Browsing by Subject "Emissions"

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Analysis of a novel thermoelectric generator in the built environment
(2011-08) Lozano, Adolfo; Webber, Michael E., 1971-; Schmidt, Philip S.
This study centered on a novel thermoelectric generator (TEG) integrated into the built environment. Designed by Watts Thermoelectric LLC, the TEG is essentially a novel assembly of thermoelectric modules whose required temperature differential is supplied by hot and cold streams of water flowing through the TEG. Per its recommended operating conditions, the TEG nominally generates 83 Watts of electrical power. In its default configuration in the built environment, solar-thermal energy serves as the TEG’s hot stream source and geothermal energy serves as its cold stream source. Two systems-level, thermodynamic analyses were performed, which were based on the TEG’s upcoming characterization testing, scheduled to occur later in 2011 in Detroit, Michigan. The first analysis considered the TEG coupled with a solar collector system. A numerical model of the coupled system was constructed in order to estimate the system’s annual energetic performance. It was determined numerically that over the course of a sample year, the solar collector system could deliver 39.73 megawatt-hours (MWh) of thermal energy to the TEG. The TEG converted that thermal energy into a net of 266.5 kilowatt-hours of electricity in that year. The second analysis focused on the TEG itself during operation with the purpose of providing a preliminary thermodynamic characterization of the TEG. Using experimental data, this analysis found the TEG’s operating efficiency to be 1.72%. Next, the annual emissions that would be avoided by implementing the zero-emission TEG were considered. The emission factor of Michigan’s electric grid, RFCM, was calculated to be 0.830 tons of carbon dioxide-equivalent (CO2e) per MWh, and with the TEG’s annual energy output, it was concluded that 0.221 tons CO2e would be avoided each year with the TEG. It is important to note that the TEG can be linearly scaled up by including additional modules. Thus, these benefits can be multiplied through the incorporation of more TEG units. Finally, the levelized cost of electricity (LCOE) of the TEG integrated into the built environment with the solar-thermal hot source and passive ground-based cold source was considered. The LCOE of the system was estimated to be approximately $8,404/MWh, which is substantially greater than current generation technologies. Note that this calculation was based on one particular configuration with a particular and narrow set of assumptions, and is not intended to be a general conclusion about TEG systems overall. It was concluded that while solar-thermal energy systems can sustain the TEG, they are capital-intensive and therefore not economically suitable for the TEG given the assumptions of this analysis. In the end, because of the large costs associated with the solar-thermal system, waste heat recovery is proposed as a potentially more cost-effective provider of the TEG’s hot stream source.
Comparison of emissions and energy consumptions between a conventional diesel school bus and a plug-in hybrid school bus, emphasizes on recharging
(2010-05) Florette, Claire Anne; Matthews, Ronald D.
Quantifying the emissions due to the charging of the batteries of the plug-in hybrid electricity school bus operated by the Austin Independent School District (AISD) is the focus of this work. This plug-in hybrid school bus is one of only nineteen in the country, and was manufactured by IC Corporation. This hybrid school bus reduces fuel consumption and CO₂, NOx and PM emissions in comparison with conventional diesel buses. This reduction is good for the health of the children who take the school bus everyday as they are part of the population the most at risk because their lungs are still developing. In order to evaluate CO₂, NOx and PM emissions, measurements of the charging of the batteries versus time were taken for the two charging periods each day during the months of April and May 2009. These measurements were repeated in October 2009 when the route was changed for the new school year: 2009-2010. An analysis of the Austin electricity mix that provides electricity to the bus center was done hour by hour to evaluate the emissions, calculated on a g/mile basis. Measurements of the vehicle speed versus time and altitude were taken during February 2010 in order to explain some of the differences observed between the two routes. Different parameters were studied to analyze the results. The first parameter studied was the impact of the season on the emissions. The second parameter studied was the impact of the route and its characteristics (road length, traffic, grade, etc.). The last parameter studied was the difference between two methods used to evaluate the emissions using the electricity mix data. These two methods are different but each of them brings something to the analysis of the results.
Comprehensive assessment of fine particulate matter emissions inventories and development of improved allocation profiles
(2006-12) Simon, Heather Aliza, 1979-; Allen, David T.
