Danilo J. Santini

Potential of Plug-In Hybrid Electric Vehicles to Reduce Petroleum Use: Issues Involved in Developing Reliable Estimates

This paper delineates the various issues involved in developing reliable estimates of the petroleum use reduction that would result from the widespread introduction of plug-in hybrid electric vehicles (PHEVs). Travel day data from the 2001 National Household Travel Survey (NHTS) were analyzed to identify the share of vehicle miles of travel (VMT) that could be transferred to grid electricity. Various PHEV charge-depleting (CD) ranges were evaluated, and 100% CD mode and potential blended modes were analyzed. The NHTS data were also examined to evaluate the potential for PHEV battery charging multiple times a day. Data from the 2005 American Housing Survey (AHS) were analyzed to evaluate the availability of garages and carports for at-home charging of the PHEV battery. The AHS data were also reviewed by census region and household location within or outside metropolitan statistical areas. To illustrate the lag times involved, the historical new vehicle market share increases for the diesel power train in France (a highly successful case) and the emerging hybrid electric vehicles in the United States were examined. A new vehicle technology substitution model is applied to illustrate a historically plausible successful new PHEV market share expansion. The trends in U.S. light-duty vehicle sales and light-duty vehicle stock were evaluated to estimate the time required for hypothetical successful new PHEVs to achieve the ultimately attainable share of the existing vehicle stock. Only when such steps have been accomplished will the full oil savings potential for the nation be achieved.

Batteries for Electric Drive Vehicles: Evaluation of Future Characteristics and Costs Through a Delphi Study

Uncertainty about future costs and operating attributes of electric drive vehicles (EVs and HEVs) has contributed to considerable debate regarding the market viability of such vehicles. One way to deal with such uncertainty, common to most emerging technologies, is to pool the judgments of experts in the field. Data from a two-stage Delphi study are used to project the future costs and operating characteristics of electric drive vehicles. The experts projected basic vehicle characteristics for EVs and HEVs for the period 2000-2020. They projected the mean EV range at 179 km in 2000, 270 km in 2010, and 358 km in 2020. The mean HEV range on battery power was projected as 145 km in 2000, 212 km in 2010, and 244 km in 2020. Experts` opinions on 10 battery technologies are analyzed and characteristics of initial battery packs for the mean power requirements are presented. A procedure to compute the cost of replacement battery packs is described, and the resulting replacement costs are presented. Projected vehicle purchase prices and fuel and maintenance costs are also presented. The vehicle purchase price and curb weight predictions would be difficult to achieve with the mean battery characteristics. With the battery replacement costs added to the fuel and maintenance costs, the conventional ICE vehicle is projected to have a clear advantage over electric drive vehicles through the projection period.

Impacts of Charging Choices for Plug-In Hybrid Electric Vehicles in 2030 Scenario

This study systematically examined the potential impacts of recharging scenarios for multiple plug-in hybrid electric vehicles (PHEVs) in the western United States—in particular, the service area of the Western Electricity Coordinating Council (WECC)—in 2030. The goal of the study was twofold: to examine the impact of scenarios for market penetration and charging of PHEVs on the electric utilities and transmission grid and to estimate the potential reductions in petroleum use and greenhouse gas (GHG) emissions attributable to PHEV miles traveled on primarily grid electricity. Three charging scenarios for PHEVS were examined: (a) begin recharging upon arrival at home at the end of the last daily trip, (b) complete recharging of batteries just before the start of the first daily trip, and (c) any additional charging opportunity during the daytime. The three charging scenarios produced distinct hourly electric load profiles, with the opportunity-charging scenario resulting in a significant increase in load during the daytime. However, when the utility dispatch simulations were run for these charging scenarios in the WECC area, they all exhibited similar marginal-generation mixes (dominated by the natural gas combined-cycle technology) to satisfy the PHEV load, and GHG emissions were within 2% of each other. A well-to-wheel analysis revealed that the marginal-generation mixes produced 40% to 45% lower GHG emissions by PHEVs than did conventional gasoline internal combustion engine vehicles.

