Suggested Citation:
Morrison, Geoffrey M. (2013) Three Essays on Energy Use and Transportation: (1) Dynamic Lifecycle Assessment of Advanced Bioenergy Pathways using GCAM Model; (2) Influence of Workplace Peers in the Commuting Decision in the U.S.; (3) Impact of Rapid Employment Growth on Traffic Congestion. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-13-44

My dissertation examines three questions related to transportation and energy use. In the first essay, I investigate the influence of workplace peers on an individual’s travel decisions to work. Using a large dataset of U.S. military commuters and instruments to address the endogeneity of the decisions of one’s workplace peers, I show that workplace peers positively influence one another’s drive/no-drive decision and carpool/drive-alone decision. I also explore whether conventional measures of social status and seniority (i.e. income, education, age, and number of years in the military) predict who exerts the strongest influence on others, and find that intragroup influence appears to be stronger and more consistent than intergroup influence, which suggests that for commute decisions, social validation is a stronger motivator towards conformity than authority.

In the second essay, I examine the short-run impacts of rapid increases in regional employment on travel time to work by exploiting exogenous variation resulting from movements of military troops during the 2005 Base Realignment and Closure (BRAC) process. Employment levels often change more quickly than other factors that influence regional travel demand (e.g. number of two-worker households, vehicle ownership rates, travel preferences, etc.), making effective anti-congestion measures difficult to plan and implement. The BRAC process provides a convenient quasi-experimental framework to measure the short-run, congestion-related effects of employment growth on travel times because it occurred exogenous to the normal transportation planning process. I use difference-in-difference, difference-in-difference-in-difference, and instrumental variable methods to estimate these effects. The results are quite robust -- each additional commuter added to the transportation network per square kilometer adds 0.0032-0.055 additional minutes of travel for all other individual commuters in the short run. According to back-of-the-envelope calculations, the short-run economic travel time cost of the 2005 BRAC is estimated to have cost communities near BRAC-affected bases between $155 million and $1.5 billion per year. This paper has relevance for both transportation planners who seek effective growth strategies and Department of Defense officials who seek to mitigate transportation impacts from troop movements and base closures.

In the third and final essay, I examine how the carbon intensity (grams CO2e/MJ) of important upstream stages of bioenergy production will change over the next century for three generic energy pathways (biogas, bioliquids, bioelectricity) and five feedstocks (miscanthus, switchgrass, jatropha, eucalyptus, and willow). I construct an updated version of the Global Change Assessment Model (GCAM) which accounts for regional, temporal, and feedstock heterogeneity in five upstream stages: fertilizer production, fertilizer application, harvest energy, biomass transport energy, and pre-processing energy. Overall, I find that the median carbon intensity of these five upstream stages across scenarios declines by about 50% between 2020 and 2095 for bioelectricity, while bioliquids and biogas remain relatively flat. These trends result from several shifts in global agriculture production and land use. The shifting cultivation of biocrops between agricultural regions increases N2O emission intensity until the year 2050 and decreases it thereafter. Similarly, carbon intensities of bioenergy will decrease due to improved yields but this effect will be dampened before 2050 and accelerated after 2050 as effective yield of bioenergy moves towards less productive and more productive land, respectively. As yields increase, the supply radii of bioenergy agrosystems decreases by an average of 21% across scenarios between 2020 and 2095 assuming an average input of 2.0 million tons of biomass per year. My results suggest that shifts in land use play as important role in determining the trajectory of upstream greenhouse gas intensity of bioenergy in the future.