Emission inventories of fine particulate matter (PM) were compared to estimates of emissions based on observational data emerging from the EPA Particulate Matter Supersites and other field programs. Six source categories for fine PM emissions were considered: on-road mobile sources, non-road mobile sources, cooking, biomass combustion, fugitive dust and stationary sources. Regional emission inventories of PM in the exhaust from on-road and non-road sources were generally consistent with ambient observations. In contrast, emission inventories of road dust were an order of magnitude larger than ambient observations, and estimated brake wear and tire dust emissions were half as large as ambient observations in urban areas. Although a comprehensive nationwide emission inventory of fine PM from cooking sources and biomass burning is not yet available, observational data in urban areas suggest that cooking sources account for roughly 5-20% of total primary emissions (excluding dust) and the magnitude of biomass burning emissions are highly dependent on the region. Finally, relatively few observational data were available to assess the accuracy of emission estimates for stationary sources. Overall, the uncertainties in primary emissions for fine PM are substantial. Because of these uncertainties, the design of fine PM control strategies should be based on inventories that have been refined by a combination of bottom-up and top-down methods, as demonstrated in this work. This approach was used in the development of a primary PM emissions inventory for air quality modeling. This emissions inventory improved upon previous inventories by updating some source strengths, temporal allocations, and chemical speciation profiles; in addition, size resolution information was incorporated into the inventory.
Dynamic traffic assignment-based modeling paradigms for sustainable transportation planning and urban development
(2014-05) Shah, Rohan Jayesh; Boyles, Stephen David, 1982-
Transportation planning and urban development in the United States have synchronously emerged over the past few decades to encompass goals associated with sustainability, improved connectivity, complete streets and mitigation of environmental impacts. These goals have evolved in tandem with some of the relatively more traditional objectives of supply-side improvements such as infrastructure and capacity expansion. Apart from the numerous federal regulations in the US transportation sector that reassert sustainability motivations, metropolitan planning organizations and civic societies face similar concerns in their decision-making and policy implementation. However, overall transportation planning to incorporate these wide-ranging objectives requires characterization of large-scale transportation systems and traffic flow through them, which is dynamic in nature, computationally intense and a non-trivial problem. Thus, these contemporary questions lie at the interface of transportation planning, urban development and sustainability planning. They have the potential of being effectively addressed through state-of-the-art transportation modeling tools, which is the main motivation and philosophy of this thesis. From the research standpoint, some of these issues have been addressed in the past typically from the urban design, built-environment, public health and vehicle technology and mostly qualitative perspectives, but not as much from the traffic engineering and transportation systems perspective---a gap in literature which the thesis aims to fill. Specifically, it makes use of simulation-based dynamic traffic assignment (DTA) to develop modeling paradigms and integrated frameworks to seamlessly incorporate these in the transportation planning process. In addition to just incorporating them in the planning process, DTA-based paradigms are able to accommodate numerous spatial and temporal dynamics associated with system traffic, which more traditional static models are not able to. Besides, these features are critical in the context of the planning questions of this study. Specifically, systemic impacts of suburban and urban street pattern developments typically found in US cities in past decades of the 20th century have been investigated. While street connectivity and design evolution is mostly regulated through local codes and subdivision ordinances, its impacts on traffic and system congestion requires modeling and quantitative evidence which are explored in this thesis. On the environmental impact mitigation side, regional emission inventories from the traffic sector have also been quantified. Novel modeling approaches for the street connectivity-accessibility problem are proposed. An integrated framework using the Environmental Protection Agency's regulatory MOVES model has been developed, combining it with mesoscopic-level DTA simulation. Model demonstrations and applications on real and large-sized study areas reveal that different levels of connectivity and accessibility have substantial impacts on system-wide traffic---as connectivity levels reduce, traffic and congestion metrics show a gradually increasing trend. As regards emissions, incorporation of dynamic features leads to more realistic emissions inventory generation compared to default databases and modules, owing to consideration of the added dynamic features of system traffic and region-specific conditions. Inter-dependencies among these sustainability planning questions through the common linkage of traffic dynamics are also highlighted. In summary, the modeling frameworks, analyses and findings in the thesis contribute to some ongoing debates in planning studies and practice regarding ideal urban designs, provisions of sustainability and complete streets. Furthermore, the integrated emissions modeling framework, in addition to sustainability-related contributions, provides important tools to aid MPOs and state agencies in preparation of state implementation plans for demonstrating conformity to national ambient air-quality standards in their regions and counties. This is a critical condition for them to receive federal transportation funding.
Effect of relative humidity on chemical off-gassing in residences
(2011-05) Nnadili, Miriam Nchekwubechukwn; Corsi, Richard L.; Kinney, Kerry A.
Relative humidity (RH) is an important parameter associated with occupant comfort in buildings. However, the effects of RH on indoor source off-gassing and interactions between air pollutants and indoor materials are poorly understood. For this study, air samples were collected in residential buildings to characterize “background” concentrations of volatile organic compounds (VOCs) in air. The interior space was then humidified for several hours prior to collection of another air sample to characterize the effects of increased RH on VOC concentrations. Samples were analyzed by GC/FID with abundance “binning” by elution time. Some samples were also analyzed using GC/MS to identify specific VOCs. Results indicate that increasing RH is associated with increases in VOC concentrations in residential indoor air. Many of the chemicals that show enhanced off-gassing are associated with architectural coating, moth repellents, and cleaning agents. The results of this study are novel and may have implications with respect to health effects associated with damp buildings and increased respiratory effects of children during sleep in bedrooms with elevated RH.
