Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 53
3
Vehicle Subsystems
This chapter discusses the vehicle systems technology areas that the Part-
nership is addressing in its research and development (R&D) programs, which
include the following: (1) advanced combustion, emission control, and fuels for
internal combustion engines (ICEs); (2) fuel cells; (3) hydrogen storage onboard
a vehicle; (4) electrochemical energy storage or technologies for storing elec-
tricity onboard a vehicle; (5) electrical propulsion systems; and (6) materials
for reducing the weight of a vehicle. The reader is referred to the presentations
from the Partnership to the National Research Council’s (NRC’s) Committee on
Review of the U.S. DRIVE Research Program, Phase 4, on the various techni-
cal areas (Appendix D provides a list of the presentations to the committee at
its meetings). The presentations can all be found in the project’s Public Access
File, available through the National Academies Public Access Records Office.
Chapter 4 addresses issues associated with hydrogen, electricity, biomass-based
fuels, and natural gas.
ADVANCED COMBUSTION ENGINES, EMISSION CONTROL,
AND HYDROCARBON FUELS
Introduction and Background
It will take decades to develop and integrate non-internal combustion engine
propulsion systems into becoming a significant fraction of the total U.S. mobility
fleet. The internal combustion engine will be the dominant power plant for mobil-
ity systems for at least the next 20 to 30 years (NRC, 2008, 2010). Consequently
it is important to maintain a dedicated effort directed at ICE improvement within
the U.S. DRIVE research portfolio.
53
OCR for page 54
54 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
Furthermore, there is reason for optimism that the drive-cycle-based effi-
ciency of ICEs can be improved, both through engine-based advancements and
through hybridization, such that the fuel consumption of engine-powered vehicles
can be significantly reduced. Also, the engine has a sophisticated and mature
manufacturing basis and is capable of using a range of fuels, from petroleum
to liquid-based biofuels to gaseous fuels, derived from a variety of feedstocks.
Liquid fuels offer the attractive characteristic of having very high energy per unit
of mass and energy per unit of volume. This characteristic facilitates long-range
and/or sustained high-power-output vehicle operation. There will be, for many
decades, applications for which the ICE-powered vehicle is the best choice.
Life-cycle analyses reported in the literature, such as that shown in Fig-
ure 3-1, suggest that total greenhouse gas (GHG) emissions for future high-
technology ICE-powered vehicles1 will be made competitive with non-ICE-
powered vehicles on a basis of total GHG life-cycle emissions, while still meeting
stringent air quality regulations (Weiss et al., 2000; Bandivadekar et al., 2008).
Uncertainty bars in Figure 3-1 denote well-to-tank GHG emissions for electric-
ity generated from coal (upper bound) and natural gas (lower bound). For the
well-to-tank GHG emissions from hydrogen fuel cell vehicles (HFCVs; shown
as “FCV” in Figure 3-1), it is assumed that the hydrogen fuel is steam-reformed
from natural gas at distributed locations and compressed to 10,000 psi.
The advanced combustion and emission control (ACEC) technical team of
U.S. DRIVE is the Partnership’s technical interface with the research commu-
nity’s activities in advanced combustion and emission control. The goals, tech-
nical targets, and program structure of the ACEC technical team build on those
from the FreedomCAR and Fuel Partnership, which in turn built on the goals and
targets from the Partnership for a New Generation of Vehicles (PNGV). For the
FreedomCAR program, the advanced combustion and emission control targets
and results were as follows:2
• Peak engine brake thermal efficiency (BTE) of 45 percent
— his BTE was demonstrated with a light-duty diesel engine and an
T
H2-fueled ICE.
• Oxides of nitrogen (NOx) and particulate matter (PM) emissions for
light-duty diesel engines at Tier 2 Bin 5 (T2B5) standards
— welve vehicle models that met this target were commercially avail-
T
able in the 2012 model year (MY).
1 Hybrid electric vehicles and plug-in hybrid electric vehicles are included in this classification
because the engine still plays a major role as the energy converter between the fuel energy and work
delivered to the wheels.
2 R. Peterson, General Motors, and K. Howden, Department of Energy, “Advanced Combustion and
Emission Control Technical Team,” presentation to the committee, January 26, 2012, Washington,
D.C.
OCR for page 55
VEHICLE SUBSYSTEMS 55
FIGURE 3-1 Predicted comparative total greenhouse gas emissions for current spark
ignition engines (SIEs) and potential 2035 propulsion systems. NOTE: Acronyms are
defined in Appendix E. SOURCE: Bandivadekar et al. (2008).
• Power-train cost of $30/kW
— his cost target guidance and status are currently under evaluation by
T
U.S. DRIVE.
To push past the targets of the FreedomCAR and Fuel Partnership, the U.S.
DRIVE Partnership addressed three engine technology pathways: (1) hybrid
optimized (low-level power density), (2) naturally aspirated (mid-level power
density), and (3) downsized and boosted (high-level power density); it identified
engine efficiency metrics at three load conditions: peak efficiency; 2-bar brake
mean effective pressure (BMEP)—2,000 revolutions per minute (rpm); and 20
percent of peak load—2,000 rpm.
The specific 2020 stretch targets were set relative to 2010 MY engines for
each technology pathway. Table 3-1 shows a compilation of these targets for each
engine technology pathway for each of the three metric conditions. Standard fuels,
either gasoline or diesel, are considered in specifying the performance metrics.
For each of the three pathways being pursued to achieve the targets shown
in Table 3-1, the fundamental approach and issues being addressed are these:
1. High-efficiency combustion with low engine-out emissions
— Low-temperature combustion (LTC)
OCR for page 56
56
TABLE 3-1 Advanced Combustion and Emission Control Efficiency Baselines (2010) and Stretch Targets (2020)
2010 Baselines 2020 Stretch Targets
Efficiencya Efficiencya Efficiencyc
@ 2-bar @ 20% of @ 2-bar Efficiencyc
Peak BMEP and Peak Load Peak BMEP @ 20% of Peak
Efficiency 2,000 rpm and 2,000 rpm Peak Loadb Efficiency and 2,000 Load and
Technology Pathway Fuel (%) (%) (%) at 2,000 rpm (%)c rpm (%) 2,000 rpm (%)
Hybrid application Gasoline 38 25 25 9.3 46 30 30
Naturally aspirated Gasoline 36 23 23 10.7 43 28 28
Downsized boosted Gasoline 37 22 29 19 44 27 35
Diesel 40 26 32 21 48 31 38
aEntries in percent brake thermal efficiency (BTE).
bEntries in bar of brake mean effective pressure (BMEP).
cEntries in percent BTE that are equal to 1.2 times the corresponding baseline BTE.
