Electric Cars 2.0
Kristina Kirby
Technology Review
Electric Cars 2.0
Plug-in hybrids could bring gas-free commutes. But will they make it
to market?
By Kevin Bullis
http://www.technologyreview.com/Energy/19181/
******************************************************
It's a hot and smoggy day in Washington, DC, and things aren't going
well for Les Goldman, a longtime energy lobbyist whose latest project
is a new kind of car that is supposed to slash gasoline consumption
and reduce greenhouse-gas emissions. We're outside his office, a block
from the White House and a quick trip down Pennsylvania Avenue from
Capitol Hill. And Goldman is sweating at the back of the "plug-in"
hybrid that I'm supposed to test-drive, checking electrical
connections and trying to figure out why it isn't working.
The car is a modified Toyota Prius with an extra battery installed in
the spare-tire compartment. Conventional hybrids like the Prius run on
an electric motor part of the time, but the electricity they use is
generated by a gasoline engine and by capturing energy from braking.
In the plug-in version of the car, the extra battery can be recharged
from an electrical outlet. The battery stores about 40 miles' worth of
electricity; if it's depleted, the car reverts to conventional hybrid
mode.
The few plug-in vehicles on the road today are prototypes that, as
Goldman is discovering, aren't always reliable. But recent advances in
battery technology have attracted the attention of major
manufacturers, raising the possibility of a mass-produced plug-in car.
General Motors has announced that it is developing plug-in hybrids
that use advanced lithium-ion batteries and could be ready within a
few years. One of the GM designs--for a car known as the Volt--calls
for a gasoline engine that kicks in after 40 miles just to recharge
the battery. Toyota also says it is researching lithium-ion batteries
and testing plug-in vehicles.
An electric battery with a 40-mile range could nearly eliminate trips
to the gas station for many drivers, since Americans drive just over
30 miles a day on average. But unlike earlier, all-electric cars, the
new hybrids could handle longer commutes; the Volt is designed to
travel 600 miles using its backup gas tank to charge the battery. And
electricity from the grid is cheap: the equivalent of a gallon of gas
costs less than a dollar.
The environmental arithmetic is also favorable. Generating the
electricity to power plug-in cars causes less greenhouse-gas pollution
than burning gasoline does, according to a recent study by the
Electric Power Research Institute and the National Resources Defense
Council. Even in the worst-case scenario, in which a plug-in vehicle
got all its electricity from coal-fired plants (in reality,
electricity in the United States comes from a mix of sources that on
average release less carbon dioxide than coal plants do), it would
still be responsible for a third less greenhouse-gas pollution than
a conventional car. And though plug-ins and conventional hybrids would
account for similar amounts of greenhouse-gas emission in most parts
of the country, plug-ins in areas with clean sources of electricity,
such as hydroelectric power, would be responsible for about half the
carbon dioxide emissions of other hybrids.
Unlike other alternative technologies, such as cars powered by
hydrogen fuel cells, plug-ins don't require any significant new
infrastructure. Existing gas stations would provide the fuel for long
trips, and electrical outlets in garages would provide the power for
short commutes. (Eventually, charging stations could be installed for
city dwellers.) And plenty of electricity is available, particularly
overnight. According to a study from the Pacific Northwest National
Laboratory, there's already enough excess generating capacity at night
to charge 84 percent of the cars, pickups, and SUVs on the road today,
if they were all suddenly converted into plug-in hybrids.
Better Batteries
A couple of weeks after my ill-fated attempt to test-drive the plug-in
car in Washington, I'm outside the headquarters of battery maker A123
Systems in Watertown, MA. Out front is the shiny, aggressively styled
GM Volt. The car is there because GM has selected A123 as one of two
companies that could end up providing the battery technology for the
Volt.
A123 makes a new type of lithium-ion battery. Lithium-ion batteries,
which are now used widely in laptops and cell phones, pack a lot of
energy into a small space. They take up just one-sixth the space of
the lead-acid batteries used in previous types of electric vehicles,
and they weigh one-sixth as much. They also take up less than half the
space of nickel-metal hydride batteries, the kind used in today's
conventional hybrids, while weighing just a third as much.
But the type of lithium-ion battery that's used in laptops and cell
phones has problems, including the occasional tendency to overheat
and, in rare cases, burst into flame. Troubling as this instability is
in personal electronics, it could be even worse in a car, which uses a
module that consists of hundreds of times the number of batteries
found in an electronic device. On top of that, although prices have
been coming down gradually, lithium-ion batteries are still
expensive.
All that could change as a result of A123's batteries, in which
electrodes based on cobalt oxide have been replaced with iron
phosphate electrodes. At relatively low temperatures, oxides release
oxygen, which can drive reactions that might heat up a battery and
cause it to explode. But phosphates continue clinging to oxygen at
much higher temperatures. What's more, iron is far cheaper than
cobalt.
Volt or Bolt?
There is a giant "if" in all this, though. To become practical and
economically viable, plug-in vehicles will need to be mass-produced.
Will automakers follow through on their highly publicized
announcements about plug-ins? GM, for one, has a reputation for
quitting on innovative engineering; the company's executives scrapped
an earlier all-electric vehicle. And even though GM had an early lead
in conventional hybrid technology, it failed to bring hybrids to
market until after the success of Toyota's Prius. What will happen to
plug-in plans if gas prices drop, or if interest in reducing
greenhouse gases wanes?
No one can predict the results of the carmakers' fickle decision-
making process. But a few things are clear. Plug-ins are the most
practical and enticing alternative to the internal-combustion engine
that has been developed in years. And their fate will depend on
whether automakers learn from the success of conventional hybrids and
fully embrace the new technology.
I did at last drive a working plug-in. The converted car glided
noiselessly along the streets of Boston as I eyed a gauge that
estimated my mileage at more than 150 miles per gallon. But on the day
that I saw the Volt on display at A123's offices, GM wasn't giving
rides; the car was just a mock-up, without the new batteries. As I sat
in the driver's seat and grasped the steering wheel, sunlight
streaming through the clear roof, it was easy to believe that plug-ins
are on the way. But the mock-up was also a harsh reminder that when it
comes to green innovation, U.S. automakers have long been more eager
to show off flashy concept cars than to manufacture vehicles that
work.
Kevin Bullis is the nanotechnology and materials science editor at
Technology Review.
Copyright Technology Review 2007.
************************************************
http://www.technologyreview.com/Energy/19181/