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Monday, June 9, 2008

With Plug-In Cars Touted as the Next Big Thing, Sandia Scientists Beat Up Futuristic Power Sources

By John Fleck
Copyright © 2008 Albuquerque Journal; Journal Staff Writer
    An automotive revolution could soon appear in a driveway near you— a car that needs a lot less gasoline than the one sitting there now.
    Depending on how you drive it, the car may need no gasoline at all. Most of its energy, if not all, could come from plugging it in and charging it all night.
    But to succeed, the battery technology underlying the revolution must make it past the torture tests going on in what Pete Roth calls "the abuse lab."
    Roth's white beard and cheerful demeanor belie the destruction that happens inside the abuse lab's concrete block cells. There, behind a heavy steel blast door, Roth and his Sandia National Laboratories colleagues are pushing a new generation of car batteries to the limit, to see how they break. Or burn. Or explode.
    In the energy conservation community, the "plug-in hybrid" is seen as the Next Big Thing. A report released Friday by the International Energy Agency included the technology on its list of must-haves for dealing with climate change and dwindling global petroleum supplies.
    It exploits the success of the current crop of hybrids, which combine a gasoline engine with on-board batteries and an electric motor to improve vehicle efficiency.
    But instead of merely storing up energy generated while the car is in motion, plug-ins would do exactly what their name implies. You plug them in overnight, then drive on power drawn from the electricity grid rather than gasoline.
    All-electric range will depend on the batteries used. Once the batteries are drained— currently technologies being discussed range from 10 to 40 miles— the gasoline engine takes over.
   
Electricity demand
    While the batteries would drive up a car's initial cost, the electricity cost would be the equivalent of 50 cents per gallon of gasoline, said David Howell, manager of the U.S. Department of Energy's energy storage research program.
    Advocates say a large-scale switch over is possible without any need for additional power plants because the cars are plugged in for recharging at night, when power demand is low and big power plants have spare capacity.
    There is enough generating capacity in the United States to fuel 70 percent of U.S. cars and light trucks as plug-in hybrids, according to a Pacific Northwest National Laboratory study.
    Combine those economics with the convenience of a car that can switch over to gasoline operation to travel longer distances, and advocates say plug-in hybrids are the best alternative on the near-term horizon to dwindling gasoline supplies.
    Unlike hydrogen, another frequently touted gasoline alternative, advocates point out that the fuel delivery system for plug-in hybrids— the power line to your house— is already in place.
    There have been all-electric cars before, but the market has been hampered by the lack of a gasoline backup to switch to once the batteries are drained. Battery technology has also been a problem.
    But the auto industry seems to think plug-in hybrids may provide the answer to those problems. At least six companies, including giants Toyota, General Motors and Ford, have said they are pursuing cars based on the technology. GM announced last week that its entrant, the Volt, would be available in 2010.
    "It's very close," said Tien Duong, leader of the Department of Energy's hybrid-electric car research team.
   
Limited driving
    The opportunity for plug-in hybrids depends on the fact that most drivers don't drive more than 40 miles in a typical day. That means, Sandia's Roth said, that if you can pack enough batteries into the car, you can do all your typical city driving on an overnight electric charge.
    "You can be in all-electric mode for maybe 40 miles," he said. "For Albuquerque, that's wonderful."
    The remaining distance between the current technological state of the art and the finish line is all about battery technology. Plug-in hybrids demand things of batteries that have never been done before on a large scale, Duong said in an interview.
    Roth's job is to make sure the batteries that are finally used can stand up to real world environments without what one industry expert euphemistically calls "unfriendly failure modes."
    In other words, you don't want them to accidentally erupt in flames or explode.
    "Everyone is being very cautious about safety," said Roth, who has a steady stream of industry and government research projects running their battery prototypes through his abuse lab.
    Mobile energy use is all about what the engineers call "energy density." You need to get as much portable energy as you can into as small a package as possible.
    The mobile phone in your pocket is an example of how it is done. One reason it can fit in your pocket now, as compared to the first-generation mobile phones of the 1980s that they called "bricks," is the battery.
    While there have been other changes as well to miniaturize the phone, one of the big reasons a mobile phone today is so small is the development of lithium-ion batteries, a technology that allows a large amount of electricity to be stored in a very tiny package.
    The race now is to convert that technology to the much larger and more powerful battery packs needed to drive a car rather than send a text message.
   
Exploding batteries
    The problem, according to Menahem Anderman, president of Advanced Automotive Batteries, a consulting firm, is that it is still not clear what happens when you shift lithium-ion to the very different demands of driving a car.
    One problem, cited by Anderman in recent congressional testimony, is the risk of those "unfriendly failure modes." Discussions of the problem frequently drift back to the publicity debacle faced by computer maker Dell in 2006 when images raced around the Internet of one of its laptops spontaneously bursting into flames, apparently because of a faulty lithium-ion battery.
    Roth's job is to help prevent that from happening.
    In his Sandia abuse lab, he and his colleagues heat car batteries to extreme temperatures to see when they might burst into flames. They crush them and short-circuit them, trying to understand how the batteries might fail under real-world stresses.
    Sometimes, the failures are not so graceful. On a recent visit, one of the lab's concrete block test cells was covered in soot, the equipment inside melted by a fire from a battery test.
    Between the test cells and the room where the employees monitor their work on computers is a 2,000-pound blast door.
    Said Roth: "There have been times I'm real glad we have that door."