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Plug 'n play: Could plug-in hybrid cars help the energy crisis?

POSTED 29 NOVEMBER 2007


Not on the lot
Don't look for a plug-in hybrid at your local car store -- they are not on the market, although you can add a conversion kit to an existing hybrid for a price somewhat north of $10,000. To have the privilege of being an early adopter, you get to pay dearly...

Auto makers have not announced dates for introducing plug-in hybrids, but the industry has pulled a switcheroo on its once-dismissive tone, says Don Hillebrand of Argonne National Laboratory. "One year ago, only GM had mentioned it, now everybody is in on it. Six months ago, Toyota said, 'No, why would you want to plug in a hybrid?' and then they announced their program. Ford said, 'We absolutely will not work on it,' and now they have a few of them driving around."

Other manufacturers working on plug-ins include Hundai, Renault, and BMW, Hillebrand adds.

Exposed guts of a car engine are hooked to computers and studied by three men in a cinder-block garage-lab
This "testbed" has instruments for checking out plug-in hybrid electric vehicle systems. Photo: Argonne National Laboratory

Plug-in hybrids are a newer wrinkle on emerging, conventional-hybrid technology, and manufacturers are still groping for the cheapest, most efficient setup. Hillebrand says General Motors has announced a design with two electric motors in the transmission. "You get more flexibility ... . The motors can be used in combination, singly, or turned off, so it can run on pure electricity, combined electricity-gasoline, or pure fuel. At first, I thought this was a lot of extra equipment, but they are getting enough return to make it worthwhile."

And while the public may now equate "hybrid" with Toyota' Prius, "I think that will change fast," says Hillebrand. "I think GM is in the lead, but they don't know it yet."

How efficient? Leaping the babble barrier
The marketing of plug-in hybrids is sure to stimulate confusion: They will be promoted as high-efficiency vehicles, but the familiar "miles per gallon" standard is not relevant for cars that get power from the wall socket.

One possibility is to rate cars on energy equivalent -- one gallon of gas and/or the energy equivalent in electricity. Such calculations, performed at Argonne National Laboratory, show that plug-in hybrids can drive 80 to 200 miles on the energy in one gallon of gasoline.

That's monstrous mileage, but the number depends greatly on how the car is driven: Shorter trips use a higher percentage of high-efficiency, all-electric miles. But who decides what trip length to use in the official efficiency calculations?

Stainless steel cylinders are bound together, an electronic interface, orange wires and bolts on the front of each.
The feds are doing research to cut the cost and boost the lifetime and safety of high-power lithium-ion batteries for hybrid vehicles. Photo: Argonne National Laboratory

Consumers may also have to choose a battery: A big, heavy and expensive battery would increase the all-electric range, but its weight would cut efficiency on shorter trips.

A buyer's financial payoff will also depend on the changing prices of gasoline and electricity. And if cheaper, off-peak electricity is available, the actual percentage of off-peak charging will also affect the payback.

The looming confusion almost makes us sentimental for the advent of high-definition TVs... Even if emerging federal standards do clarify the matter, the arrival of the second generation of "vehicle-to-grid" hybrids is sure to bollix things up further.

The idea of using those big batteries to store electricity until it's needed by the electric grid is confusing -- but promising.

Can "vehicle to grid" improve the energy picture?

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Megan Anderson, project assistant; Terry Devitt, editor; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

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