Interactions among transportation fuel substitution, vehicle quantity growth, and national economic growth

Abstract Hypotheses concerning the micro- and macroeconomic effects of historically important fuel switches in the vehicles operating on the dominant U.S. transportation modes are statistically tested using nineteenth and twentieth century data. Estimates of annual rates of change of fuel switching are constructed using logistic curve models fitted to often sparse data on fuel use. The estimated annual rate of loss of market share of an old fuel is then shown to be positively and consistently correlated with five-year averages of declines in the rate of growth of the fleets of vehicles affected by ongoing fuel switch. Other statistical tests show that five-year average changes in the rate of growth of the quantity of vehicles positively correlate with five-year average changes in the rate of growth of macro-economic activity when the affected vehicles are directly (through production and sales) responsible for a large share of macroeconomic activity (real GNP). The vehicle types shown to have this effect are locomotives from 1885–1915 and automobiles thereafter. The third set of tests supports an interpretation that the indirect effects of fuels switches, acting through their effects on the costs of transporting factors of production (both labor and physical inputs), have a significant and consistent GNP effect throughout the 1880–1980 period, even during the WWII-influenced period when the test for direct effects of automobiles fails. In case study discussion of each fuel switch it is shown that a pronounced drop in GNP growth occurs at the time when the important fuel switches are most rapidly being accomplished. Results of the statistical and case study analyses are compared to the authors prior research on vehicle engine innovation. The timing of peak rates of fuel switching and vehicle engine innovation are graphically shown to coincide for locomotives and automobiles from the 1880s to the 1980s. Further, the peak rates of fuel switching are graphically shown to occur when current real GNP relative to trend real GNP is declining and/or below the trend.

Introduction of Hybrid and Diesel Vehicles: Status Within the Life Cycle of Technology Adoption

The positions of the diesel and hybrid light-duty passenger vehicles in the technology adoption life cycle are examined with a mid-2004 stated preference study of 1,036 households. Implications of the technology life cycle for historical consumer preference estimates obtained for use in prior models of market share are briefly discussed. The hypothetical life-cycle segments addressed in this paper are early adopters, early buyers, and majority buyers. Survey respondents are segmented into subgroups, or markets, in light of hypothesized attributes of consumers within the product life cycle. Emphasis is placed on delineating the preferences of new instead of used vehicle buyer segments. These categories are compared with the five categories in the high-tech technology adoption life-cycle paradigm of G. Moore. One purpose of the analysis is to use the survey as a test of the reasonableness of the three categories used here. The implications of the survey for use of the rational buyer model of consumer trade-offs of incremental new vehicle capital cost (of a diesel or hybrid) against reduced fuel cost are addressed. Competition of desires for fuel efficiency, acceleration, and towing is also addressed, as are the effects of gender, income, education, and age.

Comparing estimates of fuel economy improvement via fuel-cell powertrains.

Several studies, conducted from 1997 to 2001, have employed vehicle and powertrain simulation models to estimate fuel economy gains for a variety of fuel-cell powertrains. Many of those studies have attempted to control for the comparability of performance between conventional and fuel-cell vehicles (FCVs), but different sets of performance goals and simulation models have been used. This paper reviews the estimates of fuel economy gain (in mpg) vs. varying measures of performance change for a set of those studies. We examine some of the potential causes for the variability of these estimates — fuel used, powertrain hybridization, vehicle raw energy requirements (load), and variations in analysts’ assumptions/estimates — when substituting several types of fuel-cell powertrains. Our study includes development of a database and detailed examination of the relationships among powertrain and vehicle characteristics and fuel economy gain estimates for the selected studies. We developed simple equations by powertrain type to systematically examine the causes of variation in mpg gain among those conventional/FCV pairs controlled to have the same peak kW per kg of vehicle test weight (a surrogate for acceleration capability).

