CAFE Standards Research Articles

Projecting the fuel efficiency of conventional vehicles: CAFE regulations, gasoline taxes and autonomous technical change

Why does the fuel efficiency of gasoline cars increase over time? Do persistent spikes in gasoline prices induce such innovation? Does the increasing stringency of regulatory standards, such as CAFE, accelerate this technical change? How much of the observed progress would have occurred without these two factors? This paper examines the evolution of fuel efficiency using data on gasoline cars entering the US market from 1984 to 2020. Our analysis controls for gasoline price and tax shocks that occurred in OECD countries during this period. The study also accounts for the increasing stringency of fuel efficiency regulations, such the US CAFE standards. In contrast to previous contributions that downplay the role of fuel prices and taxes in shaping fuel efficiency, the study shows that their effect may be significant and robust. Doubling the user cost of gasoline with a stringent carbon tax is associated with an irreversible increase in fuel efficiency, by 5%. Increasing the stringency of the US CAFE standards by 10% raises average fuel efficiency by up to 1.2%. The progress stemming from other factors has an annual rate of 0.3–0.4% and accounts for 60% of the recorded change in fuel efficiency.

CAFE in the city — A spatial analysis of fuel economy standards

We identify and examine a new effect of fuel economy (CAFE) standards on welfare through a long-run spatial expansion of the urban form (“urban adjustment effect”) caused by lower per-mile driving costs and the distortion in the vehicle market due to CAFE standards. By integrating household-level vehicle choice and the automobile market into a calibrated monocentric city model, we find that, for a carbon emission decrease of 80 percent, the long-run urban adjustment effect adds a relevant monthly welfare cost of up to 20 Dollars to the medium-run welfare cost of CAFE compliance of 128 Dollars per month (+15 percent). This welfare cost can be alleviated by about one third through the combination of CAFE with urban growth boundaries. For fuel taxes, on the other hand, the urban adjustment effect causes a welfare gain of a similar magnitude.

Enable a Carbon Efficient Power Grid via Minimal Uplift Payments

The COVID-19 has slowed down global economic growth. Meanwhile, it also significantly cuts the global carbon emission, which provides a golden opportunity for the whole world to combat the climate change together. While the former policies (e.g., the CAFE standards, renewable portfolio standards, etc.) have reduced certain level of fossil fuel consumption, the most effective measures (such as carbon tax, cap-and-trade programs) are still far from ready for global implementation. This paper investigates an alternative way to achieve a more carbon efficient power grid using the uplift payment scheme. Specifically, we propose an effective algorithm to guarantee carbon efficiency with minimal uplift payments. We also submit that this scheme provides more flexibility to realize carbon reduction than carbon tax, which is exemplified by thorough numerical studies. Furthermore, we show that the stability of the power grid can be ensured under our uplift payment scheme, both from theoretical analysis and numerical studies. The results strengthen our belief that our uplift payment scheme is practicable for carbon reduction in the electricity market.

Proposing effective strategies for meeting an environmental regulation with attainable technology improvement targets

AbstractThe Japanese government will adopt the CAFE standard after 2020. By using a “modified” slacks‐based measure (SBM) model, this study analyzed the technical efficiency of 113 gasoline vehicle models (GVs) and 54 hybrid vehicle models (HVs) sold by Japanese manufacturers in 2016. We also estimated attainable fuel efficiency of specific vehicle models that can be further improved referring to the nearest point on the best practice frontier. The improved CAFE values and standards of the nine automobile manufacturers were calculated. The technology gap from the vehicle technology frontier was more noticeable among gasoline vehicles than among hybrids. Moreover, most automobile manufacturers can achieve the CAFE standard through an effective achievement strategy based on best practice technologies, whereas the others will not achieve the CAFE standard even given a rapid technology innovation beyond the best practice frontiers for GVs and HVs.

