| Dear
EarthTalk: Should we expect to see “plug-in”
hybrid cars anytime soon? I’ve been hearing they are
on the horizon but I wonder if that means in one year or
10.
-- Bill A., Stratford, CT
| |
The
electricity cost for powering a plug-in hybrid is
only about one-quarter of the cost of powering a like-sized
gasoline vehicle. Pictured here: a regular Toyota
hybrid Prius converted to a 100 miles-per-gallon (avg.)
plug-in by the California Cars Initiative, a nonprofit
group dedicated to accelerating the availability of
the technology.
© jurvetson, courtesy Flickr |
Gasoline-electric
hybrids now, like Toyota’s popular Prius, don’t
need to plug in—you just fill their tanks with gasoline
and the battery keeps charged by the internal combustion
engine and by energy generated from the wheels when braking
(a feature known as “regenerative braking”).
The battery then powers the electric motor when it is called
into service during idling, backing-up, crawling in gridlock,
maintaining speed while cruising, and for extra uphill power
when needed. As such, the electric motor is essentially
a back-up engine while the hybrid relies mainly on the gasoline
engine.
Plug-in
hybrids take the concept further by plugging into a regular
electric outlet to enable the vehicle to operate solely
on its electric motor for ranges of 40-50 miles or more
on a single charge. This has profound implications for commuters
who need only drive short distances to and from work every
day and who may be able to do so solely on electric power.
The gasoline engine then becomes the supplemental one for
when the car needs to travel farther than the electric engine
can take it.
According
to researchers at the University of California Davis, the
electricity cost for powering a plug-in hybrid is only about
one-quarter of the cost of powering a like-sized gasoline
vehicle. Other benefits include far fewer fill-ups at gas
stations and the convenience of recharging at home.
Toyota,
currently the world’s largest producer of hybrid vehicles
by far thanks to the success of its Prius, announced that
it expects to have a commercially viable plug-in hybrid
available to consumers as early as 2010 and is now testing
prototype versions of plug-in hybrids at two California
universities.
Felix
Kramer of the California Cars Initiative (CCI), a non-profit
dedicated to promoting plug-ins, called Toyota’s announcement
“stunning and very welcome,” and says that these
vehicles will be the cleanest practical cars on the road
in a world where gas stations dot just about every intersection.
The promise of such cars, says CCI on its website, is that
drivers will have a “cleaner, cheaper, quieter car
for local travel, and the gas tank is always there should
you need to drive longer distances.”
U.S.
automakers are also jumping onto the plug-in bandwagon.
General Motors says that it will have mass-market plug-in
hybrids—modifications of its Saturn Vue and Chevrolet
Volt—on the road by 2010. Ford has also developed
a small fleet of plug-ins, but is not yet ready to offer
them to the public. Fisker, a U.S. start-up focusing on
the creation of high performance, energy efficient vehicles,
plans to sell an $80,000 plug-in hybrid sports car by late
2009. Chrysler’s Sprinter van was the first plug-in
from a major U.S. manufacturer, but it is only presently
available to a limited number of institutions as a fleet
vehicle.
Plug-ins
have also caught on elsewhere. Chinese carmaker BYD plans
to sell a plug-in hybrid sedan in the U.S. within five years.
And Volkswagen hopes to have a plug-in hybrid Golf ready
to roll by 2010.
CONTACTS:
California
Cars Initiative; BYD;
General
Motors; Fisker.
Dear
EarthTalk: I was intrigued to hear that there
were a number of ways one could modify or construct a roof
on a house or office facility that would provide great environmental
benefit. Can you enlighten?
-- Bill Teague, Menlo Park, CA
| |
Green
roofs utilize living plant matter and soil on top
of a building in order to absorb, collect and reuse
rainwater while preventing run-off. Pictured: A green
roof demonstration project at the Chicago Center for
Green Technology.
© Andrew Ciscel, courtesy Flickr |
Most buildings
are designed to shed rain, and as such are built with hard,
impenetrable roofing surfaces. As a result, rainwater bounces
off and collects as runoff, picking up impurities—including
infectious bacteria from animal waste as well as harmful
pesticides and fertilizers—on the way to municipal
storm sewers, which in turn eventually empty out into local
bodies of water.
Minimizing this
run-off means that more impurities will remain in local
soils where they can be broken down more easily into their
constituent elements than if they are concentrated downstream.
In order to achieve this goal, landscape architects have
developed so-called “green roofs,” which utilize
living plant matter and soil on top of a building in order
to absorb, collect and reuse rainwater while preventing
run-off. Many buildings employing green roofs are able to
find abundant uses for the water they collect, from watering
exterior plantings at ground level to flushing toilets inside.
According to
Steven Peck of the Toronto-based non-profit Green Roofs
for Healthy Cities, green roofs can play an important role
in maintaining ecological integrity within otherwise paved
over areas. “The roofscapes of our cities are the
last urban frontier—from 15 percent to 35 percent
of the total land area—and the green roof industry
can turn these wasted spaces into a force for cleaner air,
cleaner water, energy savings, cooling, beauty and recreation,”
he says.
The U.S. Environmental
Protection Agency (EPA) encourages the creation of green
roofs for mitigating the urban “heat island effect,”
whereby temperatures in crowded cities can soar some 10
degrees Fahrenheit higher than in less developed areas nearby.
Other benefits, says the EPA, include: providing amenity
space for tenants (in effect replacing a yard or patio);
reducing building heating and cooling costs due to the buffering
effect of the plant matter and soil; filtering pollutants
like carbon dioxide out of the air and heavy metals out
of rainwater; and increasing bird habitat in otherwise built-up
areas.
Beyond going
all out to build a “living” green roof, certain
inorganic materials can also make an existing roof greener.
The non-profit Cool Roof Rating Council (CRRC), for instance,
suggests roofing surfaces that reflect the sun’s heat
so as to reduce the urban heat island effect while improving
residential energy efficiency. According to the group, “a
cool roof reflects and emits the sun’s heat back to
the sky.” Builders can check out CRRC’s website
for a database of information on the radiative properties
of various roofing surfaces so as to make the smartest choice
for clients and the environment.
Another quality
that makes certain roofs greener than others is how long
they last. Metal roofs are known to be relatively maintenance
free and last longer than shingles in most situations. Slate
roofs also have an excellent reputation for lasting long,
although getting work done on them can be expensive when
they do need repairs. The Slate Roofing Contractors Association
reports that sea green slates can last anywhere from one
to two centuries, depending on where the slate is quarried
and how well it’s eventually installed.
CONTACTS:
Green
Roofs for Healthy Cities; CRRC. |
