Emissions Inventories for the Southern Appalachian Mountains Initiative

Calvin Ogburn, Laura Boothe, Maureen Mullen, Patricia Brewer

Carolina Power & Light, P.O. Box 326, New Hill, NC 27562; Division of Air Quality/Planning, North Carolina Department of Environment and Natural Resources, P.B. Box 29580, Raleigh, NC 27626-0580; Pechan-Avanti Group, 5528-B Hempstead Way, Springfield, VA 22151; Southern Appalachian Mountains Initiative, 59 Woodfin Place, Asheville, NC 28801

ABSTRACT

The Southern Appalachian Mountains Initiative (SAMI) is evaluating emissions management strategies to protect air quality and air quality related values in the Southern Appalachian Mountains. SAMI’s Integrated Assessment links emissions, atmospheric transport, environmental effects, and socioeconomic consequences to evaluate impacts of SAMI emissions management strategies. Strategies represent air regulatory requirements being implemented at the time of SAMI’s formation, expected emissions reductions under recent federal regulatory actions, and additional strategies that SAMI might recommend for regional, state, or community-based actions. SAMI’s emissions inventories characterize precursors of ozone, fine particulate matter, and acid deposition and support air quality photochemical and environmental effects modeling. Emissions inventories are being developed for air quality photochemical modeling for specific episodes in 1991-1995 and for two future years: 2010 and 2040. Inventories are also being developed for selected SAMI strategies for 2000, 2020, and 2030 to provide better understanding of future emissions trends.

INTRODUCTION

The Southern Appalachian Mountains Initiative (SAMI) is a voluntary partnership of state and federal agencies, industry, environmental groups, academia, and interested public. SAMI was established to identify and recommend air emissions management strategies to remedy existing and prevent future adverse air quality impacts to resources in Southern Appalachia, with particular focus on Class I national park and wilderness areas.

SAMI’s integrated assessment is focusing simultaneously on ozone, visibility impairment and acid deposition¹. Emissions management strategies developed by the Policy Committee are evaluated in the linked assessment models and the results are provided back to the Policy Committee for evaluation and policy recommendations. The SAMI area of concern (Figure 1) encompasses the mountainous regions of the eight SAMI states (AL, GA, KY, NC, SC, TN, VA, and WV) and includes 10 Class I areas. The entire eastern United States is represented in emissions inventories and air quality photochemical modeling.

Figure 1. Southern Appalachian Mountains Initiative Geographic Domain

Emissions inventories are being developed for precursors of ozone, aerosols, and acid deposition for the major source categories in the eastern United States. Two of the future year inventories, 2010 and 2040, will be evaluated in the air quality photochemical model. Interim year inventories for 2000, 2020, and 2030 will be defined for selected SAMI strategies to better understand future emissions trends. These results, combined with photochemical model results, will guide the design of future air quality projections for SAMI’s environmental effects models. Emissions inventories for 2010 and 2040 have been completed for two cases representing implementation of federal regulatory requirements. Inventories are being developed for SAMI emissions strategies.

An episodic modeling approach is being used to represent the complex meteorological and atmospheric processes that control ozone, aerosols, and acid deposition in the Southern Appalachian Mountains². Nine week-long episodes (total of 68 days) were selected to represent air quality and meteorological conditions over the five-year period (1991-1995) in Great Smoky Mountain National Park (GRSM) and Shenandoah National Park (SHEN). Air quality modeling results for the 68 days will be combined to represent the seasonal and annual air quality metrics that are most relevant for evaluating visibility, aquatic, and forest effects. Air quality will be projected for 2010 and 2040 for the two reference cases and the SAMI strategies.

Environmental effects models will project visibility and aquatic and forest ecosystem responses in future years to SAMI emissions strategies. These results will be summarized with cost and benefit information and provided to SAMI’s Policy Committee as guidance for SAMI policy recommendations. All SAMI products will be available for public review and use.

EMISSIONS INVENTORY

Unique Contribution:

SAMI’s inventories provide comprehensive treatment of precursors of ozone, aerosols, and acid deposition. In addition to summer-season inventories for ozone precursors (NOx, VOC, CO), SAMI has developed annual inventories for all major precursor species. Seasonal inventories for winter, spring, and summer episodes in 1991 – 1995 are also being developed. These inventories represent implementation of federal regulations and of SAMII strategies to reduce ozone, aerosols, and acid deposition in the Southern Appalachian Mountains. SAMI selected 2010 and 2040 as the future projection years to address both short and long-term trends for SAMI emissions strategies.