The EPA, NHTSA, and the Multiple Streams drive climate policy outcome

ABSTRACTAlthough United States environmental policy is frequently being decided in administrative agencies, it is unclear what factors influence policy outcomes. Some limited scholarship has explored whether the Multiple Streams Framework (MSF) used for congressional policymaking can be used to explain rulemaking outcomes. This research explores the validity of the MSF via a case study of the controversial 2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards Rule (CAFE Standards Rule) jointly published by the Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA). This research relies on original interviews with 30 agency staff and stakeholders to conclude that the model is helpful in understanding why these agencies produced the policy they did. However, the results here illustrate the importance of understanding the role and impact of the political stream on outcomes earlier in the process than ou...

Supply elasticity matters for the rebound effect and its impact on policy comparisons

We develop a model of the rebound effect which explicitly accounts for both the demand and supply sides of the energy sources. We consider a transportation sector originally using a “dirty” (fossil) fuel and examine the relative effectiveness of alternative policies: efficiency improvements in the dirty fuel technology sector (e.g., CAFE standards) and technology shifts by partial adoption of a new clean technology (e.g., low-carbon fuel standards). The model generates endogenous equilibrium quantities and prices for the dirty and clean fuels. We characterize the magnitude of the rebound effect as a function of demand and supply elasticities and use the equilibrium values to compare policy options. When the supply of the dirty fuel is inelastic, we find that introducing a new technology with non-zero emissions may actually increase the total level of emissions, similar to the leakage effect. A technology shift policy can perform better than an efficiency improvement policy in the dirty fuel sector only when the dirty fuel supply is sufficiently elastic, the emission intensity of the new technology very low, and the technology shift is greater than a threshold value. Using data for gasoline (as a proxy for the dirty technology) and several other cleaner technologies, we show that these conditions are satisfied by a hypothetical zero-emission technology, but not by electric vehicles using the average US generation mix or the current US corn based E85. Our results demonstrate the importance of accounting for the supply side in estimating the magnitude of the rebound effect and its impact on fuel consumption in a large-scale policy implementation.

Evaluating Rigid and Semiflexible Fiber Orientation Evolution Models in Simple Flows

As American vehicle fuel efficiency requirements have become more stringent due to the CAFE standards, the auto industry has turned to fiber reinforced polymer composites as replacements for metal parts to reduce weight while simultaneously maintaining established safety standards. Furthermore, these composites may be easily processed using established techniques such as injection molding and compression molding. The mechanical properties of these composites are dependent on, among other variables, the orientation of the fibers within the part. Several models have been proposed to correlate fiber orientation with the kinematics of the polymer matrix during processing, each using various strategies to account for fiber interactions and fiber flexing. However, these all require the use of empirical fitting parameters. Previous work has obtained these parameters by fitting to orientation data at a specific location in an injection-molded part. This ties the parameters to the specific mold design used. Obtaining empirical parameters is not a trivial undertaking and adds significant time to the entire mold design process. Considering that new parameters must be obtained any time some aspect of the part or mold is changed, an alternative technique that obtains model parameters independent of the mold design could be advantageous. This paper continues work looking to obtain empirical parameters from rheological tests. During processing, the fiber–polymer suspension is subjected to a complex flow with both shear and extensional behavior. Rather than use a complex flow, this study seeks to isolate and compare the effects of shear and extension on two orientation models. To this end, simple shear and planar extension are employed, and the evolution of orientation from a planar random initial condition is tracked as a function of strain. Simple shear was imparted using a sliding plate rheometer designed and fabricated in-house. A novel rheometer tool was developed and fabricated in-house to impart planar extension using a lubricated squeeze flow technique, where a low-viscosity Newtonian lubricant is applied to the solid boundaries to minimize the effect of shearing due to the no-slip boundary condition. The Folgar–Tucker model with a strain reduction factor is used as a rigid fiber model and compared against a bead–rod model (a semiflexible model) proposed by Ortman. Both models are capable of predicting the data, with the bead–rod model performing slightly better. Orientation occurs at a much faster rate under startup of planar extension and also attains a much higher degree of flow alignment when compared with startup of steady shear.