SOURCE: R. Peterson, General Motors, and K. Howden, Department of Energy, “Advanced Combustion and Emission Control Technical Team,” presentation
to the committee, January 26, 2012, Washington, D.C.
REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
OCR for page 57
VEHICLE SUBSYSTEMS 57
— Dilute spark-ignited combustion
— Clean diesel
2. Improved efficiency with waste energy recovery
— Solid-state and mechanical approaches
— Improved air handling and lubricants
3. Efficient aftertreatment systems that reduce the energy penalty and meet
emissions regulations
— NOx, PM, hydrocarbons (HC), and carbon monoxide (CO)
At first glance the above list of technology pathways appears to focus
on development-type issues that would best be addressed by industry as part
of product development. However, the barriers to achieving the targets given
above are fundamental understandings of the controlling phenomena for each
pathway, and this is the focus of the U.S. DRIVE activities. The optimization
of the interaction among the following is very complicated: the ambient condi-
tions; the details of the gas exchange processes (intake and exhaust processes,
exhaust gas recirculation [EGR], boost, intercooling, manifold geometry, valv-
ing events, etc.); the in-cylinder processes (injection characteristics, in-cylinder
flow, combustion chamber geometry, fuel chemistry, etc.); and the exhaust-gas
aftertreatment system (PM traps, NOx reduction systems, CO and HC oxida-
tion systems, etc.) for minimum fuel consumption while meeting emissions
standards. To address these challenges, industry uses analysis-led design, in
which computational fluid dynamics (CFD) is used to predict the optimum
combinations of power-train system control parameters for each engine operat-
ing regime.
This process is only as good as the accuracy and fidelity of the CFD pro-
grams being used. Consequently, the lack of a detailed fundamental under-
standing of the various thermo-fluid-chemical processes and their incorporation
into CFD submodels is a barrier to further engine system optimization. Certain
aspects of the challenges that industry must deal with are not understood at this
time: for example, there is no accepted explanation for how lubricating oil is
involved in the particulate formation processes within the engine cylinder. This
is a relevant example of the importance of a lack of fundamental understanding,
because higher-efficiency engines will rely on controlled air-fuel heterogeneity
within the cylinder, which can lead to significant nanoparticle formation. Lack
of understanding of the detailed processes occurring in the combustion chamber,
like the particulate formation, subsequently impedes the optimization of engine
performance through simulation.
The engine combustion and emission research community is collaborating
with industry to address these fundamental issues through experiment and simu-
lation. To best duplicate the conditions in which to probe a deeper fundamental
understanding of these phenomena, researchers perform experiments and simula-
tions in representative engine geometries under real operating conditions.
OCR for page 58
58 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
The primary framework through which the U.S. DRIVE ACEC technical
team engages with research activities on combustion and emission controls is
through the U.S. Department of Energy’s (DOE’s) Office of Vehicle Technologies
Program (VTP). This office supports fundamental research in combustion, energy
recovery, and aftertreatment performance. Within these programs there is partici-
pation from industry, DOE national laboratories (Argonne National Laboratory
[ANL], the Sandia National Laboratories [SNL] Combustion Research Facility,
Oak Ridge National Laboratory [ORNL], Pacific Northwest National Laboratory
[PNNL], Lawrence Livermore National Laboratory [LLNL], and Los Alamos
National Laboratory [LANL]), and universities.
DOE’s vision of the collaborative activities between national laboratories,
universities, and industry is a progression from fundamental to applied research
to technology maturation and deployment. Fundamental R&D is the focus of
activities at the following:
• Sandia National Laboratories
— .g., Combustion Research Facility (lean-burn, LTC, advanced direct
E
injection)
• Pacific Northwest National Laboratory
— E.g., catalyst characterization (NOx and PM control)
• Argonne National Laboratory
— E.g., x-ray fuel spray characterization
• Lawrence Livermore National Laboratory
— E.g., chemical kinetics models (LTC and emissions)
• Los Alamos National Laboratory
— E.g., CFD modeling of combustion (KIVA code development)
• Universities
— Complementary research
The fundamental to applied bridging R&D is performed at the following:
• Oak Ridge National Laboratory
—
E.g., experiments and simulation of engines and emission control
systems (bench-scale to fully integrated systems)
• Argonne National Laboratory
— E.g., H2-fueled ICE, fuel-injector design
Finally, competitively awarded cost-shared industry R&D is done by the
following:
• Automotive and engine companies and suppliers
—
E.g., engine systems and enabling technologies (sensors, variable
valve actuation, waste heat recovery)
OCR for page 59
VEHICLE SUBSYSTEMS 59
The advanced combustion and emissions control program is well managed.
The organizational structure of its activities involves memoranda of understanding
between companies and government laboratories. It is usual for individual projects
to include one or more of the national laboratories, a university, and an industrial
partner. To ensure relevance, industry cofunding or matching is often required.
In addition to the regular research meetings within a specific project, two formal
research reviews are held each year, one at the Sandia Combustion Research
Facility in Livermore, California, and one at the U.S. Council for Automotive
Research (USCAR) in Southfield, Michigan. The researchers also participate in
the DOE Annual Merit Review.
Additional avenues for technical interchange are promoted through CLEERS
(Crosscut Lean Exhaust Emission Reduction Simulation) and the Engine Com-
bustion Network (ECN).
CLEERS sponsors monthly teleconferences and an annual workshop to pro-
mote the development of improved computational tools for simulating realistic
full-system performance of lean-burn diesel/gasoline engine and associated emis-
sion control systems. This activity helps in the development of emission control
models that are integrated into vehicle simulations for drive-cycle analysis within
the vehicle systems and analysis technical team (VSATT).
The ECN supports a website and teleconferences to share and leverage
research between experimenters and modelers on direct-injection fuel sprays
and combustion.
Overview of Technologies Being Investigated
To implement new combustion strategies, effective exhaust-gas energy recov-
ery, and aftertreatment systems that promote efficient engine operation, the air
handling, combustion, and exhaust subsystem must be optimized as a system.
