Changes to Criteria-Pollutant Standards
The federal Clean Air Act requires the EPA to review the standard for each criteria pollutant every five years to ensure that it provides the required level of health and environmental protection. Federal clean-air standards cover six air pollutants: ozone, particulate matter, carbon monoxide, lead, nitrogen dioxide, and sulfur dioxide. Over the years, attaining the ozone standard has been the biggest air quality challenge in Texas.
2008 Ozone Standard
In January 2010, the EPA published a proposed reconsideration of the 2008 eight-hour ozone standard of 0.075 parts per million (ppm). In September 2011, at President Obama’s request, the EPA withdrew the proposed reconsidered ozone standard.
Soon after, the EPA announced it would proceed with initial area designations under the 2008 eight-hour ozone standard, starting with the recommendations states had made in 2009 and updating them with more current, certified air quality data (2008 through 2010).
Based on the latest available certified monitoring data, Governor Rick Perry revised the March 2009 Texas designation recommendation for the 2008 eight-hour ozone standard. The revised recommendation indicated that the nine-county Dallas–Fort Worth (DFW) area—Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwall, and Tarrant counties—and the eight-county Houston-Galveston-Brazoria (HGB) area—Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller counties—should be designated nonattainment.
Ozone Compliance Status
1997 Eight-Hour Ozone
2008 Eight-Hour Ozone
|Dallas–Fort Worth (DFW)
|Beaumont- Port Arthur, El Paso, Austin, Corpus Christi, Victoria,
San Antonio, East Texas, Waco
Note: The HGB area includes the counties of Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller. The DFW area includes the counties of Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwall, and Tarrant; also Wise for the 2008 eight-hour ozone standard.
In late 2011, the EPA indicated it intended to modify the state’s recommendations to include Wise County in the DFW nonattainment area and Matagorda and Hood counties in the HGB nonattainment area.
At the behest of the TCEQ, the governor in February 2012 asked the EPA to reverse its plan to expand the DFW and HGB ozone nonattainment areas, pursuant to EPA’s 2008 eight-hour ozone standard, because of insufficient scientific justification for the action. Texas’ position was supported by the TCEQ’s comprehensive technical analysis.
In May 2012, the EPA published final designations and classifications for the 2008 eight-hour ozone standard. It also published a final rule for the 2008 eight-hour ozone standard that included classification thresholds, establishing December 31 of each relevant calendar year as the attainment date for each classification. The EPA also revoked the 1997 eight-hour ozone standard for purposes of transportation conformity.
The DFW area was designated nonattainment with a “moderate” classification and the HGB area was designated nonattainment with a “marginal” classification. Matagorda and Hood counties were designated attainment/unclassifiable. Wise County was designated nonattainment with a “moderate” classification and became part of the DFW nonattainment area. The effective date was July 20, 2012.
Ground-level ozone, a component of smog, is not emitted directly into the air but forms through a reaction of nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. The major sources of NOx and VOCs are industrial facilities, electric utilities, car and truck exhaust, and chemical solvents.
Types of Sources
Emissions that affect air quality can be characterized by their sources.
Point sources: industrial facilities such as refineries and cement kilns
Area sources: dry cleaners, gasoline stations, and residential heating
On-road mobile sources: cars and trucks
Nonroad mobile sources: construction equipment and engines such as locomotives
Identifying control measures that are reasonable—as well as technologically and economically feasible—has presented a challenge for the TCEQ, considering the magnitude of emission reductions already achieved under the 1990 one-hour ozone standard.
Two of the main control strategies implemented in the HGB area for the one-hour ozone standard were as follows:
- An annual cap-and-trade program to reduce emissions of nitrogen dioxides (NOx) by an average of 80 percent from utility, industrial, commercial, and institutional combustion sources.
- An annual cap-and-trade program to reduce emissions of highly reactive volatile organic compounds (VOCs) from process vents, flares, and cooling-tower heat exchange systems.