In contrast, the inventories developed under the Ozone Transport Assessment Group (OTAG) and under EPA’s call for State Implementation Plans (SIP) for regional NOx reductions focused on summer season emissions of ozone precursors. These inventories are projected to 2007 and support control strategy design for ozone attainment in urban areas.

SAMI Emissions Inventory Objectives:

1) Develop comprehensive inventories of precursor emissions contributing to ozone, aerosols, and acid deposition in the SAMI region

2) Document assumptions for future population growth patterns, demand for energy and transportation, penetration of clean technology, and regulatory drivers that determine future emissions trends

3) Project future year inventories for emissions management strategies developed by SAMI’s Policy Committee

4) Describe confidence in emissions projections, by source sector and emissions species

5) Define direct costs of controls in 2010

Inventory Assumptions

SAMI’s emissions inventories for precursors of ozone, aerosols, and acid deposition characterize utility, industrial, highway vehicle, non-road engines, and area (e.g. small point sources, agricultural) source categories. Inventories have been developed for the 1990 base year³ and for nine episodes in winter, spring, and summer of 1991 through 1995. Inventory projections are being developed for SAMI emissions management strategies. Inventories for 2010 and 2040 will be evaluated in the air quality photochemical model. Inventories for 2000, 2020, and 2030 for selected emissions strategies will better define future emissions trends and will provide guidance to the design of air quality projections for effects models.

Each inventory includes point source and source sub-category, county-level records for the following emissions:

· sulfur dioxide (SO₂)

· nitrogen oxide (NO_x)

· carbon monoxide (CO)

· particles less than 10 and less than 2.5 microns (PM₁₀ and PM_2.5)

· ammonia (NH₃)

· volatile organic compounds (VOC)

· elemental carbon (EC)

· organic

· primary sulfate and nitrate (SO₄ and NO₃)

Biogenic emissions are not included in this inventory, however biogenic emissions are calculated as part of the photochemical model.

Future Year Projections

The SAMI 1990 base year emissions inventory was projected to both a near-term year (2010) and a long-term year (2040) for the photochemical modeling. Two inventories represent implementation of federal regulations and will allow SAMI to interpret benefits of these actions for the Southern Appalachian Mountains region. SAMI’s Policy Committee is considering emissions management strategies beyond current federal requirements. Full implementation of these SAMI strategies would not likely be feasible by 2010, whereas by 2040, the long-term effects of these strategies should be evident. The objective of the 2040 projections is to understand the future emissions trends under SAMI strategies. Emissions growth patterns can be projected with a greater level of certainty to 2010 than to 2040, so SAMI will describe the assumptions and the confidence in the 2010 and 2040 inventories for the major source sectors and emissions species.

Population projections used for growth of source sub-categories were based on Bureau of Economic Analysis (BEA)⁴ and available state projections (Kentucky and North Carolina) for 2010. Similarly, industrial growth projections were based on BEA growth data.

Due to the highly uncertain nature of making emission projections to 2040, SAMI convened several source sector workgroups to review and contribute to assumptions on expected trends for growth in demand, emission regulations, and technology drivers⁵. Source sector workgroups were convened for the following four sectors: electric generation, highway vehicles, nonroad engines, and industrial boilers and were composed of industry, government, academia, and environmental representatives. Each of these workgroups held two to three conference calls during spring 1998 with the participants encouraged to give their views on expected trends in growth, technology, and regulatory and market drivers. These discussions laid the groundwork for the 2040 emissions projections.

Growth Projections

This section discusses the approaches used to project growth in emission-generating activity. Because the methods used to estimate growth differed by source sector, each of these source sectors is discussed separately below.

Electric Utilities

Representatives of the electric generation source sector have provided expected technology types for new electric generating units to fill unmet electricity demand and expected emissions rates for these new units. Representatives have also provided significant review and revision to assumptions about utility emissions trading, control technology installation, and expected emissions for the 2010 inventories.

Based on the SAMI electric generating source sector workgroup recommendations, coal-fired boilers were grouped by size and age to determine a future year capacity utilization. The chart below shows the capacity utilization factors that were applied to coal-fired boilers for use in calculating emissions in 2010 and 2040.

Table 1. Coal-fired, electric generation units by capacity, age, and capacity factor.