Such optimization requires advanced computational fluid dynamics. It is now
common that the design of a new power-train system is led by CFD. To extract
increasingly better performance from the power train requires more accurate and
detailed computational models. These models are developed through the coupling
of fundamental experiments and computational submodel development. This is
the interface at which the U.S. DRIVE effort is focused.
In the area of high-efficiency combustion, the emphasis continues to be on
low-temperature combustion. LTC is in essence controlled knock, and it relies
on the auto-ignition chemistry of the fuel. Regardless of the fuel, the underlying
approach to achieving acceptable LTC is the same. One wants to get the fuel
vaporized and partially mixed with the cylinder gases such that when the auto-
ignition chemistry reaches the point of ignition, the energy release is volumetric.
Furthermore there needs to be sufficient inhomogeneity of the mixture within
the combustion chamber that the entire mixture does not auto-ignite all at once,
which would lead to excessive rates of pressure rise. This inhomogeneity can be in
OCR for page 60
60 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
temperature, air-fuel ratio, or degree to which the local mixtures have kinetically
traversed their auto-ignition pathway. If this is achieved, the engine efficiency is
higher and the in-cylinder emissions are very low. The approach taken to control
LTC will be dependent on the fuel type—gasoline-like, diesel-like, or dual fuels—
and the load demanded of the engine. Since the NRC (2010) Phase 3 review of
the FreedomCAR and Fuel Partnership carried out in 2009, five new combustion
projects have been started to address these challenges.
Regardless of how efficient the engine is, there will always be some usable
energy in the exhaust that leaves the cylinder. As the engine efficiency gets
higher, the usable energy in the exhaust gets smaller. Thermodynamically, it is
known that as the portion of recoverable energy in the exhaust decreases, the
efficiency of an exhaust-gas energy recovery system also decreases. However, in
the quest to maximize engine efficiency, gains can still be made by the inclusion
of exhaust-gas energy recovery systems. This imposes challenging constraints
on the cost-benefit assessment of implementing energy recovery systems in
the exhaust, and on maintaining a highly efficient exhaust-gas aftertreatment
system.
The fundamental research being pursued on exhaust-gas energy recovery
within the ACEC technical team is to develop energy recovery systems that
maximize the conversion of usable exhaust energy in ways that are economically
viable. Research programs addressing exhaust-gas energy recovery involve elec-
tricity generation with thermoelectrics, as well as more efficient turbomachinery
and air handling. In addition, work is being supported on advanced lubricants,
improved friction management, and materials for higher operating pressures and
temperatures.
Within the aftertreatment research programs, there are activities on devel-
oping efficient catalysts that operate at lower exhaust temperature, improved
NOx and PM aftertreatment systems, reducing the platinum group metal (PGM)
requirement for the aftertreatment systems, and combining multiple aftertreatment
systems into a single unit.
The predictive capabilities of the current CFD programs are good. The
simulation code used most widely at this time is KIVA III, developed by DOE.
KIVA is an open-source-code program, which allows researchers to incorporate
new understanding directly into the code for any aspect of the thermophysical
processes occurring within the engine. For example, improved kinetic schemes
for different fuel types or new submodels that more accurately represent liquid
fuel-combustion chamber surface interactions can be implemented into the code
and then exercised for more detailed predictions of combustion results. How-
ever, KIVA III is more than 12 years old and lacks important, modern numerical
technologies such as parallel computing and using an object-oriented structure.
Having an up-to-date, open-source CFD program for researchers to use is a criti-
cal aspect of achieving the improvement potential of the ICE and aftertreatment
power trains.
OCR for page 61
VEHICLE SUBSYSTEMS 61
The DOE is supporting work on a new version of the code, KIVA IV. To
date the code has not been widely adopted. Discussions of committee members3
with academic users led to a list of possible reasons for the code not being widely
adopted:
• A code with KIVA IV’s level of physics and geometry (engines) needs
to be modular and needs to have a data structure that is object-oriented.
• The current effort allocated does not appear to provide the level of
development support required for doing an acceptable job—an increased
effort was suggested by academic users and submodel developers.
• Code development for KIVA needs to be strongly tied to the activities
of its “customers,” which are predominantly the universities where the
advanced submodels are being developed and implemented.
• Intellectual property (IP) issues associated with the code and submodels
may be jeopardizing the open-source designation. If this key element
is lost, the university following could disappear, which seems to be
happening.
Perhaps if a more active interface could be established between researchers
working on the code development, university and research groups developing
submodels, and industry partners, who will be the ultimate users of the code, the
adaptation of the new code could be expedited.
The energy companies continue to be engaged, and the program of Fuels
for Advanced Combustion Engines (FACE), organized under the Coordinating
Research Council (CRC), is supplying an important database for quantifying
the impact of fuel characteristics on engine emission processes and alternative
combustion process facilitation.
In response to questions from the committee, U.S. DRIVE Partnership offi-
cials commented that natural gas is not included in the Partnership’s technical
scope. The committee believes that in light of the increased supply of natural gas
and the high interest in using it to displace petroleum, an assessment should be
made of whether natural gas is in any way an enabler for achieving U.S. DRIVE
goals. For example, does natural gas facilitate the advanced combustion modes
under investigation within U.S. DRIVE?
The ACEC technical team’s responses to the recommendation of the previous
review were good. The team is continuing to look for opportunities to enhance
collaboration and has a program in KIVA code development. As discussed above,
the committee believes that the KIVA code development effort could be improved.
The ACEC technical team is making more use of the vehicle simulation that
is being developed by the VSATT, and although it is not engaged in biofuels
research, the team is aware of activities in the field. Also, the approach being
3 In particular, David Foster, committee member, had discussions with academic users.
OCR for page 62
62 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
FIGURE 3-2 Department of Energy advanced combustion engine research and develop-
ment (R&D) funding—FY 2010 to FY 2012. SOURCE: R. Peterson, General Motors, and
K. Howden, Department of Energy, “Advanced Combustion and Emission Control Techni-
cal Team,” presentation to the committee, January 26, 2012, Washington, D.C.
taken within the ACEC technical team’s programs in developing kinetic models
for combustion process simulation is compatible with the inclusion of compo-
sitional changes that could occur to the fuel when biomass-derived compounds
are blended with the fuel.
Funding
Even though the U.S. DRIVE Partnership’s ACEC technical team does not
exercise control over a budget, it did offer to the committee an overview of the
DOE funding within the advanced combustion and emission control programs for
FY 2010 through FY 2012 (see Figure 3-2).
