The Energy Blog

More News on EEStor

The latest about EEStor, the promising developer of ultracapacitors can be found in a post by Tyler in Clean Break, EEStor Powered cityZenn targeted for fall 2009 the key item is taken from Zenn Motor Company's  press release following its annual general meeting of March 28:

The cityZENN is planned to be a fully certified, highway capable vehicle with a top speed of 125 KPH/ 80 MPH and a range or 400 kilometres/250 miles. Powered by EEStor, the cityZENN will be rechargeable in less than 5 minutes, feature operating costs 1/10th of a typical internal combustion engine vehicle and be 100% emission-free! The Zero-Emission, No-Noise cityZENN will be designed to meet the transportation requirements of a large percentage of drivers worldwide.

"EEStor's game-changing energy storage technology is in the advanced stages of commercialization", stated Ian Clifford, Chief Executive Officer. "EEStor has publicly committed to commercialization in 2008 and their first production line will be used to supply ZENN Motor Company."

EEStor is believed to have had trouble developing its product, an ultracapacitor claimed to have a specific energy of 280 watt-hours per kilogram, compared to a lithium ion battery with about 120 watt-hours and a lead-acid gel battery, with only 32 watt hours. (Although ElectroVaya claims 330Wh/kg, so they may not be alone) 

The problem is believed, by some, to be in producing the ultra-pure barium-titanate used in the capacitor, which is the key to having the high specific energy. A January 2007 announcement indicated that 1) An automated production line had been proven to meet the requirements for precise chemical delivery, purity control, parameter control and stability and 2) they had completed the initial milestone of certifying purification, concentration, and stability of all of its key production chemicals notably the attainment of 99.9994% purity of its barium nitrate powder. At that time they claimed that they would be shipping product to Zenn in 2007, a year earlier than indicated in the current announcement. 

EEStor's recently announced collaboration with Lockheed Martin, which gives the company credibility and is a further indication that the company is making progress. The current announcement seems to be in agreement with the timing indicated in the Lockheed Martin announcement, although, based on past performance, a wait and see position must be held. 

Sodium Sulfur Batteries to be Used for Energy Storage at MN Windfarm

Xcel Energy, (NYSE: XEL)in partnership with the University of Minnesota, the National Renewable Energy Laboratory and the Great Plains Institute, will soon begin testing a one-megawatt sodium-sulfur battery storage system to demonstrate its ability to store wind energy and dispatch it to the electricity grid when needed.

Fully charged, the batteries could power 500 homes for six and one-half hours. Xcel Energy will purchase the batteries from NGK Insulators, Ltd. that will be an integral part of the project. The sodium-sulfur battery is commercially available and versions of this technology are already being used in Japan and in a few US applications, but this is the first U.S. application of the battery as a direct wind energy storage device.

The 50-kilowatt battery modules, 20 in total, will be roughly the size of two semi trailers and weigh approximately 60 tons. They will be able to store about 6.5 megawatt-hours of electricity, with a charge/discharge capacity of one megawatt. When the wind blows, the batteries are charged. When the wind calms down, the batteries can be used to supply energy to the grid as needed.

"Energy storage is key to expanding the use of renewable energy. This technology has the potential to reduce the impact caused by the variability and limited predictability of wind energy generation."

-- Dick Kelly, Xcel Energy chairman, president and CEO.

The project will take place in Luverne, Minn., with the battery installation beginning this spring adjacent to a nearby 11-megawatt wind farm owned by Minwind Energy, LLC. Testing will begin in October and is expected to last up to two years.

Commercial projects are now underway that use flow batteries, compressed air energy storage, thermal energy storage, pumped hydro, and sodium sulfur batteries for energy storage in connection with renewable energy projects.  American Electric Power (AEP) is also using NaS batteries in a couple of their systems, but not in connection with wind power. While not enough experience has been gained with any of these technologies to make any decision as to which technology is best under what conditions, pumped hydro and sodium sulfur batteries are the most well proven and thus seem to be the first choice of electric utilities. Thermal storage is gaining acceptance for use with thermal solar systems, the only energy technology that it is suitable for use with. As Mr. Kelly stated, energy storage is essential to widespread use of renewable energy technologies. 

FYI: Zenn Still Planning on EEStor

ZENN (TSX: ZNN) the Canadian manufacturer of low speed electric car vehicles has a statement in its first quarter 2008 report that they anticipated EEStor technology being commercialized and is making plans to incorporate it into its products. In addition ZENN is invstigating longer-range highway capable vehicles both as a retrofit for certain existing automobiles and producing small to midsize cars that have a top speed of 65 to 75 MPH (105 to 120 KPH) and a single-charge range of 200 to 400 miles (325 to 650 Km).

This indicates that they must still believe that EEStor's potentially disruptive technology for unique capacitor based energy storage systems is progressing to the point that they are willing to expend time designing their vehicles to use EEStor's systems, although they did not indicate when such vehicles will be available. See this post and this one for more information on EEStor.

Thanks for the tip from Tyler of Clean Break

EEStor, Lockheed Martin to Collaborate on Military and Homeland Security Applications

After quite a period of silence, there is some news on EEStor today. Maybe the company is for real and we will finally get some more meaningful information. Working with Lockheed Martin certainly gives them some credability. It looks like the company is about a year behind on its initial production schedule. Several previous posts on EEStor can be found in the energy storage category. The bold emphasis in the press release is mine.

The entire lockheed Martin press release:

Lockheed Martin [NYSE: LMT] has signed an exclusive international rights agreement to integrate and market Electrical Energy Storage Units (EESU) from EEStor, Inc., for military and homeland security applications.  Specific terms of the agreement were not disclosed.

