Comparing the Energy Efficiency of a Gas Powered Vehicle to an EV

Sunday, February 7, 2010
The goal of transportation is get something from Point A to Point B as efficiently as possible.  If you take your car as an example, all you really want it to do is get you from your home to work...comfortably.  If you had a choice, you probably wouldn't choose to waste money heating the engine up to 220F degrees or to keep the engine quiet while it silences the millions of explosions your car makes.  You also probably would pass on the hundreds of pounds of cooling equipment to keep the engine from overheating either..that's all waste when your goal is just to move something.
 
I thought it would be interesting to find a report comparing the difference between the efficiency of a vehicle powered by an Internal Combustion Engine (ICE) and an Electric Motor...but I couldn't find one.

I've known from DOEs site that Gas Powered engines only convert about 20% of the gasoline's energy down to the wheels...while EV's convert about 75% of the battery's energy to the wheels.  This is a HUGE difference, but I was wanting to see a breakdown of how they got this number.

Then I found the above graphic on DOEs site under the Energy Requirements menu.  This breaks things down nicely, but there's no comparison to EVs...so I made a SWAG at from other data I could find and filled in the table below. 



Internal Combustion
Engine Losses
Electric Drive
Losses
Notes
Energy In 100%
100%
Fuel or Electricity
Engine Losses
(friction, heat, charge)
-62.4%
-15%
10% for motor and 5% for power management.
Standby/Idle -17.2% 0%Electric Motors use nothing at 0mph
Accessories
(A/C, Heater, etc.)
-2.2%
-3%
I assumed higher because of cabin heat
is more expensive in an Electric Vehicle
Driveline Losses
-5.6%
-2%
Most EVs that I know of have no transmission
which makes driveline losses much less
Total Available Energy
for Acceleration
12.6%
80%EVs have 67.4% more energy available to move the vehicle than ICE powered vehicles...that's a HUGE difference in Efficiency!

So there you are, an unvalidated breakdown of how EVs are much more efficient than ICE vehicles...it's really all about wasted heat.  Once the new EVs hit the street later this year, maybe someone will actually compare two similar cars (like a Nissan Versa and a Nissan Leaf) and we can see how close these guesses are to reality.

Given the fact that petroleum is only going to become more scarce in the future, it's only sensible to use this resource more efficiently as time goes on...and using it in ICE powered vehicles is a waste compared to EVs!

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