Energy and environmental contexts of cities, transportation systems, and emerging vehicle technologies : how plug-in electric vehicles and urban design influence energy consumption and emissions
(2013-12) Nichols, Brice G.; Kockelman, Kara
This thesis is divided into two parts. The first evaluates the role of the built environment in life-cycle energy consumption, by comparing different neighborhood and city styles. Through a holistic modeling and accounting framework, this work identifies the largest energy-consuming sectors, among residential and commercial buildings, personal vehicles and transit trips, and supporting infrastructure (roads, sidewalks, parking lots, water pipes, street lighting). Life-cycle energy calculations include operational energy use (e.g., gasoline for vehicles, electricity and natural gas for buildings) and embodied energy used to produce materials and construct buildings and infrastructure. Case study neighborhoods in Austin, Texas, and larger-scale regional models suggest that building energy demands comprise around 50% of life-cycle energy demands, while transportation demands (from driving and infrastructure alike) contribute around 40%, across all cases. However, results also suggest that population density and average residential unit size play a major role in defining per-capita energy consumption. Operational demands made up about 90% of life-cycle energy demands, suggesting that v most urban energy savings can be obtained from reduced personal vehicle trips and more efficient vehicles and buildings. Case study comparisons suggest that neighborhoods and regions with greater density and higher share of multi-family housing units tend to reduce operational (and thus life-cycle) energy demands with less travel demand and decreased home and work energy use, per capita. The second part of this modeled plug-in electric vehicle (PEV) emissions impacts in Texas, by considering four possible vehicle adoption scenarios (where PEVs make up 1, 5, 10, and 25% of total passenger vehicles). The analysis anticipates PEV electricity demand and emissions rates, based on current Texas power grid data. Results indicate that PEV emissions depend significantly on which specific power plants are used to power the vehicles, but that PEVs' average per-mile emissions rates for NO[subscript x], PM, and CO₂ are all likely to be lower than today's average passenger car, when today's average mix is used. Power produced from 100% coal plants could produce 14 times as much NO[subscript x], 3,200 times as much SO₂, nearly 10 times as much CO₂ and CO₂eq, 2.5 times as much PM₁₀, and VOCs, and nearly 80 times the NO₂ compared to a grid with 100% natural gas plants.
Environmental impacts of onshoring lithium and lithium-ion battery production
(2022-07-06) Harner, Zakariah Quinton; Childress, Tristan M.; Chuchla, Richard J. (Richard Julian)
Life cycle assessment was conducted to quantify prospective environmental impacts of a transition to onshore supply of lithium battery materials and onshore production of lithium-ion battery cells in the United States. Life cycle assessments were compiled for current lithium raw materials and lithium-ion battery cell supply chain pathways, dominated by a Chinese midstream monopoly on refinement and lithium-ion battery component production, and compared with prospective American-based supply chain pathways. Differences in global warming potential (GWP) (kg of carbon dioxide equivalents), water consumption, and land use of differing supply chain pathways were the primary environmental impacts under comparison and analysis. Both “Traditional” (current) and prospective American supply chain pathways were developed for lithium carbonates, lithium hydroxides, nickel-cobalt-aluminum (NCA) based battery cells, and lithium-iron-phosphate (LFP) based battery cells. Each product was modeled from cradle-to-gate, meaning from raw material extraction through transportation to point of sale. Transition from Traditional lithium carbonate supply chain pathways to American-based pathways resulted in a 66% reduction in the GWP of transportation of refined materials, thanks largely to elimination of the need for cross-Pacific freight shipping. Transition from Traditional supply chain pathways to American-based lithium hydroxide pathways resulted in a 49% reduction in the GWP of electricity usage during refinement when transitioning from Chinese and Japanese electricity grids to United States counterparts, due largely to lower amounts of coal-based electricity generation within the United States electricity grid. During the simulated production of 100 kWh of NCA and LFP-based lithium-ion battery cells, NCA cells were found to produce 11% less GWP than LFP equivalents on average. Utilizing lithium raw materials sourced from the Americas, American based production of NCA and LFP cells was found to produce an average of 13% less GWP than Traditional supply chain pathway counterparts
Estimating emissions impacts to the bulk power system of increased electric vehicle and renewable energy usage
(2013-12) Meehan, Colin Markey; Webber, Michael E., 1971-; Baldick, Ross
