This document presents the 1996 Emissions Inventory for the 12 county region of the Alamo Area Council of Governments (AACOG). The 12 counties included in this emissions inventory are Atascosa, Bandera, Bexar, Comal, Frio, Gillespie, Guadalupe, Karnes, Kendall, Kerr, Medina and Wilson. In analyzing air quality, three critical pollutants were inventoried: Volatile Organic Compounds (VOC), Oxides of Nitrogen (NOx), and Carbon Monoxide (CO). The source of these pollutants is broken down into six major categories for this report: Non-road mobile sources, Military/Airports, Area sources, Biogenic sources, Point sources and On-road mobile sources.
Non-road mobile sources consist of all vehicles and equipment not routinely operated on streets and highways. These include recreational boats, recreational vehicles, railroad cars, agricultural equipment, construction equipment, mining equipment, logging equipment, residential equipment (lawnmowers etc.), and commercial and industrial equipment. These account for 52.0 tons per day of VOC, 260.5 tons per day of CO and 38.5 tons per day of NOx in Bexar County. Chapter 2 lists the methodologies for estimating emissions for each subcategory in non-road mobile sources. Also, a chart is provided showing a breakdown of the emissions in tons per weekday, Saturday, and Sunday.
Military/Airport sources include both public and military aircraft, as well as military groundside emissions and airport support vehicles. Military/Airport emissions also include on-road emissions generated on base and non-road mobile source emissions. Military activity is only found in two counties within the AACOG region, those being Bexar and Comal counties. Although Hondo AFB is in Medina County, there are no significant emissions. Both of the civilian airports included in the inventory, San Antonio International Airport and Stinson Airfield, are located in Bexar County. These sources account for 2.9 tons per day of VOC, 15.1 tons per day of CO and 7.1 tons per day of NOx in Bexar County. Chapter 3 contains the methodologies used in the calculation of the inventory emissions for military and airport sources.
Area sources encompass a large number of diverse sources-everything from bakeries and breweries to asphalt paving and degreasing operations. These sources include facilities whose individual emissions do not qualify them as point sources (each facility emits less than 100 tons of VOC or NOx per year), however; collectively they can release significant quantities of pollutants. Area sources emit 78.3 tons per day of VOCs, 2.4 tons per day of CO and 2.3 tons per day of NOx in Bexar County. The methodologies used for estimating emissions from area sources varied by subcategory. These can be found individually in Chapter 4 of the emission inventory.
Biogenic sources are emissions from natural sources such as vegetation and microbial activity. This is the only category that is from a non-anthropogenic source. Example sources include trees and grasses, as well as emissions from soil microbes. This category accounts for 41.5 tons per day of VOCs, 0 tons per day of CO and 0 tons per day of NOx in Bexar County. The methodology used for this category is located in Chapter 5 of the emissions inventory.
Point source emissions are from stationary sources such as electrical generating plants and other industrial facilities. These sources are well documented, in accordance with TNRCC rules, and emit over 100 tons of NOx or 100 tons of VOC per facility each year. This category contributes 7.0 tons of VOCs per day, 8.7 tons per day of CO and 64.3 tons per day of NOx to the inventory of emissions in Bexar County. Chapter 6 contains the data for point sources by company and county.
On-road mobile sources consist of vehicles operated on the streets and highways. The vehicles are broken down into gasoline- and diesel-powered vehicles. This category represents the largest source of emissions from non-stationary sources, producing 127 tons per day of VOCs, 1,042 tons per day of CO and 147 tons per day of NOx in the AACOG region. The methodology used for calculating these emissions and the results of the emissions calculations are provided in Chapter 7.
Different agencies contributed information to this inventory, making preparation of the document possible. Population data for 1996 were obtained from the Texas Water Development Board "Most Likely Scenario." Employment figures were taken from the Texas Workforce Commission. The Texas Department of Transportation (TxDOT) supplied highway vehicle registration data and developed vehicle miles traveled (VMT) estimates and vehicle travel parameters, which were used as input into the MOBILE5 emissions model. Texas Transportation Institute provided on-road emission estimates for Bexar County. The Texas Natural Resource Conservation Commission (TNRCC) provided data for a number of categories including point source emissions, the location of aboveground and underground storage tanks, and autobody shop emissions.
This emission inventory is based on average ozone seasonal data for county-wide estimation of the emissions. For some of the categories, a map is provided showing the location of emissions based on 4 km. grid cells. This is to illustrate that the emissions are not just countywide estimations, but also have specific geo-coded locations.
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