Within the scope of the U.S. DRIVE goals, the work allocation for the
continued development of the ICE and vehicle electrification seems appropriate.
OCR for page 63
VEHICLE SUBSYSTEMS 63
Accomplishments
This section presents a summary of accomplishments related to R&D activi-
ties in the areas of advanced combustion, emission control, and fuels for internal
combustion engines.4
Low-temperature combustion has proven to be an effective means of improv-
ing closed-cycle efficiency and reducing the formation of NO x and particulates.
By reducing the formation of NOx, both the cost and the complexity of additional
aftertreatment can be reduced. The benefits of LTC are known, and include dra-
matic reductions in the formation of NOx. However, controlling the in-cylinder
processes leading to successful LTC operation is a challenge. The ACEC technical
team has demonstrated a number of successes both in the control of LTC and in
expanding its operational range within the engine duty cycle.
One example of this success is a project at ANL where researchers were
able to use 87 research octane number (RON) gasoline in a 1.9-liter turbocharged
engine while retaining a full load range and diesel levels of efficiency with sub-
stantially reduced NOx.
The Sandia National Laboratories achieved indicated thermal efficiencies as
high as 48 percent by using partial fuel stratification in a boosted homogeneous
charge compression ignition (HCCI) engine.
The ORNL has a project using E85 (a mixture of 85 percent ethanol and
15 percent gasoline) in a spark-assisted HCCI engine. A 17 percent increase in
indicated thermal efficiency was achieved as compared to that of gasoline and
over a wide range of loads.
The use of two fuels, while adding some complexities and costs, also adds
to the capabilities of controlling combustion and emissions. Reactivity controlled
compression ignition (RCCI) engines involve the in-cylinder blending of two
fuels with differing reactivity in order to tailor the reactivity of the fuel charge.
Researchers at ORNL and the University of Wisconsin have used a diesel/gasoline
multicylinder engine RCCI to demonstrate efficiencies up to 5 percent greater
than diesel efficiencies. To better understand how dual fuels provide the benefits,
fuel mixing and RCCI combustion were imaged from inside an optical engine by
researchers at SNL and the University of Wisconsin.
In other combustion research approaches, researchers from ANL, SNL, and
the Ford Motor Company, using advanced direct injection of hydrogen, were
able to achieve 45.5 percent peak brake thermal efficiency of a hydrogen-fueled
ICE. Further, it is expected that minimal exhaust aftertreatment will be required
to meet stringent emission goals. The researchers were also able to demonstrate
a part-load efficiency of 31 percent while meeting T2B5 emissions standards.
4A full summary of accomplishments can be found in U.S. DRIVE Highlights of Technical
Accomplishments: 2011, available at http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/
2011_usdrive_accomplishments_rpt.pdf.
OCR for page 101
VEHICLE SUBSYSTEMS 101
in this program; however, there is no significant effort to benchmark the target
improvements of these projects over inverters employed in production vehicles
that use electric propulsion.
A proposed project is investigating the use of the same power switching
devices for both the charger and the inverter. AC Propulsion is already marketing
such a system, and it is being used in the Tesla and BMW Mini electric vehicles.
It is hoped that the proposed project endeavors to improve on these production
systems.
Electric Motors
The cost of rare earths used for permanent magnets has increased substan-
tially, some by as much as an order of magnitude,25 in the past few years, and the
Partnership has initiated projects to develop magnets without, or with a minimum
of, rare earths. Extensive research on this subject is being done at the national
laboratories. It is too early to evaluate the results, but this activity should be
encouraged. Recently Mitsubishi has claimed success with magnet alloys with 1
to 4 percent rare-earth content with performance comparable to the magnets in
the Prius, which contain approximately 10 percent rare-earth. 26
There is also a need for improved soft magnetic materials. Soft magnetic
materials, which are used in motors, inductors, and transformers with higher per-
meability, high flux density, and low loss, are needed. The standard for decades
has been high-silicon steel with a maximum of 4 percent Si. More recently a
Japanese company27 has developed a new process for making 6.5 percent Si,
which will have lower loss but perhaps lower peak flux density. The suitability
of this development needs to be determined.
The program is also investigating new permanent-magnet motor designs. A
possible design uses open slots to facilitate the insertion of formed coils, reduc-
ing costs and reducing resistance loss but increasing eddy current losses on the
magnets. It is hoped that this and other such projects bring about improvements
over production motors used in hybrid vehicles on the road. In the Phase 3 report
(NRC, 2010), it was recommended that induction motors for electric propulsion be
investigated. Several hybrid vehicles on the road, such as the GM Buick LaCrosse,
Tesla, and BMW, are using induction motors. Thus it may be worthwhile to com-
pare induction and permanent-magnet motors to determine the relative efficiency
and cost trade-offs for the two systems. Switched reluctance motors are also being
investigated; however, acoustical noise continues to be an issue with this design.
25 See, for example, http://www.ft.com/intl/cms/s/0/751cab5a-87b8-11e0-a6de-00144feabdc0.html
#axzz28AaO9ofv.
26 SAE, 2012, Powertrain Electric Motors Symposium for Electric and Hybrid Vehicles (April 20,
2012).
27 JFE Steel Hibiya Kokusai Building, 2-3 Uchisaiwaicho 2-chome, Chiyodaku, Tokyo 100-0011,
Japan; see http://www.jfe-steel.co.jp/en/.
OCR for page 102
102 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
On the other hand, ASEA-Brown Boveri claims that a synchronous reluctance
motor has a better efficiency than an induction motor at smaller sizes.
Thermal Management
Heat removal from the silicon chip is a key determinant of the efficiency
and size of the power electronics; thus thermal management plays an important
role in meeting the program targets. Furthermore, matching differential expan-
sion between the silicon chip and the (typically) aluminum heat sink is a tough
problem, especially over the temperature range of –40°C to 200°C. There are
many ways to minimize the thermal resistance from the silicon to the heat sink.
One alternative is to use only aluminum and no copper plates to remove the heat.
Other techniques consist of using direct sintering or double-sided cooling. The
Oak Ridge National Laboratory claims to build a small, high-efficiency, planar
bonded power electronic module for improved thermal management (Olszewski,
2011).28 A study to evaluate and compare the various alternative techniques and
their relative merit to production units would be appropriate.
The Nissan Leaf battery is air cooled, and other vehicles use liquid cooling.
