EEStor

EEStor is a company based in Cedar Park, Texas, United States that has developed a type of capacitor for electricity storage, which EEStor calls 'Electrical Energy Storage Units' (EESU). [http://www.lockheedmartin.com/news/press_releases/2008/010908_LockheedMartinSignsAgreement.html] The EEStor EESU is an integral part of the ZENNergy drive-train. Its CEO and president is Richard Weir, who is also a co-inventor named on their principal technology patent.Cite web|url=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7033406.PN.&OS=PN/7033406&RS=PN/7033406
title=United States Patent 7,033,406|publisher=United States Patent Office|date=2006-04-25|accessdate=2007-11-24]

According to its patent application, these units will use high-purity 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 of the prototype is 1 MJ/kg; existing commercial supercapacitors typically have an energy density around 0.02 MJ/kg, while lithium ion batteries are around 0.54–0.72 MJ/kg.Cite web|url=http://www.technologyreview.com/Biztech/18086/page2/|title=Battery Breakthrough?|last=Hamilton|first=Tyler|publisher=Technology Review|date=2007-01-22|accessdate=2007-11-24] For comparison, gasoline has an energy density around 45 MJ/kg. However, the combustion process is unable to extract the majority of this energy and overall energy delivered to the wheel is typically less than 20% of this value; a value of 9 MJ/kg is more indicative. EEStor has stated that production examples should be about 2.5 MJ/kg, better than 1/4th the usable energy density of gasoline. This would represent an enormous leap in energy storage technology, which is the reason the company generates so much excitement and skepticism at the same time. (As part of the review process for patents, the U.S. Patent Office does not test the validity of the technical assertions in the patent application. Instead, it only checks whether earlier publications disclose the same idea. [ [http://www.uspto.gov/web/offices/pac/doc/general/index.html#examination - "USPTO Frequently Asked Questions"] , 17 September 2008] )

Based on these claims, a full charge should give the capacitor sufficient energy to drive a small car convert|300|mi|km. Although the technology should allow very fast charging (e.g., 5 minutes), 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. [ [http://www.news.com/8301-10784_3-9771053-7.html?tag=tb news.com - "Hard-charging electric vehicles?"] , 5 September 2007] Overnight charging at home should still be practical, [ [http://www.news.com/5208-10784_3-0.html?forumID=1&threadID=30828&messageID=309175&start=0 news.com - "YOUR point: CNET News.com"] ] 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 - and deliver cheap electric power to the house too, making expensive peak power plants obsolete. [ [http://www.economist.com/science/displaystory.cfm?story_id=10601407 economist.com - "Ne plus ultra"] , 31 January 2008] Also, according to Ian Clifford, a normal household outlet with 110 volt supply can fully charge the EEStor powered CityZENN in 4 hours for a convert|250|mi|km|sing=on range and a normal household outlet with 220 volt supply can fully charge the EEStor powered CityZENN in 2 hours for a convert|250|mi|km|sing=on range. [ [http://gm-volt.com/2008/06/01/exclusive-ceo-of-zenn-motor-company-on-eestor-eestor-storage-units-cityzenn-and-zennergy-drive-systems/#comments "Ian Clifford interview at GM-VOLT.com"] , 1 June 2008 ]

Technology

EEStor's product is a ceramic-based unit fabricated with integrated-circuit techniques.cite news |first=Ed |last=Beardsworth |title=UFTO Note - "EEStor Ultracapacitor and Ultrabattery" |url=http://www.ufto.com/clients-only/uftonotes04.html#Subject:%20UFTO%20Note%20-%20EEStor%20Ultracapacitor |work= |publisher=Utility Federal Technology Opportunities |date=2004-05-05 |accessdate=2008-06-17 ] The 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 aluminum electrodes [name=wipo.int] instead of more expensive nickel or platinum electrodes.

