Friday, December 14, 2007

Driving a PHEV is Like Buying Gasoline at 20 Cents a Gallon

While you might think a Plug-in-Hybrid-Electric-Vehicle (PHEV) is simply an ordinary hybrid with a plug added for charging, there is another significant difference between the two. Typical hybrid cars on the road today have a gasoline motor and an electric motor, and either of them can be used to drive the wheels. On the other hand, power to the wheels on the new breed of PHEV’s will come ONLY from the electric motor. The gasoline motor is used to recharge batteries. This design is inherently more fuel-efficient, since the gasoline motor will run at a constant speed. It’s called a “series” hybrid, and the Chevrolet Volt is an example. The plug-in Volt is expected to be available in 2010. It will have a 16kwh lithium-ion battery that will take 6 to 6 ½ hours to charge, and a fully-charged battery can propel the car for the first 40 miles. The gasoline motor kicks-in after that, extending the range of the car. For those who drive less than 40 miles per day, which is most of us, the car will use no gasoline at all.

Based on that information, it’s easy to calculate operating expenses. Assuming that electricity costs ten cents per kwh, the cost to charge the battery should not exceed $1.60, which is ten cents per kwh times 16kwh. In reality, the battery will not be fully drained, and therefore the actual cost will be less than that. But for no more than $1.60 worth of electricity, the car will go 40 miles. It takes $3.00 to $6.00 worth of gasoline to go that far in a typical gasoline-powered car!

Nighttime electric rates are much less than daytime rates in many locations, and I’ve signed up for a plan that gives me rates as low as two cents per kwh in the early morning hours. My rate will change from day to day and hour to hour, but if it averages less than four cents per kwh at night, I’ll be able to charge my Volt for as little as twenty six cents. Needless to say, I can hardly wait to own one. When compared to a car that gets 30 mpg, this is equivalent to gasoline at 20 cents per gallon for the first 40 miles of driving each day!

In reality, state and federal legislators will soon realize that I’m not paying my fair share of road use taxes, and somehow I’ll be forced to make up the difference, but I’ll certainly have some unbelievably inexpensive transportation in the mean time.

Here’s the info from Chevy:



d said...

Hi SJ,

Thanks again for a clear explanation!

I've just started looking at pure electric cars, but the hybrid you describe is an interesting intermediate step if you can't be sure of getting to a charging point or have the odd long journey.

I've managed without a car at all until now, but in order to get more space for better RE solutions I may have to move somewhere a little further from public transport, and a electric or hybrid car might make that possible.



solar john said...

I would also like to own an electric scooter or bike. Weather permitting, I'd use it for trips to the post office, bank, grocery store, etc. For times when I can get by without a car, it's much more efficinet than propelling a 2000lb car around town.


d said...

Hmm yes, I thought about a scooter too, briefly.

But it isn't going to get my 2-year-old from place to place!

If we can't walk to local shops and regular public transport then I think that we probably need a car of some sort.