IEEE Electrification Magazine - September 2015 - 34

Figure 3. A PEV with battery storage. (Source: NREL.)

is designed to develop and test integrated PV, inverters, fuel
cells, wind turbines, microturbines, biomass-based generators, engine/generator sets, vehicles, and DESS control technologies. The facility has the capability to develop and test
systems that are grid-connected and islanded and to transition between these operating modes.
The ESIF can be used to model both PV and battery
technologies. A rapid drop in PV module and installation
cost will make the cost of PV power close to or less than
that of grid electricity in some areas in the United States
and will have a profound impact on grid power supply and
DG integration. The usefulness of the solar renewable
resource as a primary energy supply in a DG system
would be greatly improved if the system could store energy to be used at a later time, when most needed. The DESS
market is reportedly among the fastest-growing markets
for energy storage globally. Growth in this market is being
fueled by the development of advanced battery chemistries, particularly lithium-ion (Li-ion), such as those used
in EVs, and other types. According to one report, the
spread of solar PV, EVs, EV charging, and home energy
networks is creating new applications and demand for
DESSs. By 2024, total worldwide capacity is expected to
exceed 12,000 MW.

Vehicular Battery Electric Storage for Transportation
For many automakers, the preferred EV energy-storage
option is the Li-ion battery because it can deliver the

Figure 4. PEVs under a solar panel shade. (Source: Dennis Schroeder,
NREL.)

I E E E E l e c t r i f i cati o n M agaz ine / SEPTEMBER 2015

required energy and power density in
a relatively small, lightweight package. Figure 3 illustrates battery storage
for a PEV. Much R&D in energy storage
seeks to perfect Li-ion technology-
e.g., by enhancing the cyclability of silicon anodes and by increasing longevity and safety through atomic
layer deposition coatings. Innovations
are being discovered as new options
are explored that can improve market
penetration-innovations in the area
of solid-state, organic liquid, lithium-
air, and magnesium-ion technologies.
PEVs face challenges on the consumer-acceptance front.
There is also concern about how a nationwide migration to
a fleet of electrified vehicles could have an impact on electricity demand. The existing utility infrastructure has limited capacity to meet ever-growing electricity needs, and the
majority of this system is powered by coal and natural gas
generators. By addressing energy-storage issues in the R&D
stages, renewable energy from solar and wind power can
offer consumers affordable, high-performance alternatives
to gasoline-powered automobiles, while also dealing with
the concurrent growth of electricity needs.
Vehicle-to-grid (V2G) technology makes it possible for
vehicles to become valuable grid resources while conserving energy and supporting clean, renewable energy sources.
For example, solar PV's variable nature and concentration
of electricity output in the middle of the day pose limitations, and the high cost of EV batteries can constrain the
cars' market potential. When PVs and EVs are deployed
together, these technologies can provide mutual benefits
(Figure 4). Since solar energy sources can increase the availability of peak-period midday electricity, EVs can be made
more affordable. At the same time, EVs can store PV energy
during periods of low demand.
PEV battery second use (B2U) provides great potential to
overcome major barriers to the life cycle of Li-ion batteries.
Figure 5 shows the B2U strategies. A single battery first serves
an automotive application, and then, once deemed appropriate, is redeployed into a secondary market. B2U could help
overcome Li-ion battery cost barriers to the deployment of
both PEVs and grid-connected energy storage. By extracting
additional services and revenue from the battery in a postvehicle application, the total lifetime value of the battery is
increased, and the cost of the battery can be shared between
both the primary and secondary users. Such battery-use strategies would reduce the nation's dependence on foreign oil and
reduce emissions of greenhouse gases by increasing PEV
adoption; but they would also improve the reliability, efficiency, and cleanliness of the grid by advancing the deployment of grid-connected storage.
PEV battery life cycle with second use indicates the possibility of B2U strategies becoming an important part of
both the automotive and electricity industries. Although

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