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Open Access Publications from the University of California
Dissertations by ITS researchers.
Cover page of Modeling Bioenergy Supply Chains: Feedstocks Pretreatment, Integrated System Design Under Uncertainty

Modeling Bioenergy Supply Chains: Feedstocks Pretreatment, Integrated System Design Under Uncertainty


Biofuels have been promoted by governmental policies for reducing fossil fuel dependency and greenhouse gas emissions, as well as facilitating regional economic growth. Comprehensive model analysis is needed to assess the economic and environmental impacts of developing bioenergy production systems. For cellulosic biofuel production and supply in particular, existing studies have not accounted for the inter-dependencies between multiple participating decision makers and simultaneously incorporated uncertainties and risks associated with the linked production systems.

This dissertation presents a methodology that incorporates uncertainty element to the existing integrated modeling framework specifically designed for advanced biofuel production systems using dedicated energy crops as feedstock resources. The goal of the framework is to support the bioenergy industry for infrastructure and supply chain development. The framework is flexible to adapt to different topological network structures and decision scopes based on the modeling requirements, such as on capturing the interactions between the agricultural production system and the multi-refinery bioenergy supply chain system with regards to land allocation and crop adoption patterns, which is critical for estimating feedstock supply potentials for the bioenergy industry. The methodology is also particularly designed to incorporate system uncertainties by using stochastic programming models to improve the resilience of the optimized system design.

The framework is used to construct model analyses in two case studies. The results of the California biomass supply model estimate that feedstock pretreatment via combined torrefaction and pelletization reduces delivered and transportation cost for long-distance biomass shipment by 5% and 15% respectively. The Pacific Northwest hardwood biofuels application integrates full-scaled supply chain infrastructure optimization with agricultural economic modeling and estimates that bio-jet fuels can be produced at costs between 4 to 5 dollars per gallon, and identifies areas suitable for simultaneously deploying a set of biorefineries using adopted poplar as the dedicated energy crop to produce biomass feedstocks. This application specifically incorporates system uncertainties in the crop market and provides an optimal system design solution with over 17% improvement in expected total profit compared to its corresponding deterministic model.

Cover page of Modeling Framework for Socially Inclusive Bikesharing Services

Modeling Framework for Socially Inclusive Bikesharing Services


Bikeshare programs are increasingly popular in the United States and they are an important part of sustainable transportation systems, offering a viable mode choice for many types of last-mile trips. This popularity means that an increasing number of people can enjoy the convenience of cycling and the associated physical health benefits without actually owning a bike (or having access to their own bikes). However, bikeshare systems have not captured high levels of ridership from disadvantaged populations. Many barriers exist that prohibit residents from disadvantaged communities from accessing bikeshare services. These barriers include absence of bikeshare stations within walking distances, lack of financial resources, cultural barriers, and/or unsafe cycling environments. Most of the current research on bikeshare programs focuses on societal benefits (e.g. reducing greenhouse gas emissions by replacing auto trips with bike trips) and bikeshare system management (e.g., bike repositioning between stations). There is some emerging research focused on equity issues in developing bikeshare. However, far less attention has been paid to bikeshare programs’ potential benefits for disadvantaged communities and virtually no quantitative research on how to design bikeshare systems to improve access for these populations. This dissertation work addresses three fundamental bikeshare equity problems. 

Cover page of Homeless Negotiations of Public Space in Two California Cities

Homeless Negotiations of Public Space in Two California Cities


People experiencing homelessness find movement in urban public space constrained. Scholars have attributed this lack of accessibility to the consequences of anti-homeless laws, social exclusions and economic factors. I draw from spatial and mobility theory to frame movement and transgression within the partitioned city. I accompanied homeless people on walking interviews to discuss their movements, transgressions, and public space they occupied. I also mapped people’s behavior in public space, comparing the movements of homeless people with the movements of people with homes. The results indicate homeless people negotiate urban space by walking, biking and riding the bus in a manner that maximizes their ability to manage relationships as they travel. Constraints in movement arise from the partitioning of the city, i.e. the division into public and private, making it difficult to both rest in public space and move in socially-acceptable manners. The findings suggest cities can improve homeless movement through setting limits on the automobile and removing limits (or partitions) on informal patterns of movement.

