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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 revolutionary new type of capacitor for electricity storage, which EEStor calls 'Electrical Energy Storage Units' (EESU), [1]. EEStor claims the EESU can store far more electrical energy than any other type of capacitor, and that it could be used to propel a small car for about 300 miles[2]. This potential for making electric vehicles fully competitive with gasoline-powered vehicles has created much interest, although the company's claims have yet to be verified. EEStor's CEO and president is Richard Weir, who is also a co-inventor named on their principal technology patents.[3][4]

Technology

EEStor's proposed future product would be a ceramic-based unit fabricated with integrated-circuit techniques.[5] The technology, described in EEStor's patent, involves sintering very small grains of coated barium titanate powder into a bulk ceramic. The process is intended 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, EEStor intends to make the bulk ceramic have properties similar to those of individual barium titanate crystals. To keep costs down, the sintering is proposed to occur at low temperatures, enabling the manufacturer to use aluminum electrodes[6] instead of more expensive nickel or platinum electrodes.

The technical specifications of the EESU would be, according to [5]:

Prototype /
Low Volume 		LightEVs
Estimate 		Mass
Production
Energy density (Wh/l) 606 700 1513
Specific energy (Wh/kg) 273 450 682
Price ($ USD/kWh) $61 n/a $40

The claims made 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.[7] This is half the price per stored watt-hour of lead-acid batteries, and potentially cheap enough to use to store grid power at off-peak times for on-peak use, and to buffer the output from intermittent power sources such as wind farms.
  • 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.
  • The unit will come equipped with a built in Buck-boost converter (DC-DC voltage converter) to provide the proper input/output voltage[8]
  • A self-discharge rate of 0.1% per month

The company appears to be proceeding with development.[9]

The capacitance of the device described in the patent is 30.693 farads. To achieve such a high energy density the capacitor has a very high breakdown voltage and uses an operating voltage of 3,475 V. In the absence of dielectric saturation the formula for stored energy of a capacitor is

which gives a total energy storage of 185.31 MJ or 51.48 kWHours.

Status

The August 15, 2005 World Patent application filed by EEStor claimed ten EESU components were tested which had an average relative permittivity of 18,500.[10] In January, 2007, an independent company certified EEStor's production line's process as capable of producing 99.9994% purity barium titanate powder. According to EEStor, this is sufficient for achieving the desired permittivity.[11] Completion of development was to occur by the end of 2007. EEStor later offered a time-frame for delivery that was interpreted as a six month delay.[12] ZENN Motor Company (ZMC) has denied that this is a delay, just a clarification of the schedule, separating "development" and "commercialization". ZMC further stated that the next milestone is permittivity testing, and there is no announced date for it at this point.[13] EEStor CEO Richard Weir has indicated he is working toward production "as soon as possible in 2009."[14]

On January 9 2008 EEStor publicly announced that Morton L. Topfer, a former vice chair of Dell, was rejoining the board.[15] He had previously left in mid-2007 for reasons not publicly disclosed.[16]

Micheal Blieden is working on a documentary about the people and internet community surrounding EEStor.

Skepticism

EEStor's claims for the EESU exceed the energy storage capacity of any capacitor currently sold, by orders of magnitude. Many in the industry have expressed great skepticism regarding the claims. Jim Miller, a capacitor expert who visited EEStor to evaluate the technology for potential investors, stated he was very skeptical because of current leakage typically seen at high voltages and because there should be microfractures from temperature changes. He stated "I'm surprised that Kleiner has put money into it."[17] Andrew Burke, another expert who visited EEStor stated the consensus among experts was that the dielectric constant could not stay as high as claimed at the voltage levels claimed (i.e. energy density could not be that high). He stated EEStor would not provide any data to contradict the experts.[18]

Despite going into talks with numerous clients, including GM, Lockheed Martin, LightEV, Venture Vehicles, Zenn, and a number of others, no EESU prototypes have been publicly independently tested or acknowledged by anyone outside the company.