A difficult road ahead: Fleet fuel economy, footprint-based CAFE compliance, and manufacturer incentives

Using detailed vehicle specifications, this paper analyzes the impact identifiable vehicle characteristics and technological progress has on fleet fuel economy by vehicle type and class. The results suggest manufacturers will face a difficult task complying with the new footprint-based CAFE standards if compliance is met by only changing identifiable vehicle characteristics. I find evidence that the stringent footprint-based standards create a manufacturer incentive to increase vehicle size to lower the burden of compliance. This undermines the standards' potential to create expected fuel savings and lower emissions levels.

Response Characteristics of a Pre-Commercial Mixed Potential Ammonia Sensor in Diesel Engine Exhaust

Advancements in both combustion system design and emission control technologies have allowed more efficient diesel engines to meet stringent exhaust emissions standards. With very stringent emission regulations currently in place, combustion system design and combustion management are used in conjunction with available exhaust after treatment technologies for optimal reduction of emissions to meet regulatory targets. Current diesel vehicles in the US are equipped with a diesel oxidation catalyst (DOC) to control CO and HC emissions, a diesel particulate filter (DPF) to control particulate matter (PM) and selective catalyst reduction (SCR) or lean-NOx trap (LNT) to control NOX emissions. In SCR, NOx is reduced to H2O and N2over a catalyst through the injection of an ammonia source provided by the onboard storage of diesel exhaust fluid (DEF), typically a mixture of urea and de-ionized water. These emission control technologies add significant complexity and cost to a vehicle and some result in additional fuel penalty needed for their operation. Meeting the EPA Tier 3 emissions reduction requirements while simultaneously increasing fuel economy to meet new CAFE standards will require optimization of advanced combustion strategies and emissions control technologies as well as their state of operation under transient vehicle operation. NH3 sensors are needed to monitor DEF injection and prevent NH3 slip—a condition under which unreacted ammonia from the SCR is emitted in the tailpipe exhaust. Ideally, both NH3 and NOxsensors would be incorporated into a closed-loop system to maintain ammonia close to stoichiometry in the SCR system, and could also serve to monitor engine out and tailpipe out emissions in order to ensure regulatory compliance. Mixed-potential sensors are electrochemical devices that develop a non-Nernstian potential due to differences in the redox kinetics of various gas species at each electrode/electrolyte gas interface1,2. The difference in the steady-state redox reaction rates between the “fast” and “slow” electrodes gives rise to the measured mixed potential response. A patented LANL sensor design incorporates dense electrodes and a porous electrolyte and reproducible and stable sensors are prepared using a high temperature ceramic co-fire approach3. The use of dense electrodes minimizes deleterious heterogeneous catalysis, and the increased morphological stability of dense electrodes yields a robust electrochemical interface, increasing lifetime durability4. The use of a dense gold-alloy working electrode (e.g. the slow electrode), imparts preferential selectivity to NH3, and avoids the stability problems one finds when using thin film, porous Au electrodes5. Previously, we reported on the response of an experimental, tape-cast version of a mixed potential ammonia sensor to simulated diesel exhaust in a high-flow bench reactor at the Oak Ridge National Laboratory (ORNL) National Transportation Research Center (NTRC)7. In this work, we present recent results from evaluating the performance of a pre-commercial form of a mixed potential-based NH3 sensor in engine exhaust conditions at the NTRC using a GM 1.9L CIDI diesel engine. A planar NH3 sensor with a protective porous overcoat was tested in diesel engine exhaust gas (20 L/min) sampled downstream of the engine’s DOC. In order to simulate NH3 slip from a full SCR emissions control system, NH3 was injected immediately upstream of the sensor using a calibrated mass flow controller. The sensor response quantitatively tracked levels of injected NH3 and transients measured via Fourier transform infrared (FTIR) analyzer, using a calibration curve derived from an ammonia staircase response measured in the engine exhaust at low NOx and HC concentrations (<20 ppm) and steady-state engine conditions. Exhaust gas recirculation (EGR) switching and EGR sweeps were used to evaluate the NH3 sensor response under different amounts of total NOx. This calibration curve was used to directly compare the [NH3] calculated from sensor response to the gas phase composition measured via FTIR. References J. W. Fergus, Journal of Solid State Electrochemistry 15 (5), 971-984 (2010).F. H. Garzon, R. Mukundan and E. L. Brosha, Solid State Ionics 136-137, 633-638 (2000).P.K.Sekhar et. al., Sensors and Actuators B: Chemical 144, 112 (2010).R. Mukundan, E. L. Brosha and F. H. Garzon, Journal of The Electrochemical Society 150 (12), H279 (2003).J. Tsitron et. al., Sensors and Actuators B 192 (2014) 283-293.E. L. Brosha et al., “Response Characteristics of a Stable Mixed Potential NH3 Sensor in Simulated Diesel Exhaust,” 228th Meeting of the ECS, Phoenix, AZ, October 2015. Acknowledgments The authors would like to thank Roland Gravel and the DOE Vehicle Technology Office for providing funding for this work. Engine-based studies were conducted at the National Transportation Research Center User Facility at Oak Ridge National Laboratory. Figure 1

