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Full-text feature article • •
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| Plugging
In to Renewable Communities |
| How transportation based on renewable
energy-powered communities may solve our addiction to
fossil resources. |
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| By Terry Penney and Jennifer
Elling |
 A
Glimpse of the V2G Future Today?
How soon could we have vehicle-to-grid (V2G) plug-in
hybrid communities? None exist yet, but Global
Electric Motorcars (GEM) gives us a glimpse of
what they might look like. The leading maker of
neighborhood electric vehicles, or NEVs, and a
DaimlerChrysler company since 2000, GEM has sold
its vehicles to entire communities that feature
NEVs as part of their basic infrastructure. In
Bay Harbor, Mich.; Celebration, Fla.; and Playa
Vista and Otay Ranch, Calif., entire neighborhoods
use NEVs for nearly all local travel. |
What if you could
virtually eliminate your reliance on petroleum and the
associated concerns about greenhouse gas emissions and
national security — without giving up your personal
car? Better yet, what if the infrastructure to power
this fossil fuel-free vehicle was tied to your neighborhood
electric grid, one that distributed electricity generated
from renewable energy to your home and
“plug-in” hybrid electric car? Your advanced
plug-in vehicle would be designed to draw electricity
from the combined renewable energy grid or a plug-in
renewable energy system. Plug-in vehicles are like today’s
hybrid vehicles, but with bigger, more costly batteries
and a smart control strategy. Now consider that in this
community, not only would renewable energy (RE) power
the homes and businesses, but buildings would be built
for maximum efficiency and on-site solar heating and
electricity generation to use zero or near-zero energy
from the grid. Most of the pollution, health and national
security concerns of fossil fuels would be a thing of
the past.
Researchers are quickly moving toward developing the
technologies to support just this type of sustainable
transportation infrastructure and RE-based community.
Many of these innovations are here today, and we catch
the first glimpse of what these communities might look
like as more builders construct developments in which
most or all of the homes are solar and use near-zero
energy. The paradigm-shifting difference in the renewable
energy community to come rests in the single integrated,
RE-based energy system for transportation and residential/commercial
buildings.
Driving
Vehicle-to-Grid Technology
Because this renewable community will be connected to
a grid that operates in two directions — both
distributing and accepting electricity — the next-generation
hybrid electric vehicles will have the ability to store
excess electricity for timely return to the grid. We
call this “two-way” plug-in a vehicle-to-grid
(V2G) hybrid. Utilities spend a tremendous amount for
capacity to continuously balance supply and demand across
the grid or provide backup electricity during outages
and peak-demand periods. Because batteries are particularly
effective for this kind of critical service, utilities
might pay V2G owners to “borrow” energy-storage
capacity (see sidebar, “Linking
It All Together”). Combined with fuel savings,
this income could pay back the more expensive battery
cost within relatively few years.
Linking
It All Together
What makes the renewable energy-based community
of the future unique is the integration of the
electric utility system with a system to power
our personal vehicles.
 |
| Source: Dean Armstrong,
NREL |
The interconnected energy system can flow two
ways, as shown by the arrows in this graphic.
A “two-way” plug-in hybrid vehicle
(also known as a vehicle-to-grid, or V2G, vehicle)
is plugged into an electric outlet in the garage
of the home or workplace, allowing electricity
to flow from the energy-management system (traditionally
the grid) to the vehicle and vice versa. An
energy-management operator can broadcast a control
signal to any number of V2Gs (including fleets)
to give or request electricity. Each vehicle’s
smart control system monitors its ability to
give and receive electricity and communicates
this information with the operator.
|
As federal regulators and electric utilities work to
revamp the aging North American electricity transmission
and distribution infrastructure, they have the opportunity
to reduce our nation’s increasing reliance on
imported oil by creating mechanisms to encourage clean
distributed generation, including V2G. This combined
power grid will enable utilities to tap a source of
competitively priced backup electricity, while investors
will have a means of profiting from the possible transition
to renewable energy. Batteries, such as those used in
a V2G-enabled car, are one of many new clean and distributed
resources that could contribute to a smart grid of the
future. This smart grid would communicate continuously
with both suppliers and consumers of electricity to
maintain the most secure, cost-effective system. It
will require cost-effective advanced interconnection
equipment that allows full functionality of a V2G plug-in
hybrid. Consensus-based standards for these vehicles
also must be developed.