EEStor, based in Cedar Park, TX, is developing a ceramic battery chemistry that could provide 10 times the energy density of lead acid batteries at 1/10th the weight and volume.  As envisioned, EESUs will be a fully “green” technology that will be half the price per stored watt-hour than traditional battery technologies.

“Lockheed Martin has a wide range of innovative energy solutions for federal, state and regional energy applications,” said Glenn Miller, vice president of Technical Operations and Applied Research at Lockheed Martin Missiles and Fire Control.  “The EEStor energy storage technology provides potential solutions for the demanding requirements for energy in military and homeland defense applications.”

EESUs are planned as nontoxic, non-hazardous and non-explosive.  Since the EESU design is based on ultra-capacitor architecture, it will allow for flexible packaging and rapid charge/discharge capabilities.  EESUs will be ideally suited for a wide range of power management initiatives that could lead to energy independence for the Warfighter.

Deeya Energy, Would be Flow Battery Supplier, Raises $15 Million, Names President

Deeya Energy, which makes large flow batteries to provide backup power to industrial plants, raised $15 million in a second round of financing, to support the construction of its factory in India and its continued R&D activities. It also named Vic Mahadevan as president and CEO. The company earlier raised $7.5 million for product development and global market expansion.

The initial focus of the company is the Indian telecom infrastructure market. The company will initially ship to this market in the second quarter of 2008. In 2009, Deeya will expand to focus on the worldwide solar and wind markets also.

“Deeya’s current focus is to be the supplier of choice to telecom operators in India with our innovative flow battery solution for cell phone tower energy back-up applications. This will allow the telecom operators to expand their market rapidly by deep penetration into India’s villages with a cost effective and high performance energy storage platform.”

Vic Mahadevan, CEO of Deeya Energy.

Deeya’s also claims its products will for the first time ever commercialize peak-off-peak load shifting, a market estimated to be worth $10B for electricity consumers and worth $160B for electricity producers and distributors. In addition, its products will enable commercial energy storage in renewable energy and UPS (Uninterruptible Power Supply) industries, presently estimated at $5B, and inadequately served mostly by the Lead-Acid batteries and diesel generators.

FYI: Altairnano Ships $1 million Storage System

Altair Nanotechnologies, Inc. (Nasdaq: ALTI), a leading manufacturer of lithium-titanate battery and energy storage products, announced today that it completed the manufacturing of battery packs to be used in a two (2) megawatt energy storage system ordered by the AES Corporation (NYSE: AES). The $1 million purchase initiated by AES was previously announced in August 2007. Altairnano expects the system to be connected to the grid and tested during the first quarter of 2008.  . . . more

Maxwell to Develop Capacitors for Mercedes

Ultracapacitors' Rapid Charge/Discharge Capabilities Boost Acceleration and Increase Braking Energy Recuperation Efficiency, Reducing Fuel Consumption and Emissions

Maxwell Technologies, Inc. (Nasdaq: MXWL) announced today that it has been awarded a contract by Mercedes Car Group to design and produce ultracapacitors for an advanced engineering hybrid-electric drive train program incorporating a braking energy recuperation system that enables it to increase fuel efficiency and reduce emissions.

David Schramm, Maxwell's president and chief executive officer, said that the contract provides for funding from Mercedes to develop a new BOOSTCAP(R) ultracapacitor cell specifically designed to meet the energy storage and power delivery requirements of one of Mercedes' torque assist and recuperative braking systems. . . . more

EEStor Update #8

FOXNews.com has a Sept. 2 article on Austin-based EEStor, a reclusive ultracapacitor startup, that has generated lots of interest, but little substance.  If the company can deliver on its promises, the auto industry could see a paradigm shift in how vehicles are powered, making engines unnecessary.  The article contains little, if any, new information about the company, but does a good job of summarizing the known information which can be boiled down to these points:

• Investments of about $4 million by ZENN Motor and a $3 million investment by the venture capital group Kleiner Perkins Caufield & Byers, who have made extensive amounts of due diligence" on EEStor's innovation, indicate that there is likely to be a great deal of truth about EEStor's claims.
• Patent No. 7,033,406 reveals some information about their device.
• EEStor's founders have a track record. Richard D. Weir and Carl Nelson worked on disk-storage technology at IBM Corp. in the 1990s before forming EEStor in 2001.
• EEStor claims an improvement of more than 400-fold over conventional capacitors, while increasing a capacitor's retention ability.
• EEStor's is a parallel plate capacitor with thousands of wafer-thin metal sheets, like a series of foil-and-paper gum wrappers stacked on top of each other.
• EEStor has created breakthrough technology in a novel formulation of a nonconductive material (dielectric) for use between the metal sheets, using a chemical compound called barium titanate. The question is whether the company can mass-produce it.
• ZENN still expects to receive shipments later this year for use in ZENN Motor's short-range, low-speed vehicles.

More posts on EEStor can be found here, here, here, here, here, here, here and here,

Improved High-Energy Density Capacitors

Science Daily reports that North Carolina State University physicists have recently deduced a way to improve high-energy-density capacitors so that they can store up to seven times as much energy per unit volume than the common capacitor. Unlike a battery, capacitors are designed to release their energy very quickly.

High performance capacitors would enable hybrid and electric cars with much greater acceleration, better and faster steering of rockets and spacecraft, better regeneration of electricity when using brakes in electric cars, and improved lasers, among many other electrical applications.