The research presented in this thesis examines the use of electric vehicles and renewable energy to reduce emissions of CO₂, SO₂ and NO[subscript x], and within the state of Texas. The analysis examines the impact of increased renewable energy output and electric vehicle charging on the emissions of fossil fuel electric generators used to serve the bulk power system within Texas. The analysis then compares those impacts to alternative scenarios in which fossil fuel generation replaces some renewable energy generation, and Internal Combustion Engine (ICE) vehicles of varying efficiency are used instead of electric vehicles. This research uses temporally-resolved regression analysis combined with a unit commitment and dispatch model that incorporates several different scenarios for EV charging and fuel mixes to evaluate emissions outcomes based on a variety of conditions. Hourly historical generation and emission data for each fossil fuel generator, combined with hourly output data for non-fossil fuel units aggregated by fuel type (i.e. nuclear, wind, hydro-electric) within the Electric Reliability Council of Texas (ERCOT) footprint is regressed to assess the impact of wind generation output on fossil-fuel generation emissions. The regression analysis is used to assess potential increases in emissions resulting from the ramping of fossil-fuel Electric Generation Units (EGUs) to compensate for variability in wind generation output due to changing weather conditions. The unit commitment dispatch model is used to evaluate the impact of changes in customer demand due to increased usage and charging of electric vehicles on the ERCOT system and any resulting increase in emissions from generation used to meet this new demand. The model uses detailed cost, performance and emissions data for EGUs in the ERCOT footprint to simulate the impact of a variety of charging scenarios and fuel mixes on EGU dispatch patterns and any resulting change in system-wide emissions. The results of this model are combined with the results of the regression analysis to present a more complete analysis of the combined impacts of increase EV and renewable energy usage on the emissions of CO₂, SO₂ and NO[subscript x] within the ERCOT footprint. Based on these analyses the increases in renewable energy generation demonstrate clear benefits in terms of emission reductions when the impacts of increased emissions due to more frequent ramping of fossil-fuel units are taken into account. This analysis also finds that EV charging generally has emissions benefits across a range of charging patterns and bulk power system fuel mixes, although in certain circumstances EV charging might result in higher emissions than the use of ICE vehicles. This research finds when future ICE vehicles with reduced emissions are taken into account, approximately half of the modeled scenarios show net emissions benefits from EV charging, while half show net emissions costs when emissions impacts across pollutants are taken into account.
Impact of variable emissions on ozone formation in the Houston area
(2009-12) Pavlovic, Radovan Thomas, 1971-; Allen, David T.; McDonald-Buller, Elena
Ground level ozone is one of the most ubiquitous air pollutants in urban areas, and is generated by photochemical reactions of oxides of nitrogen (NOx) and volatile organic compounds (VOCs). The effectiveness of emission reduction strategies for ozone precursors is typically evaluated using gridded, photochemical air quality models. One of the underlying assumptions in these models is that industrial emissions are nearly constant, since many industrial facilities operate continuously at a constant rate of output. However, recent studies performed in the Houston-Galveston-Brazoria area indicate that some industrial emission sources exhibit high temporal emission variability that can lead to very rapid ozone formation, especially when emissions are composed of highly reactive volatile organic compounds. This work evaluates the impact of variable emissions from industrial sources on ground-level ozone formation in Houston area, utilizing a unique hourly emission inventory, known as the 2006 Special Inventory, created as a part of the second Texas Air Quality Study. Comparison of the hourly emissions inventory data with ambient measurements indicated that the impact of the variability of industrial source emissions on ozone can be significant. Photochemical modeling predictions showed that the variability in industrial emissions can lead to differences in local ozone concentrations of as much as 27 ppb at individual ozone monitor locations. The hourly emissions inventory revealed that industrial source emissions are highly variable in nature with diverse temporal patterns and stochastic behavior. Petrochemical and chemical manufacturing flares, which represent the majority of emissions in the 2006 Special Inventory, were grouped into categories based on industrial process, chemical composition of the flared gas, and the temporal patterns of their emissions. Stochastic models were developed for each categorization of flare emissions with the goal of simulating the characterized temporal emission variability. The stochastic models provide representative temporal profiles for flares in the petrochemical manufacturing and chemical manufacturing sectors, and as such serve as more comprehensive input for photochemical air quality modeling.
Indoor air quality in retail stores
(2011-05) Rhodes, Joshua Daniel; Siegel, Jeffrey A.; Xu, Ying
Retail stores are understudied given the energy, occupant health, and potential sales impacts associated with poor indoor air quality (IAQ). There is also evidence of elevated pollutants in retail environments. This thesis is an exploration of the indoor air quality of retail stores. The first section of this thesis is a literature review on field investigations of the indoor air quality in retail buildings. Sixteen investigations report different measurements in 17 specific types of retail environments. Measurements vary depending on the specific investigation, but include VOCs, SVOCs, particles, microbiological species, and radon. When reported, indoor to outdoor ratios of almost all pollutants are greater than unity, suggesting the importance of indoor sources in retail environments. The second section of this thesis is an analysis of the whole store net emission factor for different retail environments. From the types of pollutants found in the retail store investigations, VOCs were the only pollutant group studied frequently enough to merit this analysis. The final section is an analysis of the potential for pollutant remediation strategies. Two methods, increasing air change rate and air cleaning, are considered with an analysis of the energy penalties associated with each.
