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EEStor

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EEstor cell

EEStor is a company based in Cedar Park, Texas, United States that claims to have developed a superior type of capacitor for electricity storage, which EEStor calls 'Electrical Energy Storage Units' (EESU). Its CEO and president is Richard Weir, who is also the inventor named on their principal technology patent.[1]

These units use barium titanate coated with aluminum oxide and glass to achieve a level of capacitance claimed to be much higher than what is currently available in the market. The claimed energy density is 1.0 MJ/kg (existing commercial supercapacitors typically have an energy density of the order of 0.01 MJ/kg and a lithium ion battery has an energy density of 0.54–0.72 MJ/kg).[2]

Based on this technology, a five-minute charge should give the capacitor sufficient energy to drive a small car 500 miles (800 km). However, standard household wiring is not capable of delivering the power required for this, so charging times this short would probably require purpose-built high capacity dispensing stations.[3] Overnight charging at home should still be practical.[4]One convenient, but more expensive, option might be to buy a second Eestor unit for the home which could be charged overnight using cheap, off-peak electricity and could then be used to charge the Eestor unit in the car in 5-10 minutes on demand.

Technology

EEStor's technology, described in its patent, involves sintering very small grains of coated barium titanate powder into a bulk ceramic. The process is designed to eliminate the pore space left by sintering. Barium titanate crystals have an extremely high permittivity; however, voids allow current to arc through the dielectric (voltage breakdown), causing the capacitor to self-discharge. By eliminating the voids, the bulk ceramic has properties similar to that of individual barium titanate crystals. To keep costs down, the sintering occurs at low temperatures, enabling the manufacturer to use nickel electrodes instead of more expensive platinum electrodes.

The claims of the EESU are:

  • Nontoxic and non-hazardous
  • Non-explosive
  • An initial production price of $3,200, falling to $2,100 with mass production.[1] Half the price per stored watt-hour as lead-acid batteries; cheap enough to use to store grid power at off-peak times for on-peak use.
  • No degradation from charge/discharge cycles
  • 4-6 minute charge time for a 336 pound, 2005 cubic inch, 52 kilowatt hour, 3500 volt unit, assuming sufficient cooling of the cables.
  • A self-discharge rate of 0.1% per month

Status

"Prototype components" have been produced in a laboratory setting with a permittivity of 18,500. In January, 2007, an independent company certified EEStor's production line's process as producing 99.9994% purity barium titanate powder, sufficient for achieving the desired permittivity.[2] Completion of development was to occur by the end of 2007. EEStor later offered a timeframe for delivery that was interpreted as a six month delay.[3] ZENN has denied that this is a delay, just a clarification of the schedule, separating "development" and "commercialization". ZENN further stated that the next milestone is permittivity testing, and there is no announced date for it at this point.[4] In November, Ian Topfer, a former vice chair of Dell, left the board of EEStor with no explanation given, leading to some concern as to the future of the company.[5]

Partnerships

Equity funding for the company appears to come predominantly from Kleiner Perkins Caufield & Byers.

Feel Good Cars (based in Toronto, Canada), which operates Zenn Motor, stated in April 2007 that it had invested $2.5 million in EEStor.[5]

Competitors

References

  1. ^ "United States Patent 7,033,406". United States Patenet Office. 2006-04-25. Retrieved 2007-11-24. {{cite web}}: Check date values in: |date= (help)
  2. ^ Hamilton, Tyler (2007-01-22). "Battery Breakthrough?". Technology Review. Retrieved 2007-11-24. {{cite web}}: Check date values in: |date= (help)
  3. ^ http://news.com.com/8301-10784_3-9771053-7.html?tag=tb
  4. ^ http://news.com.com/5208-10784_3-0.html?forumID=1&threadID=30828&messageID=309175&start=0
  5. ^ "ZENN Motor Company Makes Equity Investment in Strategic Partner, EEStor, Inc". Marketwire. Retrieved 2007-09-10.

See also

In the news

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