A study on the effects of the CAFE standard on consumers

In this paper, we analyzed how the CAFE standard has affected improvements in the fuel economy of vehicles, as examined in other preceding studies, but in addition, we also analyzed how these standards have affected the level of consumer interest in fuel economy. Our goal was to determine what effects the government intervention has had on consumers, and whether such intervention ought to be continued. The results showed that not only has the CAFE standard had a direct and significant impact on improving fuel economy and increasing the market share of fuel-efficient vehicles, it has also boosted the development of technologies for enhancing fuel economy and raised consumer interest in fuel economy, thus indirectly contributing to overcoming market failure. The significance of this study is that we used publically available observed data and analyzed the recent impact of the CAFE standard specifically with a focus on the behavior and strategies exhibited by consumers and automakers. Another significance of this study is that it extends our purview to examine the effects that the CAFE standard has had in other countries (Korea).

Petroleum refinery greenhouse gas emission variations related to higher ethanol blends at different gasoline octane rating and pool volume levels

AbstractRefinery GHG emissions were predicted for 10% and 30% ethanol blends at refinery blendstock octanes between 77 and 89 AKI at any gasoline pool energy content between parity and constant gasoline pool volume. Linear programming analyzed how separate E30 blending scenarios of 2017 PADD 2‐based refineries affect greenhouse gas (GHG) emissions relative to status quo gasoline (i.e., E10, 87 AKI and 93 AKI premium). The compliance synergy of higher ethanol blends illustrated here is pertinent to national policy goals and multiple environmental objectives. Study results have implications for CAFE Standards, US EPA Tier 3 fuel standards, and Clean Air Act regulations of stationary source CO2 emissions from refinery operations. Results varied by amounts and types of crude oil processed, refinery operations, refinery gasoline blendstock produced (and fuel ethanol blended), and produced refinery product composition and properties. Significant differences exist in total refinery GHG emissions (including emissions from purchased electricity and hydrogen) with the largest differences from coke burn in the fluidized catalytic cracker and refinery fuel gas combustion principally related to reformer operations. The concept of refinery GHG emissions intensity was introduced to differentiate between differences in refinery throughput (an extensive factor) and severity of refinery operations (intensive factors). Refinery GHG emissions decline 12% to 27% from a 2017 base case for the various 30% ethanol cases, highlighting a significant gap in current life cycle analysis (LCA) and supporting incorporation of this improved approach into LCA related to higher ethanol blends. This methodology can be adapted to other PADDs and/or for the USA. ©2015 The Authors. Biofuels, Bioproducts, Biorefining published by Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Response Characteristics of a Stable Mixed Potential Ammonia Sensor in Simulated Diesel Exhaust

