Economic Benefits of Improvements in Visibility: Acid Rain Provisions of the 1990 Clean Air Act Amendments

The Acid Rain Provisions (Title IV) of the Clean Air Act Amendments of 1990 call for about a 10 million ton reduction in annual SO₂ emissions in the United States. Although the provisions apply nationwide, most of the reduction will occur in the eastern half of the country, where use of high-sulfur coal for electricity generation is most common. One potentially large benefit of Title IV is the expected improvement in visibility conditions in the eastern United States due to the reductions in secondary sul-fate aerosols. This paper combines available economic estimates of willingness to pay for improvements in visibility with current estimates of the difference between expected visibility conditions in the eastern United States with and without Title I V, to estimate the expected visibility benefits of Title IV. The results suggest an annual value of $2.3 billion (in 1994 dollars) in the year 2010, as a result of visibility improvements due to Title IV in residential areas of the eastern United States. The results also suggest a possible additional annual value for eastern U.S. residents of as much as $1-2 billion for visibility improvements at national parks in the Southeast.     

Sulfur Dioxide Emissions and Market Effects under the Clean Air Act Acid Rain Program

ABSTRACT

The Clean Air Act Amendments of 1990 (CAAA90) established a national program to control sulfur dioxide (SO₂) emissions from electricity generation. CAAA90's market-based approach includes trading and banking of Soumissions allowances. We analyzed data describing electric utility SO₂ emissions in 1995, the first year of the program's Phase I, and market effects over the 1990-1995 period. Fuel switching and flue-gas desulfurization were the dominant means used in 1995 by targeted generators to reduce emissions to 51% of 1990 levels. Flue-gas desulfur-ization costs, emissions allowance prices, low-sulfur coal prices, and average sulfur contents of coals shipped to electric utilities declined over the 1990-1995 period. Projections indicate that 13-15 million allowances will have been banked during the program's Phase I, which ends in 1999, a quantity expected to last through the first decade of the program's stricter Phase II controls. In 1995, both allowance prices and SO₂ emissions were below pre-CAAA90 expectations. The reduction of SO₂ emissions beyond pre-CAAA90 expectations, combined with lower-than-expected allowance prices and declining compliance costs, can be viewed as a success for market-based environmental controls.     

The Regulation of Toxic Air Pollutants A Critical Review

ABSTRACT

Passage of the 1990 Clean Air Act Amendments launched the Acid Rain Program in the United States. This initiative, based on the market mechanism of a sulfur dioxide tradable “allowance” system, was a dramatic departure from traditional command and control strategies designed to reduce air pollution emissions. Power plant managers have flexibility under the program to select and implement a variety of options to reduce emissions below mandated levels. Federal agencies have collected annual performance data for affected facilities covered by the program for a number of years. Coal-burning plants are typically greater generators of sulfur dioxide (SO₂) than oil burners of equivalent size. This study examined the effect of fuel type as a significant factor influencing a plant's achievement in reducing pollution emissions. Achievement was measured by using a derived variable, delta (A), defined as the difference between pounds of SO₂ produced divided by the energy (in million Btu) generated, for the years 1990 and 1995. Rigorous nonparametric statistical analyses were used to compare the two populations of coal-fired and oil-fired plants. Results indicated that coal-burning facilities achieved greater program success, measured by the expected value of delta, than the oil combustors for the five-year period reviewed. Since utility managers must take steps to ensure all applicable requirements of the program are met, findings of the inquiry should prove to be useful in assessing achievable emissions reductions and aid in long-range facility planning.     

