EV In Your Future: What's A Watt?

Chances are, if your next car is a passenger car, you'll be looking
at some EV--Electric Vehicle--models. If you aren't needing a car
until a few years from now, you'll be looking at a lot of EV choices.
There will even be EV trucks by then.

We all live with electricity and gasoline, but few of us have
a gut feeling for how the energy in a kilowatt-hour of electricity
compares to the energy in a gallon of gas.

A kilowatt-hour (kWh) is 1000W (watts) for 1 hour. Your toaster uses
1000W, but only for a minute or two. Toasting a bagel is maybe 0.033kWh;
not much compared to the average home, which uses about 28kWh (about 840
bagels) per day. Let's roll that bagel down the road.

A reasonably efficient EV passenger car, say, a Prius Prime, gets
about 4 miles per kWh during the summer. So 28kWh of daily home electricity
rolls that Prius 112 miles down the road.

Gasoline has a /lot/ of power in it and that power can be expensive.
Play with numbers and units, and it turns out that 1 gallon of gasoline
is the same thing as 33.7kWh. Wait a minute, here. If 28kWh gets you
112 miles, then 33.7kWh gets you...almost 135 miles down the road.

Does this mean EV cars are getting 135MPG? It's not
that simple, but yes. Electric motor drive, thanks to fewer moving
parts and no energy going out a tailpipe, converts about 60% of the
power in a battery to motion; a gas engine drive uses only 20% of the
power in its fuel. Fewer parts also mean lower maintenance cost
(imagine no more motor oil changes).

But, wait, it gets better. If you charge the EV battery at home,
the fuel cost savings (electricity vs. gasoline) is amazing.
The $3 you pay per gallon at the pump would buy you about 20kWh.
The gallon might get you maybe 40 miles but the 20kWh could get you
80 miles. Not bad at all but, if you have extra Solar PV power that you
sell back to the power company, the $3 could get you 120kWh...or 480 miles.
Your fuel cost savings can help finance those Solar PV panels!