This effort is just one of the critical areas on which
researchers are focused. At the National Renewable Energy
Laboratory (NREL), experts are working to advance smart
control systems in vehicles to make V2G technology a
reality and to create a more efficient, reliable distribution
system. Probably the biggest challenge to commercialization
of plug-in hybrids is the cost and weight of batteries.
NREL is researching thermal-management, modeling and
systems solutions to improve energy-storage technology
(see the sidebar, “Overcoming the Battery Technology
Challenge”). Even at today's battery costs,
however, plug-ins may be able to repay their costs within
a few years. NREL scientists and engineers also research
improved power electronics and smart control systems
critical to hybrid efficiency and conduct sophisticated
modeling and analysis to demonstrate the economic viability
of plug-ins and identify key areas for improvement.
Envisioning
the RE-Powered Community
Let’s examine what the sustainable communities
that underpin the V2G paradigm will look like.
Imagine living in an RE-based community in a few years
that emphasizes low utility bills and reduced petroleum
use. It is designed using sustainable practices and
materials to minimize the environmental damage of site
development and conventional energy and water use and
to promote quality of life.
Your zero- or near-zero-energy home is constructed for
maximum comfort and energy efficiency, with appliances
and heating and cooling systems that dramatically reduce
the electricity demand. Rooftop photovoltaic (PV) power-generating
systems supply most of the little energy the house does
need. Excess PV generation is used to charge your V2G
hybrid or is sold back to your electric utility company.
The V2G in the garage operates mostly on $0.03-per-mile
electricity rather than $0.10-per-mile gasoline. The
hybrid vehicle’s batteries store extra electricity
for the home as a backup to the PV system. In this way,
the vehicle actually may serve as a mobile utility.
The local utility generates energy from wind, solar
and other renewable sources the small amount of grid
electricity your home may need. What little fuel the
V2G needs may also be generated from renewable sources,
such as ethanol or biodiesel in the near term, or hydrogen
for the vehicle’s fuel cell in the long-term.
Nearby workplaces and commuter stations could also have
two-way electrical outlet “docks” to enable
battery charging or, when the V2G car is not in operation
for long periods, to provide electricity back to the
grid. Many high-tech companies already have auxiliary
generators because they need more consistent power than
the grid provides, and such companies might be delighted
to rely on employee car batteries instead. As for the
town, our streets will be clean and quiet because V2Gs
would run on their electric motors much more than regular
hybrids. Operating in electric-motor mode would also
mean greatly reduced emissions from the vehicles themselves.
Creating
the V2G Reality
Sound like a pipe dream? It isn’t.
Energy-efficient homes, PV systems, geothermal heat
pumps and other effective renewable energy technologies
are offered by many homebuilders or suppliers. Commercially
available plug-in hybrids are just years away. Integrating
multiple energy systems is the key, and the technology
to do so is available today. Yet cost, risk, consumer
demand, and other issues cause business to pause at
the opportunity. With the team of experts at NREL, we’ve
begun to respond to these issues by analyzing a number
of renewable community scenarios that link transportation,
homes and the electric grid, as well as enabling the
delivery of large quantities of renewable energy to
the grid. Analyses show that the homeowner would gain
a net cost advantage by integrating a near-zero-energy
home with a plug-in or V2G hybrid. Although a number
of variables affect this calculation, the economics
of the integrated system are substantially better than
an analysis of each piece would suggest.
Overcoming
the
Battery Technology Challenge
 |
2001
Panasonic
NiMH module |
 |
Redesigned
2004
Panasonic NiMH module |
|
If battery technology is the key to realizing
the benefits of plug-in hybrid vehicles, then
the thermal management of these batteries is
essential for their longevity and performance.
During the past 10 years, the National Renewable
Energy Laboratory (NREL) has developed a world-class
laboratory for energy-storage thermal management.