Assessing the impact of the acid deposition control program

A goal of the acidic deposition control program in the United States has been to link emissions control policies, such as those mandated under Title IV of the US Clean Air Act Amendments (CAAA) of 1990, to improvements in air and water quality. Recently, several researchers have reported trends in the time series of pollutant data in an effort to evaluate the effectiveness of the CAAA in reducing the acidic deposition problem. It is well known that pollutant concentrations are highly influenced by meteorological and climatic variations. Also, spatial and temporal inhomogeneities in time series of pollutant concentrations, induced by differences in the data collection, reduction, and reporting practices, can significantly affect the trend estimates. We present a method to discern breaks or discontinuities in the time series of pollutants stemming from emission reductions in the presence of meteorological and climatological variability. Using data from a few sites, this paper illustrates that linear trend estimates of concentrations of SO₂, aerosol SO₄²⁻, and precipitation-weighted SO₄²⁻ and NO₃⁻ can be biased because of such complex features embedded in pollutant time series.     

Emissions of Sulfur Trioxide from Coal-Fired Power Plants

Abstract

Emissions of sulfur trioxide (SO₃) are a key component of plume opacity and acid deposition. Consequently, these emissions need to be low enough to not cause opacity violations and acid deposition. Generally, a small fraction of sulfur (S) in coal is converted to SO₃ in coal-fired combustion devices such as electric utility boilers. The emissions of SO₃ from such a boiler depend on coal S content, combustion conditions, flue gas characteristics, and air pollution devices being used. It is well known that the catalyst used in the selective catalytic reduction (SCR) technology for nitrogen oxides control oxidizes a small fraction of sulfur dioxide in the flue gas to SO₃. The extent of this oxidation depends on the catalyst formulation and SCR operating conditions. Gas-phase SO₃ and sulfuric acid, on being quenched in plant equipment (e.g., air preheater and wet scrubber), result in fine acidic mist, which can cause increased plume opacity and undesirable emissions. Recently, such effects have been observed at plants firing high-S coal and equipped with SCR systems and wet scrubbers. This paper investigates the factors that affect acidic mist production in coal-fired electric utility boilers and discusses approaches for mitigating emission of this mist.     

Impact of Light Duty Diesels on Visibility in California

This paper investigates the impact of light duty diesels on California visibility in the early 1990s. It is found that, without increased dieselization, there will be little change in statewide visibility levels from the late 1970s to the early 1990s. Visibility impacts from diesels are calculated for various scenarios of diesel use and particulate control. The likely dieselization (20%), do nothing particulate control (0.4 g/ml) scenario will change projected statewide emissions slightly for HC ( –2 % ) , NO _x (+1%), SO _x (+5%), and TSP (+1%) but will increase statewide emissions of elemental carbon (soot) by about 80%. Simplistic haze budget calculations indicate that this increase In soot emissions should reduce visibility about 10 to 25% in California. More precise and geographically detailed visibility calculations are performed by applying a lead tracer model to data for 86 California locations. The lead tracer model indicates that the likely dieselization, do nothing control scenario will reduce visibility by about 10 to 35%, with the greatest impacts occurring in and near urban areas. Actual visibility decreases for this scenario may even be much greater, 20 to 50%, because the analysis does not address two other significant factors: (1) increased SO₄ ^–2 levels due to catalytic SO₂ oxidation by soot and to higher SO₂ emissions, and (2) increased soot emissions due to dieselization of the medium and heavy duty fleets.     

Study of the Relationship of Distant SO2 Emissions to Dallas-Fort Worth Winter Haze

ABSTRACT

A study was conducted to estimate the changes in wintertime visual air quality in Dallas-Fort Worth (DFW) that might occur due to proposed reductions in SO₂ emissions at two steam electric generating plants in eastern Texas, each over 100 km from the city. To provide information for designing subsequent investigations, the haze was characterized broadly during the first year of the study. Meteorological data acquired then demonstrated that, during haze episodes, emissions from only one of the two plants were likely to be transported directly to DFW. Therefore, the second year of the study was centered on just one of the power plants. Air quality was then characterized within the urban area and at rural locations that would be upwind and downwind of the plant during transport to DFW. An instrumented aircraft measured plume dispersion and the air surrounding the plume on selected days. A mathematical model was used to predict the change that would occur in airborne particulate matter concentrations in DFW if SO₂ emissions were reduced to reflect the proposed limitations. The contribution of particles in the atmosphere to light extinction was estimated, and simulated photographs were produced to illustrate the visibility changes. The study concluded that the proposed emission reductions would, at most, subtly change perceived wintertime visibility.     

