Browsing by Subject "Air quality management--Texas"
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Item Evaluating the air quality impacts of NO[subscript x] emission trading(2001-05) Nobel, Carolyn Eve; Liljestrand, Howard M. (Howard Michael); Allen, David T.Emission cap and trade programs are viewed as innovative and economically efficient mechanisms for reducing ozone precursor emissions and are beginning to see widespread use. However, few studies have examined the air quality impacts of trading emissions of nitrogen oxides (NOx). Emission trading is expected to change the spatial distribution of NOx emissions, and changes in the spatial distribution of NOx emissions can have a significant impact on ozone formation, since ozone formation is a strong, non-linear function of the local concentrations of volatile organic compounds (VOC) and NOx (i.e., a ton of NOx emitted at one time and location may not have the same ozone productivity as a ton of NOx emitted at a different time and location). The research described in this thesis develops and applies a computational framework to evaluate the vii potential air quality benefits of NOx emission trading compared to the air quality benefits of across the board NOx reductions for point sources in Eastern Texas. The comparison was performed by first determining, using the Comprehensive Air Quality Model with extensions (CAMx), the changes in ozone concentrations associated with NOx reductions at more than 50 individual facilities in Eastern Texas. These facility specific changes in ozone concentrations due to NOx reductions were then converted into a variety of indices that quantify ozone reduction benefits. Trading scenarios were then evaluated through Monte Carlo simulations. The results indicate that approximately 20% of all trading scenarios deviate by 25% or more from the ozone reduction benefits achieved by across the board reductions. This result was independent of the index used to evaluate ozone reduction benefit. This variability in the benefits associated with trading scenarios was comparable to the variability in benefits associated with changes in meteorological conditions over the days that were modeled. Additional Monte Carlo simulations indicated that the average benefit associated with NOx trading could be improved and the variability in benefit reduced by creating a trading program where a small group of high impact facilities are allowed to sell, but may not buy, NOx allowances.Item Inter-pollutant and reactivity-weighted air pollutant emission trading in Texas(2006) Wang, Linlin; Allen, David T.; McDonald-Buller, ElenaEmission trading is a market-based approach designed to improve the efficiency and economic viability of emission control programs. Although air pollutant emission trading typically has been confined to trades among single pollutants, inter-pollutant trading (IPT) allows for trades among emissions of different compounds that impact the same air quality end-point, such as ambient ozone concentrations. Designing IPT programs for emissions that lead to elevated ozone concentrations can be challenging because equivalent reductions of different categories of emissions may not always lead to equivalent reductions of ozone. Because emissions of different compounds impact air quality end-points related to ozone concentrations differently, weighting factors or trading ratios (e.g., tons of NOx emissions equivalent to a ton of volatile organic compound (VOC) emissions) must be developed to allow for inter-pollutant trading. This thesis examines two types of IPT of emissions that lead to ozone formation, that have been or may be implemented in Texas. Interpollutant trading of NOx and VOC (ozone precursor) emissions was examined using air quality conditions in Houston and Austin as case studies. Analysis of the Austin case study indicated that inter-pollutant trading ratios were, with few exceptions, constant. The IPT trading ratios were independent of the source category of the emissions and the exact manner in which ozone concentrations were evaluated. In contrast, IPT ratios in Houston were far more variable, due in part to strong spatial and temporal gradients in emissions of ozone precursors. These results suggest that IPT of VOC and NOx emissions will be far more straightforward to implement in Austin than in Houston. Interpollutant trading of various types of VOCs, especially a group of Highly Reactive VOCs (HRVOCs) was also examined, using Houston as a case study. This type of IPT was investigated because a program for trading of HRVOCs is due to be implemented in Houston in 2007. The focus of the analyses was on whether the trading program, as currently designed, could produce undesired localized high concentrations of ozone (“hot spots”). The analyses indicated that the implementation of the trading program would be unlikely to produce ozone hot spots.Item Restricting the use of reverse thrust as an emissions reduction strategy(2001) Rice, Colin Christopher; Walton, C. MichaelAs more metropolitan areas approach “non-attainment” status for ozone, air pollution at airports is becoming an increasingly important topic. Most proposed emissions reduction strategies target passenger automobiles and airport ground service equipment (GSE). At many airports, the future growth in oxides of nitrogen (NOx) emissions from aircraft is likely to offset any reduction achieved from GSE or passenger vehicles. In some metropolitan areas, airports may be responsible for as much as 10% of the regional NOx. As a result, other alternatives are needed for emissions reduction at airports. Reverse thrust is commonly used along with wheel brakes to slow aircraft during landing and occasionally to “power-back” aircraft away from a boarding gate. Currently, air pollution emissions generated during reverse thrust are not included in airport emissions inventories. Since the majority of aircraft NOx emissions occur offairport during climbout and approach, reverse thrust can be responsible for an additional 15% or more of the on-airport NOx. This can create significant air quality impacts in the vicinity of the busiest airports. This dissertation will attempt to quantify and model the air quality effect of NOx emissions produced during reverse thrust, using Dallas/Ft. Worth International Airport as a case study. A policy analysis will also be performed, identifying the legal and safety ramifications resulting from a restriction on thrust reverse usage.