IEEE Electrification Magazine - September 2015 - 35

NREL's analysis does not suggest that
B2U will significantly reduce the
upfront cost of PEVs, it does show that
B2U can eliminate end-of-service costs
for the automotive battery owner and
provide low- to zero-emission peaking
services to electric utilities-reducing
cost, use of fossil fuels, and greenhouse gas emissions. Thus, the overall
benefit to society may be quite large.

Energy-Storage Development
by NREL Transportation Research

Vehicle-to-grid
technology makes it
possible for vehicles
to become valuable
grid resources while
conserving energy
and supporting
clean, renewable
energy sources.

Automotive
Service

Post-Auto Battery
Assessment

Original
Manufacture

Repurposing

Recycling

Second-Use
Application

Second Use

NREL innovations accelerate the development of high-performance, costeffective, and safe energy-storage systems to power the next generation of
EVs. Hybrid EVs, PEVs, and all-EVs promise to curb greenhouse gas emissions and slash the United States's need for
imported oil. However, considerable challenges are presented
by battery price and performance. Recognized as a U.S. leader in battery R&D, NREL seeks to address these issues and
help put new EVs on the road.
Batteries are often the most expensive component of
an EV, but they are essential because they not only power
the motor and other electrical systems but also store
kinetic energy from regenerative braking as well as energy from the grid. All-electric, hybrid, and plug-in hybrid
vehicles may be more attractive to consumers if their
batteries were more affordable, had better performance,
lasted longer, were safer, and operated at maximum efficiency in a wide range of driving conditions and climates. The U.S. DOE's EV Everywhere Grand Challenge
sets a target range of 250-300 mi per charge for the next
generation of electric-drive cars. This target adds considerable pressure on the vehicles' battery packs. In addition, battery costs need to drop to US$125/kWh from its
current US$350-550/kWh. Furthermore, the life span of a
battery must reach 15 years-from its current eight years
for electric-drive vehicles-if it is to gain meaningful
market share.
The Li-ion batteries in most of today's electric-drive vehicles are smaller and lighter weight than the previous nickel-
metal hydride technology. However, they are more sensitive
to overheating, overcharging, and extreme spikes in temperature. High temperatures reduce battery life and increase
battery replacement costs; in contrast, low temperatures
decrease battery power and capacity, thus impacting vehicle
range, performance, and affordability.
Battery development through the "build-test-break"
cycle takes considerable time and money. Thus, multiphysics computer simulation of energy-storage devices
provides a less expensive, faster, and more-controlled supplement to in-lab testing of batteries. The outcome is longer-lasting, dependable, affordable batteries that power
electric-drive vehicles. NREL wants to ensure that

computer models produce verifiable
results. Therefore, it bases its models
on real-world data supplied through
partnerships with major automotive
and battery manufacturers, combined
with data collected in NREL's thermal
characterization laboratories.
Figure 6 diagrams an experimental system for integrating the grid
and vehicle systems and enables
hardware and HIL simulation of command, communication, and control
systems for V2G integration. All of
this is done while maximizing the
benefits of energy provided by renewable resources. This facility features
the following:
xx
a purpose-built configurable distribution grid to support advanced energy-management concepts
xx
a PEV fueling station with four parking spaces
xx
a solar tree with a tracking system (~20 kW)-enough
energy to deliver more than 300 electrified mi/day
xx
the ability to simulate wind turbines or loads from
other sources
xx
two dc fast chargers-up to 150 kW
xx
the community energy-storage system
xx
low-power dc charging facilities for integrating with
building dc power networks
xx
the smart grid interface monitor and controls.
NREL researchers conduct energy-storage R&D at various levels-from materials, cell, battery, and pack, to systems. Researchers use NREL capabilities to
xx
develop and evaluate materials for coatings, electrodes, anodes, and other energy-storage components
xx
conduct thermal testing and characterization of components to enhance performance, life span, and safety
xx
model, simulate, and evaluate systems to assess performance, reliability, life span, safety, and economic impacts
and to accelerate battery development and design.
Using a full portfolio of sophisticated testing and analytical
and modeling tools, researchers can comprehensively evaluate

Figure 5. The PEV battery life cycle with second use.

IEEE Electrific ation Magazine / S EP T EM BE R 2 0 1 5

Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2015