Meeting the eight-hour ozone standard in the HGB area has also been complicated by unique meteorological conditions along the Gulf Coast and the complex chemistry of ozone formation.
In June 2012, the EPA published its final rule to determine that the HGB area did not attain the one-hour ozone standard by the attainment date of Nov. 15, 2007. Although the EPA had revoked the one-hour standard in 2005, states must continue to meet the one-hour ozone anti-backsliding requirements when triggered by a finding of failure to attain by the applicable attainment date. The requirements are contingency measures and the Clean Air Act’s major stationary source fee programs.
Reductions from contingency measures have already been achieved in the HGB area, so a final determination of failure to attain does not trigger additional emission reductions. However, a final determination of failure to attain by the area’s one-hour attainment date does trigger the one-hour anti-backsliding obligation to implement the penalty fee program under the Clean Air Act, unless that obligation is terminated.
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2010 Sulfur Dioxide Standard
In 2010, the EPA published a final rule strengthening the primary sulfur dioxide (SO2) standard. The rule sets a new one-hour standard of 75 parts per billion (ppb), determined by a three-year average of the 99th percentile of the annual distribution of daily maximum one-hour average concentrations. The rule revokes the previous annual SO2 standard of 0.03 parts per million and the 24-hour standard of 0.14 ppm. The rule, which took effect in August 2010, was challenged in federal court by Texas and other states. That challenge was dismissed by the D.C. Circuit Court of Appeals in July 2012. Texas and the other parties to the lawsuit chose not to appeal the decision.
In 2011, Texas recommended the following designations: nonattainment for Jefferson County; attainment for Dallas, Ellis, El Paso, Galveston, Gregg, Harris, Kaufman, McLennan, and Nueces counties; and unclassifiable for all remaining counties. Texas revised its recommendation for Jefferson County to attainment in April 2012. The EPA’s initial designations were delayed beyond the June 2012 anticipated release. All Texas counties with regulatory monitors have 2011 design values indicating compliance with the 2010 SO2 one-hour standard.
The EPA’s initial implementation guidance required maintenance plans and modeled demonstration of attainment for unclassifiable areas. In April 2012, the EPA put those requirements on hold. Roundtable meetings were held with stakeholders at EPA headquarters to determine how best to implement and assess compliance with the standard. By February 2014, states must submit State Implementation Plans (SIPs) to demonstrate attainment of the standard by August 2017 in nonattainment areas. By June 2013, states must submit infrastructure and transport SIPs.
The EPA was moving forward with designations focused on areas with sufficient air quality monitoring data. No attainment designations are anticipated, while areas in which monitored data indicate violation of the standard will be designated nonattainment. All other areas are expected to be designated unclassifiable.
As part of the final rulemaking for the 2010 standard, new SO2 monitors are required in Amarillo, Austin–Round Rock, Beaumont–Port Arthur, Dallas–Fort Worth–Arlington, Houston–Sugar Land–Baytown, Longview, and San Antonio. The monitors must be operational by Jan. 1, 2013
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2010 Nitrogen Dioxide Standard
In February 2010, the EPA published the final rule to strengthen the primary standard for nitrogen dioxide (NO2). The rule establishes a new one-hour NO2 standard at 100 parts per billion. The new standard focuses on short-term exposures to NO2, which are generally greater on and near major roads. No area in Texas has monitored above the 100 ppb standard.
The EPA retained the current annual average NO2 standard of 53 ppb, but changed the monitoring network requirements to capture both peak NO2 concentrations that occur near roadways and community-wide NO2 concentrations.
In February 2012, the EPA published in the Federal Register the initial designations identifying all counties and parishes in the United States as unclassifiable/attainment. Two near-road NO2 monitors in DFW and HGB must begin operating no later than Jan. 1, 2013, while two near-road NO2 monitors in San Antonio and Austin–Round Rock must begin operating no later than Jan. 1, 2014.
