A second category of major stationary sources is made up of facilities that burn material for energy, waste disposal, or both. Utilities, waste incinerators, industrial boilers, and cement kiln facilities are the major examples of combustion sources of air pollution. Because these facilities burn materials at very high temperatures, they emit chemicals and gases that sometimes result in dangerous chemical reactions. Many of these facilities – particularly utilities – were built before 1971 and had been "grandfathered" from some air pollution control requirements under the Texas Clean Air Act. However, legislative changes enacted in 1999 forced utilities to apply for permits and commit to reducing emissions of sulfur dioxide and nitrogen oxides, while another legislation passed in 2001 forced all remaining facilities to apply for permits (Footnote: 76th Legislature, SB 7; 77th Legislature, HB 2912).

CRITERIA AIR EMISSIONS (IN TONS) FROM MAJOR POWER PLANTS IN TEXAS BY FUEL TYPE, 2000 FUEL TYPE PM -10 SULFUR DIOXIDE NITROGEN OXIDES VOLATILE ORGANIC COMPOUNDS CARBON MONOXIDE TOTALS Coal 9,884 224,796 113,437 1,260 16,495 365,872 Lignite 8,284 325,305 113,963 1,228 7,496 457,276 Coal & Lignite 18,168  551,101  227,399 2,489  23,992  823,148 Natural Gas & Co-generation 5,697 8,549 157,704 3,713 41,200 216,863 Nuclear 1 1 39 2 10 53 Totals 23,865 559,651 385,142 6,203 65,202 1,040,064 Source: Texas Commission on Environmental Quality,, 2000 State Summary of Emissions Database, July 2002. Data comes from 131 plants reporting to the Texas Emissions Inventory and does not include some smaller generating plants.

Texas is home to some 175 electric utilities operating 437 generating stations.^* About 39 percent of the state's electricity is derived from coal and lignite,  about 32 percent comes from natural gas, and the remainder comes from industrial and other non-utility co-generation (18.6 percent), hydroelectric power (0.3 percent), nuclear power (10 percent), and renewable energy sources (less than 1 percent).(U.S. Energy Information Administration, Electric Power Industry Generation by Energy Source, 1999, information from website, www.eia.doe.gov)^* It is important to note that almost all of the industrial co-generation sources rely on natural gas as the primary fuel, making natural gas -- at about 52 percent -- overall the largest energy source in Texas. Electric utilities that use western coal or Texas lignite coal as their combustible material pump millions more tons of carbon dioxide, carbon monoxide, sulfur dioxide, and nitrogen oxides into the atmosphere than do those using natural gas or a combination of petroleum and natural gas. Recently a number of wind farms have been built in West Texas as utilities meet a legislative requirement to have 3 percent of the total energy come from renewable resources. The Energy section of this website provides more information on these clean energy alternatives.

Four of the top five facilities in Texas that released the largest volume of criteria pollutants in 1997 are coal- or lignite-fired electric power plants.^* The fifth facility -- an Aluminum Company of America (ALCOA) plant in Milam County -- consists of an aluminum smelter factory and the coal-fired power plants used to run it.^* Information from EPA studies indicates that electric generating plants are significant emitters of air toxics such as mercury, arsenic, nickel, hydrogen fluoride, and hydrochloric acid, among others.^* In the 1998 reporting year, electric utilities were required for the first time to report toxics emissions and transfers as part of the Toxics Release Inventory Program. Texas electric utilities reported releasing 7.5 million pounds of toxics to the atmosphere in 1999, and 14.9 million pounds of toxics in 2001.^*

Most of the major utilities in Texas that emit the largest amounts of nitrogen oxides per year are located outside ozone non-attainment areas. Nonetheless, the nitrogen oxides emissions, as well as the ozone formed as a result of such emissions from power plants, can be carried by prevailing winds up to 500 miles and can increase background levels of nitrogen oxides and ozone in nonattainment areas in Texas and other states as well.^* This regional ozone problem is just beginning to be understood. In addition, fine particulates formed from nitrogen oxides and sulfates from sulfur dioxide emissions can travel even farther and are believed to contribute to visibility impairment throughout Texas, including in Big Bend and Guadalupe Mountains..^* The state is currently working in conjunction with eight other states to address regional haze impacting visibility in the national parks and wilderness areas.*

