only device' nor is it necessarily sufficient.
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From page 200... ...
Improved Efficiency of Equipment and Processes Significant opportunities exist for fuel saving through improvements of effectiveness of electrical equipment used in various applications and through re-optimization of electricity consuming industrial processes. Several examples are included here to illustrate the potential for modifications of demand for.
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From page 201... ...
201 i i 1 The propose itself such of oo.1 pec yeas.
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From page 202... ...
FLUE GAS DESULFURIZATION (FGD) Introduction Are flue gas desulf:arization systems reliable and operable for scrubbing stack gas effluents from the combustion of high sulfur coal of the eastern`United States?
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From page 203... ...
That is, the operation must work in the closed loop mode. only lime and limestone scrubbers have yet , operated successfully on coal at the commercial scale for extended periods of time, and we have considered the foregoing question in detail only for these systems.
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From page 205... ...
If we could regard the operation at Paddys Run as typical of conditions to be encountered by designers of lime scrubbers for wide distribution in the eastern United States, the performance compari signs among the abo~re-named scrubbers might provide an adequate technical base for design. Unfortunately, Paddys Run is not type cal .
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From page 206... ...
We reiterate, however, that lime scrubbing in the unsaturated mode is furthest along in its development. A resolution of the question of its commercial viability can be acquired soon, through easily obtained commercial experience that will allow adequate pert ormance comparisons s .
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From page 207... ...
Limestone Scrubbing in the Supersaturated Mode The sucessful operation of a large limestone scrubber at the Cholla Station of Arizona Public Service contributes relatively little to the technical base for design of scrubbers for medium or high sulfur coals, because of the low sulfur in the coal burned at Cholla Station.
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From page 208... ...
Availability of the Will County scrubber has recently been good, but the operation now blends Western low sulfur coal into high sulfur Illinois coal, to provide a fuel at an average.sulfur level of about 1.5 percent. The IaCygne operation is on coal containing 5.5 percent sulfur, and is subject to fouling and plugging that is dealt with by cleaning out each of seven scrubbing modules about once every five nights.
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From page 209... ...
1 1 1 1 1 1 1 ~ 1 ~ . : _l' _ :.:: At' Limestone scrubbing in the unsaturated mode has been demonstrated in EPA':e tiny bench It at Research Triangle Park.
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From page 210... ...
Other scrubbing techniques await commercial demonstration on such coals. Regenerative Flue Gas Desulfurization Processes The Wellman-Lord and magnesium oxide processes, both of which recover a useful byproduct, are now being installed in high sulfur coal plants.
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From page 211... ...
Residuals Produced from Flue Gas Desulfurization ~ conical 1000 ;, encouraging. Capability of Vendors and Utility Companies 48-255 0 _ 75 - 17 - I ~~ ~~ i, .
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From page 212... ...
CONTROL OF AMBTENT SULFUR DIOXIDE CONCENTRATIONS WITH TAI.L STACKS ARDOR INTERMITTENT CONTROL SYSTEMS t Temporal emission controls for reducing ambient sulfur dioxide levels, otherwise known as intermittent control systems (ICS) , have been recognized as a viable air pollution control technique in this country only for certain limited situations, and have been the focus of a lively debate between various regulatory agencies and some parts of the electric utility industry.
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From page 213... ...
EPA claims the dispersion concept is not compatible with the Clean Air ACt requirement that constant emission limitations be enforced whenever possible. In the most significant legal decision to date on this subject, Natural Resources Defense Council v.
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From page 214... ...
ICS measures could provide an alternate means of attaining and maintaining sulf ur dioxide ambient air quality standards, independent of reliance on f lue gas desulfurization (FGD) technology or use of low sulfur fuels.
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From page 215... ...
HIS iven application of ICS technOoblogs,wOu~d be anticipated in implementing ICS control. Constraints on ICS Control Implementation Availability of control by tall stack-ICS methods S a function of ParamaeitnersFor nine TVA ~ iff ent sets of Conditions r r4ed4UCeedrceemnt of the time on an hou s per y ar babsiSuppTlhied either by load shifting or fuel shifting; a number of constraints apply concerning each of these t th potentia for US te Cihaneiqueseductions by th se methods at vario plants.
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From page 216... ...
It is important to note here that Application of tall stack-ICS technoic~gy does not significantly reduce total emissions of sulfur oxides; hence, this strategy does not decrease ambient sulfate concentrations. so ambient sulfate concentrations will not be reduced.
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From page 217... ...