Advancements in both combustion system design and emission control technologies have allowed more efficient diesel engines to meet stringent exhaust emissions standards. With very stringent emission regulations currently in place, combustion system design and combustion management are used in conjunction with available exhaust after treatment technologies for optimal reduction of emissions to meet regulatory targets. Current diesel vehicles in the US are equipped with a diesel oxidation catalyst (DOC) to control CO and HC emissions, a diesel particulate filter (DPF) to control particulate matter (PM) and selective catalyst reduction (SCR) or lean-NOx trap (LNT) to control NOX emissions. In SCR, NOx is reduced to H2O and N2 over a catalyst through the injection of an ammonia source provided by the onboard storage of diesel exhaust fluid (DEF), typically a mixture of urea and de-ionized water. These emission control technologies add significant complexity and cost to a vehicle and some result in additional fuel penalty needed for their operation. Meeting the EPA Tier 3 emissions reduction requirements while simultaneously increasing fuel economy to meet new CAFE standards will require optimization of advanced combustion strategies and emissions control technologies as well their state of operation under transient vehicle operation. NOx sensors are needed to reduce variations in emissions control, lower the cost of closed loop DEF dosing control, improve consumption of both fuel and DEF. NH3 sensors are needed to monitor DEF injection and prevent NH3 slip—a condition under which unreacted ammonia from the SCR is emitted in the tailpipe exhaust. The ammonia slip is treated as a more harmful pollutant than the NOx emissions. Ideally, both NH3 and NOx sensors would be incorporated into a closed-loop system to maintain ammonia close to stoichiometry in the SCR system, and could also serve to monitor engine out and tailpipe out emissions in order to ensure regulatory compliance. Mixed-potential sensors are electrochemical devices that develop a non-Nernstian potential due to differences in the redox kinetics of various gas species at each electrode/electrolyte gas interface1,2. The difference in the steady-state redox reaction rates between the “fast” and “slow” electrodes gives rise to the measured mixed potential response. A patented LANL sensor design incorporates dense electrodes and a porous electrolyte and reproducible and stable sensors are prepared using a simple ceramic tape cast approach3. The use of dense electrodes minimizes deleterious heterogeneous catalysis, and the increased morphological stability of dense electrodes yields a robust electrochemical interface, increasing lifetime durability4. The use of a dense gold wire-working electrode (e.g. the slow electrode), imparts preferential selectivity to NH3, and avoids the stability problems one finds when using thin film, porous Au electrodes5. In this work, we present recent results from testing a Au/YSZ/Pt tape cast sensor in ORNL’s high flow reactor at the NRTC that was especially constructed to simulate the exhaust gas constituents produced by lean burn vehicles powered by CIDI diesel engines with, and without emissions controls. The sensor was characterized at 525 and 625°C for NH3, CO, C3H6, C3H8, and NOx in a pre-heated base gas composition of 1%O2, 5%H2O, 5%CO2 flowing at 15 slpm. The sensor exhibited fast response time equal to the response time of the system’s switching valve (T90<0.6s). Moreover, in simulations of ammonia slip resulting from overdosing an SCR, the sensor was able to easily measure 20ppm injections of NH3 in the presence of the interferent gas species at combined concentrations ten times higher than the NH3. These data provide experimental confirmation of the concept of using a mixed-potential electrochemical NH3 sensor for tail pipe out applications. New data from recent engine out testing of pre-commercial prototype sensors that utilize design principles of tape sensors but are based on High Temperature Ceramic Co-Fire (HTCC) construction6 will be presented and discussed. References J. W. Fergus, Journal of Solid State Electrochemistry 15 (5), 971-984 (2010).F. H. Garzon, R. Mukundan and E. L. Brosha, Solid State Ionics 136-137, 633-638 (2000).R. Mukundan, E. L. Brosha, and F. H. Garzon, Tape Cast Sensors and Method for Making, US Patent no. 7,575,709.R. Mukundan, E. L. Brosha and F. H. Garzon, Journal of The Electrochemical Society 150 (12), H279 (2003).J. Tsitron et. al., Sensors and Actuators B 192 (2014) 283-293.P.K.Sekhar et. al., Sensors and Actuators B: Chemical 144, 112 (2010). Acknowledgments The authors would like to thank Roland Gravel and the DOE Vehicle Technology Office for providing funding for this work.