Once the expanded network of NO2 monitors is fully deployed and three years of air quality data have been collected—in 2016 or 2017—the EPA intends to redesignate areas based on data from the new monitoring network. The 2010 NO2 attainment date is January 2021 or 2022, about five years after the date of the nonattainment designations.
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2008 Lead Standard
In 2008, the EPA revised the primary standard for lead from 1.5 to 0.15 micrograms per cubic meter (μg/m3), measured in total suspended particulate matter. In 2010, the EPA published a final rule designating a portion of Collin County—surrounding the Exide Technologies facility for recycling lead-acid batteries in Frisco—as nonattainment for the 2008 lead standard. The effective date of the designation was Dec. 31, 2010. The EPA’s designation was identical to the revised recommendation the governor had submitted.
In 2011, the commission approved proposal of the Collin County attainment demonstration SIP revision for the 2008 lead standard. The SIP revision demonstrates attainment using an air-dispersion modeling analysis that includes existing control strategies, as well as the control strategies described in an agreed order with Exide. The agreed order was being processed concurrently with the SIP revision. A public hearing on this proposal was held in Frisco in July 2011.
In June 2012, the City of Frisco and Exide approved an agreement that would result in the closure of Exide’s plant. Under the terms of the agreement, about 180 acres of undeveloped land surrounding the plant will be sold to the Frisco Community Development Corporation and the Frisco Economic Development Commission Corporation. As stipulated by the agreement, Exide will retain ownership of the federal and state permitted plant site, and it will cease business operations no later than Jan. 6, 2014. Also the Exide permits will be voided by Dec. 31, 2015.
The commission approved the Collin County attainment-demonstration SIP revision and agreed order in August 2012. The attainment date is Dec. 31, 2015.
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The standard for particulate matter with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (PM2.5) was proposed in June 2012. The EPA’s proposal would reduce the annual primary PM2.5 standard to a range of 12 to 13 μg/m3. The EPA has been taking comments on alternative levels down to 11 μg/m3. The EPA has proposed to retain the current 24-hour primary PM2.5 standard of 35 μg/m3 and the current coarse-particulate (PM10) standard. Based on 2009–2011 air quality monitoring data, Harris County could be in nonattainment for primary PM2.5 if the design value is set at 11 or 12 μg/m3.
The EPA has proposed adding a separate 24-hour secondary standard for fine particles to protect visibility in urban areas. The proposal is for two levels: 28 and 30 deciviews. The EPA has also been taking comment on alternative levels down to 25 deciviews. Based on current air quality monitoring data, all of Texas would meet the secondary PM2.5 standard.
The El Paso area is classified as moderate nonattainment for the PM10 standard. In January 2012, the commission adopted a SIP revision to incorporate a revised memorandum of agreement between the TCEQ and the City of El Paso to reflect a concurrent rulemaking to amend the PM control measures.
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Evaluating Health Effects
The TCEQ relies on health- and welfare-protective values developed by its toxicologists to ensure that airborne concentrations of pollutants stay below levels of concern.
In 2006, the TCEQ finalized state-of-the-science guidelines for developing safe levels of chemicals in air, and in 2011 began the process of updating the guidelines to incorporate the latest scientific advancements. The updated guidelines have been subject to two rounds of public comment and an external scientific peer review by experts in assessing human-health risk. The document should be final in fiscal 2013.
The draft development support documents outlining the scientific procedures used to develop effects screening levels (ESLs) and air monitoring comparison values for individual chemicals are subject to a 90-day public comment period before they become final. In addition, the development support documents for some individual chemicals have undergone a technical review or independent external peer review by subject experts. Updated toxicity assessments were derived for 21 chemicals using this process in fiscal 2011, and proposed development support documents for three chemicals were opened for public comment in fiscal 2012.
