Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportations Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
PHEV Charging and Electrical Generation
Most PHEVs will not require changes to residential electrical systems, with PHEVs
expected to have both 120-volt and 240-volt AC charging capabilities. It is expected that
suburban vehicle owners, who have garages available for charging PHEVs in their homes,
will be more likely to adopt this technology than urban owners, who may not have
overnight plug access available. For those operators without access to an outlet for
overnight charging, the typical total cost for installation of a 120V AC, single phase, 20A
circuit for residential vehicle charging is estimated between $500 and $1,000, while the
cost for installing a 240V AC, single phase, 40A circuit are substantially higher (Samaras,
2009). Outlet installation can also be cumbersome due to permitting and inspection
requirements.
The time necessary to recharge a PHEV20 from 20 percent to a full 100 percent charge
utilizing a standard 120-volt outlet ranges from 4 to 8 hours for battery pack sizes ranging
from 5.1 to 9.3 kWh, although the time to charge to approximately 80 percent of capacity
can be substantially shorter (Hadley and Tsvetkova, 2008). 37
While the power source for charging PHEVs at most residences is readily available, there
is a need to develop some level of publicly accessible charging infrastructure to allow
PHEVs to be charged away from users’ homes. Public access recharging could
substantially extend a PHEV’s effective AER, depending upon trip lengths and available
charge time (although the impact of multiple daily charge cycles would need to be clearly
demonstrated with respect to battery durability and life-cycle costs). While residential
infrastructure installation for PHEVs is fairly straightforward, public access charging
facilities are necessarily more expensive. The estimated cost for a 10-space commercial
recharging facility would be approximately $18,500 (U.S. DOE, 2008). This cost includes
labor, material, signage, and permits. Some utilities such as Southern California Edison
are currently preparing public access charging plans.
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PHEVs with particularly
large battery capacities (e.g., SUVs and large trucks and/or vehicles with higher AERs)
may require charging through 240-volt outlets, which allow for faster charging, in order to
obtain acceptable charge times (Elgowainy et al., 2009). There are designs for fast chargers
available, but battery life is negatively impacted by increased charge rates. In addition,
battery life also is generally determined by the total number of charge cycles. Charging
twice per day is more likely to necessitate the replacement of the battery near the middle
of the vehicle’s life, at significant cost (Kromer and Heywood, 2007).
While PHEVs will increase total electrical power demand they may not require increases
in generation capacity, at least in the near term, since PHEVs will most commonly be
charged during off-peak hours and total vehicle numbers will likely be small (EPRI,
37 Near-term battery technologies may require additional time for cooling after use before recharge
commences (EPRI, 2007a).