Fuel Economy Improvement via Hybridization vs. Vehicle Performance Level

Although many of the studies that use vehicle simulation models to estimate fuel economy gains for a range of hybrid vehicles have attempted to control for the comparability of performance between conventional and hybrid vehicles, different rules and simulation models have been used. This paper reviews the estimates of city, highway, and corporate average fuel economy gain vs. varying measures of performance change for a set of those studies. We examine the causes for the wide range in estimates when hybridizing a vehicle, establish a database, and provide detailed discussions of relationships using several of the studies. Statistical models developed on the basis of the data reveal the causes of variation in mpg gain among conventional/hybrid pairs that have the same 0–60 mph acceleration times. Our study reveals that potential mpg gain via hybridization is greater as the 0–60 mph acceleration time of the pair of compared vehicles drops (and power-to-weight ratios increase). We demonstrate that engine downsizing is necessary to obtain large benefits, and that an increase in electric motor power relative to engine power — up to a point — improves the fuel economy of hybrids.

An Assessment of Oil Supply and Its Implications for Future Prices

This paper examines three issues related to both the U.S. and world oil supply: (1) the nature of the long-term, postpeak production profile for the U.S. and, by inference, other regions (the Hubbert curve is used as a “strawman” model); (2) implications on U.S. energy security of using a modified Hubbert-type conceptual model of prepeak production, testing the adequacy of Latin America to be the primary source of U.S. oil imports; and (3) the cyclic behavior of oil prices. it shows that U.S. production will exhibit a more attenuated decline than that simulated by the Hubbert curve and not decline to zero. it asserts that U.S. production is better predicted by past reserves than past production, but that this argument does not apply to nations that keep a much larger proportion of reserves in the ground. Such nations could considerably expand production without any growth in reserves. The paper concedes that the potential total production for these nations could be examined with a Hubbert curve model linked to reserves, but with great uncertainty. Such an uncertain optimistic forecast predicts that the cumulative production of Latin America could far exceed that of the United States. Nevertheless, a statistical model of oil prices since 1870 implies that real wellhead oil prices in the United States are on a long-term upward path, underlying a much more “noisy” cyclical pattern estimated to include 22- and 27-year cycles. The statistical model predicts a severe oil shock within a few years (of 1998) but also predicts that through 2030, real oil prices will not reach 1981 levels again. The paper examines U.S. and world trends in seismic exploration, drilling locations and depths, drilling costs, oil/gas reserves, oil/gas use rates, and oil demand. After taking these factors into consideration, it concludes that the statistical model of oil prices cannot be disputed, despite its lack of basis in economic theory.

Enhancing energy price stability through consistent and balanced energy technology R&D

Abstract Despite the significant decline in energy prices and the large budget deficit, the US government must maintain a well-balanced energy technology development programme ranging from basic science through to the demonstration of technical feasibility and technology transfer. Having technology in technical readiness before an energy price shock will moderate economic problems due to the price shock and thereby promote economic stability. Based on evolving knowledge about the relationships among energy prices, technology commercialization, and recessions and depressions, development of efficient energy technologies must be far better managed by government and the private sector during both normal economic growth and energy crisis.

Hybridizing with Engine Power Reduction

Although many studies that use vehicle simulation models to estimate fuel economy gains for a range of hybrid vehicles have attempted to control for the comparability of performance between conventional and hybrid vehicles, different rules and simulation models have been used. The fuel economy gain estimates versus performance change for a set of those studies are reviewed, and causes for the wide range in estimates of fuel economy gain when hybridizing a gasoline-fueled vehicle are examined. Data are compiled, and relationships are discussed in detail for 18 cases: three studies of four or more cases each. The data are used to develop statistical models to evaluate the causes of variation in fuel economy gain within and across the studies. Three studies (each evaluating one case only) that predict lower fuel economy gains than the first three are also examined. Explanations and adjustments are provided to illustrate that the differences across the studies are less than a cursory reading would imply. Most notably, potential fuel economy gain via hybridization increases as the 0-to-60-mph times of the compared vehicle pairs drop (and power-toweight ratios increase). Also a reduction in engine power is necessary to obtain large benefits. The most complex statistical model developed indicates that an increase in electric motor power relative to engine power improves the fuel economy of hybrids, up to a point. Finally, results indicate that continuous top-speed and grade-climbing ability will drop if a less powerful engine is used.