Permittivity

EEStor reports a large relative permittivity (19818) at an unusually high electric field strength of 350 MV/m; this would allow the EEstor capacitors to operate at high voltages, allowing them to store more energy than other capacitors. In such a strong electric field, the permittivity usually decreases due to a phenomenon called dielectric saturation, or the dielectric may break down, causing a short circuit between the capacitor electrodes. The world patent filed by EEStor in August 2005[19] contains relative permittivity data averaging 19,818 at a field strength of 500 MV/m. The EEStor patents ascribe their combination of permittivity and high breakdown voltage to the sintering process used to combine the PET plastic, Aluminum Oxide and composition-modified Barium Titanate. This high permittivity in a very strong electric field is the basis for EEStor to claim in their World Patent energy density of 2526 MJ/m3 (52 kWh or 188 MJ, in a package 4541 cubic inches, or 0.0744 m3). Northrop Grumman filed a patent in 2006[20] that theorized similar permittivity and energy density are possible with a different Perovskite-type dielectric. BASF filed a patent in 2003[21] that theorized energy densities twice as high are possible.

The EEStor patents cite a 1993 article [22] and a Philips Corporation year 2000 patent[23] as exact descriptions of its "calcined composition-modified barium titanate powder." In the Philips patent, this material is more precisely identified as "doped barium-calcium-zirconium-titanate". The Philips patent reports a permittivity of up to 33,500 at 1.8 MV/m. The Philips patent does not report the permittivity at a high electric field strengths, but it states it has "a low voltage-dependence," - i.e. that dielectric saturation had only a minor effect. Replacing some of the barium with calcium broadens the optimum temperature range, and replacing some of the titanium with zirconium increases the permittivity. The other doping reduces the Curie temperature, Tc, that allows the peak permittivity to be at 85 °C. EEStor uses an aluminum oxide coating on the barium titanate grains that was not used in the capactors the Philips patent describes.

An EEStor patent references a 2001 patent[24] that uses similar coatings on sub-micrometre particles of modified barium titanate. Under one set of conditions, they achieved a permittivity of only 2400 and did not report the permittivity at high voltages. Their breakdown voltage was 4 times less, a little over 100 MV/m.

EEStor says that purified aluminum oxide, in the range that EEStor, Inc. has certified, can have a voltage breakdown of 1,100 MV/m. The target working voltage of EEStor's chemical processes is at 350 MV/m. [25]

In addition, the July 29, 2008 press release[25] states that the plastic matrix allows for better crystal polarization and that this "along with other proprietary processing steps provides the potential of a polarization saturation voltage required by EEStor, Inc." Polarization by a strong electric field is done in the final steps of manufacturing so that the material will form domains that are oriented in the proper direction for the best permittivity and energy storage. The world patent states this is done at 180 C with 4000 V.

EEStor's US patent filed in 2001 mentions aluminum oxide and calcium magnesium aluminosilicate glass as coatings. The WIPO filed in 2005 mentions only aluminum oxide. Nickel was mentioned in the US patent as the electrode but it was changed to aluminum (1 micrometre thick) in the WIPO patent as a better and less expensive alternative. As stated in the patents, both changes were made possible by selecting the PET matrix (or coating) because it is pliable enough to fill voids at only 180 C.

Partnerships

Kleiner Perkins Caufield & Byers invested $3 million in EEStor in July 2005.[26][27] It is not known if they have invested more since then and have not had any comment on the technology or company.

ZENN Motor Company (based in Toronto, Canada), which manufactures the ZENN, stated in April 2007 that it had invested $2.5 million in EEStor.[28] Total ZENN Motor Company investment in EEStor is $3.8 million.

On January 9 2008 Lockheed-Martin signed an agreement with EEStor for the exclusive rights to integrate and market EESU units in military and homeland security applications[29] but did not invest any money.[30][31] Lockheed has not tested prototypes, but toured 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.[32]

On December 24 2008 a patent from Lockheed-Martin was published by the WIPO for a GARMENT INCLUDING ELECTRICAL ENERGY STORAGE UNIT (WO/2008/156903) that mentions EEStor by name as possible electrical energy storage unit.[33]

On September 24, 2008, Light Electric Vehicles Company's (LightEVs) president, Carl Watkins, announced the signing of a worldwide Exclusive Technology Agreement with EEStor to provide Electric Energy Storage Units for the two and three wheel market. [34]

