230 miles per gallon

We seem to have set the bar quite low with our expectations for advanced compact vehicles delivering anywhere between 50 and 80 miles per gallon (mpg). Popular hybrids such as the Honda Insight and Toyota Prius deliver about 50 mpg in mixed traffic. Some European and Asian diesels reach 80 mpg. But 230 mpg?

That's the news for General Motors and its anticipated (late) 2010 Chevrolet Volt which has an all-electric range of 40 miles. Then its on-board gasoline generator needs one gallon to provide enough electricity to propel it for another 10 miles. Unlike regular hybrids that have a sizable internal combustion engine and a small electric motor, the Volt is more like a GE diesel-electric freight train locomotive that uses a small engine to generate electricity for the electric motor that exclusively propels the car.

And propels it does, as early accounts of pre-production samples show that a Volt pulls of the line with four adults in it stronger than a well-tuned V6 car. See a video here. Volt's electric motor is powered by batteries which are charged at home overnight with cheaper off-peak electricity.

As seen in the link above, a large Internet community has spawned around the Volt and some commuters in the U.S. (the all important "early adopters") are ready for an all-electric vehicle. The news of a 230 mpg all American vehicle made national headlines. Here is a sample from the New York Times.

Does a Volt make sense in Hawaii? Let's analyze this by using HECO prices and regular gas prices on Oahu for the past 12 months. The table below sums up the calculations. Three scenarios are shown for the Volt: (1) Use it for up top 40 miles per day in which case it is operated in "all electric" mode and needs no gasoline, (2) Use it for up to 50 miles per day in which case it uses battery power for the first 40 miles and then the generator consumes gasoline to provide electricity for another 10 miles, and (3) Use it for 80 miles per day, so battery and gas usage have a 50-50 share. The results show that the most economy is achieved at the "all electric" mode even at Hawaii's very high cost per KWh.


So does a Volt make sense in Hawaii? One positive aspect is that the limited range of electric vehicles is much less of an issue on a small island, although even nationally, almost 8 out of 10 commuters use their vehicle for no more than 40 miles per day.

On the other hand, Hawaii's electricity is all dirty (coal and oil) so green benefits will be rather minimal. A Volt would make a difference in greenhouse gas production in cities which receive hydroelectric or nuclear power.

A Volt would make good economic sense for someone who drives a large, heavy but fairly efficient SUV which in Oahu's sluggish traffic outputs about 16 miles to the gallon. But if the choice is between a $40,000 Volt or a $28,000 loaded Prius III, then the answer does not favor the Volt. (A Volt without its battery pack will be priced at around $25,000.)

However, energy prices fluctuate and in the long term fossil fuel prices have only one way to go: up. So if in a few years from now gas is at $5 per gallon and you live in the mainland where a KWh costs 10 to 15 cents (as opposed to 20 to 30 on Oahu), then over five years the Volt has a $8,000 advantage over an SUV and a slim advantage over a hybrid.

Plug-in electric vehicles are economical to maintain by having minimal maintenance requirements, basically limited to tires and brake pads. However, Volt's roughly $10,000 battery pack may need replacement sometime between year 6 and year 10 of the car's life.

Overall it is interesting to see where transportation technology is going. Only in 2009 car buyers had the choice of two fully competent hybrid cars, the Honda Insight and the Toyota Prius. These two are joined by a number of lower-end hybrids which offer smaller improvements to the fuel efficiency.

Come 2011 there will be two competent full-electric vehicles: The Chevy Volt and the Nissan Leaf. And there are many more electrics and other alternative energy vehicles in the works, such as fuel cell and biodiesel powered vehicles.

Green transport is here and on balance its features and limitations make it suitable for a large number of households.

[Revised August 15, 2009]