Apr 3, 2005 (From the CalCars-News archive)
In response to a comment by an individual interviewed in today's NY Times
story that "coal is more polluting than gasoline," we've added
a new section at
http://www.calcars.org/vehicles.html (with a link from the excerpt of
the Times story)
4. How Much Cleaner than a Gasoline Car is a PHEV Charged
from the Dirty (Coal) Grid ?
California, New York, Massachusetts and other
states have had Zero-Emission Vehicle Programs since the early 1990s
because battery electric vehicles in those states, taking into account
power plants, are far cleaner than gasoline cars in reducing urban air
pollution and smog. The comparison keeps being raised, though the studies
are conclusive.
Studies show that what is called the "well-to-wheel emissions"
of electric vehicles are lower than those from gasoline internal
combustion vehicles. In California, Air Resources Board studies show that
battery electric vehicles emit at least 67% lower "greenhouse
gases" than gasoline cars -- even more assuming renewables. A
plug-ifPBOV with only 20 miles all-electric daily range is 62% lower: see
printed page 95 in the
2004 study,
As for numbers keyed to the national grid, two government studies found
plug-in HEVs would result in large reductions even with the national grid
(50-60% coal). The
GREET 1.6
model in 2001 by the US Department of Energy's Argonne National Lab
estimates hybrids reduces greenhouse gases by 22%, and a plug-in hybrid
by 36% -- see table 2. An Argonne researcher reached consensus with
researchers from other national labs, universities, the Air Resources
Board, automakers, utilities and AD Little to estimate in July 2002 that
plug-in HEVs using nighttime power reduce greenhouse gases by 46 to 61
percent. Summarized in slide 11 at the
November 2003 presentation by EPRI.
Only PHEVs and battery EVs get cleaner as they get older - because the
electric grid gets cleaner every decade. Plus more people are installing
rooftop solar photovoltaic systems, and clean wind power is vastly
expanding nationally (see study by eminent environmentalist Lester Brown
cited at CalCars Kudos).
Finally, looking at the fuel, not electric component (also of course part
of the well-to-wheel totals), instead of using gasoline for long-trips
PHEVs could use bio-fuels to further reduce greenhouse gases.
Finally, PHEVs will generally recharge at night from power plants that
can't shut down completely -- they don't add to the peak load, and might
one day actually help reduce it by providing power from parked PHEVs'
batteries during daytime hours (see 7. Vehicle-To-Grid
below).