The toxicity assessments conducted by the agency have received widespread attention. In 2009, the Ontario Ministry of the Environment deemed the TCEQ toxicity assessment for 1,3-butadiene as the most defensible assessment of health risk over the assessments made by the EPA and other states. In 2010, Texas became the only state to have its toxicity factors posted to the International Toxicity Assessments for Risk Assessment database.
The EPA has recommended review of Texas’ guideline levels to other states, and Texas has received compliments from the Agency for Toxic Substances and Disease Registry. Other countries now use Texas’ values, including Australia, Israel, Taiwan, China, Austria, Belgium, Mexico, and the Netherlands.
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Air Pollutant Watch List
Air toxics are pollutants known or suspected to cause cancer or other serious health effects. The TCEQ routinely reviews and conducts health-effects evaluations of ambient air monitoring data from across the state by comparing air-toxic concentrations to their respective air monitoring comparison values (AMCVs) or state standards. The TCEQ evaluates areas for inclusion on the air pollutant watch list (APWL) where monitored concentrations of air toxics are persistently measured above AMCVs or state standards.
The purpose of the APWL is to reduce air-toxic concentrations below levels of concern by focusing TCEQ resources and heightening awareness for interested parties in areas of concern.
The TCEQ also uses the APWL to identify companies with the potential of contributing to elevated ambient air-toxic concentrations and to then develop strategic actions to reduce emissions. An area’s inclusion on the APWL results in more stringent permitting, prioritized investigative efforts, and in some cases increased monitoring.
Ten areas of the state are on the APWL (see Air Pollutant Watch List). In fiscal 2011 and 2012, the TCEQ conducted boundary reevaluations, which resulted in the redefinition of two APWL areas and the removal of one. Monitoring data indicated significant improvement in several other APWL areas, including Galena Park, Texas City, and Port Arthur. The TCEQ has evaluated these areas to determine whether the improvements in air quality are expected to be maintained. In the last two years, no new areas were added to the APWL.
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Residential Exposure Studies
The TCEQ’s Toxicology Division has been involved in numerous studies investigating human exposure to airborne toxic chemicals and the potential of these exposures to cause adverse health effects. These studies lead to a greater understanding of air pollution and more knowledgeable decision making at the TCEQ. They are also a valuable way to address community concerns, since many of the study requests come from individuals.
Two significant scientific research projects sponsored by the TCEQ were completed in fiscal 2011 and 2012:
- The Frisco Blood Lead Testing study was a collaborative sampling event in which the Texas Department of State Health Services collected blood samples to determine lead concentrations in Frisco-area residents. This occurred after the EPA lowered the standard for lead, which resulted in a portion of Frisco being identified as a nonattainment zone. The study found that all adult and child blood lead levels were below levels of concern and consistent with those of national and state data.
- The Hillcrest Community Environmental Investigation was a collaborative investigation, with citizen input, to address local concerns in the Corpus Christi community about potential sources of VOCs within the community and other environmental impacts. The investigation found that all measured levels of VOCs, polycyclic aromatic hydrocarbons and total petroleum hydrocarbons in soil and groundwater were below a level of health concern.
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Oil and Gas: Barnett Shale and Eagle Ford Shale
As mentioned in Chapter 1, the TCEQ has conducted numerous air-monitoring projects in the Barnett Shale area, which encompasses 24 counties in the Dallas–Fort Worth area. From August 2009 to May 2012, the TCEQ surveyed 2,247 sites using the GasFind infrared (IR) camera; at 2,203 of these sites, employees also used a hand-held volatile-compound sampler.
Based on these instrument observations, 1,175 canister samples were collected. The agency’s Toxicology Division provided health effects evaluations for all of the canister samples and posted the information on the TCEQ’s Barnett Shale Web page. The site also features an interactive map to show the location and results of sampling conducted in the Barnett Shale area.
