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* 4-6 minute charge time for a 336 [[pound (mass)|pound]] (152 [[kilogram|kg]]), 2005 [[cubic inch]] (33 [[litre|L]]), 52 [[kilowatt hour]] (187 [[megajoule|MJ]]), 31 [[farad]], 3500 [[volt]] unit, assuming sufficient cooling of the cables.
* 4-6 minute charge time for a 336 [[pound (mass)|pound]] (152 [[kilogram|kg]]), 2005 [[cubic inch]] (33 [[litre|L]]), 52 [[kilowatt hour]] (187 [[megajoule|MJ]]), 31 [[farad]], 3500 [[volt]] unit, assuming sufficient cooling of the cables.
* A self-discharge rate of 0.1% per month
* A self-discharge rate of 0.1% per month

The capacitance in the patent is 31 [[Farads]]. To achieve such a high energy density the capacitor has a very high breakdown voltage and uses an operating voltage of 3,500v. In the absence of [[dialectric saturation]] the formula for stored energy of a capacitor is 1/2mv^2, which gives a total energy storage of 189 MJ or 52 KWHours.


== Status ==
== Status ==

Revision as of 08:22, 25 February 2008

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 around 0.01 MJ/kg, while lithium ion batteries have an energy density of around 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 300 miles (480 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], as is using a second EESU for the home which could be charged overnight using cheap, off-peak electricity to then charge the EEStor unit in the car in 5-10 minutes on demand.[5]

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
  • For a 52 kWh unit, an initial production price of $3,200, falling to $2,100 with mass production is projected.[6] This is half the price per stored watt-hour as lead-acid batteries, and potentially 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 (152 kg), 2005 cubic inch (33 L), 52 kilowatt hour (187 MJ), 31 farad, 3500 volt unit, assuming sufficient cooling of the cables.
  • A self-discharge rate of 0.1% per month

The capacitance in the patent is 31 Farads. To achieve such a high energy density the capacitor has a very high breakdown voltage and uses an operating voltage of 3,500v. In the absence of dialectric saturation the formula for stored energy of a capacitor is 1/2mv^2, which gives a total energy storage of 189 MJ or 52 KWHours.

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.[7] 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.[8] 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.[9]

On January 9, 2008, EEstor publicly announced that Morton L. Topfer, a former vice chair of Dell, was joining the board.[10]

Critics have suggested that measurements of the permittivity of the Eestor components were made only at low voltage and that permittivity would have been much lower at the operating voltage of 3,500v due to the phenomenon of dialectric saturation. However, the latest version of the Eestor patent.[11] contains measured permittivity at 85oC averaging 19,869 at an unspecified voltage, 19,837 at 3,500v and 19,818 at 5000v, demonstrating that little dialectric saturation occurs below 5000v.

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.[12]

On January 9th, 2008, Lockheed-Martin signed an agreement with EEStor for the exclusive rights to integrate and market EESU units in military and homeland security applications.[13] This was widely seen as lending a great deal of credibility to the company and its technology; ZENN, who had been taking flak for their investment in EEStor, saw their stock increase by 28%.[14] Lockheed has not yet tested prototypes, but did tour EEStor's facility and analyzed their technology and methodology. Lockheed was "very impressed" with EEStor, noting "they are taking an approach that lends itself to a very quick ramp-up in production." The two companies look to complete joint product testing over the course of 2008.[15]

Competitors

References

  1. ^ "United States Patent 7,033,406". United States Patent 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. ^ news.com - Hard-charging electric vehicles? - September 5, 2007
  4. ^ news.com - YOUR point: CNET News.com
  5. ^ economist.com - Ne plus ultra - January 31, 2008
  6. ^ The Energy Blog - EEStor Ultracapacitor Shuns Publicity - January 27, 2006
  7. ^ greencarcongress.com - EEStor Announces Two Key Production Milestones; 15 kWh EESU on Track for 2007 - 17 January, 2007
  8. ^ news.com - Is EEStor delaying its power system for cars? - September 4, 2007
  9. ^ "Battery Breakthrough?". Technology Review. 2007-01-22.
  10. ^ "EEStor, Inc. is Pleased to Announce that Morton L. Topfer has Joined the EEStor, Inc. Board of Directors". Reuters. Retrieved 2008-01-09.
  11. ^ wipo.int - (WO/2006/026136) Utilization of Poly(ethyene Terephthalate) Plastic and...
  12. ^ "ZENN Motor Company Makes Equity Investment in Strategic Partner, EEStor, Inc". Marketwire. Retrieved 2007-09-10.
  13. ^ "Lockheed Martin Signs Agreement with EESTOR, Inc., for Energy Storage Solutions". Pressmediawire. Retrieved 2008-01-09.
  14. ^ "ZENN stock leaps on Eestor's deal". The Toronto Star. Retrieved 2008-01-10.
  15. ^ "Lockheed Martin Signs Agreement with EEStor". GM-VOLT.com. Retrieved 2008-01-10.
  16. ^ "Nanowire battery can hold 10 times the charge of existing lithium-ion battery" (HTML). Stanford News Service. 2007-12-18.

See also

In the news

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