In a capacitor electrical energy is stored by a difference in charge between two metal surfaces. The amount of energy that a capacitor can store depends on the insulating material in between the metal surfaces, called a dielectric.

A polymer called PVDF has interested physicists as a possible high-performance dielectric. Mixing a second polymer called CTFE with PVDF results in a material with regions that can change their structure, enabling it to store and release unprecedented amounts of energy.

The team, led by Vivek Ranjan, concluded that a more ordered arrangement of the material inside the capacitor could further increase the energy storage of new high-performance capacitors, which already store energy four times more densely than capacitors used in industry. Their predictions of higher energy density capacitors are encouraging, but have yet to be experimentally tested.

ZENN Invests in EEStor

Adapted From ZENN press release:

Feel Good Cars Corporation (TSX VENTURE:ZNN), operating as ZENN Motor Company ("ZENN"), announced on April 30 that it has made a US $2.5 million equity investment in Austin-based energy storage developer, EEStor, Inc. The negotiated investment terms also grant ZENN an additional investment option of up to US $5 million on the same terms, following EEStor's successful completion of its next major milestone: permittivity testing.

Permittivity is a measurement of how much energy can be stored in the EEStor production materials. The requirements of permittivity levels are specified in detail in the existing Technology Agreement between ZENN Motor Company and EEStor, Inc. The verification of permittivity levels will be conducted by an independent 3rd party laboratory. This testing is required to show consistent and replicable results of both the production line and materials produced.

VRB Power Systems VRB-ESS for Sorne Hill "Has a Strong Economic Case"

VRB Power Systems (TSX-V: VRB) announced that the Vanadium Redox Battery Energy Storage System (VRB-ESS™) being sold to Tapbury Management Limited (“Tapbury”), previous post, for Phase II of the Sorne Hill Wind Farm in County Donegal, Ireland (“Sorne Hill”) has been increased in size from a 1.5MW x 8hr system to a 2MW x 6hr system.

The value of this contract to VRB Power has increased from US$6.3 million to approximately US$9.4 million. The agreement remains subject to execution of final contracts between Tapbury and VRB Power.

The re-sizing of this system follows completion of the independent feasibility study, by Grant Thorton, on the implementation of the VRB-ESS at Sorne Hill jointly commissioned by Sustainable Energy Ireland (SEI) and Tapbury. This study validates a number of the key revenue streams that will be generated by the VRB-ESS. It also concludes that the optimum size of the system is 2MW of power with 6 hours of storage and the ability to provide 3MW of pulse power for 10 minute periods every hour in order to deal with short term volatility in wind generation.

“We are delighted with the findings of this study,” stated John Ward, Director of Tapbury. “The report provides technical and economic validation for a number of the key revenue streams that we had previously identified for the planned implementation of the VRB-ESS at Sorne Hill. The increase in the size of the system enables us to maximize these revenue streams and, when combined with additional market based payments, shown in the Grant Thornton report included in the study, provides a strong economic case for this purchase. In particular, the study demonstrates the potential for purchasers of VRB Energy Storage Systems in the Irish market to achieve a very healthy IRR of 17.5% on their investment.”

Digitated Energy Storage Devices (DESDs)

The desirability of storing energy in a low cost device with a high energy density, a low weight, long life and that have the ability to absorb and discharge this energy quickly, such as is required in hybrid vehicles for the absorption of the energy wasted in braking and discharging energy quickly as needed for spurts of acceleration, has been the subject of much R& D over the past couple of decades.  These are tasks that lead acid batteries do not do well, advanced batteries, NIH and lithium batteries, do better do much better in terms of weight, energy density, and lifetime, but they are much more expensive than the heavy and bulky lead acid batteries that they would replace. Costs of advanced batteries will come down as the scale of production is increased, but not as low as Pb-acid batteries because of the cost of materials. Capacitors charge and discharge rapidly but to date they have not been able to handle the energy needs of automobiles in a reasonable size or cost.

The newest technology being developed to fill this need, that I have heard of, is that being done by Researchers at The University of Arizona who are developing an ultracapacitor technology based on DESDs (Digitated Energy Storage Devices) built on Nani-scale structures that could be used in hybrid vehicles to improve their performance.

Cold Storage for Wind Power

The production of wind energy is quite variable, relatively unpredictable and not necessarily occurring at peak demand, thus as its use becomes more widespread it becomes more problematic to integrate it into the grid than conventional sources of power as it is not easily accommodated by switching on and off conventional energy suppliers, like coal fired power plants. The "Night Wind" project in the Netherlands uses an energy management methodology in which existing refrigerated warehouses are used to store wind energy produced during periods of low demand (at night) and then recover this energy during high demand periods (primarily during the day) thus relieving the grid of some of its demand during peak periods. An article in Nature described the process as follows:

The idea seems simple. Say you lowered the temperature of all large coldstores in Europe by just 1°C during the night when electricity demand is low, then let it rise 1°C by switching them off during the day when demand is at peak. The net effect would be that the warehouses would act as batteries -- potentially storing 50,000 megawatt-hours of energy -- i.e. store over twice the projected 2010 EU average hourly wind power production.

