Collaboration in Civic Spheres

U.S. Model Estimates Green Car Costs Per Mile

by Andrew Hart April 12th, 2011

SUMMARY: Assuming that new technical and business strategies can be successfully adopted to accelerate transition to electric and hybrid electric vehicles, the potential long-term savings to consumers could be substantial. The National Renewable Energy Laboratory of the U.S. Department of Energy has developed a model for assessing the relative operating costs of a conventional vehicle, a hybrid-electric, a plug-in hybrid electric and an all-electric vehicle. The model yields an estimate of “levelized cost per mile” for a mid-size vehicle in each category, factoring in vehicle and component cost, battery and fuel prices, location, driving behaviors, charging costs, and infrastructure requirements. Predicted miles per gallon or equivalents are 26 to 32 for a conventional vehicle; 35 to 44 for a hybrid electric vehicle; 95 to 135 for an all-electric vehicle; and for the plug-in hybrid electric, 54 to 74 on gas and 263 to 327 when operating on electricity alone. 

BACKGROUND:

  • Around the world, countries are calling for innovation in the transportation sector to reduce dependence on fossil fuels and curb green house gas (GHG) emission. Of particular interest have been electric vehicles (EV) and other alternatives to conventional gas-powered vehicles (CV). But obstacles have prevented mass adoption: high prices of batteries, long refueling time, and lack of infrastructure.
  • Introducing battery technology into vehicles and the energy infrastructure would lead to significant petroleum reduction and cost to the EV driver. While there are several proposals for making EVs more practical, it has been difficult to compare the options due to their differences. The NREL developed the Battery Ownership Model (BOM) to evaluate the various strategies. The dynamic model calculates the cost of vehicle ownership under various scenarios: vehicle and component cost, battery and fuel prices, location, driving behaviors, charging costs, and infrastructure requirements. The result is a “levelized cost per mile” (LCPM).

KEY DOCUMENT: “Battery Ownership Model: A Tool For Evaluating The Economics Of Electrified Vehicles And Related Infrastructure,” National Renewable Energy Laboratory, U.S. Department of Energy; January, 2011

KEY FINDINGS:

  • For the study, the NREL compared the LCPM for sample pure electric vehicles (EVs), conventional gasoline-powered vehicles (CVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs).
  • The results of the model show that “there are scenarios where HEVs, PHEVs, and even EVs can be less expensive than CVs, and it highlights which parameters have the largest influence over the vehicle levelized cost per mile.”
  • The model presents a scenario assessing the LCPM for a mid-size vehicle of four different power-train options: a CV, HEV, a PHEV with 40 miles of electric range (PHEV40), and an EV with 100 miles of electric range (EV100). For all, the vehicle is assumed to be owned for 15 years and have a similar initial cost. The design variables include: cost for GHG emissions in dollars per ton of CO2 equivalent emitted per year; the amount of federal tax incentive offered to buyers of the EV100 and PHEV40; the Energy Information Administration gasoline forecast scenario used: reference or high-oil price case; the annual VMT per year; the magnitude of accessory loads on the vehicle from 0.7 to 2.2 kW; the battery energy cost coefficient; and the battery life coefficients representing different battery life curves.
  • “Over the range of design variables examined, the model predicts fuel economy to be between approximately 26 and 32 mpg for the CV, 35 and 44 mpg for HEV, and between 248 and 353 Watts-hours per mile (WH/M) or 95 to 135 mpg for the EV100,” based on the conversion formula of 33,705WH/gallon. The model predicts that the PHEV40 has aggregate fuel consumption between 54 and 74 mpg gasoline; and 103 to 128 WH/M on electricity-only, or 263 to 327 mpg.
  • The model showed that accessory load is a major factor behind the change in fuel consumption rate of EVs, and an EV with a 100-mile electric range was found to be most sensitive to battery cost and cycle life.

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