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Are Electric
Cars Really a Cleaner Energy Solution?
Posted
by Greg Carr on January 26, 2010
The January 2010
Detroit Auto Show featured a number of new electric car
models or EV's, (short for Electric Vehicles). These
cars are just
around the corner for production. Check out
the
Nissan Leaf, Audi e-Tron and
GM Volt,
which are all going into assembly line production later this
year for 2011 deliveries. This train is rolling and
that's good news for all of us, here and abroad.
However, there
are plenty of EV naysayers out there who often dismiss the
energy efficiency and CO2 emissions benefits by saying
something along the lines of "you're
just hiding the energy waste and CO2 emissions back at the
electric power plant".
Many others are simply confused and just want
the truth about all the EV claims, as illustrated by the
recent blog comment below.
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Recent Comment & Question
"With almost 50% of our electricity
coming from coal and 22% from gas, how much more
"green" are electric cars? I would assume they would
not give off any CO2 like gas powered cars but does
the amount of electricity to run a electric car have
much less of an impact? I honestly just don't know the
answer to this question and have been trying to find
out so if anyone can answer it for me please do! :)" |
So let's have a serious
technical look, after all, that's our specialty here.
First, let's start with
the economics part of the equation. No one argues that
a gallon of gasoline or diesel fuel costs between
$2.50 and $3.50 per gallon, depending on where you live, and
twice that overseas. So, with that in hand, it's
fairly simple to calculate the equivalent cost per gallon
for EV's, something referred to in industry as the "gge" or
Gasoline Gallon Equivalent.
Let's compare a gasoline
car that get's 25 miles/gallon (mpg) with a similarly sized
EV. For EV's, the fuel economy metric to learn is "kpm",
or kiloWatt hours per mile (kWh/mile). Depending
on the size, EV's can range from 0.15 kpm up to 0.40 kpm.
For our example, we'll choose a comparable size electric
vehicle to the 25 mpg gas car that runs at a rate of 0.22
kpm (kWh/mile). Let's plug it in using my current
power bill rate of $0.12 per kWh.
Time to do the
math. To drive 25 miles in the EV, we have the
following:
0.22 kWh/mile x
$0.12 $/kWh x 25 mile = $0.66
Wow!
That's a gge of only $0.66/gal of gasoline equivalent for
the 25 mile drive. Or, putting it another way, it
costs $0.66/gal to fuel this EV. That's only 1/4th the
cost of a gallon of gas. Not bad. And if you
drive 30,000 miles per year, that EV is going to save you a
bundle, like $2,800 per year in saved driving costs.
Here's the math,
$3,600/year for gasoline ($3 gas) - $792/year of total
electric fueling cost = $2,808 savings
Okay, now let's
examine the CO2 claims for EV's. That one gallon of
gas to drive 25 miles creates exactly 18.9 lbs of CO2
emissions right out of the tailpipe, no arguments there.
And of course it's true that while our EV makes zero
emissions, the power plants supplying the grid certainly do.
The US average grid mix emissions rate is 1.6 lb of CO2
produced for each kWh of electricity demand by end users.
So, let's do the
math for the 25 mile EV drive and compare our CO2 emissions.
0.22kWh/mile x 1.6 lbs/kWh x 25 mile = 8.8 lbs CO2
There you have
it, the EV creates about 10 lbs less CO2 per gasoline gallon
equivalent.
Gasoline Car 18.9 lbs CO2/gge - EV Car 8.8 lbs
CO2/gge = 10.1 lbs more CO2 for Gasoline
Now, if this same
EV is charged-up with 100% renewable-generated electricity,
then the CO2 emission rate truly drops to absolute "Zero".
The bottom line
here says that EV's have a very bright future.
The fuel economy is about 1/4th the cost of gasoline or
diesel, and at worse they cut the CO2 emissions
in-half, and with renewable electricity the CO2 emissions
are cut 100%.
The current
challenge for EV makers is in extending the range between
re-charges from 100 miles up to about 300 miles where
most gasoline vehicles are today. Given what's been
accomplished so far, I'm confident they'll get there sooner
than later. Cheers.
Leave a Comment below,
thanks
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