The TCEQ continues to conduct research projects aimed at improving oil and gas emissions inventory estimates and emissions factors, including a special emissions inventory in the Barnett Shale area. A summary of the Barnett Shale emissions inventory data, along with the other research to improve oil and gas emissions inventory estimates and emissions factors, is available at the TCEQ’s Point Source Emissions Inventory Web page. The TCEQ uses this data to update the periodic emissions inventory submitted to the EPA.
In late 2009, the TCEQ implemented a procedure to respond to all complaints received concerning oil and gas facilities in the Barnett Shale area. Average response time to Barnett Shale complaints has been less than five hours from the time the complaint is received until arrival of investigators on-site. From early 2009 to mid-2012, more than 1,175 complaints had been investigated.
New drilling activity is expected to continue, based on recent rig counts. However, drilling activity has slowed considerably in the “dry gas” areas of the Barnett Shale since October 2008.
The TCEQ will continue to analyze how the oil and gas sector affects overall air quality in the state, specifically the Dallas–Fort Worth area. Because of continued lower pricing for natural gas, drilling in the Barnett Shale has been shifting to the more oil-rich area of that shale or moving out of the area. Relocation areas are the oil-rich area of the Eagle Ford Shale play in South Texas and various Permian Basin shale zones in West Texas.
Based on lessons learned from the TCEQ’s work in the Barnett Shale area, a number of activities have been conducted or will take place in other areas of the state. This includes meeting with county judges, conducting workshops for local government agencies and industry, making presentations, conducting flyovers using the infrared camera, performing reconnaissance investigations, and developing guidance documents (see www.TexasOilandGasHelp.org) for oil and gas compliance issues.
The TCEQ belongs to the Railroad Commission of Texas’ Eagle Ford Task Force and is a member of the Energy Sector Impacts Task Force led by the Texas Department of Transportation.
The TCEQ is in the early development stages of determining what additional air monitoring might be needed in the Eagle Ford Shale area. The goal would be to gather baseline data on VOCs and NOx so the agency can evaluate, anticipate, and address the impact of oil and gas drilling and production activities on air quality throughout the Eagle Ford Shale play.
In addition, the data would be used to evaluate the potential transport of ozone precursors into the San Antonio area.
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CAMR, CAIR, and CSAPR
In 2005, the EPA issued new rules to significantly reduce emissions for new and existing electricity-generating units.
The Clean Air Mercury Rule (CAMR) was designed to permanently cap—for the first time—mercury emissions from new and existing coal-fired power plants. This rule promised to make the United States the first country to regulate mercury emissions from electricity-generating utilities. In 2006, the TCEQ approved rulemaking to implement the CAMR trading program for mercury.
The Clean Air Interstate Rule (CAIR) was intended to help nonattainment areas for ozone and fine particulate matter (PM2.5) control NOx and SO2 emissions from new and existing electricity-generating utilities. In 2006, the TCEQ approved rulemaking to implement the CAIR trading program for NOx and SO2 and incorporated the provisions of Texas House Bill 2481, passed in 2005, and Texas Senate Bill 1672, passed in 2007.
In 2008, the D.C. Circuit Court of Appeals vacated CAMR. In a decision later that year, the court vacated CAIR and remanded it back to the EPA until the EPA could replace it with another rule that addressed the flaws the court identified in CAIR. The commission adopted the CAIR SIP and rule revisions in 2010. Texas electric generating units were only included in CAIR for the PM2.5 requirements, not for both ozone and PM2.5, as was the case in more than 20 other states in the eastern half of the United States.
In 2011, the EPA finalized a rule, called the Cross-State Air Pollution Rule (CSAPR), requiring 28 eastern states to reduce emissions from electric generating units that contribute to ozone and PM2.5 pollution in other states. The rule is intended to help eastern states meet federal air quality obligations regarding interstate transport of air pollution for the 1997 ozone and PM2.5 and 2006 PM2.5 standards. The rule requires reductions in ozone season NOx emissions for states under the ozone requirements, and reductions in annual SO2 and NOx for states under the PM2.5 requirements. The proposed rule had included Texas only under the ozone requirements, but the final rule required Texas to be included in both the ozone and PM2.5 programs.