Investigation of acoustically forced non-premixed jet flames in crossflow
(2011-05) Marr, Kevin Chek-Shing; Clemens, Noel T.; Ezekoye, Ofodike A.; Hall, Matthew J.; Raman, Venkat; Varghese, Philip L.
The work presented here discusses the effects of strong acoustic forcing on jet flames in crossflow (JFICF) and the physical mechanisms behind theses effects. For forced non-premixed JFICF, the jet fuel flow is modulated using an acoustic speaker system, which results in a drastic decrease in flame length and soot luminosity. Forced JFICF are characterized by periodic ejections of high-momentum, deeply penetrating vortical structures, which draws air into the jet nozzle and enhances mixing in the nearfield region of the jet. Mixture fraction images of the non-reacting forced jet in crossflow are obtained from acetone planar laser-induced fluorescence and show that the ejected jet fluid is effectively partially premixed. Flame luminosity images and exhaust gas measurements show that forced non-premixed JFICF exhibit similar characteristics to unforced partially-premixed JFICF. Both strong forcing and air dilution result in net reductions in NOx, but increases in CO and unburned hydrocarbons. NOx scaling analysis is presented for both forced non-premixed and unforced partially-premixed flames. Using flame volume arguments, EINOx scales with amplitude ratio for forced non- premixed flames, but does not scale with air dilution for unforced partially-premixed flames. The difference in scaling behavior is attributed to differences in flame structure. The effect of forcing on the flowfield dynamics of non-premixed JFICF is investigated using high-speed stereoscopic particle image velocimetry and luminosity imaging. The frequency spectra of the windward and lee-side flame base motions obtained from luminosity movies of the forced JFICF show a peak at the forcing frequency in the lee-side spectrum, but not on the windward-side spectrum. The lee-side flame base responds to the forcing frequency because the lee-side flame base stabilizes closer to the jet exit. The windward-side flame base does not respond to the forcing frequency because the integrated effect of the incident crossflow and vortical ejections leads to extinction of the flame base. From the PIV measurements, flowfield statistics are conditioned at the flame base. The local gas velocity at the flame base did not collapse for forced and unforced JFICF and was found to exceed 3SL. The flame propagation velocity was determined from the motion of the flame base, which is inferred from regions of evaporated seed particles in the time-resolved PIV images. The flame propagation velocity collapses for forced and unforced JFICF, which implies that the flame base is an edge flame; however, the most probable propagation velocity, approximately 2-3SL, is larger than propagation velocity predicted by edge flame theories. A possible explanation is that the flame propagation is enhanced by turbulent intensities and flame curvature.
Measuring sustainability in an Austin-based start-up
(2023-05-11) Wedel, Steven J.; Amato, Richard A.; Butler, John C. (Clinical associate professor); Jiao, Junfeng
New technology is key to creating a sustainable future, and start-ups are crucial to creating new technology. Here we examine an Austin based payload transportation start- up, Tubular Network, to determine if it produces less emissions than other payload delivery systems. Delivery drones have been proven in theory as sustainable alternatives to industry standards for first- and last-mile delivery, and Tubular Network is expected to have the same results. Data from independently conducted experiments was used to compare which delivery system, delivery drones or Tubular Network shuttles, is more sustainable, and a better option for the future. Results indicate that while both options are more sustainable than current industry standards, the drones performed slightly more efficiently than the Tubular Network shuttles and had advantages in movement flexibility leading to delivery drones being a better last-mile solution. However, the delivery drones could only carry a fraction of the weight that the Tubular Network shuttle can carry and thus are not as good an option for scaled growth and varying parcel weight, making Tubular Network a better option for first-mile transportation. Both drones and Tubular Network are deemed better delivery solutions option and are expected to decrease emissions.
The metallic elephant in the room : short range flights, high-speed rail, and the environment
(2011-05) Johnson, Donovan Theodore; Zhang, Ming, 1963 Apr. 22-; Loftus-Otway, Lisa D.
It is of nearly universal acceptance that one of the pillars of American economic success over the course of the 20th century was the rapid development of infrastructure. Transportation infrastructure has been of particular importance in the rise of the United States and attributed to the spread of an increasingly mobile culture. Americans undoubtedly enjoy traveling, and the ability to do so with relative ease is of immense value to many. In Texas, the majority of economic activity takes place within what is colloquially known as the “Texas Triangle”, an area bounded by the large metropolitan areas of Houston, Dallas-Ft. Worth, and San Antonio. Intensive population growth in Texas, anchored by the triangle, has led to increasing road congestion on many routes, especially along Interstates 35 and 10. This congestion, and the wasted time and money that comes with it, are of increasing concern to the future economic vitality of the state. The Texas Triangle is also served by extensive aviation links via major airports in the major metropolitan areas, as well as smaller airports in other parts of the region. These flights, operated by American Airlines, Continental Airlines, and Southwest Airlines are frequent, but emit large amounts of greenhouse gases that contribute to ground level pollution and possibly climate change. High-speed rail has been considered by many to be a superior environmental option for intercity routes with lengths inherent to the Texas Triangle. However, given the fact that Texas is the top emitter of carbon dioxide in the U.S. and relies on an energy mix that is primarily fossil fuel powered; would a potential high-speed rail in Texas outperform the current air system environmentally, given similar passenger miles traveled? This report examines the environmental emissions of high-speed rail and compares it to the environmental emissions of our current aviation system, taking into account a life-cycle perspective.
