|
Abstract:
|
Demand for liquid fuels (i .e . , petroleum products ) has burdened the U .S . with major challenges , including national security and economic concerns stemming from rising petroleum imports ; impacts of global climate change from rising emissions of CO2 ; and continued public health concerns from criteria and hazardous (i .e . , toxic ) air pollutants . Over the last decade or so , biofuels have been touted as a supply -side solution to several of these problems . Biofuels can be produced from domestic biomass feedstocks (e .g . , corn , soybeans ) , they have the potential to reduce GHG emissions when compared to petroleum products on a lifecycle basis , and some biofuels have been shown to reduce criteria air pollutants . Today , there are numerous policy incentives—existing and proposed—aimed at supporting the biofuels industry in the U .S . However , the Renewable Fuel Standard (RFS ) Program stands as perhaps the most significant mandate imposed to date to promote the use of biofuels . Overall , the RFS stands as the key driver in a transition to biofuels in the near term . By mandating annual consumption of biofuels , increasing to 36 bgy by 2022 , the program has the potential to significantly alter the state of the U .S . liquid fuels sector .
Fuel transitions in the transportation sector are the focus of this thesis . More specifically , the increasing consumption of biofuels in the transportation sector , as mandated by the RFS , is examined . With a well -developed , efficient , and expensive , petroleum -based infrastructure in place , many barriers must be overcome for biofuels to play a significant role in the transportation sector . Identifying and understanding the barriers to a biofuels transition is the objective of this thesis .
Although fuel transitions may seem daunting and unfamiliar , the U .S . transportation sector has undergone numerous transitions in the past . Chapter 2 reviews major fuel transitions that have occurred in the U .S . liquid fuels sector over the last half century , including the phasing out of lead additives in gasoline , the transition from MTBE to ethanol as the predominant oxygenate additive in gasoline , and the recent introduction of ULSD . These historical transitions represent the uncertainty and diversity of fuel transition pathways , and illustrate the range of impacts that can occur across the fuel supply chain infrastructure . Many pertinent lessons can be derived from these historical transitions and used to identify and assess barriers facing the adoption of alternative fuels (i .e . , biofuels ) and to understand how such a transition might unfold .
Computer models can also help to explore the implications of fuel transitions . In order to better understand the barriers associated with fuel transitions , and to identify options for overcoming these barriers , many recent research efforts have used sophisticated modeling techniques to analyze energy transitions . Chapter 3 reviews a number of these recent modeling efforts with a focus on understanding how these methodologies have been applied , or may be adapted , to analyzing a transition to biofuels . Four general categories of models are reviewed : system dynamics , complex adaptive systems , infrastructure optimization , and economic models .
In chapter 4 , scenarios created from a high -level model of the liquid fuels sector (the Liquid Fuels Transition model ) are presented to explore potential pathways and barriers to a biofuels transition . The scenarios illustrate different pathways to meeting the requirements of the RFS mandate , and differ based on the overall demand of liquid fuels , how the biofuels mandate is met (i .e . , the mix of biofuels ) , and the status of the ethanol blend limit in the motor gasoline sector . The scenarios are used to evaluate the infrastructure implications associated with a biofuels transition , and illustrate the uncertainty that exists in assessing such a transition . |