Waste incinerators are another source of combustion-generated air pollutants. Both municipalities and industries sometimes incinerate a variety of wastes as a means of reducing their volume and generating energy. There are currently some 30 permitted hazardous waste incinerators in Texas. These facilities are operated by large corporations, chiefly to dispose of their own wastes. Four of the facilities in Texas have permits to be commercial waste incinerators, accepting liquid wastes from both in-state and out-of-state generators. Others are "captive" facilities which only accept waste from their own companies.

Cement plants are another source of combustion pollution. Traditional cement production -- where natural gas, coal, or fuel oils are used to heat the kiln -- can cause air pollution problems during the combustion process itself, which produces air pollutants such as carbon monoxide, sulfur dioxide and particulate matter, and some toxics. However, one cement company in Texas --TXI Inc. -- is also burning a wide variety of hazardous wastes to fire its kilns. This "alternative" production process is controversial because of the possibility of increasing emissions of criteria air pollutants as well as toxic emissions. New contaminants, known as Products of Incomplete Combustion (PICs) also are produced during the burning of hazardous wastes in the cement kiln and released into the atmosphere through stack emissions. These products include highly toxic compounds known as dioxins and furans – types of endocrine disruptors -- which are formed when hazardous and other wastes that contain chlorine are burned. But even cement plants burning traditional fuels also can release dioxins. These compounds are also a concern in municipal and industrial waste incineration. However, the emissions of air pollutants and toxics depend upon the fuel type, pollution control equipment and temperature at which the fuel and cement inputs are burned making direct comparisons between cement operators challenging.

In 1991, citizen groups in Midlothian, near Dallas, expressed concerns about health effects from the burning of hazardous wastes in three cement-making facilities -- TXI, Holcim and North Texas Cement --  and the dumping of cement-kiln ash in quarries. At that time, two of the three cement-kiln plants in the Midlothian area were burning waste-derived fuels, while a third was burning tires.^* Presently, only Texas Industries in Midlothian is burning hazardous waste, and, despite citizen opposition and a hearing, in 1999 the state issued a permit that potentially doubles the burning of hazardous waste by the facility. In addition, TXI has applied for a permit modification and has conducted test burns to once again burn tires at its facility, as have several cement plants throughout the state in an effort to dispose of hundreds of thousands of tires around the state. TXI is the leading releaser of toxics and one of the leading releasers of criteria pollutants to the atmosphere among cement operators.

CRITERIA POLLUTANTS IN TONS, 2000, AND TOXIC AIR EMISSIONS IN POUNDS FROM CEMENT PLANTS IN TEXAS, 2001 FACILITY COUNTY PM10 SULFUR OXIDES NITROGEN OXIDES ORGANIC COMPOUNDS CARBON MONOXIDE TOXICS (lbs) DIOXINS (grams) TXI Ellis 309 6,302 4,515 73 818 936,373 0.7 Holnam Ellis 200 4,483 3,475 614 4,383 170,731 1.3 NTCC Ellis 505 4,368 2,905 13 530 96,807 0.1 Capitol Bexar 170 2,293 2,204 441 772 52,892 0.1 Lehigh Hays 464 1,822 2,628 186 5,528 26 3.1 CEMEX Comal 179 71 2,961 43 1,617 60 1.3 Alamo Bexar 115 1 2,527 33 1,133 34 0.2 TXI Comal 137 16 1,253 54 694 5,482 2.3 CEMEX Ector 283 329 1,789 120 1,316 76,675 1.2 Lone Star Nolan 155 139 1,217 47 252 7,718 2.3 Lehigh McLennan NR 456 836 NR NR NR NR Sources: U.S. Environmental Protection Agency, 2001 Toxics Release Inventory Database, 2003. Criteria pollutant information from Texas Natural Resource Conservation Commission, 2000 Emissions Inventory, 2002. Note: NR = not reported.

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