Cover page of Economic and Econometric Analyses of the World Petroleum Industry, Energy Subsidies, and Air Pollution

Economic and Econometric Analyses of the World Petroleum Industry, Energy Subsidies, and Air Pollution


The decisions made by petroleum producers in the world oil market are both dynamic and strategic, and are thus best modeled as a dynamic game. In the first chapter of my dissertation, I review the literature on the world oil market and discuss my research on econometric modeling of the world oil market as a dynamic game. My research on econometric modeling of the world oil market as a dynamic game research builds on the previous literature by combining three erstwhile separate dimensions of modeling the world oil market: dynamic optimization, game theory, and econometrics.

In the second chapter of my dissertation, I develop and estimate a structural econometric model of the dynamic game among petroleum-producing firms in the world petroleum market. My model incorporates the dynamic behavior and strategic interactions that arise as petroleum-producing firms make their investment, production, merger, and acquisition decisions. I allow firms that are at least partially state-owned to have objectives other than profit maximization alone. I use the structural econometric model to analyze the effects of changes in OPEC membership, a ban on mergers, the privatization of state-owned oil companies, and demand shocks on the petroleum industry. Although I do not assume or impose that OPEC producers collude to maximize joint profits, but instead infer the strategy and payoffs for OPEC firms from the data, I find that OPEC behaves in such a way that is consistent with its mission and also with cartel behavior. Results of counterfactual simulations also show that a ban on mergers would decrease average firm payoff for both OPEC and non-OPEC firms, and decrease consumer surplus.

Gasoline taxes have been touted by many economists as an efficient and relatively simple tool to address environmental concerns and other problems associated with gasoline consumption. Nevertheless, rather than removing subsidies and increasing gasoline taxes, many countries still subsidize gasoline, which may have the opposite effect of exacerbating air pollution and other problems associated with gasoline consumption. The Iranian government has heavily subsidized petroleum products since the early 1980s. As a result of these energy subsidies and artificially low national energy price, Iran is one of the most energy-intensive countries in the world. The Iranian government has recently taken a series of measures to reform and cut back on the energy subsidies. In the third chapter of my dissertation, I evaluate the effects of the Iranian subsidy reform on air quality using a regression discontinuity design. My results provide evidence across multiple different empirical specifications that the subsidy reform in Iran led to improvements in air quality. In particular, the first subsidy reform event, which increased gasoline prices and implemented a gasoline consumption quota; and the second subsidy reform event, which increased energy prices and decreased energy subsidies, both led to declines in concentrations of CO, O3, and NO2. In contrast, the fourth subsidy reform event, which increased fuel prices but removed the gasoline consumption quota, was less effective in reducing air pollution.

Cover page of Environmental and economic costs, benefits and uncertainties of vehicle electrification: a life cycle approach

Environmental and economic costs, benefits and uncertainties of vehicle electrification: a life cycle approach


Battery electric vehicles (BEVs) have been proposed as a pathway for reducing the environmental impacts of transportation systems. While BEVs are often referred to as zero-emission vehicles, production and operation consume resources and emit pollutants through the vehicle supply chain and generation of electricity for vehicle charging. Life cycle assessment is a standardized methodology for assessing the environmental impacts of product systems from a system-wide perspective; considering the total supply chain and the product life cycle from cradle-to-grave. However, conventional LCAs are often limited; based off static supply chain analysis, omitting system interactions or indirect effects, and insufficiently reflecting the underlying variability and uncertainty to support robust public policy decisions.

The objective of this dissertation is to develop and refine methods of assessing the life cycle environmental impacts and economic costs of electric vehicle technologies and policies. The chapters of this dissertation make contributions in advancing spatial and temporal dynamics in LCA modelling, integrating vehicle operations with evolutions in technology, background systems, and product development, and offers novel estimates of the costs and emissions abatement potential of light and heavy duty electric vehicles. As shown herein, a systems perspective is required to estimate the environmental benefits and costs of vehicle electrification strategies. Efforts to achieve pollution abatement through technology change must address risks of leakage, substitution, and unintended environmental consequences.

