Vehicle Energy Use

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Vehicle Energy Use

• Mark Schipper
• Energy Information Administration
• American Statistical Association
• Committee on Energy Statistics
• October 20, 2005

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Acknowledgements

• Federal Highway Administration, U.S.DOT
• National Highway Traffic Safety Administration,
  U.S. DOT
• Bureau of Transportation Statistics
• Oak Ridge National Laboratory, Center for
  Transportation Analysis, U.S. Department of
  Energy (ORNL)

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Energy Use by End-Use Sector
Transportation sector use of energy experienced
tremendous growth overall, but registered
noticeable pauses in 1974, 1979-1982, 1990 and
1991, and 2001. In 2004, petroleum accounted for
97 percent of the sectors energy, and motor
gasoline accounted for two-thirds of all
petroleum used in the sector.
Transportation
Industrial
Commercial
Residential
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Why were we interested?

• EIAs Surveys on the Demand-Side of the Energy
  Equation Residential Buildings, Manufacturing
  Plants, Commercial Buildings
• Residential Transportation (known as RTECS) was
  conducted in 1983, 1985, 1988, 1991, and 1994
  then discontinued
• Investigate using 2001 National Household Travel
  Survey as a replacement for discontinued data
  series next release NPTS 2008 (?)

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What we did Augmented NHTS

• Vehicle-Level Data
• Fuel Economy (mpg)
• Fuel Type
• Energy Consumption (equivalent gallon)
• Energy Price (cents per equivalent gallon)
• Energy Cost ( per year)
• Energy Consumption
• EIA On-Road, In-Use mpg-1 x vmt

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Data Sources

• Fuel Economy
• NHTSA Corporate Average Fuel Economy program
• EIA data/experts on pre-78 model years
• Fuel Prices (month by state)
• EIA Monthly Supplier Surveys
• Form EIA-782A, Refiners/Gas Plant Operators
  Monthly Petroleum Product Sales report, and
• Form EIA-782B, Resellers/Retailers Monthly
  Petroleum Product Sales Report
• Federal, State and Local Excise Taxes (FHWA)

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Schema for Estimating Energy and Energy-Related
Statistics, 2001
From NHTS/EIA Vehicle-Miles Traveled (VMT)
From EPA/NHTSA Fuel Economy (MPG)
From EIA Retail Fuel Price (DPG)
1) Select Vehicle 2) Adjust Fuel Economy to
On-road, In-use Values
Merge
Merge
Vehicle Fuel Consumption VMT During
Possession/MPG
Vehicle Fuel Expenditures DPGGallons
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Linking 1 to Many
Volkswagen, Jetta, 2001, Auto, ??.?
MPG 45/55
Volkswagen, Jetta, 2001, Auto, 44.8 Volkswagen,
Jetta, 2001, Auto, 26.3 Volkswagen, Jetta, 2001,
Auto, 52.6 Volkswagen, Jetta, 2001, Auto,
29.4 Volkswagen, Jetta, 2001, Auto,
29.2 Volkswagen, Jetta, 2001, Auto,
25.1 Volkswagen, Jetta, 2001, Auto,
31.7 Volkswagen, Jetta, 2001, Auto,
31.4 Volkswagen, Jetta, 2001, Auto,
31.3 Volkswagen, Jetta, 2001, Auto, 29.5 Source
NHTSA, CAFE Program A. Berkowitz.
Select One
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Linking Results
High
Presumed Imputation Quality
Low
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Adjusted Fuel Economy

• On-Road, In-Use Fuel Economies Differ from EPAs
  Unadjusted 45/55 Combined Estimates
• Adjust for On-Road Shortfall (Hellman and
  Murrell, 1985)
• Adjust for In-Use (Crawford, 1983)
• Details www.eia.doe.gov/emeu/rtecs/nhts_survey/200
  1/index.html
• Verified in 1991 and 1994 RTECS

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Adjustment Equations for Vehicle i in Month j
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Example of MPG Adjustments (Composite MPG 25.1)
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Sensitivity Analysis and Guidance

• Various Selection Routes versus Single Value
  Selection
• Sales-Weighted Value of Fuel Economy
• Lowered Consumption by 2 percent
• Maximum Fuel Economy 95th Percentile
• Lowered Consumption by 9 percent
• Minimum Fuel Economy 5th Percentile
• Raised Consumption by 7 percent
• Given these bounds, along with survey sampling
  and non-sampling errors, the use and usefulness
  of an enhanced NHTS should be evaluated against a
  researchers project requirements. (Authors
  Note)
• Interactive Tables for Data Quality, based on (1)
  Sample Counts and (2) Measures of Precision

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Working with NPTS 2008

• Verification of EIAs Adjustments (unlikely)
• Fuel purchase and travel diaries
• Minimize Imputation Errors (likely)
• Collect additional vehicle characteristics type
  of fuel, price paid for fuel, number of
  cylinders, Vehicle Identification Number (VIN)
  for more characteristics data
• Capture Vehicle Disposition Data (likely)
• CIPSEA ensures confidentiality and the enhanced
  ability to share data among some agencies (done)

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Questions for the Committee

• Do the extensive assumptions in creating this
  data set cause any concern about this as an
  official EIA data release
• Should EIA expend resources to do this again with
  the NPTS 2008
• If so, should EIA establish any ground rules with
  U.S. DOT before undertaking such work
• Improvements? Data, Methods, and so on.

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Thank you kindly for your time and attention

• Contact
• Mark Schipper (202.586.1136)
• mark.schipper_at_eia.doe.gov

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EPA Testing Protocols
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More EPA Testing Protocols

• The "city" program is designed to replicate an
  urban rush-hour driving experience in which the
  vehicle is started with the engine cold and is
  driven in stop-and-go traffic with frequent
  idling. The car or truck is driven for 11 miles
  and makes 23 stops over the course of 31 minutes,
  with an average speed of 20 mph and a top speed
  of 56 mph.
• The "highway" program, on the other hand, is
  created to emulate rural and interstate freeway
  driving with a warmed-up engine, making no stops
  (both of which ensure maximum fuel economy). The
  vehicle is driven for 10 miles over a period of
  12.5 minutes with an average speed of 48 mph and
  a top speed of 60 mph.
• Both tests are performed with the vehicle's air
  conditioning and other accessories are turned off.