EEStor in Technology Review

Tyler Hamilton, known to bloggers as the publisher of the Clean Break blog has authored a comprehensive article about EEStor that appeared in the January 22 issue of MIT's Technology Review. The article reviews the claims of the company, Tyler gets a rare interview with Richard Weir, EEStor's co-founder and chief executive officer and talks to several experts that are skeptical about the capacitor based electrical energy storage unit (EESU). The article was timed based on EEStores "milestone" announcement that was reported in an earlier post indicating:

1) That it remains on track to begin shipping production 15 kilowatt-hour EESU to ZENN Motor Company in 2007 for use in their electric vehicles.
2) An automated production line has been proven to meet the requirements for precise chemical delivery, purity control, parameter control and stability of its barium nitrate powder.
3) The company has completed the initial milestone of certifying purification, concentration, and stability of all of its key production chemicals notably the attainment of 99.9994% purity of its barium nitrate powder.
4) EEStor is now in the process of producing on its automated production line, composition-modified barium titanate powders and is moving toward completing its next major milestone of powder certification.

EEStor on Schedule to Deliver Units to ZENN

At last some more news about EEStor. The biggest news is that they are on schedule to deliver their first products to ZENN:

The first commercial application of the Electrical Energy Storage Units (EESU) is intended to be used in electric vehicles under a technology agreement with ZENN Motors Company. EEStor, Inc. remains on track to begin shipping production 15 kilowatt-hour EESU to ZENN Motor Company in 2007 for use in their electric vehicles. The production EESU for ZENN Motor Company will function to specification in operating environments as sever as negative 20 to plus 65 degrees Celsius, will weigh less than 100 pounds, and will have ability to be recharged in a matter of minutes.

Additionally in a company press release they outlined meeting several milestones:

1) An automated production line has been proven to meet the requirements for precise chemical delivery, purity control, parameter control and stability.

VRB: Update on Tapbury, Financial Results

VRB Power Systems Inc. (TSX-V: VRB), producer of Vanadium Redox Batteries for energy storage, reported financial results for the quarter and nine months ended November 29 and further details of its largest order ever to Tapbury Management Limited of Letterkenny, Co. Donegal, Ireland ("Tapbury") for approximately US$6.3 million. This VRB-ESS will be coupled to Phase II (6.9MW of wind generation) at Sorne which is due to be installed in Fall, 2007.

The company reported a loss of   on sales of

a 1.5MW x 8hr (12MWH) VRB-ESS will be coupled to Phase II (6.9MW of wind generation) at Sorne which is due to be installed in Fall, 2007.

Sustainable Energy Ireland ("SEI") and Tapbury jointly funding a study to ascertain and quantify the full potential economic benefits of coupling Vanadium Redox Batteries with wind farms in Ireland. This study focuses on Sorne and the benefits that will accrue through the coupling of the 12 MWH VRB-ESS to Phase II at Sorne.

Maxwell: New Capacitor Module for Vehicles

Maxwell Technologies, Inc. (Nasdaq: MXWL) has introduced a compact, fully integrated, 125-volt ultracapacitor module to provide an easy-to-integrate building block for scalable energy storage and power delivery solutions for heavy hybrid and electric vehicles and heavy duty industrial applications requiring up to 1,500 volts.

“This high-performance module is designed specifically to satisfy rapidly growing global demand for ultracapacitor-based braking energy recuperation and torque assist systems for hybrid bus and truck drive trains and electric rail vehicles,” Balanson said. “It meets or exceeds transportation industry requirements for watt-hours of energy storage and watts of power delivery per kilogram, and is designed to perform reliably through one million or more deep charge/discharge cycles, which equates to more than 15 years of operational life.” said Dr. Richard Balanson, Maxwell’s president and chief executive officer.

He added that the new module incorporates proprietary balancing, monitoring and thermal management capabilities to ensure industry-leading charge/discharge performance, high reliability and long operational life.

Michael Everett, Maxwell’s vice president and chief technical officer, said that integrated monitoring capabilities and a highly efficient cooling configuration enable the new module to sustain continuous current of up to 150 amps with minimal temperature increase in high-temperature environments.

The module is encased in a rugged, splash-proof, aluminum chassis, weighs less than 50kg and measures 315x425x744mm. Up to 12 modules may be linked in series to deliver a total of as much as 1,500 volts.

A Little More About EEStor

On Nov. 5, the Austin-American Statesman had an article about EEStor Inc. and its potentially disruptive energy storage technology (previous post).  Not anything new about the technology, but quite a bit of background information on founders Richard Weir and Carl Nelson. The following are the most interesting excerpts from the article:

The company has come up with a new method for making ultracapacitors, battery-like devices that can store large amounts of electricity. EEStor's energy storage unit can hold enough charge to power a car 300 miles, according to its patent, and it can be recharged in the time it takes to pump a tank of gas. And it can do that at only a small, if any, premium to the cost of a gas-powered engine.

In his May 2004 report, Ed Beardsworth said the company expected to eventually produce its energy storage devices for as little as $2,100 — roughly half the cost of a standard gas engine and power train. Beardsworth used to publish a report called Utility Federal Technology Opportunities.

"That's why the technology that EEStor is developing really breaks the mold," said Ian Clifford, CEO of Feel Good Cars Corp., a Canadian electric-vehicle company that has signed a deal to put EEStor units in its cars. "It's low weight, low cost and it has the rapid recharge technology that suddenly makes electric vehicles viable."

EEStor is building a production line in Cedar Park.  Feel Good Cars had expected to receive some of the energy storage units by now. "There have been slight delays, completely acceptable delays from our perspective," said Clifford. "For this, we're happy to wait."

Thanks to Tyler at Clean Break for the tip.

Another EEStor Update

Tyler at Clean Break has another post on EEstor referring to a write up about them in Business 2.0.  The three main points of the article are:

• Feel Good Cars, which plans to incorporate EEStor's technology in vehicles by 2008. That is a year later than previously reported.
• An EEStor-powered engine with a range roughly equivalent to that of a gasoline-powered car would cost about $5,200. That's a slight premium over the cost of the gas engine and the other parts the device would replace.
• Their aim is to compete with the internal combustion engine. The engine technology is not just for the small passenger vehicles, but could easily replace the 300-horsepower brutes in today's SUVs.