Unit Capacity	Unit Age	Capacity Factor
> 250 MW	< 40 years	0.90
> 250 MW	40 to 55 years	0.77
> 250 MW	> 55 years	0.65
100 to 250 MW	< 50 years	0.77
100 to 250 MW	> 50 years	0.46
< 100 MW	all ages	0.20

For other types of units, including oil- or gas-fired boilers and combustion turbines, base year 1990 emissions were grown to 2010 or 2040 using default growth factors that were developed from Department of Energy (DOE) generation projections by National Energy Reliability Council (NERC) region and fuel type⁶. Planned future units that were identified in DOE’s Form 860⁶ were added in 2010 or 2040. Additional generation demand that was not supplied by the set of existing and planned units was met using generic units. A mixture of fuel sources was assumed for each megawatt of future generic unit capacity that was added. Pulverized coal boilers, integrated gasification combined cycle (IGCC) units, and natural gas-fired combined cycle (NGCC) units were assumed to supply 20, 40, and 40 percent of the future new generic unit capacity, respectively. Table 2 shows the emission rates assumed for these generic units.

Table 2. Basis for Calculating Emissions from Electric Generation Generic Units in 2040

	Generation Share			(Btu/kWh)			(lb/MMBtu)			Heat Rate	Emission
Pollutant	PC	IGCC	NGCC	PC	IGCC	NGCC	PC	IGCC	NGCC	(Btu/kWh)	Factors
NOX	0.20	0.40	0.40	8,800	7,582	5,500	0.1000	0.0600	0.0300	6,993	0.0606
SO2	0.20	0.40	0.40	8,800	7,582	5,500	0.1000	0.0200	0.0000	6,993	0.0338
PM10	0.20	0.40	0.40	8,800	7,582	5,500	0.0200	0.0100	0.0000	6,993	0.0094
VOC	0.20	0.40	0.40	8,800	7,582	5,500	0.0027	0.0027	0.0120	6,993	0.0056
CO	0.20	0.40	0.40	8,800	7,582	5,500	0.0230	0.0230	0.0084	6,993	0.0184
PM25	0.20	0.40	0.40	8,800	7,582	5,500	0.0105	0.0053	0.0000	6,993	0.0049
NH3	0.20	0.40	0.40	8,800	7,582	5,500	0.0000	0.0000	0.0000	6,993	0.0000
PC = Pulverized Coal Boiler
IGCC = Integrated Gasification Combined Cycle
NGCC = Natural Gas Combined Cycle

Electric generating units, with the exception of units greater than 350 MW, were assumed to be retired after 65 years. Coal-fired units greater than 350 MW were assumed to be repowered rather than retired after 65 years. A capacity factor of 0.77 was applied to these repowered units. Under these assumptions, few of the present-day coal-fired power plants were retired by 2010. By 2040, 32 percent of the base year (1990) coal-fired power plant capacity was assumed to be retired, 41 percent was assumed to be repowered, and the remaining 27 percent was assumed to remain on line.

Non-utility Point Sources

Growth in emissions from non-utility point sources was based on Bureau of Economic Analysis (BEA) Gross State product (value added) projections by industry⁴. For the fuel consumption sectors, energy intensity factors were applied to the BEA-based growth factors. These energy intensity factors account for projected fuel efficiency gains and fuel switching and were based on DOE data⁶. Separate factors were applied for industrial, commercial/institutional, and residential fuel depending on fuel type. All non-utility point source growth was assumed to occur through either existing source modifications or new sources (i.e., no emissions growth through increased capacity utilization at existing plants). Source retirement was factored into these point source projections using retirement rates from DOE⁶. Emissions were retired based on these rates and replaced by sources emitting at new source emission levels. One exception to the DOE retirement rates was made for industrial boilers. The SAMI Emissions Inventory Subcommittee believed that life expectancy of these units assumed by DOE (greater than 100 years) was not economically realistic, so a retirement age of 65 years (the same as assumed for electric utility boilers) replaced the DOE assumption.

Different emission projection procedures were applied for the eight SAMI States than were applied for the remaining States within the modeling domain. A “Detailed Approach” was applied in the eight SAMI States that included the modeling of emission offset requirements. This approach distinguished between new and existing source growth, estimated the size and number of new emission sources, and reflected a disincentive for emissions growth to occur in current ozone nonattainment areas and near Class I areas. For the remaining States, a “Generic Approach” was applied that did not model emission offset requirements. This approach allocated all growth to existing sources so that each individual plant was a composite of residual base year emissions (after source retirement), modifications, and new sources.