For example, the Volt uses a 50/50 mix of ethylene glycol for cooling the battery
and possibly the inverter, whereas other vehicles use transformer oil.
Traction Drive System
The emphasis on the traction drive system in this program seems to be on
components rather than on investigating the traction drive as a system. In fact,
a thorough systems analysis of the traction drive may result in more optimized
targets for the necessary components. Such an analysis is highly encouraged.
For example, it may be possible to trade off the cost of improving the motor
efficiency versus increased battery cost. The electric motor efficiency is targeted
to be 95 percent or higher over a range of torque of 20 to 100 percent and over
speeds of 10 to 100 percent. Such high efficiency over such a wide range of load
seems overly ambitious. It may be more cost-effective to improve the battery
performance by 2 percent compared to the cost of raising the drive efficiency
from 93 percent to 95 percent.
Also, there seems to be little work on “less costly mild hybrids.” Recently
GM started selling the Buick LaCrosse Hybrid (Hawkins et al., 2012) with great
improvements in the Environmental Protection Agency’s fuel economy (in miles
per gallon) ratings.29 This remarkable result was achieved by a systems approach
in which hybridization includes aggressive fuel cutoff during decelerations and
stop-start.
28J. Czubay, General Motors, and S. Rogers, Department of Energy, “Electrical and Electronics
Technical Team,” presentation to the committee, January 26, 2012, Washington, D.C.
29 See http://www.fueleconomy.gov/feg/hybridCompare.jsp.
OCR for page 103
VEHICLE SUBSYSTEMS 103
Significant Barriers and Issues
Although electric machines and power electronics have been developed for
many years for a variety of commercial applications, there are significant barriers
to their utilization in electric drive vehicles, including BEVs, HEVs, PHEVs, and
HFCVs. Barriers include inadequate efficiency and inadequate volumetric and
gravimetric power density, and, most importantly, excessive costs.
As discussed, a significant issue with this program is a lack of a thorough
systems analysis of the complete traction drive system. Such an analysis not
only would guide the program to which activity will provide the best results, but
also would provide more optimized targets for efficiency, weight, volume, and
cost for the various components constituting the system. Ideally, this should also
include the battery, fuel cell, and internal combustion engine, so that the whole
system can be optimized, and would involve separate analysis and targets for
HEVs, PHEVs, BEVs, and HFCVs.
As noted, significant improvements in various components and systems are
being made at the national laboratories in this program. However, not much of this
effort is finding its way to commercial applications. Also, establishing a supplier
base for the large number of components involved in building an electrical drive
system is warranted.
Response to Recommendations from Phase 3 Review
NRC Phase 3 Recommendation 3-19. The Partnership should continue to
focus on activities to reduce the cost, size, and losses in the power electronics
and electrical machines. [NRC, 2010, p. 105.]
U.S. DRIVE seems to have pursued this recommendation. Prime examples
are the GM, Delphi, and GE contracts that have improved on the state of the art.
NRC Phase 3 Recommendation 3-20. The Partnership should conduct a
project to evaluate the effect of battery charging on lithium-ion battery packs
as a function of the cell chemistries, cell geometries, and configurations in the
pack; battery string voltages; and numbers of parallel strings. A standard-
ized method for these evaluations should be developed to ensure the safety
of battery packs during vehicle operation as well as during plug-in charging.
[NRC, 2010, p. 105.]
The committee believes that this recommendation needs more attention.
There is no evidence that the Partnership considered how high-rate charging
affects the life of the battery.30 This issue needs to be addressed together with the
30 The following inaccurate and factually wrong sentence was removed from the report: “It is
particularly surprising that nothing seems to have been done regarding safety even after the fires
developed on the Volt in mid-2011.”
OCR for page 104
104 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
electrochemical energy storage team and affects not only the charging regimen
but also the monitoring and equalizing of the voltage of the cells. The role of the
electrical and electronics technical team would be to specify the charging rates;
presumably it can meet the need. Lithium-ion batteries have a history of causing
fires in several instances. In addition to safety, there is a need to worry about bat-
tery life, especially with “fast charging” at 440 V. The committee believes that
continued work in this area is important and that the U.S. DRIVE Partnership
should revisit Phase 3 (NRC, 2010), Recommendation 3-20.
NRC Phase 3 Recommendation 3-21. The Partnership should consider
conducting a project to investigate induction motors as replacements for the
permanent-magnet motors now almost universally used for electric propul-
sion. [NRC, 2010, p. 105.]
U.S. DRIVE seems to have relied on preliminary findings from an ongoing
DOE motor assessment indicating that induction motors will not meet its targets.31
This is interesting in that a mild hybrid vehicle (2012 Buick LaCrosse using the
eAssist mild hybrid system) on sale by one of the Partnership’s partners demon-
strated great improvement in fuel consumption, as discussed above. Clearly other
factors contributed, but induction motors will meet some of the targets. Also, one
of the new partners, Tesla, uses an induction motor in its vehicles. BMW also
uses induction motors in some of its BEVs.
Appropriateness of Federal Funding
There is tremendous interest in electric propulsion worldwide, and a great
deal of money is spent on improving the state of the art. However, HFCVs, BEVs,
PHEVs, and even HEVs are unlikely to capture a significant share of the market
unless dramatic improvements take place in all elements of the drivetrain. In addi-
tion to the battery and fuel cell systems, which are discussed in other sections of
this report, the cost, volume, and weight of power electronics and motors need
significant breakthroughs. The Partnership is focusing on these three areas, which
are interdependent. For example, better cooling of electronics reduces not only
cost but also volume and weight; integrating the motor and electronics reduces not
only cost but also volume; replacing rare-earth magnet materials has the potential
of significantly reducing cost, although volume and weight may go up. Most of
the funding goes to national laboratories, which will produce fresh thinking that
would complement industry efforts, while the Partnership combines the best
thinking of both. The fact that the electric propulsion components are used for
all types of electric drive vehicles makes this a very strategically attractive R&D
31 J. Czubay, General Motors, and S. Rogers, Department of Energy, “Electrical and Electronics
Technical Team,” presentation to the committee, January 26, 2012, Washington, D.C.
OCR for page 105
VEHICLE SUBSYSTEMS 105
investment and, in the committee’s view, the government has an appropriate role
in helping with the introduction of electric propulsion and providing the United
States with leadership.
