{"id":3436,"date":"2011-06-03T16:16:07","date_gmt":"2011-06-03T23:16:07","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=3436"},"modified":"2011-06-03T16:19:02","modified_gmt":"2011-06-03T23:19:02","slug":"taking-it-to-extremes","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/taking-it-to-extremes\/","title":{"rendered":"Taking it to eXtremes"},"content":{"rendered":"

\u201cIf I were to make a prediction, I\u2019d think there\u2019s a good chance that it is not batteries. But capacitors.\u201d\u00a0 Karl Young, CEO of eXtreme Capacitor, Inc<\/a>. started his presentation at the fifth annual Electric Aircraft Symposium with these words from Tesla Motor\u2019s Elon Musk.\u00a0 The reference to capacitors superseding batteries as an energy source for electric cars came from Musk\u2019s address at the Cleantech Forum in San Francisco on 16 March 2011.<\/p>\n

Young\u2019s talk before the April 29 gathering in Santa Rosa, California detailed the double-layer supercapacitors his company produces, and what Young feels are the advantages these have over \u201ctraditional\u201d lithium and other batteries.\u00a0 He is \u201ctrying to overcome the issues of batteries,\u201d including, according to Young, their weight, slow charge and discharge times, their short operational lifetimes (typically 500 to 3,000 cycles), and their toxicity and flammability.<\/p>\n

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Typical lithium cell construction (http:\/\/www.electricitystorage.org\/ESA\/technologies\/)<\/p><\/div>\n

Young contrasted that with the specifications for his eXtreme X-Cap\u2122 \u201cdouble-layer capacitor-based energy storage technology,\u201d which can last through over one million deep cycles, essentially making it a perpetual battery.\u00a0 While batteries sometimes take hours to charge, ultracaps can be charged in minutes or even seconds.\u00a0 Coupled with this is a \u201cround-trip efficiency\u201d of over 98 percent \u2013 meaning the capacitor loses less than two percent of the energy used to recharge it.\u00a0 Lead-acid batteries have a round-trip efficiency of around 50 to 70 percent, and lithium cells might approach 95 percent.\u00a0<\/p>\n

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eXtreme Cap construction (http:\/\/www.electricitystorage.org\/ESA\/technologies\/)<\/p><\/div>\n

eXtreme\u2019s high power-to-weight ratio, 250 Watt-hours per kilogram compared to lithium cells\u2019 128 watt-hours per kilogram, overcomes one objection to capacitors as energy storage devices.\u00a0 Most capacitors have markedly higher power outputs over short times than batteries can deliver, but cannot produce that power for extended periods. \u00a0This makes capacitors wonderful for sprints, but not for marathons, but usually heavier as they extend their energy capacity.\u00a0 X-Caps are also safer, not being made from toxic or flammable materials, according to Young.\u00a0<\/p>\n

He also noted a cost goal of $300 per kilowatt-hour, making them half to one-fifth the cost of current lithium batteries.\u00a0 This would be a great deal less expensive than the $1,000 per kilowatt-hour <\/a>projected last year by Carnegie Mellon University for the Chevrolet Volt battery pack \u2013 a price General Motors said was at least $200 over its estimates.<\/p>\n

Activated carbon, used in currently available supercapacitors, but Carbon nanotubes are the big thing in making supercapacitors into ultra and eXtreme capacitors. \u00a0Massachusetts Institute of Technology researchers use a forest of carbon filaments as a way to gain additional area for electrodes, and some battery and capacitor manufacturers use a carbon nanontube paper, looking a bit random and loosely packed, to gain additional surface area.\u00a0 eXtreme has developed a spinning method, which looks much like a textile manufacturing technique used in spinning wheels to pull individual strands of fleece together to make woolen yarn.\u00a0 In this instance, carbon nanotubes are pulled together into long, three-dimensional structures that are light, strong, and provide a high \u201cpacking factor,\u201d and therefore a high wetting area against which the battery\u2019s electrolyte can react.\u00a0<\/p>\n

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Electric Eagle air taxi<\/p><\/div>\n

This lightweight, high-energy package seems ideal for aircraft use, and Young closed his presentation with a concept air taxi, the Electric Eagle, looking much like the Beechcraft Starship of the 1970\u2019s, but a proprietary design of eXtreme Capacitor, Inc.\u00a0 A 300 mph, 500-mile range aircraft, the Eagle would be a great demonstrator for the energy storage devices we trust can become a soon-realized reality.<\/p>\n