Highway Vehicles

Growth in emissions from highway vehicles was characterized by the estimated change in vehicle miles traveled (VMT). Growth in VMT from 1990 to 1995 was based on actual VMT data from the Federal Highway Administration’s Highway Statistics publications^7,8. From 1995 to 2010, growth factors used to project these SAMI VMT were developed for each Metropolitan Statistical Area (MSA) and rest-of-state area by vehicle class. These VMT growth factors were calculated by multiplying national VMT growth factors by vehicle type by the ratio of MSA-specific population growth to national population growth. The national VMT growth factors were calculated from national VMT projection data by vehicle type output by EPA’s MOBILE4.1 Fuel Consumption Model (FCM)⁹. VMT was projected to 2040 by extrapolating this FCM VMT data, assuming annual growth rates from 2020 to 2040 will be the same as those indicated in the FCM from 2010 to 2020. Once these growth factors were calculated, 2010 and 2040 VMT databases were developed at the county/roadway type/vehicle type level by multiplying the 1990 SAMI VMT database by the appropriate growth factors. Georgia provided its own 2010 VMT database for use in SAMI based on the State’s VMT projections. The 2040 VMT for Georgia was then calculated using this State-supplied 2010 VMT database as the starting point, and growth factors developed as discussed above.

Nonroad Engines

Growth in the nonroad engine sector from 1990 to 2000 was based on annual growth rates by nonroad equipment and fuel type from 1989-1996 Power Systems Research (PSR) equipment population data¹⁰. For most nonroad categories, post-2000 growth rates were based on Bureau of Economic Analysis (BEA) Gross State product (value added) projections by industry⁴. Methods used to calculate growth factor for specific categories of nonroad engines are listed in Table 3. EPA’s Nonroad model was not available at the time that the inventory was first developed and therefore was not used for the inventory projections.

Table 3. Growth Indicators Used for Nonroad Engines Sector

Sector	Source for Growth Data				Geographic Detail
	1990 to 2000	2000 to 2010	2010 to 2020	2020 to 2040
Aircraft (operations)	FAA1	FAA1	FAA2	Linear extrapolation	SAMI States - county level for major airports/ rest-of-State; State-level for non-SAMI States
Aircraft (fuel use)	DOE	DOE	DOE	Linear extrapolation	National
Construction	PSR	BEA	BEA	BEA	State
Farm	PSR	BEA	BEA	BEA	State
Locomotives	DOE	DOE	DOE	Linear extrapolation	National
Airport Service Equipment	PSR	BEA	BEA	BEA	State
Logging Equipment	PSR	BEA	BEA	BEA	State
Lawn & Garden Equipment	PSR	BEA	BEA	BEA	State
Industrial Equipment	PSR	BEA	BEA	BEA	State
Recreational Vehicles	PSR	BEA	BEA	BEA	State
Marine (commercial)	DOE	DOE	DOE	Linear extrapolation	National
Marine (recreational)	EPA	EPA	EPA	EPA	National
Light Commercial Equipment	PSR	BEA	BEA	BEA	State

NOTES: BEA - Bureau of Economic Analysis⁴; used Gross State Product for specific industry or population indicators.

DOE - U.S. Department of Energy⁵

EPA - U.S. Environmental Protection Agency¹¹

FAA1 - U.S. Department of Transportation, Federal Aviation Administration¹²

FAA2 - U.S. Department of Transportation, Federal Aviation Administration¹³

PSR - Power Systems Research¹⁰; used historical growth rate for the various equipment

Stationary Area Sources

Growth in emission-generating activity from stationary area sources was generally estimated using BEA Gross State product (value added) projections by industry⁴. The methods (activity surrogates) used to estimate growth factors for the stationery area source emissions are listed in Table 4.

Table 4. Activity Indicators used to Project Growth for Stationary Area Sources

Source Category Description		Activity Surrogate Description
Stationary Source Fuel Combustion
	Electric Utility, Industrial, Commercial/Institutional, Total Area Source Fuel Combustion	BEA with energy intensity factors applied from DOE
	Residential	Population
Mobile Sources
	Paved Roads	Vehicle Miles Traveled
	Unpaved Roads	Historical unpaved road mileage
Industrial Processes		BEA
Solvent Utilization
	All Surface Coating Categories Composite, miscellaneous Non-industrial	Population
	Surface Coating- Categories for Degreasing, Dry Cleaning, Graphic Arts, Rubber/Plastic, Miscellaneous Indutrial	BEA
Storage and Transport
	Petroleum and Petroleum Product Storage: all categories except Bulk Stations/Terminals Breathing Loss: Gasoline; Gasoline Service; Diesel Service Stations; All storage types: Working Loss: all products, Gasoline Petroleum and Petroleum Product Transport: all categories except All Transport Types: Gasoline	BEA
	Petroleum and Petroleum Product Storage: Bulk Stations/Terminals Breathing Loss: Gasoline; Gasoline Service Stations; Diesel Service Stations; All Storage Types: Working Loss: All Gasoline Petroleum & Petroleum Product Transport: All Transport Types Gasoline	Gasoline Consumption
Waste Disposal, Treatment, and Recovery
	On-site Incineration: All Categories, Commercial/Institutional; Open Burning: Industrial, Commercial/Institutional; Wastewater Treatment Industrial; TSDFs	BEA
	On-Site Incineration: Residential; Open Burning: All Categories, Residentail, Lnadfills, Wastewater Treatment: All Categories, Public Owned, Residential/Subdivision Owned	Population
	Leaking Underground Storage Tanks	Gasoline Consumption
Natural Sources
	Biogenic Horses and Ponies	BEA
	Geogenic Wind Erosion	Zero Growth
Miscellaneous Area Sources
	Agriculture Production – Crops	Planted Crop Acreage (USDA)
	Agriculture Production – Livestock, Catastrophic/Accidental Releases, Health Services	BEA
	Other Combustion: Forest Wildfires, Managed Burning, Structure Fires	Zero Growth
	Other Combustion: Charcoal Grilling, Firefighting training, Cigarettes	Population
	Other Combustion: Motor Vehicle Fires	Vehicle Miles Traveled