Recommendations
Recommendation 3-14. The U.S. DRIVE Partnership should leverage the vari-
ous investigations on wide-band-gap materials such as silicon carbide (SiC) and
should determine how best to utilize these in power electronics for vehicular
applications.
Recommendation 3-15. The U.S. DRIVE Partnership should determine the
potential and limitations of designing motors with permanent-magnet materials
using less rare earth metal.
Recommendation 3-16. The U.S. DRIVE Partnership should make a comprehen-
sive assessment of the various methods available (some of these are discussed in
the section titled “Thermal Management” in this chapter) to reduce the thermal
resistance between the chip and the heat sink and establish their relative value to
existing techniques in production vehicles.
MATERIALS
Goals and Challenges
A critical component of any automotive manufacturer’s strategy to reduce
fuel consumption and meet increasingly stringent Corporate Average Fuel Econ-
omy (CAFE) standards and greenhouse gas emissions requirements is to reduce
vehicle weight. For example, DOE has estimated that a 10 percent reduction in
vehicle weight can result in up to a 6 to 8 percent improvement in fuel economy.
Consequently, the U.S. DRIVE materials technical team (MTT), like the Freedom-
CAR and Fuel Partnership before it, has adopted a stretch goal of 50 percent
reduction in vehicle weight (versus 2002 comparable vehicles) with equal afford-
ability (emphasis added). Previous committees (NRC, 2008, 2010) found this goal
unrealistic, and it remains so today.
Nevertheless, reducing vehicle weight is important, and doing so at the least
incremental cost, while challenging, is worthy of pursuit, since achieving the 50
percent goal would result in up to a 35 percent fuel economy improvement. The
DOE has developed a roadmap for a 30 percent weight reduction by 2025, which,
if achieved, would result in up to a 21 percent fuel economy improvement.
One factor that potentially assists with the task of major weight reductions
is that of mass decompounding. That is, a reduction of weight in basic vehicle
structure permits secondary weight reduction in brakes, suspension, power
OCR for page 106
106 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
train, and other components. The materials technical team has estimated that
each 1.0 lb of primary weight reduction may enable 1.0 to 1.5 lb of secondary
weight reduction, provided that the entire vehicle can be redesigned to capture
this opportunity. Nevertheless, large-scale weight reduction is an extremely
challenging task, particularly since the addition of enhanced fuel-efficiency
systems such as electrification results in the opposite effect, namely, mass
compounding.
Broadly speaking, there are three obstacles to achieving the Partnership’s
stated stretch goals regarding vehicle weight: increasing vehicle content, main-
taining structural integrity, and managing cost.
• A 2011 Massachusetts Institute of Technology study (Zoepf, 2011)
found that average passenger-car weight had increased by greater than
11 percent, or 160 kg, since 1990, despite the base car weight remain-
ing unchanged. The entire weight increase was attributable to increas-
ing comfort and convenience content and to added safety features and
requirements. The pressure to keep adding feature content and more
safety features will undoubtedly continue, in conflict with the need to
reduce weight. Furthermore, the enhanced electrification of vehicles,
while improving inherent fuel efficiency, adds considerable mass in bat-
teries, motors, electronics, cooling, and so on, which must all be offset,
including the mass compounding effect noted above, to yield the greatest
fuel consumption benefits.
• Compliance with the full suite of Federal Motor Vehicle Safety Standards
provides confidence in the overall safety performance of a vehicle, but it
becomes increasingly challenging as weight is reduced. This has led to
increased use of sophisticated structural analysis tools and demand for
stronger, lighter materials such as high-strength steels and carbon fiber.
This trend can only accelerate in the future.
• Cost is arguably the greatest challenge of the three: a detailed analy-
sis in the NRC (2010) Phase 3 report illustrated both the high cost of
weight reduction and the extent to which the reduction in fuel con-
sumption can offset part of the cost to the ultimate consumer. However,
the offset in fuel cost is only a fraction of the material cost penalty,
and furthermore, much of the proverbial “low hanging fruit” has been
harvested already.
In light of these challenges, having the Partnership’s activities focused as
they are on enabling advanced high-strength lightweight materials and reduc-
ing their cost appears to be appropriate, even if the ultimate stretch goal is
unrealistic.
OCR for page 107
VEHICLE SUBSYSTEMS 107
Achievements
In the materials area, the Partnership listed eight areas of major achievement
in its presentations to the committee on January 26, 2012.32 These were as follows:
• Completed design and manufacturability assessment of a magnesium
front-end structure.
• Completed design, tooling, fabrication, and testing of a one-piece com-
posite underbody, saving 11.3 kg.
• Optimized engineering and manufacturing processes for advanced high-
strength steel (AHSS).
• Developed a process for warm forming of aluminum and magnesium
sheet.
• Enhanced the formability of aluminum at room temperature.
• Demonstrated a conversion technique for low-cost textile precursor for
carbon fiber.
• Improved performance of AHSS welds.
• Developed a unique process for producing low-cost highly ductile mag-
nesium sheet.
Response to Recommendations from the Phase 3 Review
Three recommendations on materials were made in the NRC Phase 3 report
(NRC, 2010, pp. 108-109). The Partnership responses are shown below as
“Updates.”
NRC Phase 3 Recommendation 3-22. The materials technical team should
develop a systems-analysis methodology to determine the currently most
cost-effective way for achieving a 50 percent weight reduction for hybrid and
fuel cell vehicles. The materials team needs to evaluate how the cost penalty
changes as a function of the percent weight reduction, assuming that the
most effective mix of materials is used at each step in the weight-reduction
process. The analysis should be updated on a regular basis as the cost struc-
tures change as a result of process research breakthroughs and commercial
developments. [NRC, 2010, p. 108.]
Updates: DOE FY 2011 solicitation results for the multimaterial vehicle car (50
percent lighter than a midsized vehicle, design, build, and validate):
• Award to Vehma (Magna International)—project started in November
2011.
32 M. Zaluzec, Ford Motor Company, and C. Schutte, Department of Energy, “Materials Technical
Team (MTT),” presentation to the committee, January 26, 2012, Washington, D.C.
OCR for page 108
108 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
• Cost analysis for multimaterial vehicle with a systematic approach is in
process at the Oak Ridge National Laboratory.
NRC Phase 3 Recommendation 3-23. The magnesium castings study is
completed, and no further technical effort is anticipated by the Partnership as
recommended in the Phase 2 report. However, magnesium castings should be
considered in completing the cost reduction recommendations listed above.