Cover page of Performance Assessment of Asphalt Mixes Containing Reclaimed Asphalt Pavement and Tire Rubber

Performance Assessment of Asphalt Mixes Containing Reclaimed Asphalt Pavement and Tire Rubber


The pavement community, including both agencies and industries, is moving toward more sustainable pavement designs and pavement network management. Increasing amounts of recycled materials, both reclaimed asphalt pavement (RAP) and recycled tire rubber, are expected to be used in new pavement construction projects in the future to reduce the use of virgin binder and aggregates. The main concern of using recycled materials in new asphalt pavement is the potential negative effect on the performance. Thus, the primary objective of this dissertation is to improve the current laboratory testing technologies and performance assessment approaches for characterizing the performance-related properties of asphalt mixes containing recycled materials and to improve understanding of how these properties affect the performance of asphalt pavements so that they can be designed and constructed better.

Cover page of Data-Driven Behavior Analysis and Implications in Plug-in Electric Vehicle Policy Studies

Data-Driven Behavior Analysis and Implications in Plug-in Electric Vehicle Policy Studies


The adoption of plug-in electric vehicles (PEVs) is considered to be a potential solution to reduce transportation-related emissions. People’s vehicle choice and driving behavior will have important implications for the realized emissions reductions from PEVs. Therefore, PEV-related policy studies require good understanding of human behavior. Traditional approaches to analyze travel behavior are mostly to build analytic models based on assumptions because of the limited accuracy and information of data. With the development of sensor technology, there are more methods than ever to collect accurate and informative behavioral data, so the crucial consideration is how to creatively use these data to better understand people’s behavior. This dissertation proposed some data-driven approaches to simulate behavior and provided a discussion of the implications for three PEV-related topics.

The first study explored the potential of greenhouse gas (GHG) reductions that can be achieved with adoption of PEVs in California by simulating vehicles’ emissions based on tracing data. It was found that assigning the right model of PEVs to drivers can help to reduce annual GHG emissions by 65%, compared to everyone driving a Toyota Corolla.

The second study presented a tool to evaluate the spatial distribution of fast charging demand and to assess how much a charger in a certain location would be used based on travel diary. Scenario analysis illustrated that en-route fast charging demand will shift from primarily inside metro areas to long distance corridors outside metro areas as the battery size increases.

The third study estimated the value of Clean Air Vehicle (CAV) decals by simulating the frequency of PEV owners’ access to high occupancy vehicle/toll (HOV/T) lanes based on survey data. The results indicated that the CAV Decals Program is one of the most attractive incentive policies, but there is spatial heterogeneity of CAV decal value across different regions.

Cover page of Interpersonal Influence within Car Buyers’ Social Networks: Observing Consumer Assessment of Plug-in Hybrid Electric Vehicles (PHEVs) and the Spread of Pro-Societal Values

Interpersonal Influence within Car Buyers’ Social Networks: Observing Consumer Assessment of Plug-in Hybrid Electric Vehicles (PHEVs) and the Spread of Pro-Societal Values


Consumer purchase behavior is central to the successful deployment of alternative-fuel passenger vehicles. This dissertation explores the role of social influence in vehicle purchase behavior via observations of car buyers’ assessments of plug-in hybrid-electric vehicles (PHEVs). Five theoretical perspectives on social influence are used to analyze these behaviors: contagion, conformity, dissemination, translation, and reflexivity. Social interactions are found to have substantial influence over the majority of participants’ assessments. Contagion and similar theoretical perspectives over-simplify processes of social influence, while translation and reflexivity better provide the language and theoretical depth required to integrate the observed perceptions and social processes with concepts of self-identity. Car buyers who are typically motivated by the private benefits of vehicles may be amenable to developing new, pro-societal interpretations of PHEVs. Social influence is important, as is the development and use of behaviorally realistic theoretical frameworks to advance transportation and energy policies that rely on the widespread adoption of new technologies.

Cover page of Future Impacts of Coal Distribution Constraints on Coal Cost

Future Impacts of Coal Distribution Constraints on Coal Cost


After years of relatively slow growth, coal is undergoing a renaissance. Some 140 coal power plants are planned, and the Energy Information Administration (EIA) projects that the U.S. will consume almost 1,800 million tons of coal in 2030, up from about 1,150 million tons this year. In addition, while EIA’s estimates do not take coal-to-hydrogen production into consideration, several recent studies suggest that if the hydrogen economy ever comes to fruition coal could be a feedstock of choice, at least in the U.S. which has huge reserves of coal (~250 years’ worth at current consumption rates), which are relatively cheap and easy to mine.