For the sources where the activity surrogate is listed as BEA, growth in emission-generating acivity was estimated using BEA Gross State product (value added) projections by industry⁴. The BEA industry category from which the growth factors were derived differed depending on the source category code (AMSSCC) of the emission record. For the area source fuel combustion sectors, DOE energy intensity factors were applied to the BEA projections to account for fuel efficiency gains and fuel switching. The energy intensity factors differed by year, source category (industrial, commercial/institutional, or residential), and fuel type. Growth in unpaved road fugitive dust emissions were extrapolated from historical trends in unpaved road mileage by region. Growth factors for the agricultural crop production source category were based on U.S. Department of Agriculture projections of crop acreage planted¹⁴. As shown in Table 4, the growth factors for a number of area source categories were based on population growth projections. For the categories in Table 4 that indicate that gasoline consumption was used as the activity surrogate, growth factors were calculated using data output by EPA’s MOBILE4.1 Fuel Combustion Model⁹. An activity surrogate of zero growth in Table 4 indicates that projection year emissions were unchanged from the base year emissions for those source categories.

EMISSIONS REFERENCE CASE AND STRATEGIES

To date, SAMI has prepared emission inventories for 2010 and 2040 for two cases that represent implementation of federal regulations. The first emissions case includes all emission control measures that have been promulgated and are relatively certain. As discussed below, this includes the 1990 Clean Air Act Amendments, the 1 hour ozone standard, and several mobile source reductions. The second emissions case considers selected federal regulatory actions that are to be implemented in the near future but that had not been promulgated at the time the inventories were created. As discussed below, this includes EPA’s call for regional NOx reductions, and the Tier 2 and low sulfur fuel rules for mobile sources. Either inventory could be used as a baseline for evaluating SAMI emissions strategies. With these two inventories, SAMI did NOT try to define new regulatory drivers. However, through the use of the source sector workgroups, SAMI did attempt to incorporate new or emerging technologies that would likely enter the marketplace without new regulations. For example, competition within the utility industry could favor more efficient, cost-effective, and cleaner technologies to be chosen over existing technologies. Where possible, such market factors were incorporated in the assumptions for future source sector growth.

SAMI’s Policy Committee intends to develop emissions inventories that consider additional federal regulatory requirements (e.g. 8 hour ozone and fine particulate matter (PM_2.5) standards, regional haze rules) and is designing additional emissions strategies that represent emissions controls that SAMI might recommend for regional, state, or local actions.

Reference Case Emissions Control Assumptions

Electric Utilities

The basic control measures that were modeled for electric utilities for the reference case representing implementation of federal regulations include:

· the NOx and SO₂ provisions of Title IV of the Clean Air Act Amendments

· NOx RACT in ozone nonattainment areas without NOx waivers

· Phase 2 of the Ozone Transport Commission NOx Memorandum of Understanding

· New Source Performance Standards (NSPS) (for new units).

The application of these electric utility control measures was revised over several iterations of inventory development. The final 2010 inventory includes utility-specific information on the NOx and SO₂ emission rates expected per unit by 2010 for most of the utilities in the SAMI states. Utilities also provided their plans for installing scrubbers by 2010. With the SO₂ emission rates and scrubber information provided by these utilities, the utility units within the SAMI States collectively expect to exceed the SO₂ allowances that would be available to units in these States in 2010. Because these utilities’ current plans for generation in 2010 do not include installation of additional scrubbers by 2010, SO₂ emissions in the SAMI states in the final 2010 inventory exceed by 45% or 1 million tons the SO₂ emissions allowance totals for the SAMI States. These excess SO₂ emissions in the SAMI states were offset in the 2010 inventory by applying scrubbers at the highest SO₂-emitting units within the modeling domain outside the SAMI States. This approach allows the national SO₂ emissions cap to be met under the assumption that utilities in the SAMI States will purchase allowances from these scrubbed units in non-SAMI states. This approach is still being reviewed within SAMI committees. Alternative assumptions for utility SO₂ emissions in 2010 may be addressed in subsequent emissions strategies that are defined by SAMI’s Policy Committee.