Minimizing vehicle emissions through transportation road network design incorporating demand uncertainty
(2010-05) Ferguson, Erin Molly; Waller, S. Travis; Machemehl, Randy B.
Traditionally, transportation road networks have been designed for minimal congestion. Unfortunately, such approaches do not guarantee minimal vehicle emissions. Given the negative impacts of vehicle pollutants as well as tighter national air quality standards, it is critical for regions to be able to identify capacity modifications to road networks such that vehicle emissions are minimal. This ability combined with land use changes and opportunities for non-auto travel are paramount in helping regions improve air quality. However, network design research has yet to directly address this topic. To fill this apparent gap in network design research, an emissions network design problem and solution method are proposed in this thesis. Three air pollutants are considered: hydrocarbons, nitrogen oxides, and carbon monoxide. The proposed model is applied to two road networks: Sioux Falls, ND and Anaheim, CA. The model is a bi-level optimization problem solved using a genetic algorithm and incorporates the influence of demand uncertainty. Findings indicate designing for minimal congestion tends to increase emissions of criteria air pollutants. However, not adding capacity to a road network also increases emissions of pollutants. Therefore, an optimization problem and solution method, such as the model presented here, is useful for identifying capacity additions that reduce vehicle emissions. It is also useful for understanding the tradeoffs between designing a network for minimal congestion versus minimal vehicle emissions.
Modernizing commercial rate design to align the private benefits of distributed energy storage with system and social welfare
(2020-05-05) Haley, Matthew Thomas; Beach, Fred Charles, 1959-
The adoption of Distributed Energy Resources (DER) – such as battery energy storage and rooftop solar - are revolutionizing the topology and operation of the electric grid. When paired with smart control and communication technologies, DERs transform traditional electricity customers into providers of (potentially zero-emission) energy and grid services. Electricity rates - the policies that govern the retail use cases for these technologies – however, lag the technological advances of the modern grid. Retail rates designed in a less technically complex era – such as demand charges – do not send price signals that align customer behavior with either grid or social benefits. In this research we investigate the retail rate incentives for the commercial segment of energy customers in Texas. Texas provides an interesting test case for commercial investment in energy storage for two reasons: first, low energy prices driven by cost declines in renewables and natural gas has caused commercial and industrial energy use in Texas to grow compared to other states, second, retail restructuring in Texas has diversified the types of rates a commercial customer can choose from. In this analysis, we formulate a linear program to optimize commercial DER behavior over a variety of increasingly time-responsive commercial rate designs. We then utilize four years of historical data from ERCOT and 15 commercial building load profiles to investigate how each retail rate design aligns with system and social objectives including emission reductions. I find that time invariant rates – such as demand charges - often provide perverse incentives to some classes of commercial DER applications that increase system-wide costs and can increase emissions. In comparison I find that exposing commercial DER customers to dynamic prices that better reflects real-time system needs decreases overall costs and decreases emissions.
Ozone transport to and removal in porous materials with applications for low-energy indoor air purification
(2013-05) Gall, Elliott Tyler; Corsi, Richard L.; Siegel, Jeffrey A.
In the U.S. and other developed countries, humans spend the vast majority of their time within the built environment. As a result, a substantial portion of our collective exposure to airborne pollutants, even those of outdoor origin, occurs in indoor environments. In addition, building construction materials and operational practices are changing as we endeavor to reduce the energy burden of the built environment. These changes result in barriers and opportunities in mitigating exposure to indoor pollutants and the accompanying implications for human health. This dissertation advances knowledge regarding low-energy control of indoor ozone. Ozone is often considered a pollutant of outdoor concern. However, ozone in indoor environments presents important challenges regarding exposure, intake, and chemistry in the built environment. The investigations in this dissertation extend the state understanding of indoor transport and transformation of ozone, and the potential for using material-surface interactions in buildings to suppress concentrations of indoor ozone. The first objective relates to the determination of magnitudes of ozone removal and product emissions at room or building scales. This objective provides new data on reactive uptake and product generation in large-scale environments, develops Monte Carlo models describing indoor ozone removal by materials in homes, and compares active and passive methods of indoor ozone removal. The second objective addresses the need to develop improved air cleaning materials through experiments and modeling that address material-ozone reactions in porous materials. This objective advances the state of modeling heterogeneous reactive uptake of ozone by characterizing material physical properties and transport phenomena, determining their impact on ozone removal, and using these data to develop a more mechanistic model of material-ozone reactions. Ultimately, these investigations advance the engineering concepts that support the development of passive indoor pollutant controls, an important tool for reducing concentrations of indoor pollutants while supporting low-energy building initiatives. The combination of experimental characterization of ozone deposition velocities and product emission rates, whole-building Monte Carlo modeling, and mechanistic material/pollutant models provide important new data and approaches that expand the state of knowledge of the fate and transport of reactive pollutants in indoor environments.