Deeya Energy Storage

Deeya Energy is a Silicon Valley technology venture company developing novel energy storage devices, based on its proprietary L-Cell technology, for Load-shifting, UPS (Uninterruptible Power Supply) and Renewable Energy industries. 

The company announced Sept. 18 that it has raised its first venture capital funding round, worth about $7.5 million, from BlueRun Ventures, Draper Fisher Jurvetson (DFJ), and DFJ Element. The investment will be used for product development and global market expansion.

Ultracapacitor Engine Starting System

PRNewswire-FirstCall: Maxwell Technologies, Inc. (Nasdaq: MXWL) and Kromberg & Schubert GmbH & Co. KG, a supplier of wire harnesses to the automotive industry, have signed a memorandum of understanding outlining terms of an alliance to incorporate Maxwell's BOOSTCAP(R) ultracapacitors into a highly efficient, low-cost, engine starting system for automobiles.

Dr. Richard Balanson, Maxwell's president and chief executive officer, said that extensive testing and analysis confirm that an ultracapacitor-based starter power node located in close proximity to the starter will not only improve starting performance, but also enable reductions in system cost, complexity and weight.

"Incorporating ultracapacitors to relieve the battery of the demanding short-duration, high-current, starting load provides several benefits, including extending battery life, downsizing the battery and reducing cabling," Balanson said. "Kromberg's wire harness and electronic systems design expertise and established relationships with automakers around the world make it an ideal development partner for this kind of system."

Arthur Kurz, manager electronic integration, said that ultracapacitors' burst power capabilities, cold temperature performance and long cycle life make them particularly well-suited for vehicle starting.

VRB Power announces sale of 12MWH VRB-ESS

An announcement was made this week when VRB, a Canadian supplier of vanadium redox  battery energy storage systems revealed the sale of a large system to an Irish wind farm. This sale is significant because the developlment of large energy storage systems is necessary before sun and wind power can become a truly integral part of our power generation system.  Because of the intermittency of these sources, they, by themselves, are not dispacthable to meet the demands of the grid. Some means of storing the energy so that it can be used (dispatched) as needed is required.  Llke a huge battery energy storage systems serve this need.  Numerous types of systems are in use at a small scale, but very few at a large enough scale to be useful to a utility.  The following is from the press release:

VRB Power Systems Inc. (TSX-V: VRB) announced that they have entered into a sale agreement with Tapbury Management Limited of Letterkenny, Co. Donegal, Ireland ("Tapbury") for the sale of a 1.5 MW x 8 hour (12 MWH) VRB-ESS(TM). Tapbury oversees the management of Sorne Hill Windfarm, a recently commissioned 32MW windfarm which is located in Buncrana, Inishowen, Co. Donegal, Ireland ("Sorne"). This 12MWH VRB-ESS will be coupled to phase II of the Sorne project which is an additional 6.9 MW of wind power for which turbines have been ordered and are due to be installed in the Fall of 2007. This will make Sorne, at 38 MW, one of the largest wind farms in Ireland. The total contract value for VRB Power from this sale is approximately US$6.3 million.

The Latest on EEStor

Clean Break recently reported the latest on EEStor, the secretive developer of supercapacitors. Highlights from his post: They have delayed the date for the testing of its barium titanate powder. The tests which will make sure the permeability and purification of the powder is up to snuff and ready for mass production, are now scheduled for September. Concurrently they are working on the power electronics and setting up a automated production facility. They plan to go directly into production following the tests. Feel Good Cars, which has a license to sell its energy storage system in the compact car market, is apparently still expecting to receive its first shipments of units in the first quarter of 2007.

The latest on EEStor and Feel Good Cars , Clean Break, August 17, 2007

Maxwell Supercapacitor Production Boosted with Chinese Alliance

Maxwell Technologies, Inc. (Nasdaq: MXWL) announced today that it has formed a manufacturing alliance with Belton Technology Group, a major Chinese manufacturer of precision components, flex circuits, circuit boards and other products, to support Maxwell’s forecasted growth to multi-million-unit annual volumes for its BOOSTCAP® ultracapacitors and multi-cell modules, driven by automotive, transportation and industrial electronics applications that are advancing toward high-volume production.

Dr. Richard Balanson, Maxwell’s president and chief executive officer, said that Maxwell will continue to produce its proprietary carbon powder electrode material internally and deliver it to Belton plants for assembly into finished ultracapacitor cells and modules.  “The worldwide ultracapacitor market is real, and the demand we foresee in 2007 and beyond requires large-scale production capabilities such as those Belton already has in place,” Balanson said.

EEStor Update

Tyler, the Clean Break publisher is also a technology reporter and columnist for the Toronto Star.  In one of his recent columns in the Star he reported on EEStor's ultracapacitor and found a few previously unreported items about the company. His lead "A much-shrouded idea could give portable power a real charge, for a change — and change, well, everything" was one of the main themes of the column. The item I found most exciting was the following:

The company, sources say, is weeks away from seeking independent verification of the product's performance, which will be conducted by the University of Texas at Austin or a U.S. army facility. If all goes well, EEStor could be in preproduction this year and full production in 2007. During this time, potential customers — from automakers and military contractors to tool and electronics makers — will get a closer look at the product.

One of the experts he quoted was Richard Baxter author of the book on Energy Storage that The Energy Blog recently reviewed. 