These factors wi11 tend to increase total sulfur emissions from power plants Nuclear capacity, which had been projected to rise sharply between now and 1985, will, as a result of recent decisions delaying its installation made by utility companies, fall far Short of early projections. Estimates by the Atomic Energy Commission in 1972 placed 1985 nuclear capacity at approximately 250,000 Mwe.
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From page 218... ...
Existing production capacity for these low-sulfur coals is inadequate and is likely to remain so. By shifting available lowsulfur coal to plants not meeting primary standards from plants which could burn higher sulfur coal and still meet the primary standards, some reduction in violations of existing ambient air quality standards could be achieved.
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From page 219... ...
However, unless the origins 1 sulf ur content is already low enough to nearly meet the sulf ur oxide emission standards, conventional coal cleaning methods will not bri ng most coals into compliance. Advanced coal cleaning methods may be able to increase the amount of sulf ur and ash removed but all of the processes are in their early stages of development and many may be high cost for the extra sulfur removal that is accomplished.
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From page 220... ...
If institutional barriers to its widespread deployment are overcome, it would reduce the use of coal for generation of electricity and release natural gas for other purposes and thus make a measurable contribution to air quality. ANALYSTS OF ALTERNATIVE STRATEGIES The basic question addressed in analyzing alternatives is whether the benefits from sulfur oxide removal by such means as flue gas desulfuxization or switching to low-sulfur coal justify the additional increment of cost in electricity generation.
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From page 221... ...
221 3~ i' let [A 'tI; I _ 11~t 8 o ~ W W ~ o ~ ~ ~ l A w < -A .
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From page 222... ...
While specific numbers are used to illustrate the calculations, it should be appreciated that many of the numbers and relationships in Ache model are uncertain, and sub j ect to considerable change as additional information becomes available. The analysis should be taken as a method for organizing and trying to place in perspective the information presently available to serve as a basis for decision making on sulfur oxide emissions control ~ The Need to Consider Decisions on a Case by Case Basis For a specific power plant, differences in fuel availability and price, plant loading, plant age, and the economics of abatement strategies may differ cc: nsiderably from the representative values used in the analysis.
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From page 223... ...
The relation between emissions of sulfur oxides and ambient levels of sulfur dioxide and sulfates, and the potential for damage to human health, vegetation and other ecological systems, material property, and aesthetic values will in general differ as a result of regional and local factors. As a result, the value of reducing emissions should be assessed separately for different power plants.
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From page 224... ...
To relate ambient levels to sulfur oxide emissions, a model for oxidation and di spersion was constructed. Together these steps allowed a pollution cost to be computed per pound of sulf ur emitted f ram the power plant.
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From page 225... ...
The most important areas of uncertainty appear to be the sulfur oxide emissions to ambient sulfate relationship and the health effects of ambient sulfate. A simple model was used for the relationship between sulfur oxide emissions from a power plant and the incremental increase in ambient sulfate in urban areas several hundred miles downwind.
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From page 226... ...
00 M~BTOl, a switch from the high sulfur to low sulfur coal is advisable if sulf ur emissions abatement is worth at least ~ 9 |
From page 227... ...
Use of low-sulfur western coal in existing plants will generally not be economic because aerating or expensive retrofitting will be required. Coal preparation appears barely competitive with flue gas desulfurization if law-sulfur coal is not available: sulfur removal `::an be accom,?
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From page 228... ...
For this case the decision very close for an existing plant between eastern low sulf ur coal and f lue gas desulf urinations the alternative of buring h~ghsulfur coal appears poor by comparison. If lowsulfur eastern coal is not available, flue gas desulfurization appears to be the best decision.
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From page 229... ...
In particular, a better understanding of the health ef f eats of sulf ates and of the chemistry of the conversion of sulfur dioxide to atmospheric sulfates could have a signif icant ef f ect on future decisions on control of sulf ur oxides. A rough calculation of the value of resoldering these uncertainties gives a value of about $2 million per year for the representative 600 MN plant in the remote rural location.
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From page 230... ...
Decisions to be made on sulfur oxide emission from power plants will involve tens of billions of dollars in electrical generation costs in the next decade and massive effects on human health and welfare. Greatly expanded efforts should be made to develop improved models and data for use on a case by case basis to improve decisionmaking on emission control strategy alternatives.
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From page 231... ...
In recent years this policy option has gained increasing acceptance among conservationists, environmentalists, policy makers here and abroad, and even industry as indicated by a recent Committee on Economic Development report. The sulfur emissions problem is a highly suitable one for the applications of emissions charges as a policy instrument.
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From page 232... ...
l: 1 ; . i PART TWO: Section 1: Relationship of Emissions to Ambient Air Quality and Chemistry of Precipitation ~.
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