Predicting the ownership, use, and environmental impacts of new vehicle technologies with a focus on the relationship between travel behavior and the built environment
(2018-12) Nodjomian, Adam Taylan; Kockelman, Kara
The field of transportation is on the cusp of major change. Innovations in how vehicles operate and are powered have the potential to elicit changes not seen since the introduction of the interstate highway system more than half a century ago. Predicting the impacts of new vehicle technologies has interested researchers and practitioners across disciplines and continents. This thesis makes a handful of such predictions. It is divided into three parts. In the first part, the results of two large-scale preference surveys and data from the U.S. Environmental Protection Agency’s (EPA) Smart Location Database (EPA, 2014) are used to estimate how land use characteristics impact Americans’ perceptions of, interest in, and willingness to pay for new vehicle technologies, while controlling for demographic attributes. The surveys were conducted by Quarles and Kockelman (2018) and Gurumurthy and Kockelman (2018) in 2017 and together represented over 4,000 U.S. households. Statistical models like the ordered probit and multinomial logit are used to estimate the impacts of demographics and land use characteristics on vehicle-related behavior. Various land use variables arise as significant depending on the question being asked of the respondents. For example, poor job accessibility via automobile is associated with higher levels of interest in automated vehicles (AVs), higher anticipated use of AV technology, a willingness-to-pay (WTP) for self-driving capability, and a greater reliance on AVs for some long-distance travel. No land use variable arises as significantly more predictive than the others at this national-level scale of analysis. The results emphasize the fact that land use policy must be considered at the local level, and that there is no “one size fits all” solution for managing future transportation behavior with land use action. The second part of this thesis evaluates the connection between land use and current travel behavior. Census tract-level measures of population and employment density (provided once again by the EPA’s Smart Location Database [EPA, 2014]) are evaluated across the nation to investigate the connection between the development conditions one experiences and his or her travel behavior. Travel data comes from the 2009 National Household Travel Survey (NHTS). The results highlight a stronger connection between population density and vehicle-miles traveled (VMT) and vehicle ownership, than with employment density. For both VMT and vehicle ownership, an improvement of only two to one can be expected by changing population density conditions in a census tract. In other words increasing population from the lowest density conditions to the highest results in a decline of VMT per capita per day from 20 miles to 10 miles. Similarly, vehicle ownership per capita generally ranges from 0.4 to 0.8. Notably, these improvements are not realized until the highest decile of population density (18 people per acre), thus indicating that simply building homes in rural or low-density suburban regions will likely have a negligible impact on transportation demand. Employment density was found to be less indicative of travel behavior. The third and final piece of the thesis predicts how an evolving light-duty vehicle (LDV) fleet will impact the amount of energy consumed by Americans and the emissions they create. Here, the results of a fleet evolution simulation, developed by Quarles et al. (2019), are used to project what a vehicle fleet with more electric (and fewer gasoline-powered) vehicles will mean for energy consumption and emissions on a per capita basis. Projections are based on historic fuel efficiency data and emission production rates from the Bureau of Transportation Statistics (BTS) and EPA (BTS, 2018b; BTS, 2018c; EPA, 2018a). Conclusions from these findings highlight the need for more efficient vehicles, better emissions control technologies on existing vehicle models and power plants, and a decreased reliance on highly-polluting energy sources for power generation. Policies aimed at achieving these objectives will help ensure that Americans’ future vehicle behavior and ownership will not create an undue burden on themselves or the environment in which they live. Although the analyses discussed in this thesis cover diverse topics such as human behavior, urban planning, and air quality, they establish the need for a proactive approach to cutting-edge vehicle technologies. If left to develop without any oversight or action, transportation network congestion will worsen, development will continue to sprawl, and the environment and public health will suffer. Policies aimed at limiting “empty” driving with AVs, increasing population density, and curbing vehicle and power plant emissions can help ensure the benefits of vehicle technology innovation are not realized at the expense of other considerations.