[NRC, 2010, p. 109.]
Updates:
• DOE award to MOxST, Inc., for a clean and low-cost domestic supply of
magnesium (Mg). If successful, this technology will introduce a lower-
cost feedstock for alloy production and die casting.
• DOE award to United States Automotive Materials Partnership (USAMP)
on Magnesium Intensive Front End, which includes a focus on the char-
acterization, optimization, and production of Mg die cast structural
components.
• Cooperative Research and Development Agreement project involving the
Pacific Northwest National Laboratory, Ford Motor Company, University
of Michigan, and MagTech (die casting supplier) to develop and vali-
date mechanistic-based ductility models for Mg die castings. This will
provide a better understanding of how die-casting characteristics affect
ductility, in turn providing insight for methods to improve ductility.
NRC Phase 3 Recommendation 3-24. Methods for the recycling of carbon-
reinforced composites need to be developed. [NRC, 2010, p. 109.]
Updates: DOE cofunding of Small Business Innovation Research work with
Materials Innovation Technologies (Fletcher, North Carolina) to research low-
cost carbon-fiber composite manufacturing using recycled aerospace carbon-fiber.
Other global recycling efforts identified are as follows:
• Nottingham University, United Kingdom: Fluidised Bed, Supercritical
Fluids, Microwave;
• Adherent Technologies, New Mexico, United States: Batch Thermo-
chemical;
• Valley Stade Consortium, Germany: Batch Pyrolysis;
• Wells Specialty Products, Texas, United States: Fluidized Bed;
• Ruag, Switzerland;
• Firebird Advanced Materials, North Carolina, United States: Microwave;
and
• Milled Carbon, United Kingdom: Continuous Pyrolysis.
OCR for page 109
VEHICLE SUBSYSTEMS 109
Discussion and Recommendations
As noted earlier, weight reduction is a crucial part of any balanced approach
to achieving aggressive fuel consumption targets and will undoubtedly entail
enhanced computational methods and widespread materials substitution. The
work being performed under the auspices of the Partnership appears to be properly
focused on relevant initiatives.
Although these initiatives appear relevant, the committee questions whether
they all satisfy the criteria of high-risk, precompetitive research judged appropri-
ate for federal involvement. Competition has raged among the steel, aluminum,
and composites automotive supply base for many years in an effort to achieve
low-cost weight reduction via materials substitution, and the aluminum, magne-
sium, high-strength steel, and composites content of production vehicles has been
steadily rising for more than 20 years. Furthermore, numerous vehicle demonstra-
tion projects have been conducted in the past, both by materials trade associations
and by industry consortia, some of which were sponsored by DOE.
As noted in Chapter 2, the committee applauds the appointment by each tech-
nical team of an associate member. However, the MTT has selected as its associ-
ate member a manufacturer of aluminum truck bodies; although the company no
doubt is competent, this selection would seem to add little in the area of greatest
need, namely, long-term high-risk research into low-cost lightweight alternative
materials. It might be productive for MTT to consider adding another associate
member with this type of expertise. Phase 3 Recommendation 3-22 emphasized
the need for systems analysis focusing on the most cost-effective way to achieve
a 50 percent weight reduction. While the analytical approach in process at ORNL
is responsive to that task, it is less clear what value the $10 million award (over 4
years) to Vehma to build another prototype multimaterial vehicle offers, especially
considering that the award abstract does not even mention cost.
Phase 3 Recommendation 3-23 reiterated the Phase 2 recommendation (NRC,
2008, p. 9) and essentially anticipated no further work on magnesium, other than
inclusion in the analytical optimization process. The Partnership nevertheless
listed in its response several continuing Mg projects within the 67 percent of
DOE’s FY 2012 budget that is devoted to metals development.
Phase 3 Recommendation 3-24 urged the development of methods to recy-
cle carbon-fiber composites. The Partnership is devoting 18 percent of its FY
2012 Lightweight Materials budget to carbon-fiber projects, including recycling.
Although this is responsive to the committee recommendation, it can be argued
that carbon fiber offers perhaps the greatest opportunity for weight reduction while
maintaining structural integrity, and hence the huge challenge of doing so at low
cost could deserve a greater share of the materials budget.
While increased emphasis on low-cost carbon fiber would be desirable, the
committee continues to believe that much of the MTT work on light metals and
materials substitution demonstrations is not precompetitive and would be best
performed by the private sector. Funding currently allocated to these activities
OCR for page 110
110 REVIEW OF THE RESEARCH PROGRAM OF THE U.S. DRIVE PARTNERSHIP
could well be used more effectively by other technical teams or on materials
research needs identified by those other teams.
Recommendation 3-17. The Partnership should expand its current work on
low-cost carbon-fiber precursors, manufacturing, and recycling. This work could
also potentially help to reduce the cost of high-pressure hydrogen storage tanks.
Recommendation 3-18. The materials technical team should expand its outreach
to the other technical teams to determine the highest-priority collective Partner-
ship needs, and the team should then reassess its research portfolio accordingly.
Any necessary reallocation of resources could be enabled by delegating some of
the highly competitive metals development work to the private sector.
REFERENCES
Bandivadekar, A., K. Bodek, L. Cheah, C. Evans, T. Groode, J. Heywood, E. Kasseris, M. Kromer,
and M. Weiss. 2008. On the Road in 2035: Reducing Transportation’s Petroleum Consumption
and GHG Emissions. MIT Laboratory for Energy and the Environment, Cambridge, Mass.
Report No. LFEE 2008-05 RP, July. Available at http://web.mit.edu/sloan-auto-lab/research/
beforeh2/otr2035/On%20the%20Road%20in%202035_MIT_July%202008.pdf.
Debe, M.K. 2011. “Advanced Cathode Catalysts and Supports for PEM Fuel Cells.” Presentation
at the DOE 2011 Annual Merit Review, May 9-13, Washington, D.C. Available at http://www.
hydrogen.energy.gov/annual_review11_fuelcells.html.
Debe, M.K. 2012. “Advanced Cathode Catalysts and Supports for PEM Fuel Cells.” Presentation
at the DOE 2012 Annual Merit Review, May 14-18, Arlington, Va. Available at http://www.
hydrogen.energy.gov/pdfs/review12/fc001_debe_2012_o.pdf.