Estimates of 1973–1982 Annual Sulfur Oxide Emissions from Electric Utilities

Estimates of 1973–1982 annual SO₂ emissions from electric utility plants are presented in this paper. Results are based on analyses of plant level data collected by the U.S. Department of Energy on consumption and quality of fuels burned. Emissions are estimated from known information about fuel consumption, sulfur content, ash content, and control equipment. Results show that electric utility emissions decreased 16% from 1973 to 1982 and that these reductions were due to the use of lower sulfur coals and to the operation of flue gas desulfurization equipment.     

Examining Impacts of Visibility and PM Strategies before Implementation

ABSTRACT

One of the major challenges facing the world today is defining paths to sustainable futures. Part of the challenge is developing a national energy strategy that promotes an adequate energy supply for the United States, while enhancing environmental quality and maintaining U.S. competitiveness in the world economy. To assist in this challenge, we have developed a screening technique to analyze the effectiveness of different proposed emissions reduction strategies. The technique, referred to as the visibility assessment screening technique (VAST), is designed to examine possible impacts on visibility of emission changes of sulfur oxides, nitrogen oxides, volatile organic compounds (i.e., SO₂, NO_x, and VOC) and fine and coarse particulate matter (PM). The influence of relative humidity, natural aerosols, and the chemical interconnections among sulfur and nitrogen components of aerosols in determining the effectiveness of Clean Air Act Amendment and other projected energy-related emissions changes on eastern and western visibility are explored.

The effectiveness of these strategies on particulate matter impacts and potentially on ozone is also noted.     

Product Gudie/1987

A computer program has been written to determine the cost of building and operating wet scrubbers on individual coal fired utilities in the states where emissions are likely to affect the acid rain problem in the eastern United States. The program differs from many other estimates since it calculates the cost for each of 831 individual sites. The capital costs for installing scrubbers on the top fifty sulfur oxide emitting plants will be about $20 billion. This will result in an increase in the cost of electricity on an average of 0.88 cents/kWh and a reduction of sulfur oxide emissions from 1980 of 7,100,000 tons per year. An additional reduction of at least 1,000,000 tons per year can be obtained by requiring all plants burning oil to burn low sulfur oil. These figures assume utilities will use least emissions dispatching and will use local coals containing at least 3.5 percent sulfur. The use of local coals should result in a further saving of at least 0.2 cents/kWh. This should make available a large supply of low sulfur coal which could reduce emissions of sulfur oxides by up to 1,000,000 tons per year. The SO₂ reductions will be continued for at least the next thirteen years and have a very significant effect through the year 2010.     

Gaseous Sulfur Pollutants from Urban and Natural Sources

Major aspects of the circulation through the atmospheric environment of sulfur pollutants have been estimated, including source magnitudes, residual atmospheric concentrations, and scavenging processes. The compounds considered include SO₂ and H₂S, as well as sulfates. One-third of the sulfur reaching the atmosphere comes from pollutant sources, mainly as SO₂. Within the atmosphere there is a net transfer of sulfur from land to ocean areas. Pollutant sources annually amount to 73 × 10⁶ tons as sulfur while natural sources amount to 142 × 10⁶ tons, mainly as H₂S and sulfate sea spray. More than two thirds of the natural and pollutant sulfur emissions occur in the northern hemisphere. When only pollutant emissions are considered, 93 per cent occur in the northern hemisphere.     

