Abstract: This report contains five substantive sections describing plug-in hybrid electric vehicle (PHEV) related research conducted over an 18-month period by faculty and graduate students at the University of Vermont. Funding for these separate but related projects was provided by the Transportation Research Center, electric utilities, and Vermont State Agency partners. Section 1.2 of this report presents a literature review of prior studies regarding the proportion of miles driven under gasoline and electric power respectively, the resulting gasoline displacement and net change in greenhouse gas (GHG) emissions associated with PHEV operation, the generating capacity available to charge PHEVs and vehicle lifetime ownership costs. Section 2 is an analysis of state and federal policies to enhance the economic competitiveness of PHEVs. Two models of the impact of electricity demand for PHEV charging are described in Sections 3 and 4. The first of these models looks at the impact of this additional electricity demand on carbon allowance prices and generating costs under an electricity sector only cap-and-trade program, while the second explores its impact on medium voltage distribution circuits. Section 5 estimates the economic potential for bidirectional interfacing between vehicles and the grid, a concept known as vehicle-to-grid or V2G, in Vermont.
Abstract: Numerous recent reports have assessed the adequacy of current generating capacity to meet the growing electricity demand from Plug-in Hybrid Electric Vehicles (PHEVs) and the potential for using these vehicles to provide grid support (Vehicle to Grid, V2G) services. However, little has been written on how these new loads will affect the medium and low-voltage distribution infrastructure. This paper briefly reviews the results of the existing PHEV studies and describes a new model: the PHEV distribution circuit impact model (PDCIM). PDCIM allows one to estimate the impact of an increasing number of PHEVs (or pure electric vehicles) on transformers and underground cables within a medium voltage distribution system. We describe the details of this model and results from its application to a distribution circuit in Vermont.
Abstract: A model estimates the short-run effect of plug-in hybrid electric vehicle (PHEV) charging on electricity costs, given a cap on carbon dioxide (CO2) emissions that covers only the electricity sector. In the short run, cap-and-trade systems that cover the electricity sector increase the marginal cost of electricity production. The magnitude of the increase in cost depends on several factors, including the stringency of the cap in relation to the demand for electricity. The use of PHEVs, which also has the potential to decrease net greenhouse gas emissions, would increase demand for electricity and thus would increase the upward pressure on marginal costs. The model described examines this effect for the New England electricity market, which as of January 2009 operates under the Regional Greenhouse Gas Initiative, a cap-and-trade system for CO2. The model uses linear optimization to dispatch power plants to minimize fuel costs given inelastic electric demand and constraints on nitrogen oxide and CO2 emissions. The model is used to estimate costs for three fleet penetration levels (1%, 5%, and 10%) and three charging scenarios (evening charging, nighttime charging, and twice-a-day charging). The results indicate that PHEV charging demand increases the marginal cost of CO2 emissions as well as the average and marginal fuel costs for electricity generation. At all penetration levels the cost increases were minimized in the nighttime-charging scenario.
Abstract: Plug-in Hybrid Electric Vehicles (PHEVs) estimate the costs and benefits associated with a transition to electric energy as a fuel for transportation. This paper reviews these results and describes the factors that result in variance among these studies. Specifically, we find that assumptions about PHEV charging and driving patterns, electric range and the greenhouse gas intensity of electrical generation are critical determinants of conclusions about PHEVs impacts on oil use, greenhouse gas emissions and the electrical grid.