Rapid characterization of emission parameters of semi-volatile organic compounds for building materials and consumer products
(2022-08-30) Li, Hongwan; Xu, Ying (Assistant professor); Novoselac, Atila; Kinney, Kerry A; Apte, Joshua; Corsi, Richard
Semi-volatile organic compounds (SVOCs), such as phthalates, organophosphates, and polybrominated diphenyl ethers (PBDEs), are emerging pollutants associated with serious health concerns. SVOCs are extensively used as plasticizers and flame retardants in building materials and consumer products. Because SVOCs are not chemically bound to polymers, they are slowly emitted from source materials to indoor environments, where people spend most of their time. However, due to our poor understanding of their sources, fate, and transport in indoor environments, effective strategies to reduce exposures remain unclear. The goal of this dissertation is to characterize SVOC emissions rapidly and investigate their fate and transport in indoor environments. The specific objectives are to 1) develop a novel rapid micro-emission-cell method to characterize SVOC emissions from building materials and consumer products; 2) develop a sensitive and accurate needle-trap-device (NTD) method for sampling and analysis of SVOCs in air; 3) investigate SVOC levels in indoor air, settled dust, and heating, ventilation, and air conditioning (HVAC) filter dust in U.S. high schools. Emissions of phthalates, organophosphates, and PBDEs from a wide range of source materials (e.g., vinyl flooring, insulation boards, crib mattress covers, and changing pad foams) were characterized in the micro emission cell rapidly. The steady state SVOC concentrations were reached within minutes or hours, which were significantly reduced from the time of previous chamber studies (weeks or months). The developed NTD method was evaluated in both laboratory and field studies. The results were in good agreement with data obtained using conventional air sampling methods, but with significantly improvements on sensitivity, repeatability, reproducibility, and reliability. Sampling volume using the NTD method was reduced by a factor of four compared to conventional air sampling methods. A number of SVOCs were detected in U.S. high school indoor environments, including certain banned or severely restricted compounds. Significant impacts of seasonal variations and building characteristics were found for certain SVOC levels in different environmental media. This dissertation, which connects emission characterizations, measurement developments, and field studies in real indoor environments, will be valuable to identify major indoor SVOC sources, monitor indoor SVOC pollutions accurately, understand the fate and transport of SVOCs in indoor environments, and develop strategies to reduce SVOC exposures.
Selecting green strategies for new stadiums : a case study of Austin FC
(2021-01-26) Leon Marquez, Sergio; Novoselac, Atila; O'Connor, James Thomas
Stadiums acting on climate change mitigation must develop strategies that contribute to reduce greenhouse gas emissions from the commercial building sector. Energy-related measures have a prominent weight on the rating system for green building certification programs that determine the level of sustainability for new construction. Project location and energy end-use requirements of the design are important to determine alternatives to minimize their carbon footprint. A baseline carbon footprint was established due to emissions associated with future end-use consumption of electricity and natural gas to compare reduction alternatives for the case study. Building energy modeling simulation of lighting and heating, ventilation and air conditioning (HVAC) systems was performed using eQUEST based on geometry observations of enclosed spaces and the canopy roof to generate hourly demand data for Austin FC’s new outdoor stadium. Reduction alternatives were identified and analyzed for different system configurations. The alternatives that were considered for the analysis are: (1) installing low wattage floodlighting, (2) a proposed solar photovoltaic (PV) carport system, and (3) replacing furnace heating fueled by natural gas with an electric heat pump. The evaluation of alternatives was carried out in terms of abatement cost estimates (ACE) normalized by the amount of emissions that can be reduced from the baseline, considering periods of 20, 30, and 50 years starting in 2021. The stadium’s floodlighting system can avoid costly demand charges and reduce a relatively small fraction of the carbon footprint. Emissions reduction budget allocation between PV and HVAC systems favors PV. Heat pumps have a higher operational expenditure relative to natural gas charges although they can continue to reduce emissions after Austin Energy’s electricity generation system becomes carbon neutral as expected by 2035.
Spatial and temporal emissions variability from upstream and midstream sources in the Eagle Ford Oil and Gas production region
(2017-06-28) Arreola Garza, Hector Ivan; Webber, Michael E.; Allen, David T
Production of natural gas, natural gas liquids and oil in the US has increased over the last 10 years. The increase is attributed to the development of two complementary technologies: directional drilling and hydraulic fracturing. However, the new energy development also expanded environmental impacts, including methane emissions, which drive radiative forcing of the atmosphere and global warming. Extensive measurements of methane emissions have been conducted over the past five years, and this work synthesizes this new information to create a comprehensive, spatially and temporally resolved inventory of methane and light hydrocarbon emissions from oil and gas production, using the Eagle Ford Shale production region as a case study. The inventory includes emissions of methane, ethane, propane, and butane from 12 emission sources (chemical injection pumps, compression systems, dehydrators, pneumatic controllers, liquid unloading, completion flow backs (pre-production), super-emitter sources, condensate flashing, water flashing, equipment leaks, processing plants, and compression stations). Total estimated methane emission are 64,002 kg/hr (95% CI: 58,380 kg/hr – 71,730 kg/hr), which constitute 1.2% of the methane produced in the region. The main contributors are flashing from condensate tanks, pneumatic controllers and mid-stream sources.