Dear EarthTalk: Should we expect to see plug-in hybrid cars anytime soon?
Ive been hearing they are on the horizon but I wonder if that means in one year
or 10. -- Bill A., Stratford, CT
Gasoline-electric hybrids now, like Toyotas popular Prius, dont need to
plug inyou 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 worlds 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
Felix Kramer of the California Cars Initiative (CCI), a non-profit dedicated
to promoting plug-ins, called Toyotas 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 hybridsmodifications of its Saturn
Vue and Chevrolet Volton 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.
Chryslers 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
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,
www.calcars.org; BYD, www.byd.com; General
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
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 impuritiesincluding infectious bacteria from animal waste
as well as harmful pesticides and fertilizerson 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 frontierfrom 15 percent to 35 percent of the total land areaand
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
suns 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 suns heat back to the sky. Builders can check out CRRCs 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 its eventually installed.
CONTACTS: Green Roofs for Healthy Cities,
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