Problems with the proposed CAFE Standards for 2020

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Problems with the proposed CAFE Standards for 2020

• Dennis Silverman
• Physics and Astronomy
• UC Irvine

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Introduction

• The Senate bill on the new CAFE standards for
  2020 mandates a fleet average of 35 miles per
  gallon (mpg) which includes both cars and small
  trucks (SUVs, trucks and vans).
• We will show here problems with the single fleet
  average in actually being able to increase the
  mpgs of small trucks.

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The problem of the total fleet average with very
efficient vehicles

• Some of the present hybrids are even now
  achieving 50 mpg ratings (Toyota Prius and Honda
  Accord hybrids).
• For each of those types made by an American
  automaker, they can preserve the total fleet
  average by making a 20 mpg SUV or small truck,
  since ½(5020)35 mpg.
• This SUV allowance is even lower than the present
  21.5 mpg group average for small trucks.
• One way around this problem is to exclude plug-in
  hybrids and electric cars from the average.

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Future plug-in hybrids or electric cars.

• Plug-in hybrids are projected to run 40 miles on
  pure battery power from the charge they acquire
  from utilities.
• In terms of greenhouse gases, utilities produce
  the electrical energy more efficiently than the
  internal combustion engines of present hybrids.
• Priuses that are outfitted as plug-in hybrids are
  said to obtain 70-75 mpg equivalent.
• Plug-in hybrids are estimated to exceed 100 mpg
  based on greenhouse gas emissions from utilities,
  while under the 40 mile all electric range.
• If the electricity is generated by nuclear,
  hydro, solar or wind power, than the greenhouse
  gas emissions are essentially negligible, and the
  effective mpg are well over 100 mpg.
• Because of this, it is hard to provide a single
  effective mpg for these vehicles. A national
  average based on the average greenhouse gases for
  the nations electricity supply could be used.

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CAFE ratings and super efficient plug-ins.

• I havent found an explication of how the NHSTA
  will decide on mpg ratings for plug-ins.
• Present tests are based on something like the
  first 12 minutes of driving, or the first 12
  miles of a drive.
• Since those ranges are covered by the electric
  charge, even natural gas powered utilities should
  give and effective mpg of 100 mpg.
• We assume this is included as the vehicle rating,
  until otherwise specified.
• The average American commute is under 30 minutes
  or miles. If recharged at work, the electric
  nature of the plug-in could completely cover a
  days driving.

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The problem with a single fleet average and the
super-efficient plug-ins.

• We use an example where each plug-in hybrid
  produced in America is rate as 100 mpg.
• Using the single fleet average, such a hybrid is
  65 mpg over the average.
• The average can then be balanced say by three
  SUVs or small trucks that get
• (35 - 1/3(65)) 35 22 13 mpg.

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The reaction of an environmental public

• By the time 2020 arrives, and without a wise
  rating or averaging policy by EPA, each
  environmentally minded citizen will know that his
  or her buying a super-efficient plug-in hybrid
  will be nullified by three purchasers of highly
  inefficient Hummer type SUVs or giant small
  trucks.
• This inequity should be fixed before the CAFE
  bill is passed by the full Congress.
• We discuss such fixes in the following slides.

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The fix for SUVs and small trucks

• It is better if SUVs and small trucks have their
  own average, whatever it is.
• Detroit has proposed a 35 mpg average for cars
  and a 30 mpg average for SUVs and small trucks.
  That should be a more safeguarded small truck
  average that is a real requirement on them.
• However, among the cars, the same unenvironmental
  countering of plug-in hybrids might occur with
  cars that are no more efficient than those that
  get the current 27.5 mpg average.

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A truer average based on the fuel consumed

• Most cars in America drive an average of 15,000
  miles per year.
• The gas that is consumed by a car or small truck
  is given by
• fuel miles driven x (gallons/mile)
• This contains the reciprocal of the miles/gallon
  ratio currently used.
• For simplicity, let us take this measure of fuel
  used in a 100 mile trip, and call it the CAFE
  Fuel Standard
• Then the sample plug-in hybrid at 100 mpg will
  give a fuel standard of unity
• fuel 100 miles / (100 mpg) 1

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The New Fuel Standard

• The typical vehicle at 35 mpg under the new fuel
  standard will be rated as
• fuel standard 100 / 35 2.86 or
  approximately 3. (Environmentally it is 3 times
  as greenhouse gas polluting as the best car
  available, the plug-in hybrid.)
• This would be the new fuel standard average for a
  100 mile trip that Congress or the states could
  adopt.

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Applying the Fuel Standard to the SUV example

• The example had a 100 mpg plug-in hybrid balanced
  by three 13 mpg SUVs under the 35 mpg average.
• Applying the fuel standard (fs), the 13 mpg SUV
  will have fs 100 / 13 7.7.
• Under a fuel standard average, the four vehicles
  above would average
• ¼ (1 3 x (7.7)) ¼ ( 24.1) 6.0
• not 3.0.

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What is the vehicle mpg that balances a plug-in
in the fuel standard?

• Take m as the mpg of the gas vehicle.
• For one gas vehicle to balance one plug-in giving
  an average fuel standard of 3
• fs ½(1100/m) 3 implies m 20 mpg.
• For two gas vehicles balancing one plug-in
• fs 1/3(12x100/m) 3 m 25.
• For three gas vehicles against one plug-in
• fs ¼(13x100/m) 3 m 27 mpg.
• For four gas vehicles balancing one plug-in
• fs 1/5(14x100/m) 3 m 29 mpg.

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How does balancing work out for a major part of
the fleet being plug-ins?

• From the previous slide, if 20 of the fleet are
  plug-ins, they are balanced 4 to 1, and the
  average requirement on gas vehicles is 29 mpg.
• If 25 of the fleet are plug-ins, the average
  requirement on the gas vehicles is 27 mpg,
  comparable to the present mpg average on cars.
• The above 3 gas to one plug-in balancing case
  used in the example with the present mpg
  averaging method only required gas vehicles to
  have a 13 mpg average.
• So we conclude that the fuel usage standard comes
  close to what the Congress intends to occur with
  enhanced CAFÉ standards.