Argonne Leads DOE's Effort to Evaluate Plug-in Hybrid
|Plug-in hybrid electric vehicle (PHEV)
technology is part of the President's Advanced Energy Initiative, which emphasizes
the development of technologies that can significantly reduce
the nation's dependence on foreign oil. |
Argonne National Laboratory has been designated by the Department
of Energy's Office of Vehicle Technologies as the lead national
laboratory for the simulation, validation and laboratory evaluation
of plug-in hybrid electric vehicles and the advanced technologies
required for these vehicles (see Plug-In Hybrid Electric Vehicle Research
Capabilities at Argonne).
What is a Plug-in Hybrid?
A plug-in hybrid electric vehicle is similar to the hybrid
electric vehicles (HEVs) on the market today, but it has a larger
battery that is charged both by the vehicle's gasoline engine and
from plugging into a standard 110 V electrical outlet for a few
hours each day. "PHEVs and HEVs both use battery-powered motors and
gasoline-powered engines to get high fuel efficiency, but PHEVs can
further displace fuel usage with off-board electrical energy charged
at home," explained Don Hillebrand, Director of Argonne's Center for
The result is a vehicle that can achieve far greater gas mileage
than today's HEVs, said Larry Johnson, Director of Argonne's
Transportation Technology R&D Center. "Experts estimate that a
PHEV could get more than 100 miles per gallon while the vehicle runs
primarily on the battery compared to the 30 to 55 miles per gallon
that most of today¹s HEVs achieve at a charging cost that¹s
equivalent to roughly $1 a gallon. For PHEVs with extra large
batteries and motors, commuters who drive less than 20 miles a day
can potentially drive exclusively with its electric motor for their
While PHEVs are a promising vehicle technology, many broad energy
and environmental considerations must be examined before they become
widely available. For example, while a PHEV might be less costly for
the consumer to drive than a gasoline-powered vehicle, it would draw
power from the electrical grid when charging.
"Whereas virtually all electricity in the United States comes
from domestic energy sources," Hillebrand said, "in some areas, much
of that electricity would be generated by coal-burning power
generation plants. The energy costs to extract and transport the
coal, as well as the environmental considerations associated with
burning the coal, are all part of the overall cost of using plug-in
These issues decrease in importance as the amount of renewable
energy in the electricity mix increases. There is also the question
of how used batteries will be recycled, and how much that recycling
will cost on a per-vehicle basis once all transport, processing, and
disposal costs are considered.
Significant technical barriers must also be overcome before PHEVs
are available at local car dealers (see Why Don't We Have Plug-In Hybrids Today?).
These include cost, battery size and performance, durability and
safety. Download the U.S. Department of Energy's Plug-In Hybrid
Electric Vehicle R&D Plan (2.2Mb).
PHEVs require additional, expensive components. Very large,
heavy, and costly batteries are required to provide vehicle range.
Also, power electronics need to be made smaller, simpler and less
The U.S. Department of Energy has determined that to be
commercially viable, a hybrid technology vehicle must repay its
extra upfront cost in the form of fuel savings within three years of
the initial purchase.
Battery size and performance
The goals for a PHEV battery are compact size, high energy, high
storage capacity and the ability to support both deep and shallow
discharge/charge cycles. With today's technology, a battery that's
powerful and durable enough to power a PHEV's electric motor takes
up more space than many vehicle makers or consumers are willing to
sacrifice. In addition to the space occupied by the battery itself,
there is also space on top of and around the battery that for safety
reasons cannot be used for design.
"Fortunately," Hillebrand said, "as battery technology evolves,
these issues are likely to diminish."
"Chances are," Johnson said, "if you own any of today's high-tech
rechargeable-battery-powered devices, such as MP3 players, PDAs or
cell phones, you understand this problem firsthand. A battery small
enough to meet the device's form factor and power needs must be
recharged frequently, and over time, it loses its ability to take
and hold a new charge."
Eventually, the battery will need to be replaced. In a car,
however, consumers would expect the battery to last the life of the
Any battery can be unsafe when mishandled or subjected to trauma
such as physical blows, extremely high-temperatures or fire. Even
though a vehicle is safe under normal conditions, a great deal of
testing is required to determine its safety in a crash or fire. As
new battery technologies are developed, they will require extensive
testing before they are deemed suitable for in-vehicle use.
Emergency responders must also learn how to safely handle new
vehicle battery technologies in a crash or fire.
To address these issues and others, the U.S. Department of
Energy's FreedomCAR and Vehicle Technologies Program is funding
research in a variety of technical areas specific to PHEVs,
- Hardware-in-the-loop analysis
- Modeling & simulation
- Research and development for critical components such as
batteries, motors and power electronics
- Component/subsystem testing and validation
- System and interface control development
- Vehicle testing and validation
- Pioneering Future PHEV Technologies and Research Protocols (7.2Mb)
- The Source for PHEV Data (7.5Mb)
- Plug-Ins: The Future for Hybrid Electric Vehicles? (8.3Mb)
- Just the Basics: Hybrid Electric Vehicles (fact sheet; 523kB)