The technical specifications of the EESU are:

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. [ [http://thefraserdomain.typepad.com/energy/2006/01/eestor_ultracap.html The Energy Blog - "EEStor Ultracapacitor Shuns Publicity" - January 27, 2006] ] 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, 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 a useful output voltagecite web|url=http://www.bizlink.com/designengineering/content/features/de_zenn_electric_car_260508.jsp|title=Electric Avenue|last=Bergeron|first=Michael|coauthors=Treena Hein|date=2008-04-10|publisher=design Engineering|accessdate=2008-07-16]
* A self-discharge rate of 0.1% per month

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

$mbox\{E\}=\; dfrac\{mbox\{C\}cdotmbox\{V\}^2\}\{mbox\{2$

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

Status

"Prototype components" have been produced in a laboratory setting with a relative 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. [ [http://www.greencarcongress.com/2007/01/eestor_announce.html greencarcongress.com - "EEStor Announces Two Key Production Milestones; 15 kWh EESU on Track for 2007" - 17 January, 2007] ] 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. [ [http://www.news.com/8301-10784_3-9770849-7.html news.com - "Is EEStor delaying its power system for cars?" - September 4, 2007] ] 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. [cite web|url=http://www.technologyreview.com/read_article.aspx?ch=specialsections&sc=batteries&id=18086&a=f|title=Official Response from Zenn on delay of eestor (under Comment section written by afjerry on 09/11/2007 at 9:47 PM)|date=2007-09-11] ZENN reiterates it expects a production unit by the end of 2008. [ [http://gm-volt.com/2008/09/30/eestor-rides-again-this-time-on-a-bike/ ZENN expects production unit by the end of 2008] ]

On January 9 2008 EEStor publicly announced that Morton L. Topfer, a former vice chair of Dell, was rejoining the board. He had previously left in mid-2007 over concerns about the technology. [http://tyler.blogware.com/blog/_archives/2007/11/1/3328442.html] [http://www.reuters.com/article/pressRelease/idUS169754+09-Jan-2008+PRN20080109] [cite web|url=http://www.reuters.com/article/pressRelease/idUS169754+09-Jan-2008+PRN20080109|title=EEStor, Inc. is Pleased to Announce that Morton L. Topfer has Joined the EEStor, Inc. Board of Directors|accessdate=2008-01-09|publisher=Reuters]

In April 2008 ZENN Motor Company announced a highway speed vehicle for an indeterminate time in the future (when the "new power storage technology is ready") using EEStor's capacitors which will achieve 80 mph (130 km/h) speeds, 250 mile (400 km) range and charge in 5 minutes [cite web|url=http://www.businessgreen.com/business-green/news/2213373/zenn-outlines-global-ambitions|title=Zenn outlines global ambitions for 80mph electric car|date=2008-05-04] CityZENN target price is around $25000 - $30000. [ [http://www.zenncars.com/media/audio/evcast.mp3 zenncars.com - "Ian Clifford discusses the ZENN, EEStor.." - June 02, 2008] ]

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.

The world patent filed by EEStor in August 2005 [http://www.wipo.int/pctdb/en/wo.jsp?wo=2006026136&IA=WO2006026136&DISPLAY=DESC wipo.int - "(WO/2006/026136) Utilization of Poly(ethyene Terephthalate) Plastic and..."] ] contains test results for ten EESUs.

Permittivity

EEStor reports a large relative permittivity (19818) at an unusually high electric field strength of 350 MV/m; this allows 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 [http://www.wipo.int/pctdb/en/wo.jsp?wo=2006026136&IA=WO2006026136&DISPLAY=DESC wipo.int - "(WO/2006/026136) Utilization of Poly(ethyene Terephthalate) Plastic and..."] ] 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) in their capacitor system. Northrop Grumman filed a patent in 2006 [ [http://www.google.com/patents?id=PfCiAAAAEBAJ&dq=Talvacchio Small volume thin film and high energy density crystal capacitors] ] that claimed similar permittivity and energy density are possible with a different Perovskite-type dielectric. BASF filed a patent in 2003 [ [http://www.google.com/patents?id=Knx4AAAAEBAJ&dq=7023687 High energy density capacitors - Patent 7023687] ] that claimed energy densities twice as high are possible. A patent application filed in 2002 [http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&co1=AND&d=PG01&s1=20060097302&OS=20060097302&RS=20060097302] states that barium titanate materials can achieve the energy density reported by EEStor, but that leakage current is a problem.

