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Ultracapacitors Aim to Fill Energy Gap

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  • RemyC
    From: http://www.computerworld.com/hardwaretopics/hardware/story/0,10801,98803,00.html?from=story_package Sidebar: Ultracapacitors Aim to Fill Energy Gap News
    Message 1 of 1 , Jan 27, 2005
      From:
      http://www.computerworld.com/hardwaretopics/hardware/story/0,10801,98803,00.html?from=story_package

      Sidebar: Ultracapacitors Aim to Fill Energy Gap

      News Story by Robert L. Mitchell
      robert_mitchell@ computerworld.com

      JANUARY 10, 2005 (COMPUTERWORLD) - Most notebook computers require about 12
      watts of power during normal operations, but at boot-up, power demand spikes
      well beyond that. Accommodating peak power demands in mobile computing
      devices is a challenge for both battery and fuel-cell makers. Peak loads cut
      into battery life while fuel cells, which are designed to generate power at
      steady levels, simply can't respond effectively.

      Ultracapacitors promise to improve efficiency in both cases by satisfying
      the demand for short bursts of power -- from a few seconds up to a few
      minutes. Ultracapacitors don't wear out like batteries do, can be recharged
      quickly and can be reused thousands of times. "There is no chemical reaction
      like a battery. It's just a charge stored in a capacitor," says Bobby Maher,
      director of technical sales at ultracapacitor maker Maxwell Technologies
      Inc. in San Diego.

      Ultracapacitors such as Maxwell Technologies' Boostcap can supply short
      bursts of power to supplement existing battery or fuel cell systems or to
      deliver transitional power in the early moments of a power outage within a
      UPS system. The model shown is the size of a standard D cell battery.

      Some fuel-cell makers are including a small lithium ion battery in early
      power packs to handle peak power demands. The battery is trickle-charged by
      the fuel cell when not in use. "The problem is they want to get rid of the
      battery," Maher say. He claims that many companies working on fuel cell
      systems are including ultracapacitors in their designs.

      Ultracapacitors will never work as a battery or fuel-cell replacement,
      however. The designs have a very low power density. "The energy density is
      very, very low. You need 10 times the size to get the same density as
      lithium ion," says Isidor Buchmann, president of Cadex Electronics Inc., a
      maker of battery charging equipment in Richmond, British Columbia.

      Ultracapacitors also don't support sustained loads well because the power
      curve drops linearly. "You can get 90% of the capacity out of a lithium ion
      battery before it drops. With ultracapacitors, you can't use more than 50%
      of the capacity [before it drops off]," says Buchmann.

      Even as a peak power supplement, ultracapacitors are unlikely to make their
      way into internal notebook computer power packs because the devices take up
      too much space for the power generated. But they may be used in externally
      mounted power packs, says Maher.

      The use of ultracapacitors with fuel cells is still a long way off, says
      Atakan Ozbek, an analyst at ABI Research in Oyster Bay, N.Y. "It takes a
      long time to get from R&D to the commercial side," he says. "I don't know if
      any [fuel-cell] companies are really going after it right now."
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