The most One hang up that many, not Tyler, have on the technology is that it would require enormous bursts of power to charge the ultracapacitor in the short recharge times that are referred to when discussing this technology. 1) the short recharge time is essential to increasing the efficiency of energy recovery from braking that present batteries can't do. 2) most charging should be done overnight in the owners garage. 3) "filling stations" will need to charge some sort of energy storage system, such as more ultracapacitors or more likely flow batteries or other energy storage systems. (I'm not expert enough to know which technology is best) using off peak power if available, or during lulls in activity at the filling station, rather than imposing a extremely high demand on the grid for the short bursts of power that would be required for "refueling". Whatever method is used it will be quite a bit more expensive to buy electricity from filling stations rather than recharging overnight at home or in the parking lot at your workplace.

Technorati tags: ultracapacitors, energy storage, energy, technology

The Energy Blog: EEStor Update

Many Roles for Supercapacitors

EV World had a link to an interesting Components in Electronics article on supercapacitors today.  Based on an interview with Richard Balanson, CEO at Maxwell Technologies they pointed out the fast recharge time, measured in seconds rather than hours for the lead acid batteries that are usually used for energy storage along with their longer shelf life and operating life. The statement that they are "cheaper than an equivalent Li-ion cell but still dearer than a lead-acid battery" was a revelation that I had not seen before.  One of the most common uses are those where a battery is used for standby power and the ultracapacitor provides a pulse of energy for a critical operation. The digital cameras where ultracapacitors can provide the extra power needed for the flash and zoom functions is a good example of the pulse power applications of supercapacitors.

As far as applications are concerned they describe a wide variety of applications including hybrid vehicles, dustbin carts, automatic meter reader transmitting systems, wind turbines, sea buoys and sea lane markers, pagers, cell phones, digital cameras, vehicle tracking systems, monitoring systems on pipelines, valve actuators, door mechanisms on the Airbus, movable road signs, fork lift trucks, trams, car jump leads, handheld power tools, catapults on aircraft carriers and airbags in helicopters where supercapacitors are being used or are being considered for use.

For a primer on ultracapacitors see the earlier post About Ultracapacitors.

Technorati tags: energy storage, supercapacitors, energy, technology

The Energy Blog: Many Roles for Supercapacitors

Energy Storage: A Nontechnical Guide

I recently received the book, Energy Storage: A Nontechnical Guide, by Richard Baxter, which I enjoyed reading and would recommend to anyone who would like a good reference on energy storage.

The book is written in a language that should be easily understandable to anyone, technically trained or not.  It clearly explains how energy storage can decouple generation from demand, thus making possible a variety of uses including:  storing power during off peak for use during peak periods, smoothing peaks and valleys in demand, eliminating or delaying expansion of generating facilities, dispatchable power, reducing the intermittency of renewable resources, making the grid more reliable and improving the quality of power.

Over one-third of the book is devoted to a description of 10 energy storage technologies. It goes through a comprehensive description of each technology from an overview to more details on several aspects of the technology, examples of installations and the status and challenges facing each storage technology. The design and operation narratives go into enough detail to fully understand the technology without bogging down the reader with theoretical details. His many examples of how energy storage is or could be used make it much easier to understand the technologies and how they can be used. 

The chapters on how energy storage can benefit the electric power industries and the role energy storage could play with renewable energy generation are very insightful to understanding the potential of energy storage systems.  The role energy storage systems can play in stabilizing our increasingly unstable grid while reducing the need for many new generating facilities and transmission lines is an important concept which shows that our grid can be more distributed than was once believed. 

Aerogel Capacitor Electrode Material Announced

Aerogel Composite, Inc. (ACI) announced today that a carbon aerogel ultracapacitor electrode material with unusually large amount of energy storage for its size is available for sale.  Aerogels are solid substances similar to gels but where the internal liquid is replaced with air. Ultracapacitors are of particular interest in automotive applications for hybrid vehicles and as supplemental storage for battery electric vehicles. The following statement from their press release defines the performance of the product:

The extremely high electrochemical surface area of ACI's ENERGel(TM) carbon aerogel enables very high rates of charge and discharge. Capacitance's of more than 104 F/g and energy densities of more than 325 kJ/kg have been demonstrated with carbon aerogels ultracapacitors. Additionally, power densities of up to 20 kW/kg have been achieved. This is orders of magnitude higher than what conventional capacitors offer. ACI believes that its ENERGel(TM) carbon aerogel is a superior option for applications such as specialized electrodes.

Reference: Aerogel Composite announces ENERGel(TM) Ultracapacitor, Greenshift press release, Feb. 21, 2005

Technorati tags: ultracapacitors, energy storage, energy, technology

MIT Researchers Propose Ultracapacitors Using Nanotubes

Researchers at the MIT Laboratory for Electromagnetic and Electric Systems (LEES) are working on an ultracapacitor that uses vertically aligned, single-wall carbon nanotubes as the electrode in an ultracapacitor.  They claim that their ultracapacitor "holds out the promise of the first technologically significant and economically viable alternative to conventional batteries in more than 200 years."

However, despite their inherent advantages -- a 10-year-plus lifetime, indifference to temperature change, high immunity to shock and vibration and high charging and discharging efficiency -- physical constraints on electrode surface area and spacing have limited ultracapacitors to an energy storage capacity around 25 times less than a similarly sized lithium-ion battery. ....