Non-utility Point Sources

Control programs that were modeled for non-utility point sources include Reasonably Achievable Control Technology (RACT), Maximum Achievable Control Technology (MACT), and Clean Air Act Section 111(d) emission guideline for municipal solid waste landfills. The RACT controls were applied in ozone nonattainment areas for sources meeting the relevant source size cutoffs based on the nonattainment area classification. NOx RACT controls were not applied in areas with current NOx waivers. New Source Performance Standards (NSPS) emission control levels were applied to new sources, although Best Available Control Technology (BACT) and Lowest Achievable Emission Rate (LAER) control levels will actually be required in some instances and may be more stringent than NSPS control levels. Regulatory exemptions (e.g., plant capacity) from the NSPS were not reflected in the inventory. Application of NSPS control levels to all new sources will overstate the impact of NSPS, and may, therefore, be more representative of BACT/LAER control levels.

Highway Vehicles

Highway vehicle VOC, NOx, and CO emission factors were calculated for 2010 and 2040 using EPA’s MOBILE5b model. These emission factors were calculated by month, speed (to represent the various roadway types), and county. National control programs included in the default MOBILE5b modeling include the Tier I emission standards, evaporative emissions test procedure, and the CO cold temperature emission standards. Additional regionwide control programs that were modeled by including the appropriate inputs in the MOBILE5b files were the National Low Emission Vehicle (NLEV) program and the 2004 NOx heavy duty diesel vehicle emission standards. Inspection and maintenance (I/M) programs, Phase 2 Federal reformulated gasoline, and oxygenated fuel were modeled in areas participating in these programs. EPA’s PART5 model was used to calculate emission factors for PM₁₀, PM_2.5, and SO₂. Since the latest year that can be modeled with PART5 is 2020, emission factors for 2040 were modeled as 2020. Emission factors for NH₃ were calculated for the SAMI region by vehicle type and by year.

Nonroad Engines

The control measures that were included for the nonroad engine sector are the Phase II Compression Ignition Standard, the Phase II Spark Ignition Standard, and the Recreational Marine Vessel Standard. The effect of these emission control regulations were based on control efficiency values from EPA’s regulatory impact analyses of nonroad control programs. All these control programs will be fully implemented by 2040. Aircraft standards were not modeled, because they are International Civil Aviation Organization (ICAO) standards and estimates of emission reductions were not available at the time the inventories were prepared. However aircraft emission reductions from the ICAO standards are expected to be relatively small. Proposed large marine compression ignition engine rules were not released in time for the SAMI inventory development, so no reduction estimates were available for use. Increased penetration of low-emitting technologies (e.g., battery-powered equipment) were not modeled because estimates of future penetration of these technologies were not available. No Phase II reformulated gasoline emission reductions were applied to nonroad engines because reduction estimates were unavailable and because the engine population that would be affected by Phase II reformulated gasoline within the SAMI States is relatively small.

Stationary Area Sources

Controls applied to stationary area sources include both national and area-specific control programs. RACT controls were applied in ozone nonattainment areas, modeling the representative RACT control level based on the applicable Control Technique Guideline. NOx RACT controls were not applied in areas with current NOx waivers. The 2- and 4-year MACT standards were applied region-wide, as were other Federal VOC rules such as the consumer products rule. Other control measures were applied in PM nonattainment areas. These included the following assumed control programs for the relevant source categories: vacuum sweeping paved roads, chemical stabilization and/or paving of unpaved roads, dust control plans for construction sites, watering of cattle feedlots, New Source Performance Standard for residential woodstoves, and propane and bale/stack burning for agricultural burning. In addition, for agricultural tilling, an increase in conservation tillage from 26 percent in 1990 to 50 percent in 2010 and beyond was assumed. Controls specific to either ozone or PM nonattainment areas were not based on a review of specific State Implementation Plans (SIPs), but rather on control assumptions developed in consultation with EPA staff members.

