Energy expert Joe Romm on CO2 emissions of gas and electric cars
Jun 13, 2005 (From the CalCars-News archive)

I'm passing on this explanation from Joe Romm -- if you want to see more
about his book, see
http://www.cool-companies.org/
See more on this subject at Section 3 of CalCars' Vehicles page
http://www.calcars.org/vehicles.html

This message can be found at
http://autos.groups.yahoo.com/group/calcars-news/message/65


Hi, I'm Joe Romm.

I ran the Office of Energy Efficiency and Renewable Energy at the US
Department of Energy during part of the Clinton Administration and wrote
"The Hype about Hydrogen" (Island Press, 2004).

Plug ins are so new for most of us that we haven't done a very good job of
putting out basic fact sheets. Heck, I didn't even talk about them in my
book. I just got educated by a bunch of people, including Felix. Then I
wrote a paper for the National Commission on Energy Policy which helped
spur a great deal of interest.

Hybrids that can be plugged into the electric grid (so-called plug-ins or
e-hybrids) will be I think the second phase of a two-phase transition that
has already begun with the hybrid revolution. The top priority for all of
us who want to reduce oil consumption and greenhouse gas emissions in the
transportation sector is certainly increasing fuel economy standards. I
personally would recommend these standards give some sort of extra credit
for meeting the standards with hybrids because we want to enable the second
phase of the transition, where dual-fuel hybrids can run partly off of a
charge from the electric grid.

Electricity has always been the ideal fuel for driving, because electric
motors are so efficient (but range and speed of refueling issues limited
the attractiveness of pure EVs). This is especially true in cities because
electricity-powered cars have zero in-airshed emissions and 10x to 1000x
lower lifecycle emissions of all criteria air pollutants, and potentially
zero life-cycle emissions in the long term as the grid gets cleaner.

My top priority has always been greenhouse gas emissions. Here plug ins
are an unadulterated home run. Let's use the high-end of actual numbers
that Felix Kramer has been getting with his modified Priuses: 250
Watt-hours per mile all electric (this should be pretty typical for modern
EVs of that size -- The large RAV4 gets maybe 300 Wh/mi). Let's compare
that to what a diligent driver will get with the Prius in warm
climates: 50 mpg (personally, my family does on average about 46 mpg year
round).

Let's compare 12,000 miles (the typical yearly vehicle miles traveled),
running all electric, which consumes 3,000 kwh, with running all gasoline
(i.e. using a regular Prius), which would be 240 gallons.

The lifecycle greenhouse gas emissions from burning a gallon of gasoline is
roughly 25 pounds (20 on-site, another 5 in the petroleum production chain
-- the number may be slightly higher for reformulated gasoline, and will be
considerably higher from oil from the tar sands). So we have 6,000 pounds
of CO2 from a Prius.

NOTE: The average new NON-hybridized car would emit 11,000 to 12,000
pounds of CO2. This is the proper baseline for those who are concerned
about whether e-hybrids would increase emissions compared to a business as
usual case.

The grid average emissions factor for electricity in this country is,
roughly, 1.3 pounds per kwh. That yields 3,900 pounds of CO2! So running
your E-hybrid on the U.S. grid is 35% better than running a Prius on
gasoline and 65% better than an average car.

If the entire grid were coal, you could double that (7,800 pounds), so even
in that worst-case scenario, you'd still have far LOWER CO2 emissions from
a plug-in Prius than from the average new car on the road running on gasoline.

In California, with its cleaner grid, you'd have under 2,000 pounds
emissions from a plug-in Prius. And, of course, people can choose to
purchase 100% renewable power.

The nice thing about plug ins is that it gives people a fuel choice, and
everyone will choose electricity since even in California, the per-mile
cost of electricity is under one half that of gasoline.

Joe Romm