The EEStor patents cite a 1993 article [S. A. Bruno, D. K. Swanson, and I. Burn, J. Am Ceram. Soc. 76, 1233 (1993)] and a Philips Corporation year 2000 patent [ [http://www.freepatentsonline.com/6078494.html Multilayer capacitor comprising barium-titanate doped with silver and rare earth metal - Patent 6078494] ] 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 April 2005 patent [ [http://www.freepatentsonline.com/6905649.html High-density barium titanate of high permittivity - Patent 6905649] ] by the University of California shows that high-density barium titanate formed from sub-micrometre grains can double the maximum permittivity, but does not discuss the permittivity at high voltages.

An EEStor patent references a 2001 patent [ [http://www.freepatentsonline.com/6268054.html Dispersible, metal oxide-coated, barium titanate materials - Patent 6268054 ] ] 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. [http://www.marketwatch.com/news/story/eestor-announces-certification-additional-key/story.aspx?guid=%7BAB6D95CC-0C6B-4734-83CB-990B4451270C%7D&dist=hppr EEStor Announces Certification of Additional Key Production Milestones and Enhancement of Chemical Purity] ]

In addition, the July 29, 2008 press release [http://www.marketwatch.com/news/story/eestor-announces-certification-additional-key/story.aspx?guid=%7BAB6D95CC-0C6B-4734-83CB-990B4451270C%7D&dist=hppr EEStor Announces Certification of Additional Key Production Milestones and Enhancement of Chemical Purity] ] 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.

Partnerships

Equity funding for the company appears to come predominantly from Kleiner Perkins Caufield & Byers although EEStor is not listed on their web site as a funded 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. [cite web |url = http://www.marketwire.com/mw/release.do?id=648733 |title = ZENN Motor Company Makes Equity Investment in Strategic Partner, EEStor, Inc. |accessdate = 2007-09-10 |publisher = Marketwire]

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. [cite web|url=http://pressmediawire.com/article.cfm?articleID=4628|title=Lockheed Martin Signs Agreement with EEStor, Inc., for Energy Storage Solutions|accessdate=2008-01-09|publisher=Pressmediawire] 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%. [cite web|url=http://www.thestar.com/Business/article/292614|title=ZENN stock leaps on EEStor's deal|accessdate=2008-01-10|publisher=The Toronto Star] 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. [cite web|url=http://www.gm-volt.com/2008/01/10/lockheed-martin-signs-agreement-with-eestor/|title=Lockheed Martin Signs Agreement with EEStor|accessdate=2008-01-10|publisher=GM-VOLT.com]

On September 24, 2008, Light Electric Vehicles Company's (LightEVs) president, Carl Watkins, announced the signing of a world-wide Exclusive Technology Agreement with EEStor to provide Electric Energy Storage Units for the two and three wheel market. [ [http://www.marketwatch.com/news/story/eestor-lightevs-sign-exclusive-technology/story.aspx?guid=%7B2972B144-0DFB-40DF-B1B3-180D8BB2FE51%7D&dist=hppr EEStor and LightEVs Sign Exclusive Technology Agreement] ]

From LightEVs' press release, "EEStor’s EESUs are expected to be highly configurable for shape, size, and power, and offer a breakthrough level of performance and price compared to existing battery technologies, including lithium iron phosphate."

"EEStor EESUs are expected to provide over 450 watt hours per kilogram and over 700 watt hours per liter, charge in minutes, and, for all practical vehicular purposes, last indefinitely. By comparison, lithium iron phosphate batteries provide about 100 watt hours per kilogram and 170 watt hours per liter. Unlike electrochemical batteries, EESUs should not break down from use or time during the life of a vehicle. They are expected to deliver high current without loss of efficiency or excess heat, and they should operate at optimum efficiency over a wide range of ambient temperatures. They will be configurable for any output voltage that optimizes vehicle performance, and will maintain that output voltage at a constant level over the span of each discharge cycle. Production is expected to start mid 2009."