Competitors

References

  1. ^ http://www.lockheedmartin.com/news/press_releases/2008/010908_LockheedMartinSignsAgreement.html
  2. ^ http://www.defensereview.com/modules.php?name=News&file=article&sid=1214
  3. ^ Weir, Richard (2006-04-25). "Electrical-energy-storage unit (EESU) utilizing ceramic and integrated-circuit technologies for replacement of electrochemical batteries". US Patent Office. Retrieved 2009-02-14. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  4. ^ Weir, Richard (2008-12-16). "Utilization of poly(ethylene terephthalate) plastic and composition-modified barium titanate powders in a matrix that allows polarization and the use of integrated-circuit technologies for the production of lightweight ultrahigh electrical energy storage units (EESU)" (PDF). US Patent Office. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ a b Beardsworth, Ed (2004-05-05). "UFTO Note - EEStor Ultracapacitor and Ultrabattery". Utility Federal Technology Opportunities. Retrieved 2008-06-17.
  6. ^ name=wipo.int
  7. ^ Fraser, James (2006-01-27). "EEStor Ultracapacitor Shuns Publicity". Retrieved 2009-02-14.
  8. ^ Bergeron, Michael (2008-04-10). "Electric Avenue". design Engineering. Retrieved 2008-07-16. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  9. ^ Petronius (January 23, 2008). "EEStor - Real or Scam?". The Agonist.
  10. ^ Leakage currents of 10 EESUs (bottom of page)
  11. ^ greencarcongress.com - EEStor Announces Two Key Production Milestones; 15 kWh EESU on Track for 2007 - 17 January, 2007
  12. ^ news.com - Is EEStor delaying its power system for cars? - September 4, 2007
  13. ^ "Official Response from Zenn on delay of eestor (under Comment section written by afjerry on 09/11/2007 at 9:47 PM)". 2007-09-11.
  14. ^ Technology Review: Better Batteries Charge Up
  15. ^ "EEStor, Inc. is Pleased to Announce that Morton L. Topfer has Joined the EEStor, Inc. Board of Directors". Reuters. Retrieved 2008-01-09.
  16. ^ Hamilton, Tyler (2007-11-01). "EEStor should talk". Clean Break. Retrieved 2009-02-14.
  17. ^ http://www.technologyreview.com/business/18086/
  18. ^ http://theeestory.com/topics/17
  19. ^ wipo.int - (WO/2006/026136) Utilization of Poly(ethyene Terephthalate) Plastic and...
  20. ^ Small volume thin film and high energy density crystal capacitors
  21. ^ High energy density capacitors - Patent 7023687
  22. ^ S. A. Bruno, D. K. Swanson, and I. Burn, J. Am Ceram. Soc. 76, 1233 (1993)
  23. ^ Multilayer capacitor comprising barium-titanate doped with silver and rare earth metal - Patent 6078494
  24. ^ Dispersible, metal oxide-coated, barium titanate materials - Patent 6268054
  25. ^ a b EEStor Announces Certification of Additional Key Production Milestones and Enhancement of Chemical Purity
  26. ^ http://www.kpcb.com/files/Fortune_article.pdf
  27. ^ http://www.businessweek.com/the_thread/dealflow/archives/2005/09/kleiner_perkins_1.html
  28. ^ "ZENN Motor Company Makes Equity Investment in Strategic Partner, EEStor, Inc". Marketwire. Retrieved 2007-09-10.
  29. ^ "Lockheed Martin Signs Agreement with EEStor, Inc., for Energy Storage Solutions". Pressmediawire. Retrieved 2008-01-09.
  30. ^ http://theeestory.com/posts/15450
  31. ^ http://theeestory.com/posts/15460
  32. ^ "Lockheed Martin Signs Agreement with EEStor". GM-VOLT.com. Retrieved 2008-01-10.
  33. ^ Bret "Bretspot" DeCelle (2009-01-27). "Steps Lockheed Martin May be Taking to Dominate the Department of Defense Portable Energy Requirements". TheEEStory.com. Retrieved 2009-02-14.
  34. ^ http://www.lightevs.com/2008-09-24LightEVsPressRelease.pdf
  35. ^ "Nanowire battery can hold 10 times the charge of existing lithium-ion battery" (HTML). Stanford News Service. 2007-12-18.
  36. ^ "New Battery Alternative Stores Huge Amounts of Energy" (HTML). Gas2.0. 2007-12-18.

In the news

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