Storage capacity in an ultracapacitor is proportional to the surface area of the electrodes. Today's ultracapacitors use electrodes made of activated carbon, which is extremely porous and therefore has a very large surface area. However, the pores in the carbon are irregular in size and shape, which reduces efficiency. The nanotubes replace the activated carbon that is typically used as the electrode in ultracapacitors.  The vertically aligned nanotubes in the LEES ultracapacitor are one thirty-thousandth the diameter of a human hair and 100,000 times as long as they are wide, only several atomic diameters in width, and have a regular shape. The result is a significantly more effective surface area, which equates to significantly increased storage capacity. ....

EEStor Ultracapacitor Shuns Publicity

Clean Break has an interesting post, much of what I have copied verbatim, on a new ultracapacitor made by start-up company EEStor of Austin TX.  I thought the technology was potentially so important that a record of it was needed on the Energy Blog.  The company is very wary of publicity and the following, which Tyler meticulously chased down, is about all that is known about their technology:

• It is a parallel plate capacitor with barium titanate as the dielectric.
• It claims that it can make a battery at half the cost per kilowatt-hour and one-tenth the weight of lead-acid batteries.
• As of last year selling price would start at $3,200 and fall to $2,100 in high-volume production
• The product weighs 400 pounds and delivers 52 kilowatt-hours.
• The batteries fully charge in minutes as opposed to hours.
• The EEStor technology has been tested up to a million cycles with no material degradation compared to lead acid batteries that optimistically have 500 to 700 recharge cycles,
• Because it's a solid state battery rather than a chemical battery, such being the case for lithium ion technology, there would be no overheating and thus safety concerns with using it in a vehicle.
• With volume manufacturing it's expected to be cost-competitive with lead-acid technology.
• As of last year, EEStor planned to build its own assembly line to prove the battery can work and then license the technology to manufacturers for volume production
• EEStor's technology could be used in more than low-speed electric vehicles. The company envisions using it for full-speed pure electric vehicles, hybrid-electrics (including plug-ins), military applications, backup power and even large-scale utility storage for intermittent renewable power sources such as wind and solar.
• They have an exclusive agreement with Feel Good Cars, a Canadian manufacturer of the ZENN, a low speed electric car, to to purchase high-power-density ceramic ultra capacitors called Electrical Storage Units (ESU).  FGC's exclusive worldwide right is for all personal transportation uses under 15 KW drive systems (equivalent to 100 peak horse power) and for vehicles with a curb weight of under 1200 kilograms not including batteries.

None of these claims except construction and cost are significantly better than other ultracapacitors. Although they sometimes refer to the technology as a battery, it is clearly an ultracapacitor.

Clean Break's resources were:

Kleiner Perkins' Latest Energy Investment, BusinessWeek online, Sept., 3, 2005
Feel Good Cars, Toronto, ON, Canada
MCL Capital Inc. announce Agreement in Principal with Feel Good Cars (In section on History and Nature of the Business this agreement refers to FGC's agreement with EEStor)

Technorati tags: ultracapacitors, energy storage, energy, technology

Maxwell Receives Order for 200,000 Ultracapacitors

From a Maxwell press release via Alternative Energy Stocks:

Maxwell Technologies announced that General Hydrogen Corporation, a leading developer of hydrogen fuel cell-based power systems for electric forklifts, has placed a 200,000 unit, three-year, purchase order for BOOSTCAP® ultracapacitors to enhance performance and energy management in its Hydricity® Pack technology.

Dr. Richard Balanson, Maxwell's President and Chief Executive Officer, said that each Hydricity system incorporates 30 to 120 BOOSTCAP MC2600 2,600-farad ultracapacitor cells

Frank Trotter, General Hydrogen's President and Chief Executive Officer, said that Hydricity Pack power systems are an economical "drop-in" replacement today for lead-acid batteries in Class I electric forklifts.

"Maxwell's ultracapacitors are a critical element that helps us triple the runtime of forklifts, eliminating the average three lead-acid battery sets per vehicle and the extensive infrastructure normally associated with the recharging and care of high-use conventional battery-electric forklifts," Trotter said. "Ultracapacitors' burst power capabilities, energy recapture efficiency and long operating life make them an ideal complement to hydrogen fuel cells.

In addition to the advantages cited above the fuel cell/ultracapacitor system eliminates the disposal problems associated with lead-acid batteries and maintain the zero emission characteristics that are necessary for indoor operation.  They use Ballard fuel cell stacks, which are probably the most proven PEM fuel cells and one of the few that is available commercially.  The fork lift application is one (if not the only) of a few applications where fuel cell/ultracapacitor usage has been proven to be commercially successful.

Maxwell Technologies Receives 200,000-Unit, Three-Year Ultracapacitor Purchase Order From General Hydrogen  Maxwell Technologies press release, January 26, 2006

Technorati tags: energy storage, ultracapacitors, batteries, energy, technology

Altair Announces High Performance Li-ion Battery

Altair Nanotechnologies Inc. (NASDAQ: ALTI) has announced that had completed testing of its lithium ion battery cells containing Altairnano's nano-structured lithium titanate electrode materials. Altairnano's battery product application labs, with rapid prototyping and battery testing capabilities, is expected to be fully equipped and operational and to have its first battery cells manufactured by the end of January.  Their press release states:

"The test results demonstrated that the performance of these lithium ion battery cells exceed the system-level power requirements set forth by the U.S. Council for Automotive Research FreedomCAR Energy Storage System Performance Goals for hybrid electric vehicle (HEVs), as well as those requirements published by major U.S. automakers," said Evan House, Ph.D., Program Director, Altairnano's Advanced Materials & Power Systems business unit."