To ensure emissions reductions, the EPA is implementing federal implementation plans (FIPs) for each of the states covered by the rule, beginning with the 2012 control periods. States may choose to develop SIP revisions to replace the FIP, beginning with the 2013 control period. The rule fully replaces CAIR.
In September 2011, the Texas Attorney General filed with the EPA a petition for reconsideration and a stay of CSAPR, as it applies to Texas. The AG’s Office also filed with the D.C. circuit court a petition for review and a motion for partial stay of the final rule.
On Dec. 30, 2011, the circuit court granted the state’s request for a stay, which halted implementation of CSAPR, pending a full review of Texas’ petition. The court heard oral arguments in April 2012. CAIR remains in place.
In June 2012, the EPA published the final rule to implement revisions. The EPA has stated that it is prudent to proceed with these amendments so the rules will be in place in case the CSAPR stay is lifted. However, given the stay, these amendments did not impose any requirements on regulated electric generating units or states.
In August 2012, CSAPR was vacated in a 2-1 decision from the D.C. Circuit Court of Appeals. The court ordered CSAPR vacated and the EPA to continue to administer CAIR while it works on a replacement transport rule. The court reiterated its language from the CAIR decision that the court did not intend an indefinite continuation of CAIR, and an expectation that the EPA would act expeditiously.
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In another strategy to lower levels of NOx and VOC emissions from mobile sources, either the TCEQ or the EPA has requirements in place to use various fuel mixtures in different parts of the state, as follows:
- Reformulated gasoline is required year round in the eight-county Houston-Galveston-Brazoria area and the four-county Dallas–Fort Worth area (Collin, Dallas, Denton, and Tarrant counties).
- Low Reid vapor pressure gasoline is required between May and October in 95 counties in East and Central Texas, the Beaumont–Port Arthur area, and El Paso County.
- Oxygenated gasoline with a minimum oxygen content of 2.7 percent by weight is required from October through March in El Paso County (to lower carbon monoxide).
- Texas low-emission diesel fuel is required year-round in 110 counties in East and Central Texas.
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Major Incentive Programs
The TCEQ has three important programs aimed at reducing emissions: the Texas Emissions Reduction Plan, Drive a Clean Machine, and the Texas Clean School Bus Program.
Texas Emissions Reduction Plan
The Texas Emissions Reduction Plan (TERP) provides financial incentives to owners and operators of heavy-duty vehicles and equipment for projects that will lower NOx emissions. Because NOx is a leading contributor to the formation of ground-level ozone, lowering these emissions is key to achieving compliance with the Clean Air Act.
In providing grants for voluntary upgrades, the program has focused largely on the ozone nonattainment areas of Dallas–Fort Worth and Houston-Galveston-Brazoria. Funding has also been awarded to projects in the Tyler-Longview-Marshall, San Antonio, Beaumont–Port Arthur, Austin, Corpus Christi, El Paso, and Victoria areas.
From 2002 through August 2012, the program awarded more than $858 million for the upgrade or replacement of 14,685 heavy-duty vehicles, locomotives, marine vessels, and pieces of equipment. Over the life of these projects, 164,965 tons of NOx are projected to be reduced, which equals to 62.4 tons per day in 2013.
Two programs were established under the TERP program in 2009.
- The Texas Clean Fleet Program provides funding for replacement of diesel vehicles with alternative-fuel or hybrid vehicles. Eight projects were awarded grants in 2011 for a total of $29.4 million. The 2012 grant round closed in August. These projects included a range of alternative-fuel vehicles, including propane school buses, natural gas refuse vehicles, hybrid delivery vehicles and refuse vehicles, and electric vehicles.