Federal Regulatory Controls Case Assumptions

The second federal regulatory case includes all of the controls in the reference case, plus several additional control measures. The Tier 2/low sulfur fuel program (finalized in December 1999) was included in this case with reduced NOx, VOC, CO, PM, and SO₂ emissions from highway vehicles. This control program was not included in the reference case because the program had not been finalized at the time the inventories were initially prepared. In addition, even though the final rulemaking has now been signed for this program, until MOBILE6 is released, the tools available to analyze the emission impacts of this program are not fully developed. Regional NOx reductions similar to those in EPA’s call for revised State Implementation Plans (SIP) were represented in the second federal regulatory case by simply assigning a emissions rate of 0.15 lb/mMBtu NOx for all electric utility units greater than 25 MW in the 22 states targeted by EPA. and for non-utility point sources that were specified in EPA’s SIP call. The 7/10-year MACT standards were also included in this emissions case. This resulted in VOC reductions from industrial point sources. Finally, additional area-specific controls were applied in Georgia and Alabama as a result of control measures included in the Atlanta and Birmingham attainment plans^15,16 for the one-hour ozone standard. Included in these controls are several point source NOx emission limits, fuel controls for highway vehicles, and I/M program specifics for the Atlanta area.

EMISSIONS INVENTORY RESULTS

Growth in population, electric generation, and vehicle miles traveled in the SAMI states (Table 5) results for the two cases representing federal regulations are assumed to continue current technology, land use, and lifestyle practices. These assumptions drive the inventory results since population projections are used to estimate growth for a number of area and non road sources, vehicle miles projections are used to estimate highway vehicle emissions, and electric utility generation demand determines electric utility emissions.

Table 5. Growth in Population, Electric Generation, and Vehicle Miles Traveled in the eight SAMI states between 1990 and 2040

Year	Population (million people)	Vehicle Miles Traveled (million miles)	Fossil Fuel Electric Utility Generation (billion kilowatt-hours)
1990	37.299	355,367	425
2000	41.905	491,978	548
2010	45.906	605,178	642
2020	49.734	719,442	705
2030	53.556	835,549	782
2040	57.128	951,485	858

Emissions of SO2, NOx, VOC, PM2.5, and NH3 in 2010 and 2040 under the reference case are illustrated in Figures 2 through 4 for the eight SAMI States. All emissions are reported on an annual basis. Given the growth assumptions listed above, SO₂ and NOx emissions are projected to decrease in 2010 and 2040 compared to 1990 emissions levels (Figure 2). VOC emissions are projected to remain level between 1990 and 2010 and to increase substantially between 2010 and 2040. NH₃ emissions and primary emissions of fine particles are projected to increase between 1990 and 2040 (Figure 2).

Figure 2. Emissions for 1990 and Emissions Projections for 2010and 2040, in the eight SAMI states, assuming implementation of the 1990 Clean Air Act Amendments.

Because the economies of the SAMI states are growing more rapidly than in the other eastern states represented in SAMI’s inventory, SO₂ and NOx reductions in the SAMI states are projected to be less than the rates of improvement projected for the eastern US as a whole.

SO₂ emissions for the two cases representing implementation of federal regulations are the same because the control assumptions added in the second federal regulatory case focus on reducing summertime ozone, not sulfate. Between 1990 and 2010 SO₂ emissions in the eight SAMI states are projected to decrease by 20% (Figure 3). Utility controls under Title IV of the 1990 Clean Air Act Amendments are primarily responsible for this reduction. This reduction reflects the southern utilities’ assumptions that they will purchase emissions credits rather than installing scrubbers at existing units. SO₂ emissions in 2040 are forecast to be much lower than 2010 levels due new source review requirements.

Figure 3. Annual SO2 Emissions projections for 2010 and 2040 compared to 1990 assuming implementation of 1990 Clean Air Act Amendments

Annual NOx emissions in the SAMI states in the reference emissions case are not projected to change between 1990 and 2010 (Figure 4). NOx reductions from utility and highway vehicles under the 1990 Clean Air Act Amendments are projected to be offset by NOx increases from the non-road mobile and area source sectors. In 2040 NOx emissions for the utility sector are projected to be lower than in 2010 due to new source review requirements. Because vehicle travel is projected to increase steadily to 2040, NOx emissions for the highway vehicle sector are projected to increase by 2040 (Figure 4).

Figure 4. Annual NOx Emissions projections for 2010 and 2040 compared to 1990 assuming implementation of 1990 Clean Air Act Amendments

Under the emissions case representing the regional NOx reductions that are expected for the NOx SIP call and Tier 2/low sulfur fuel rules, NOx emissions in the SAMI states in 2010 are estimated to be 15% lower on an annual basis than in 1990. Essentially all the NOx reductions are attributable to the electric utility and highway vehicle source sectors. For just the five summer months targeted for seasonal NOx reductions, NOx emissions are projected to be 40% lower in 2010 than in 1990 (Figure 5).