Sub-region (district) and sector level SO2 and NOx emissions for India: assessment of inventories and mitigation flexibility

Sub-regional and sector level distribution of SO₂ and NO_x emissions inventories for India have been estimated for all the 466 Indian districts using base data for years 1990 and 1995. Although, national level emissions provide general guidelines for assessing mitigation alternatives, but significant regional and sectoral variability exist in Indian emissions. Districts reasonably capture this variability to a fine grid as 80% of these districts are smaller than 1°×1° resolution with 60% being smaller than even 1/2°×1/2°. Moreover, districts in India have well-established administrative and institutional mechanisms that would be useful for implementing and monitoring measures. District level emission estimates thus offer a finer regional scale inventory covering the combined interests of the scientific community and policy makers. The inventory assessment methodology adopted is similar to that prescribed by the Intergovernmental Panel on Climate Change (IPCC) for greenhouse gas (GHG) emissions. The sectoral decomposition at district level includes emissions from fossil fuel combustion, non-energy emissions from industrial activities and agriculture. Total SO₂ and NO_x emissions from India were 3542 and 2636 Gg, respectively (1990) and 4638 and 3462 Gg (1995) growing at annual rate of around 5.5%. The sectoral composition of SO₂ emissions indicates a predominance of electric power generation sector (46%). Power and transport sector emissions equally dominate NO_x emissions contributing nearly 30% each. However, majority of power plants are situated in predominantly rural districts while the latter are concentrated in large urban centers. Mitigation efforts for transport sector NO_x emissions would therefore be higher. The district level analysis indicates diverse spatial distribution with the top 5% emitting districts contributing 46.5 and 33.3% of total national SO₂ and NO_x emissions, respectively. This skewed emission pattern, with a few districts, sectors and point sources emitting significant SO₂ and NO_x, offers mitigation flexibility to policy makers for cost-effective mitigation.     

Needed: A National R&D Effort To Develop Individual Air Pollution Monitor Instrumentation

The results from the regional air quality analysis for the Four Corners Study are discussed in this paper. This study was one of five regional studies conducted for the National Commission on Air Quality. Potential regional air quality impacts were evaluated through the year 1995 for alternative energy scenarios under current and alternative regulatory policies. The alternative regulatory policies include emission fees, technology standards, emission ceilings, and prevention of significant deterioration class elimination. The alternatives were compared in terms of their impacts on regional visibility and on the ambient concentrations of SO₂, SO₄, and primary fine particulates. The fate of the pollutants was estimated. The alternative regulatory policies were quite different with respect to their control of SO_X emissions and their impacts on regional visibility. Sources located outside of the study region were estimated to have a major impact on regional air quality within the study region.     

Regional trends in wet deposition of sulfate in the United States and SO2 emissions from 1980 through 1995

Regional trends of seasonal and annual wet deposition and precipitation-weighted concentrations (PWCs) of sulfate in the United States over the period 1980–1995 were developed from monitoring data and scaled to a mean of unity. To reduce some effects of year to year climatological variability, the unitless regional deposition and PWC trends were averaged (hereafter termed CONCDEP). The SO₂ emissions data over the same period from the United States, Canada, and northern Mexico, aggregated by state and province, were weighted appropriately for each deposition region in turn to produce scaled trends of the emissions affecting each region. The emission-weighting factors, which were held constant year to year, were estimated by exercise of a regional transport model. The sulfate CONCDEP regional trends are generally similar to those of regionally weighted SO₂ emissions, although the latter trends are less steep and the former trends have more year to year variability. In eastern regions, sulfate CONCDEPs and SO₂ emissions patterns both generally show an initial decrease, an essentially trendless middle period, and a final decrease as reductions mandated by the Acid Rain Provisions of the 1990 Clean Air Act Amendments began. Linear regressions of regional sulfate CONCDEPs on corresponding regionally weighted SO₂ emissions produced statistically significant relationships in all regions. The analysis indicated that although regional sulfate CONCDEPs decreased relatively faster than did SO₂ emissions during the period in all regions except the Great Plains, in general the slopes were not significantly different from unity.     