- The New Technology Implementation Grant Program funds incremental costs of reducing emissions from facilities and other stationary sources in Texas. Two grants were awarded in 2011 for a total of almost $6.2 million. These projects involve systems to capture and store energy from wind-powered generation sources.
In 2011, the Legislature established additional programs to support alternative fuel vehicles in Texas.
- The Clean Transportation Triangle Program provides grants to support the development of a network of natural gas vehicle-fueling stations along the interstate highways connecting the Houston, Dallas, Fort Worth, and San Antonio areas. The program is allocated up to $2.3 million per fiscal year. Plans called for the first grants to be awarded in the fall of 2012, with an additional grant application period anticipated for December 2012.
- The Alternative Fueling Facilities Program provides grants for the construction, reconstruction, or acquisition of facilities to store, compress, or dispense alternative fuels in areas of Texas designated as nonattainment. This program is allocated $1.1 million per fiscal year. Plans called for the first grants to be awarded in early fiscal 2013.
- The Texas Natural Gas Vehicle Grants Program provides grants for the replacement or repower of heavy-duty or medium-duty diesel- or gasoline-powered vehicles with natural gas–powered vehicles and engines. Eligible vehicles must be operated in the counties intersected by the interstate highways designated under the Clean Transportation Triangle program and in counties designated as nonattainment. This program is allocated at least $9.1 million per fiscal year. The first application period opened in July 2012 and will extend until May 2013 or until all funds are awarded, whichever occurs earlier. These grants are awarded on a first-come-first-served basis.
TERP grants and activities during the last two years are detailed in a separate report, Texas Emissions Reduction Plan (TERP) Biennial Report to the Texas Legislature (SFR-079/12).
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Drive a Clean Machine
The Drive a Clean Machine program (see www.driveacleanmachine.org) was established in 2007 as part of the Low Income Repair Assistance, Retrofit, and Accelerated Vehicle Retirement Program (LIRAP) to remove older, polluting cars and trucks and replace them with newer, cleaner-running vehicles.
Backed by a $45 million annual appropriation from fiscal 2008 through 2011 and $5.6 million in fiscal 2012, the Drive a Clean Machine program is available in the areas of Houston-Galveston-Brazoria (Brazoria, Fort Bend, Galveston, Harris, and Montgomery counties), Dallas–Fort Worth (Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwall, and Tarrant counties), and Austin–Round Rock (Travis and Williamson counties). These counties conduct annual inspections of vehicle emissions.
From the program’s debut in December 2007 through May 2012, about $161 million was provided to qualifying vehicle owners in the Houston-Galveston-Brazoria, Dallas–Fort Worth, and Austin–Round Rock areas. This funding helped retire or replace a total of 49,729 vehicles and repair an additional 24,213 vehicles.
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Texas Clean School Bus Program
The Texas Clean School Bus Program provides grants for technologies that reduce diesel-exhaust emissions inside the cabin of a school bus. In addition to grant funding, the program offers educational materials to school districts on other ways to reduce emissions, such as idling reduction. By the end of August 2012, the Texas Clean School Bus Program had reimbursed approximately $18.9 million in grants to 181 public school districts or charter schools to retrofit 6,692 school buses in Texas.
Environmental Research and Development
The TCEQ supports cutting-edge scientific research into the causes of air pollution in Texas. The agency sponsored the Texas Air Quality Study (TexAQS) field campaign in 2000, and the TexAQS II from 2005 to 2006.
More recently, the TCEQ and the Air Quality Research Program supported a range of projects. Among the air quality topics studied by TCEQ-sponsored researchers in fiscal 2011 and 2012 are the following:
- estimates of industrial emissions (especially flares) and emissions from oil and gas production;
- analyses of the transport of pollutants from city to city within the state and from out of state into Texas;
- detailed analyses of ozone production chemistry to develop more accurate simulations of the chemical processes that create and destroy ozone in Houston and Dallas; and
- advanced meteorological simulations for high pollution episodes in Houston, Dallas, and eastern Texas.