An increase in future coal demand fuels legitimate concerns about the impacts on global climate and regional air pollution. While carbon capture and storage is often mentioned as a solution to these two problems, another impact, often overlooked, is the possibility that the current coal distribution infrastructure may not be able to reliably deliver the additional demand. Railroads deliver about two-thirds of U.S. coal at present, but certain coal-carrying rail corridors are already up against their capacity limits. Any future demand increases will probably necessitate significant capital investment by rail companies.

This study seeks to identify existing capacity and potential constraints within the coal distribution infrastructure and to identify the costs of alleviating these constraints under several growth scenarios for coal demand. The scenarios differ based on whether or not pulverized coal (PC) or integrated gasification combined cycle (IGCC) power plants are built, as well as the amount of coal that is used to produce hydrogen for fuel cell vehicles.

Coal transportation along the nation’s vast rail network is modeled with a freight routing model that uses the Surface Transportation Board’s confidential Carload Waybill Sample data as an input. For each coal demand growth scenario, I identify the rail corridors that could potentially reach their capacity limits in the future due to increasing coal traffic, and I quantify the investment that might be needed to boost the coal-carrying capacity along these lines.

Some of important questions that I have attempted to answer through this analysis include the following: (1) Will the nation’s rail-coal distribution system be able to handle the future increases in coal demand that could result from traditional uses, as well as from coal-to-hydrogen production; and (2) What is the trade-off between building more efficient, albeit more expensive, IGCC power plants versus modern PC plants, if costly investments in coal transportation infrastructure can be avoided?

Cover page of Commercializing Light-Duty Plug-In/Plug-Out Hydrogen-Fuel-Cell Vehicles:“Mobile Electricity” Technologies, Early California Household Markets, and Innovation Management

Commercializing Light-Duty Plug-In/Plug-Out Hydrogen-Fuel-Cell Vehicles:“Mobile Electricity” Technologies, Early California Household Markets, and Innovation Management


Starting from the premise that new consumer value must drive hydrogen-fuel-cell-vehicle (H2FCV) commercialization, a group of opportunities collectively called “Mobile Electricity” is characterized. Mobile Electricity (Me-) redefines H2FCVs as innovative products able to import and export electricity across the traditional vehicle boundary. Such vehicles could provide home recharging and mobile power, for example for tools, mobile activities, emergencies, and electric-grid-support services. To characterize such opportunities, this study first integrates and extends previous analyses of H2FCVs, plugin hybrids, and vehicle-to-grid (V2G) power. It uses a new electric-drive-vehicle and vehicular-distributed-generation model to estimate zero-emission-power vs. zeroemission- driving tradeoffs, costs, and grid-support revenues for various electric-drive vehicle types and levels of infrastructure service.

Next, the initial market potential for Me-enabled vehicles, such as H2FCVs and plug-in hybrids, is estimated by eliminating unlikely households from consideration for early adoption. 5.2 million of 33.9 million Californians in the 2000 Census live in households pre-adapted to Me-enabled vehicles, 3.9 million if natural gas is required for home refueling. The possible sales base represented by this population is discussed. Several differences in demographic and other characteristics between the target market and the driving-age population are highlighted, and two issues related to the design of H2FCVs and their supporting infrastructure are discussed: vehicle range and home hydrogen refueling. These findings argue for continued investigation of this and similar target segments—which represent more efficient research populations for subsequent study by product designers and other decision-makers wishing to understand the early market dynamics facing Me- innovations.

Next, Me-H2FCV commercialization issues are raised from the perspectives of innovation, product development, and strategic marketing. Starting with today’s internalcombustion hybrids, this discussion suggests a way to move beyond the battery vs. fuelcell zero-sum game and towards the development of integrated plug-in/plug-out hybrid platforms. H2FCVs are described as one possible extension of this Me- product platform for the supply of clean, high-power, and profitable Me- services as the technologies and markets mature.

Finally, the major findings of this study are summarized and directions for future work discussed. Together, the parts of this Mobile Electricity innovation assessment reveal an initially expensive and limited but compelling (and possibly necessary) set of opportunities to help drive H2FCV and other electric-drive-vehicle commercialization. Keywords: Hydrogen-fuel-cell vehicle, Mobile Electricity innovation, Plug-in hybrid, Plug-out hybrid, Vehicle-to-grid power, Vehicular distributed generation, Household market potential, product development, market development.