Ship emissions and their externalities for Greece

The existing and emerging international and European policy framework for the reduction of ship exhaust emissions dictates the need to produce reliable national, regional and global inventories in order to monitor emission trends and consequently provide the necessary support for future policy making. Furthermore, the inventories of ship exhaust emissions constitute the basis upon which their external costs are estimated in an attempt to highlight the economic burden they impose upon the society and facilitate the cost–benefit analysis of the proposed emission abatement technologies, operational measures and market-based instruments prior to their implementation.The case of Greece is of particular interest mainly because the dense ship traffic within the Greek seas directly imposes the impact of its exhaust emission pollutants (NO_x, SO₂ and PM) upon the highly populated, physically sensitive and culturally precious Greek coastline, as well as upon the land and seas of Greece in general, whereas the contribution of Greece in the global CO₂ inventory at a time of climatic change awareness cannot be ignored. In this context, this paper presents the contribution of Greece in ship exhaust emissions of CO₂, NO_x, SO₂ and PM from domestic and international shipping over the last 25 years (1984–2008), utilizing the fuel-based (fuel sales) emission methodology. Furthermore, the ship exhaust emissions generated within the Greek seas and their externalities are estimated for the year 2008, through utilizing the fuel-based (fuel sales) approach for domestic shipping and the activity-based (ship traffic) approach for international shipping.On this basis, it was found that during the 1984 to 2008 period the fuel-based (fuel sales) ship emission inventory for Greece increased at an average annual rate of 2.85%. In 2008, the CO₂, NO_x, SO₂ and PM emissions reached 12.9 million tons (of which 12.4 million tons of CO₂) and their externalities were found to be around 3.1 billion euro. With regard to shipping within the Greek seas, the utilization of the fuel-based (fuel sales) analysis for domestic shipping and the activity-based (ship traffic) analysis for international shipping shows that the ship-generated emissions reached 7.4 million tons (of which 7 million tons of CO₂) and their externalities were estimated at 2.95 billion euro. Finally, the internalization of external costs for domestic shipping was found to produce an increase of 12.96 and 2.71 euro per passenger and transported ton, respectively.     

Sulfur Dioxide and Nitrogen Oxides Emissions from U.S. Pulp and Paper Mills, 1980–2005

Abstract

Comprehensive surveys conducted at 5-yr intervals were used to estimate sulfur dioxide (SO₂) and nitrogen oxides (NO_x) emissions from U.S. pulp and paper mills for 1980, 1985, 1990, 1995, 2000, and 2005. Over the 25-yr period, paper production increased by 50%, whereas total SO₂ emissions declined by 60% to 340,000 short tons (t) and total NO_x emissions decreased approximately 15% to 230,000 t. The downward emission trends resulted from a combination of factors, including reductions in oil and coal use, steadily declining fuel sulfur content, lower pulp and paper production in recent years, increased use of flue gas desulfurization systems on boilers, growing use of combustion modifications and add-on control systems to reduce boiler and gas turbine NO_x emissions, and improvements in kraft recovery furnace operations.     

Emission Inventory Case Studies—Policy Aspects

The Clean Air Act (and proposed Clean Air Act Amendments in H.R. 5252) are addressed relative to quantification of emission data. Six case studies performed for the National Commission on Air Quality (NCAQ) are reviewed. The models used to quantify the amount of emissions needed to meet air quality standards for O₃, particulates, and SO₂ are reviewed for each case study city. Technical and resource limitations in meeting the Act’s emission inventory requirements for nonattainment plans.and PSD permitting are outlined.     