The most important studies are summarized as follows:
- The destruction and removal efficiency of industrial flares. Flares burn waste gases from industrial processes. Standard operating practices are assumed to destroy at least 98 percent of the gases, but recent measurement studies using state-of-the-science technology by the TCEQ indicated that the waste gases may not always be burned with the assumed efficiency. Based on these preliminary investigations, the TCEQ, the University of Texas at Austin, and John Zink (a flare manufacturer) developed a project to test flares under different conditions to quantify the true emissions of vent gases from high-volume flares being operated at low volume (i.e., as process flares instead of emergency flares). One of the key factors found to affect flare destruction efficiency is the amount of steam assist or air assist supplied to the flare during combustion. Steam or air assist is used to reduce smoke from the flame and to mix the gases thoroughly with air. The TCEQ’s Comprehensive Flare Study found that it was easy to over-assist the flare, which could dramatically reduce its destruction efficiency and thus dramatically increase the emission of gases that were supposed to be destroyed. UT conducted computer simulations of ozone episodes to test the effects of lowered destruction efficiency and found that the increased emissions could increase ozone formation within flare plumes. Therefore, this study identified one of the major underreported sources of highly reactive VOC emissions in the Houston area. Fourteen papers, based on the research during the TCEQ Comprehensive Flare Study, have been published in Industrial and Engineering Chemistry Research.
- Direct measurements of emission fluxes. In 2009, the TCEQ sponsored researchers from the University of California–Los Angeles and other universities to conduct a field study in the Houston area to examine industrial emission sources with advanced remote sensing devices, including devices that could directly quantify the emissions of organic compounds. Analysis of these measurements in 2011 to 2012 found that formaldehyde, an important ozone precursor, can be emitted directly from the tip of the flame atop an industrial flare and from the unit that refreshes the catalyst used in fluidized catalytic cracking processes. These observations also determined that the destruction and removal efficiency and combustion efficiency of vent gases from the flares ranged from 70–99 percent. Since the assumed efficiencies are 98–99 percent, the emissions of vent gases are presumably greatly underestimated. These observations are corroborated by other on-site measurements, and by the results from the TCEQ Comprehensive Flare Study. Short-term SO2 flux measurements were found to agree with the reported emissions inventories, but short-term flux measurements of highly reactive VOCs were found to exceed the emissions inventory rates by up to two orders of magnitude.
- Sources of formaldehyde. The TCEQ funded scientists at the National Oceanic and Atmospheric Administration to investigate the relative importance of primary versus secondary sources of formaldehyde. Primary formaldehyde is directly emitted, whereas secondary formaldehyde is created from chemical reactions of highly reactive VOCs in the ambient air. The investigation was based on measurements collected during five field studies in 2000, 2006, and 2009. Secondary formation of formaldehyde was the dominant source. Small amounts of ambient formaldehyde were contributed by primary emissions from industrial facilities, secondary production from vehicle emissions, and primary emissions from vehicles. The primary emissions from both industry and vehicles are well-quantified by current emission inventories.
- DFW field study. The TCEQ and the Air Quality Research Program funded a field study in the Dallas–Fort Worth area in 2011. One of the purposes was to characterize emissions from the Barnett Shale oil and gas production region. The emission flux measurements performed during the study found that the largest sources of hydrocarbons at oil and gas locations near Fort Worth were gas-treatment facilities, combined with large compressor stations. Emissions were an order of magnitude lower from smaller compressor stations and well pads; however, flashing emissions on one occasion from a condensate tank were estimated at 140 kg/h methane and 10 kg/h ethane (and other species), suggesting further study for this potentially important intermittent source.
The latest findings should help in solving some of the persistent air quality issues faced by the Houston area. However, challenges remain for Dallas–Fort Worth and the southeastern portions of the state, as the revised air quality standards proposed by the EPA will be challenging to meet.
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