THE LIMITS OF IRRATIONALITY AS A RATIONALE FOR REGULATION

THE LIMITS OF IRRATIONALITY AS A RATIONALE FOR REGULATION

Quantifying efficiency technology improvements in U.S. cars from 1975–2009

Quantitative measurements of historic improvements in fuel efficiency technology help to illuminate the feasibility of future fuel economy standards. Past investigations have produced widely varying estimates of this rate of improvement, though all seem to indicate that fuel consumption reductions implied by the 2025 U.S. CAFE standards cannot be met solely through technological improvements at historic rates. In this paper, we use the characteristics of U.S. cars between 1975 and 2009 to estimate that holding all else equal, a 1% increase in weight increases a car’s fuel consumption by 0.69%, and a 1% reduction in 0–97km/h acceleration time increases fuel consumption by 0.44%. These tradeoff parameters are combined with the results of related work by the authors and others, yielding a more comprehensive measure of technological improvements than has been previously reported. When accounting for all of these sources of improvement, we conclude that the per-mile (or per-kilometer) fuel consumption of new cars in the U.S. could have been reduced by 5% per year from 1975 to 1990, if acceleration, features, and functionality had remained at their 1975 levels. Approximately 80% of this potential was realized as actual reductions in fuel consumption. Between 1990 and 2009, in contrast, technological improvement averaged just 2.1% per year, only 34% of which was realized as actual fuel consumption reductions. To meet the 2025 CAFE standards for cars without sacrificing capabilities that consumers have come to expect, technology must improve quickly enough to reduce fuel consumption by 4.3% per year for 14years — considerably faster than has occurred since 1990, but consistent with the pace of improvements observed between 1975 and 1990.

The role of CAFE standards and alternative-fuel vehicle production credits in U.S. biofuels markets

This paper investigates the impact of CAFE standards and alternative-fuel vehicle production incentives on the biofuel market and mandate, in particular. The study develops a structural model of the domestic light-duty vehicle sector, as well as reduced-form versions of domestic gasoline, diesel, and biofuel markets. The results suggest that holding CAFE standards at the 2010 level could facilitate U.S. ethanol market expansion, making it easier to meet the mandate. Alternative-fuel vehicle production incentives appear to have small effects. However, there is uncertainty about the level of automaker response to those incentives, and analysis indicates the model is fairly sensitive to the assumed level of response.

Mixed-Potential NOx and NH3 Sensors Fabricated by Commercial Manufacturing Methods

Meeting EPA Tier 3 emissions reduction requirements while simultaneously increasing fuel economy to meet new CAFE standards will require optimization of advanced combustion strategies and emissions control technologies. There is an immediate need for suitable exhaust gas sensor technologies to monitor internal combustion engine tailpipe emissions and to control and maintain efficient operation of the engine and exhaust after treatment systems. NH3, NOx, and HC sensors could enable onboard diagnostics and combustion control in lean-burn engines, analogous to the role of O2 sensors in stoichiometric burn engines. Commercial manufacturing methods have been used to fabricate self-heated mixed-potential sensors in a planar automotive configuration. By altering materials composition and operating conditions, we are able to obtain sensitivity/selectivity to each NH3, NOx and HCs. Additionally, these devices exhibit stable performance over months of testing as a result of the stable morphology of the electrode/electrolyte/gas three-phase interface.