Figure 5. Summer Day NOx Emissions in the eight SAMI states assuming implementation of the 1990 Clean Air Act Amendments (OTB) and implementation of regional NOx reductions from utility, industrial, and mobile sources (OTW).

Future Inventory Work

SAMI expects to develop and evaluate additional emissions strategies by the end of 2000. Direct costs of emission controls, including both capital expenditures and operation and maintenance costs, will be analyzed and documented for each strategy. SAMI will qualitatively evaluate the uncertainty for inventory projections, and where possible, quantify the range of uncertainty for specific emissions categories or source sectors of the projection inventories. In addition, SAMI expects to quantify the emission inventory changes that would be expected if different approaches had been used in inventory projections. For example, SAMI is evaluating the difference in emissions from the non-road engines sector if EPA’s NONROAD model had been applied for that sector.

CONCLUSIONS

SAMI is developing comprehensive emissions inventory projections for precursor emissions of ozone, aerosol, and acid deposition.

Participation by representatives of the specific source sectors in the development of assumptions for growth, technology, and regulatory drivers and in reviewing the resulting inventories has improved the quality of SAMI inventories.

SAMI’s inventories are in the public domain and will be available for the SAMI states to apply in future regulatory responsibilities.

Acknowledgements

SAMI’s Integrated Assessment is funded by a combination of EPA, state, and private sector contributions as well as significant in-kind contributions and committee participation. The authors wish to acknowledge the contributions of the Emissions Inventory subcommittee and SAMI participants who directed and reviewed the products described in this report and Pechan-Avanti Group, the contractor who developed these products.

References

1) Neeley, D., Brantley, W. P., Brewer, P.F. Southern Appalachian Mountains Initiative: An Overview, In Proceedings of Annual Meeting of Air and Waste Management Association, Salt Lake City, Utah, June 2000.

2) Odman, T., Boylan, J., Wilkinson, J., Yang, Y-J, and Russell, A. G. Ozone Modeling for the Southern Appalachian Mountains Initiative. In Proceedings of Annual Meeting of Air and Waste Management Association, Salt Lake City, Utah, June 2000.

3) E.H. Pechan and Associates, Inc. Development of the SAMI 1990 Base Year Emissions Inventory, Report prepared for the Southern Appalachian Mountains Initiative, January 1999.

4) Bureau of Economic Analysis, U.S. Department of Commerce, “BEA Regional and State Projections of Economic Activity and Population to 2045: Volume 1: States,” Washington, DC, July 1995.

5) Pechan-Avanti Group. Southern Applachian Mountains Initiative (SAMI) Projections Background Document II: Source Sector Workgroup Implementation. Report to SAMI. October 1997.

6) U.S. Department of Energy, “Annual Energy Outlook 1998,” Energy Information Administration, Washington, DC, January 1998.,

7) Federal Highway Administration, Highway Statistics 1990, ISBN 0-16-035995-3, U.S. Department of Transportation, Washington DC, 1990.

8) Federal Highway Administration, data tables from Highway Statistics 1995, obtained electronically, U.S. Department of Transportation, Washington DC, 1996.

9) U.S. Environmental Protection Agency, “MOBILE4.1 Fuel Consumption Model (Draft),” Office of Mobile Sources, Ann Arbor, MI, August 1991.

10) Dolce, G., “Nonroad Engine Growth Estimates” Report No. NR-008, EPA, Office of Mobile Sources, March 6, 1998.

11) Environmental Protection Agency, "Regulatory Impact Analysis, Control of Air Pollution; Emission Standards for New Nonroad Spark-Ignition Marine Engines," June 1996.

12) U.S. Department of Transportation, Federal Aviation Administration, "Terminal Area Forecasts, Fiscal Year 1997-2010," December 1997

13) U.S. Department of Transportation, Federal Aviation Administration, "Long-Range Aviation Forecasts Fiscal Years 2010, 2015, and 2020," July 1997.

14) U.S. Department of Agriculture, “USDA - Agricultural Baseline Projections to 2007,” World Agricultural Outlook Board, Office of the Chief Economist, Staff Report No. WOAB-98-1, 1998.

15) Georgia Department of Natural Resources, “State Implementation Plan for the Atlanta Ozone Non-attainment Area, Executive Summary,” Environmental Protection Division, Air Protection Branch, August 9, 1999.

16) Summary of Birmingham Proposed 1-hour Ozone Plan for SAMI, provided to The Pechan-Avanti Group by Alabama Department of Environmental Management, September 21, 1999.

Key Words:

Emissions inventory, emissions projections, emissions sources, ozone, particles,