Influence of ship emissions on air quality and input of contaminants in southern Alaska National Parks and Wilderness Areas during the 2006 tourist season

The impact of ship emissions on air quality in Alaska National Parks and Wilderness Areas was investigated using the Weather Research and Forecasting model inline coupled with chemistry (WRF/Chem). The visibility and deposition of atmospheric contaminants was analyzed for the length of the 2006 tourist season. WRF/Chem reproduced the meteorological situation well. It seems to have captured the temporal behavior of aerosol concentrations when compared with the few data available. Air quality follows certain predetermined patterns associated with local meteorological conditions and ship emissions. Ship emissions have maximum impacts in Prince William Sound where topography and decaying lows trap pollutants. Along sea-lanes and adjacent coastal areas, NO_x, SO₂, O₃, PAN, HNO₃, and PM_2.5 increase up to 650 pptv, 325 pptv, 900 pptv, 18 pptv, 10 pptv, and 100 ng m^?3. Some of these increases are significant (95% confidence). Enhanced particulate matter concentrations from ship emissions reduce visibility up to 30% in Prince William Sound and 5–25% along sea-lanes.     

Environmental assessment on a soil washing process of a Pb-contaminated shooting range site: a case study

In this study, an environmental assessment on a soil washing process for the remediation of a Pb-contaminated shooting range site was conducted, using a green and sustainable remediation tool, i.e., SiteWise ver. 2, based on data relating specifically to the actual remediation project. The entire soil washing process was classified into four major stages, consisting of soil excavation (stage I), physical separation (stage II), acid-based (0.2 N HCl) chemical extraction (stage III), and wastewater treatment (stage IV). Environmental footprints, including greenhouse gas (GHG) emissions, energy consumption, water consumption, and critical air pollutant productions such as PM₁₀, NO _x , and SO _x , were calculated, and the relative contribution of each stage was analyzed in the environmental assessment. In stage I, the relative contribution of the PM₁₀ emissions was 55.3 % because the soil excavation emitted the fine particles. In stage II, the relative contribution of NO _x and SO _x emissions was 42.5 and 52.5 %, respectively, which resulted from electricity consumption for the operation of the separator. Stage III was the main contributing factor to 63.1 % of the GHG emissions, 67.5 % of total energy used, and 37.4 % of water consumptions. The relatively high contribution of stage III comes from use of consumable chemicals such as HCl and water-based extraction processes. In stage IV, the relative contributions of GHG emissions, total energy used, and NO _x and SO _x emissions were 23.2, 19.4, 19.5, and 25.3 %, respectively, which were caused by chemical and electricity demands for system operation. In conclusion, consumable chemicals such as HCl and NaOH, electric energy consumption for system operation, and equipment use for soil excavation were determined to be the major sources of environmental pollution to occur during the soil washing process. Especially, the acid-based chemical extraction process should be avoided in order to improve the sustainability of soil washing processes.     

Analysis of Industrial Boiler Solid Waste Impacts

This paper presents an examination of industrial coal-fired boiler waste products. Presently the atmospheric emissions from all new boilers larger than 250 × 10⁶ Btu/hr are controlled by existing New Source Performance Standards, and boilers smaller than 250 × 10⁶ Btu/hr are controlled to levels required by the regulations of the particular state in which the facility is located. The 1977 Clean Air Act Amendments, however, specify categories of sources for which EPA must develop revised New Source Performance Standards. Industrial coal-fired boilers are included as one of these categories, and a relevant issue concerns the potential amount of solid waste generated as a result of tightened emission standards that require flue gas desulfurization. This paper examines the air quality and solid waste impacts of moderate and stringent emission controls for particulate and SO₂ emissions from industrial coal-fired boilers.

Comparisons are presented of physical and chemical characterizations of the emissions and solid wastes produced when boilers are equipped with particulate and SO₂ control equipment. The SO₂ systems examined are lime spray drying, lime/limestone, double alkali, sodium throwaway, physically cleaned coal, and fluidized-bed combustion. The solid waste disposal alternatives and the disposal costs are discussed. The most common disposal methods used are landfill for dry wastes and impoundment for sludges, with special wastewater treatment requirements for the sodium throwaway aqueous wastes.