DOE (U.S. Department of Energy). 2010a. FY 2010 Progress Report for the Hydrogen and Fuel Cells
Program. Available at http://www.hydrogen.energy.gov/annual_progress.html.
DOE. 2010b. Multi-Year Program Plan 2011-2015. December. Washington, D.C.: Office of Vehicle
Technologies, Energy Efficiency and Renewable Energy.
DOE. 2011. FY 2011 Progress Report for the Hydrogen and Fuel Cells Program. Available at http://
www.hydrogen.energy.gov/annual_progress.html.
DOE. 2012a. Department of Energy FY 2013 Congressional Budget Request. Vol. 3. DOE/CF-0073.
February. Washington, D.C.: DOE Office of the Chief Financial Officer.
DOE. 2012b. FY 2011 Annual Progress Report for Energy Storage R&D, Hybrid Electric Systems
Team. January. Washington, D.C.: Office of Vehicle Technologies, Energy Efficiency and Re-
newable Energy.
FCFP (FreedomCAR and Fuel Partnership). 2011. 2010 Highlights of Technical Accomplishments.
U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Available at
http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/2010_fcfp_accomplishments_rpt.
pdf.
Gaines, L. 2011. Recycling of Li-ion Batteries. Illinois Sustainability Technology Center,
P
rairie Research Institute. November 15. Available at http://www.istc.illinois.edu/about/
SustainabilitySeminar20111115.cfm.
Hawkins, S., F. Billotto, D. Cottrell, A. Houtman, et al. 2012. Development of General Motors’ eAssist
Powertrain. SAE Int. J. Alt. Power. 1(1):308-323. doi:10.4271/2012-01-1039.
OCR for page 111
VEHICLE SUBSYSTEMS 111
Howell, D. 2012. “Overview of Battery R&D Activities.” Office of Vehicle Technologies Program,
Energy Efficiency and Renewable Energy. Presentation at the DOE 2012 Annual Merit Review,
May, Arlington, Va. Available at http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_re-
view_2012/energy_storage/es000_howell_2012_o.pdf.
Myers, D., X. Wang, N. Kariuki, R. Subbaraman, R. Ahluwalia, and X. Wang 2011. “Polymer Elec-
trolyte Fuel Cell Lifetime Limitations: The Role of Electrocatalyst Degradation.” Presentation
at the DOE 2011 Annual Merit Review, May 9-13, Washington, D.C. Available at http://www.
hydrogen.energy.gov/pdfs/review11/fc012_myers_2011_o.pdf.
Myers, D., X. Wang, N. Kariuki, S. DeCrane, T. Nowicki, R. Subbaraman, S. Arisetty, and R. Ahlu-
walia. 2012. “Polymer Electrolyte Fuel Cell Lifetime Limitations: The Role of Electrocatalyst
Degradation.” Presentation at the DOE 2012 Annual Merit Review, May 14-18, Arlington, Va.
Available at http://www.hydrogen.energy.gov/pdfs/review12/fc012_myers_2012_o.pdf.
NRC (National Research Council). 2008. Review of the Research Program of the FreedomCAR and
Fuel Partnership: Second Report. Washington, D.C.: The National Academies Press.
NRC. 2010. Review of the Research Program of the FreedomCAR and Fuel Partnership: Third Re-
port. Washington, D.C.: The National Academies Press.
Olszewski, M. 2011. Oak Ridge National Laboratory Annual Progress Report for the Power Electron-
ics and Electric Machinery Program. October. ORNL TM-2011/263. Available at http://info.
ornl.gov/sites/publications/files/Pub31483.pdf.
Snyder, K. 2012. “Overview and Progress of United States Advanced Battery Consortium (USABC)
Activity.” Presentation at the DOE 2012 Annual Merit Review, May, Arlington, Va. Avail-
able at http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/energy_storage/
es097_snyder_2012_o.pdf.
Stetson, N.T. 2010. “Hydrogen Storage.” Presentation at the DOE Annual Merit Review,
June 8, Washington, D.C. Available at http://www.hydrogen.energy.gov/pdfs/review10/st00a_
stetson_2010_o_web.pdf.
Stetson, N.T. 2011. “Hydrogen Storage—Session Introduction.” Presentation at the DOE Annual
Merit Review, May 9, Washington, D.C. Available at http://www.hydrogen.energy.gov/pdfs/
review11/st000_stetson_2011_o.pdf.
Stetson, N.T. 2012. “Hydrogen Storage Overview.” Presentation at the DOE Annual Merit Review,
May 15, Arlington, Va. Available at http://www.hydrogen.energy.gov/pdfs/review12/St000_
Stetson_2012_o.pdf.
Sunita, S. 2011. “Overview of Hydrogen and Fuel Cell Budget.” DOE Fuel Cell Technologies Pro-
gram, Stakeholders Webinar—Budget Briefing, February 24. Available at http://www1.eere.
energy.gov/hydrogenandfuelcells/pdfs/budget_webinar_fy12.pdf.
U.S. DRIVE. 2011. Highlights of Technical Accomplishments. U.S. Department of Energy, Office of
Energy Efficiency and Renewable Energy. Available at http://www1.eere.energy.gov/vehicle-
sandfuels/pdfs/program/2011_usdrive_accomplishments_rpt.pdf.
Wagner, F.T., B. Lakshmanian, and M.F. Mathias. 2010. Electrochemistry and the future of the auto-
mobile. Journal of Physical Chemical Letters 1:22014.
Weiss, M.A., J.B. Heywood, E.M. Drake, A. Schafer, and F.F. AuYeung. 2000. On the Road in
2020: A Life-Cycle Analysis of New Automobile Technologies. MIT Energy Laboratory Report
No. MIT EL 00-003, Cambridge, Mass. Available at http://web.mit.edu/energylab/www/pubs/
el00-003.pdf.
Wipke, K., S. Sprik, J. Kurtz, T. Ramsden, C. Ainscough, and G. Saur. 2012. National Fuel Cell Elec-
tric Vehicle Learning Demonstration Final Report. Technical Report NREL/TP-5600-54860.
July. Contract No. DE-AC36-08GO28308. Golden, Colo.
Zoepf, S.M. 2011. Automotive Features: Mass Impact and Deployment Characterization. Thesis,
Massachusetts Institute of Technology, Master of Science in Technology and Policy. Available
at http://web.mit.edu/sloan-auto-lab/research/beforeh2/files/Zoepf_MS_Thesis.pdf.