To Sell and to Provide? The Economic and Environmental Implications of the Auto Manufacturer's Involvement in the Car Sharing Business

Several auto manufacturers have recently introduced car sharing programs. Although the structure of most programs is the same, there is no clear dominant strategy regarding the type of vehicles OEMs should provide through car sharing. In this paper, we consider an OEM who contemplates car sharing and designs its product line by accounting for the trade-off between driving performance and fuel efficiency under CAFE standards. Customers have different valuations of driving performance and decide whether to buy, join car sharing, or rely on their outside option. We find that the OEM increases the fuel efficiency of the vehicles it provides through car sharing. This higher efficiency enables the OEM to charge a higher selling price to the higher end of the market, increasing its profit from selling. This is especially beneficial to higher-end OEMs who face greater cannibalization and can explain why Daimler and BMW have been particularly active in introducing car sharing. Offering car sharing is not always environmentally beneficial. Even when it is, we find that doing so may reduce the OEM's CAFE level. In such cases, incentive multipliers should be granted for each shared car. Finally, if anticipating aggressive CAFE standards, OEMs may introduce car sharing to better absorb the increase in the production cost.

Metropolitan density, energy efficiency and carbon emissions: Multi-attribute tradeoffs and their policy implications

Of all the potential benefits of urban containment, compaction, and densification, just two are the central focus here: attainment of greater energy efficiency and reduction in carbon emissions. In cities these are largely associated with the transport and building sectors. This paper probes the form-efficiency relation in the transport sector across 57 census-defined urbanized areas in the United States in 2000. Thirty-six of the forty largest are included. Increase in core area population density is correlated with modest gain in energy efficiency in the urban transport sector and modest decrease in its carbon emissions. Densification's lagged effects related to travel rationalization and growth in transit receptivity may increase overall metro transport energy efficiency beyond the degree revealed here. These impacts are associated with two off-setting negative externalities: (1) diminished housing affordability, and (2) increased roadway congestion. Each may moderate over time. Such effects are non-additive, owing to a difference of metrics. Elevated CAFE standards provoking new transport technologies may reduce total energy consumption and associated emissions ceteris paribus, lessening densification's marginal efficiency payoff while magnifying the significance of densification's opportunity costs. Categories of policy interventions to promote metro-scale energy efficiencies and emissions reductions, with and without urban densification, conclude the paper.

Net Air Emissions from Electric Vehicles: The Effect of Carbon Price and Charging Strategies

Plug-in hybrid electric vehicles (PHEVs) may become part of the transportation fleet on time scales of a decade or two. We calculate the electric grid load increase and emissions due to vehicle battery charging in PJM and NYISO with the current generation mix, the current mix with a $50/tonne CO(2) price, and this case but with existing coal generators retrofitted with 80% CO(2) capture. We also examine all new generation being natural gas or wind+gas. PHEV fleet percentages between 0.4 and 50% are examined. Vehicles with small (4 kWh) and large (16 kWh) batteries are modeled with driving patterns from the National Household Transportation Survey. Three charging strategies and three scenarios for future electric generation are considered. When compared to 2020 CAFE standards, net CO(2) emissions in New York are reduced by switching from gasoline to electricity; coal-heavy PJM shows somewhat smaller benefits unless coal units are fitted with CCS or replaced with lower CO(2) generation. NO(X) is reduced in both RTOs, but there is upward pressure on SO(2) emissions or allowance prices under a cap.

Going Beyond CAFE Standards: Feebate Financing Incentives for Fuel Economy

Vehicle efficiency or emission standards such as U.S. CAFE standards and California's Pavley standards have only been able to motivate a fraction of the technology investments in efficiency that would be cost-effective based on fuel savings alone. Vehicle feebates could create technology-development incentives that are not limited by any predetermined performance standard; but it may not be practicable or politically feasible to create feebate incentives approaching the limits of feasibility and cost effectiveness because of the wealth transfer that feebates create between low- and high-efficiency vehicles. This paper proposes a feebate-type vehicle financing program that combines loans for fuel-efficient vehicles with refundable fees on inefficient vehicles to create regulatory incentives far surpassing CAFE standards. The program would be revenue-neutral within the regulated sector and would not impose long-term revenue transfers between vehicle owners or manufacturers. In essence, it would operate to internalize the lifecycle benefits of fuel-efficient vehicle technologies, and the lifecycle costs of inefficient vehicles, in upfront vehicle prices, so that consumers fully consider long-term operating costs in their vehicle choice preferences.