John Stephens, Executive Vice President of LightEVs, said, “We expect to be able to provide performance characteristics exceeding those of existing light electric and gasoline powered vehicles. For example, we are planning an electric bicycle that will have a one kilowatt-hour EESU weighing less than five pounds which should provide approximately 100 miles or more of range, and we are considering a three-wheel two-passenger electric vehicle which could offer EESU options permitting ranges from about 120 miles to over 500 miles on a single charge, and a top speed of over 85 mph.”

"The light electric vehicle category is the largest established electric vehicle market in the world, with an estimated 20 million units sold per year. Some countries are seeing a 50% increase in sales of electric bikes and scooters per year. Light electric vehicles provide advantages in cost of purchase and operation, faster charge time, parking availability, reduced traffic congestion, and storage."

Competitors

*Nanowire battery from Stanford University [cite web |url=http://news-service.stanford.edu/news/2008/january9/nanowire-010908.html |title=Nanowire battery can hold 10 times the charge of existing lithium-ion battery |date=2007-12-18 |format=HTML |work=Stanford News Service ]
*graphene ultracapacitors from University of Texas at Austin [cite web |url=http://gas2.org/2008/09/26/new-battery-alternative-stores-huge-amounts-of-energy/ |title=New Battery Alternative Stores Huge Amounts of Energy |date=2007-12-18 |format=HTML |work=Gas2.0 ]
*Maxwell Technologies
*AltairNano

See also

* Capacitor
* Supercapacitor
* Ceramic capacitor
* ZENNergy drive-train
* graphene ultracapacitor

References

External links

* http://eestor.us - Official Website (Under Construction)
* http://www.TheEEstory.com - EEStor Discussion Group
* http://www.eestorbatteries.com - Information, News, Articles, and Discussion Board for EEstor Batteries
* http://www.ultracapacitors.org - Site dedicated to ultracapacitor technology
* http://peswiki.com/index.php/Directory:EEStor
* http://www.techknowforum.org - TechKnow Forum: Auto and Energy Industries coming together to talk about the issues surrounding electric vehicles.
* http://www.dipity.com/user/EEBretspot/timeline/EEStor_Timeline - EEStor Timeline

In the news

* [http://www.marketwatch.com/news/story/eestor-announces-certification-additional-key/story.aspx?guid=%7BAB6D95CC-0C6B-4734-83CB-990B4451270C%7D&dist=hppr EEStor Announces Certification]
* [http://pesn.com/2007/01/17/9500448_EEStor_milestones/ EEStor Announces Production Milestones] .
* http://news.com.com/8301-10784_3-9770849-7.html
* http://www.technologyreview.com/Biztech/18086/page1/
* http://www.technologyreview.com/Biztech/20090/
* http://www.itwire.com/content/view/8884/1066/
* http://tech.monstersandcritics.com/news/article_1351747.php
* http://www.nytimes.com/aponline/technology/AP-No-More-Batteries.html?em&ex=1189310400&en=55dc28f02299ee53&ei=5087%0A
* [http://tyler.blogware.com/blog/_archives/2007/11/1/3328442.html a blog post with a discussion disputing the validity of EEstor’s claims and targets]
* [http://www.economist.com/science/displaystory.cfm?story_id=10601407 An article from The Economist dated Jan. 31, 2008 that contains a reference to EEStor]
* [http://www.zenncars.com/media/audio/evcast.mp3 zenncars.com - "Ian Clifford discusses the ZENN, EESTor..." - June 02, 2008]
* [http://bariumtitanate.blogspot.com/2008/07/eestor-beyond-permittivity.html bariumtitanate.blogspot.com - "EEstor Beyond Permittivity" - July 19, 2008]