New
Vehicle Technologies:
How
Soon Can They Make a Difference?
By
Nancy Stauffer, MIT Laboratory
for Energy and the Environment
MIT
transportation experts have some pragmatic projections that send a clear
warning: we must not be overly optimistic about how quickly changes
in vehicle technology can reduce America’s staggering consumption
of petroleum for transportation.
According
to their calculations, it will be some two decades before even moderately
improved technology vehicles will be on the roads in sufficient numbers
to make a difference. And the much-touted hydrogen fuel cell hybrid
vehicle is unlikely to be a common on-road sight for more than 50 years.
Given such long lead times, it is imperative that we begin to pursue
those changes immediately and aggressively.
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For
the past year, Professor John B. Heywood and graduate student Anup P.
Bandivadekar have been examining how various government policies may
affect long-term US petroleum use and emissions (see energy &
environment, January–June
2004). Among those policies are regulations that encourage development
of improved and new technologies for vehicles and fuels.
According
to a comprehensive life-cycle assessment by Dr. Malcolm A. Weiss, Professor
Heywood, and their colleagues, these improved and new vehicle and fuel
technologies promise to be far more energy efficient than today’s
vehicles are (see references 2 and 3).
But these technologies will not actually affect America’s energy
consumption until they come into widespread use, and predicting how
long that change will take is a challenge.
Vehicle
technologies have changed in the past. For example, fuel-injection systems
replaced carburetors, and engine cylinders began having four valves
instead of two—relatively minor changes that took about 15 years
to occur. The expansion of diesels from 15% to roughly 50% of the new
cars sold in Europe has taken about 20 years.
“But
for a new technology like the hybrid, there’s no prior example
case study that says it’ll take 15 years or 20 years,” said
Professor Heywood. “We haven’t made this large a change
in the last eighty-odd years. You have to go back to the 1920s for there
to be competition between significantly different types of propulsion
systems.”
So
how can one estimate the time needed for a technology to go from a not-ready-for-market
concept to a large enough fraction of the on-the-road fleet to make
a difference? As a framework for tackling the problem, Professor Heywood
and Mr. Bandivadekar divided the market-penetration process into three
phases.
First,
the technology must be developed to the point where it is market competitive.
Financial incentives from government may help; but in the end the cost,
performance, and convenience must be close enough to standard technology
that people will want to buy the new vehicle in significant numbers.
Next,
the new technology must grow from a modest fraction to a significant
fraction of new vehicle production. To achieve that expansion, a manufacturer
must use the new technology in numerous vehicle classes, say, compact
cars and SUVs and pickup trucks. Each application will require new components
(bigger batteries and motors, for example), so the company will need
to build new production facilities. Even more time-consuming is the
task of developing good designs for the different sizes and versions
of the new technology.
Finally,
the new technology must become a significant fraction of the on-the-road
fleet and—most important—of total miles driven in the United
States. The length of time required depends both on how many of the
new vehicles are being manufactured (the previous phase) and on the
typical lifetime of vehicles that are already in circulation (a determinant
of the potential market for new purchases).
Before
assessing specific technologies, the researchers had to define what
“a significant fraction” meant in phases two and three.
Professor Heywood stressed the importance of this definition. “We’re
trying to estimate ‘time to impact,’” he said. “We’re
not concerned with getting a few new vehicles out there but rather with
getting enough on the road to have an impact that in some ways you could
discern or measure.”
Guided
by previous research experience, they estimated that a new vehicle technology
would have a measurable impact on energy use when that technology is
responsible for about 35% of the total US miles driven. To permit that
level of market penetration, in phase 2 the new technology must be in
35% of the new vehicles produced.
The
table on page 1 shows the researchers’ assessment of four illustrative
vehicle technologies: an improved gasoline spark-ignition engine, a
diesel engine with improved fuel efficiency and very low emissions,
a gasoline spark-ignition-engine hybrid, and a hydrogen fuel cell hybrid
(with hydrogen stored onboard the vehicle).
The
researchers estimated that the time needed for the first phase is roughly
the same for the first three vehicle types. Each is about one “development
cycle”—roughly 5 years—away from becoming market competitive.
The hydrogen fuel cell is almost completely new technology, so the time
required for the first phase is considerably longer.
The
estimates in the second phase show more variation. Moving from improved
gasoline to cleaned-up diesel to gasoline hybrid to fuel cell hybrid,
the times become longer because the technologies become increasingly
different from those in use today. As a result, expanding production
to additional model types becomes more difficult.
The
third-phase estimates show less variation from technology to technology
but also increase as the technology becomes less familiar and production
buildup is slower. In all cases, the lifetime of vehicles already on
the road was assumed to be 15 years, the current average.
Finally,
the researchers added up the times required for each technology, then
subtracted a bit to account for overlap between the phases. The totals
tell a surprising story. The improved gasoline engine—a technology
that would seem relatively easy to develop and implement—will
take some 20 years to have impact. The diesel requires about 30 years,
the hybrid about 35 years, and the hydrogen fuel cell 50 to 60 years.
“I
think the value of our approach is that it helps us avoid the trap of
being overly optimistic as to how quickly through changes in technology—even
near-term technology—we can impact overall US vehicle fleet fuel
consumption,” said Professor Heywood. “The idea that hydrogen
will save us in the near term from our energy appetite is just nuts.
You have to go through these stages; and while you can say we’ll
get through each stage much faster, there’s no evidence that we’ve
ever done that before.”
The
researchers have presented their analysis to audiences at MIT, in the
automotive industry, and elsewhere; and the response has been supportive.
People commend the researchers’ new three-phase framework for
thinking about the market-penetration process. Industry personnel stress
the value of stepping back from near-term production challenges and
taking this broad, strategic view. And there have been few quibbles
with the numbers. Indeed, the researchers’ initial estimate for
the hydrogen fuel cell to become market competitive was 10 to 15 years.
But “just about everybody in the business said they’ll never
do it in 10 years,” so the lower number was dropped.
“The
point is not that the numbers are tightly accurate,” Professor
Heywood said. “The point is that these time scales are all long,
and some are very long. It adds urgency to the fact that we should start
trying to prompt these changes right away.”
John
B. Heywood is the Sun Jae Professor of Mechanical Engineering and director
of the Sloan Automotive Laboratory. Anup P. Bandivadekar is a Ph.D.
candidate in MIT’s Engineering Systems Division. Malcolm A. Weiss
is a visiting engineer in the Laboratory for Energy and the Environment.
This research was supported by the Alliance for Global Sustainability.
Publications are forthcoming.
References
Weiss,
M., J. Heywood, A. Schafer, E. Drake, and F. AuYeng. On the Road
in 2020: A Life-cycle Analysis of New Automobile Technologies.
LFEE Report No. EL 00-003. October 2000. (Ref. 2)
Weiss,
M., J. Heywood, A. Schafer, and V. Natarajan. Comparative Assessment
of Fuel Cell Cars. LFEE Report No. 2003-001RP. February 2003. (Ref.
3)
(Note:
This article was originally published in the March 2005 issue of energy
& environment, the newsletter of the MIT
Laboratory for Energy and the Environment.)
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