The lab uses the latest modeling software, hardware
and thermal-imaging techniques to improve the
performance and design of advanced batteries
such as nickel-metal hydride (NiMH), lithium-ion
and lithium polymer batteries.
 These
infrared images taken at NREL show how Panasonic
improved the thermal performance of its NiMH
module. The 2004 module has a lower maximum
temperature and is much more uniform. The U.S.
Department of Energysponsored work at national
labs and industry is aimed at overcoming the
barriers to implementing advanced batteries
in vehicles such as cost, calendar life, abuse
tolerance and low-temperature performance. Access
www.nrel.gov.
|
For example, typically a near-zero-energy home with
PV panels and energy-efficient measures can be expensive,
raising the initial cost of this home. When included
in original construction cost — in the home mortgage
— however, energy use can be reduced as much as
50 percent with no increase in total monthly bills.
For instance, a U.S. Department of Energy handbook (www.buildingamerica.gov)
for hot and humid climates posed an example of spending
an additional $1,500 for an ENERGY STAR home (including
various energy-efficiency features, but not PV or a
geothermal heat pump). For an additional mortgage cost
of only $9 per month, energy bills were reduced $40
per month — for net savings of $31 per month.
As another example, for a 2,600- square-foot, two-story
home in Sacramento, Calif., efficiency measures can
be added cost-effectively to achieve 60 to 65 percent
energy savings. At an incremental cost of about $20,000
and assuming a $600,000 asking price in the California
market, this investment represents an upfront cost increase
of only 3 percent. In addition to immediate savings
in utility bills, added PV electricity-generation and
other energy-savings features will also be “paid
back” in home resale value.
Establishing the renewable community with V2Gs, of course,
requires much more interaction among disparate disciplines.
It requires a fresh look at state and local zoning laws.
This transition may seem like a difficult undertaking,
but when we consider escalating housing and utility
costs, we find that the effort and investment have the
potential to pay off by many measures.
Developing
Transportation-Wise Suburbs Today
Your home and car probably represent your biggest personal
impact on our nation’s increasing energy demand,
and therefore on national security, trade deficits,
global warming and air quality. The renewable communities
concept presented in this article marries energy-responsible
homes and cars for a sustainable lifestyle. By leveraging
new technologies and sustainable building practices,
RE-based communities can demonstrate that it is possible
to minimize the detrimental effects of fossil energy,
while addressing the greatest energy challenges of the
American suburban lifestyle.
Our team at NREL views renewable communities using V2G
technology as an ideal way to demonstrate the effectiveness
of the wide range of energy-efficiency and renewable
energy technologies the laboratory is helping to develop.
Rooftop photovoltaic and utility-scale solar thermal
systems are a prime option. Depending on location, the
community can also rely on wind, solar thermal or biomass
energy. Our analysts can model the near-zero-energy
buildings to identify the most cost-effective efficiency
measures, model the V2G vehicles to identify optimal
battery and other component sizes and matches, and design
systems to most effectively use the communities' mix
of distributed and central electrical generation. Ethanol
from cellulosic biomass can supply what liquid fuel
the vehicles must use. We see renewable communities
as a path to minimizing energy import, fossil-fuel use
and greenhouse gas emissions, while providing the highest-quality
lifestyle.
What will it take to start building these renewable
communities? Any new venture involves risk, but we believe
Americans are eager to live in communities that minimize
their contribution to greenhouse gases and reduce national
dependence on imported oil. Several organizations and
business entities have contacted us about this vision,
and we see elements of it around the world. It is only
a matter of time before we see integration of all the
pieces of advanced technology, putting us on a path
to sustainability based on renewable energy. It’s
not a question of “if,” but of “when,
who and where” this vision will become a reality.
Terry Penney is
the FreedomCAR and Advanced Vehicle Technology manager
at NREL, Golden, Colo. Prior to joining NREL in 1979
as an aerospace engineer, he worked on the space shuttle.
He has worked on hybrid vehicle technology since 1992.
Contact Penney at terry_penney@nrel.gov.
Jennifer Elling is a senior communicator and project
lead for the Renewable Community at NREL. Contact Elling
at jennifer_elling@nrel.gov.
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