The battery cells using Altairnano's nano-structured lithium titanate electrode materials in battery cell tests developed for HEV applications demonstrate a useable state-of-charge range twice that of conventional nickel metal hydride (NiMH) batteries presently used in hybrid electric vehicles. Nano-structured lithium titanate electrode materials offer a near-term promise of lithium ion batteries that exhibit rapid charge and discharge, longer cycle life and more inherently safe performance than either currently available nickel metal hydride or lithium ion batteries. These results support the feasibility of a power lithium ion battery pack half the size of those currently being tested for HEV applications.

Vanadium Redox Flow Batteries

The vanadium radox battery energy storage system (VRB) is a flow battery that is capable of storing energy in multi megawatt ranges and for durations of hours or days - from any available input source such as the grid, renewable resources or a diesel generator. The stored energy can be returned to the grid or supplied to a load as required and directed. The VRB is capable of being charged as quickly as it was discharged and is able to respond to all forms of power quality variations and can be operated in a UPS mode as well. For loads which require reactive energy, the VRB can provide VARS on a continuous basis either when charging or discharging. Flow batteries are further described in this previous post.

The durability and wide design options of vanadium batteries promise large markets for many applications, such as load leveling, storage in renewable energy systems (e.g. wind and solar) and uninterpretable power supplies.

VRB's are based on the patented vanadium-based redox regenerative fuel cell that converts chemical energy into electrical energy. Redox is the term used to describe electrochimical reactions in which energy is stored in two solutions with electrochemical potentials sufficiently separated from each other to provide an electromotive force to drive the oxidation-reduction reactions. In the VRB energy is stored chemically in different ionic forms of vanadium in a dilute sulfuric acid electrolyte.  This creates a current that is collected by electrodes and made available to an external circuit.  The reaction is reversible allowing the battery to be charged, discharged and recharged.

More on Firefly Batteries

A Firefly Energy press release on January 17 revealed a little more information, now that one of their patents has been issued on their battery technology.

Firefly Energy has received a U.S. patent for a new lead acid battery technology that it believes has the potential to revolutionize the existing $16 billion worldwide lead acid battery market as well as serve applications like hybrid electric vehicles which historically aren't suitable for lead acid batteries. ....

The invention is a battery comprised of an electrical current collector constructed of carbon or lightweight graphite foam. This foam exhibits a sizeable increase in surface area for chemical reactions to take place and eliminates the need for heavy lead plates found in traditional batteries. The graphite material resists corrosion and sulfation build-up, thus contributing to longer battery life and is lighter in weight than today's lead acid batteries. ....

The overwhelming restriction to lead acid battery efficiency to this point has been the lack of interface area between the active chemistry and the electrodes. Today, the chemistry is capable of delivering approximately 170 Watt Hours per Kilogram (Whr/kg), yet lead acid batteries only average around 30 Whr/kg. Up to now, achieving a higher surface area within a given lead-acid battery box required the addition of more and thinner lead electrodes. However, lead electrodes corrode, so increasing surface area by putting thinner lead electrodes in the battery increases corrosion and decreases battery life.

"By removing the corrosive heavy lead grids and replacing them with a graphite foam, Chief Scientist Kurt Kelley's invention has helped unleash the innate power of lead acid chemistry," adds CEO Williams. "It introduces a material that doesn't corrode and enables the weights and sizes of lead acid batteries to be reduced significantly." ....

Mil Ovan, senior vice president and Firefly Energy's other co-founder, believes the invention also addresses important environmental problems. "One of the reasons 'Firefly' was picked as the name of our company was because it's a green technology, since our battery's design drives one-half to two-thirds of the lead out of the battery through use of the graphite foam composite material. The graphite form is also easily recyclable through the existing infrastructure of lead acid battery recycling."

Firefly Energy is a Peoria, Illinois-based company which has developed a next generation lead acid battery technology that has the opportunity to address major portions of the $30 billion worldwide battery marketplace. Firefly's graphite foam-based battery technology can deliver a unique combination of high performance, extremely low weight, low cost and, all in a battery which utilizes the best aspects of lead acid chemistry while overcoming the corrosive drawbacks of this same chemistry. This product technology delivers to battery markets a performance associated with advanced battery chemistries (Nickel Metal Hydride & Lithium), but for one-fifth the cost, and can be both manufactured as well as recycled within the existing lead acid battery industry's vast infrastructure. The Company was formed after its technology, technical founder, and initial seed funds were spun out of Caterpillar, Inc. a Fortune 90 company, in May 2003, and is headed by co-founders Edward Williams (CEO), Mil Ovan (Senior VP), and Kurtis Kelley (Chief Scientist).

A previous post (1/15/06) decribed Firefly's batteries with information available at that time.

Technorati tags: batteries, storage technology, energy, technology

About Sodium-Sulfur (NaS) Batteries

Sodium Sulfur (NaS) batteries are high capacity battery systems developed for electric power applications.  A NaS battery consists of liquid (molten) sulfur at the positive electrode and liquid (molten) sodium at the negative electrode as active materials separated by a solid beta alumina ceramic electrolyte. The electrolyte allows only the positive sodium ions to go through it and combine with the sulfur to form sodium polysulfides.

2Na + 4S = Na2S4

During discharge, as positive Na+ ions flow through the electrolyte and electrons flow in the external circuit of the battery producing about 2 volts. This process is reversible as charging causes sodium polysulfides to release the positive sodium ions back through the electrolyte to recombine as elemental sodium. This hermetically sealed battery is kept at approximately 300 ^oC and is operated under conditions such that the active materials at both electrodes are liquid and the electrolyte is solid. At this temperature, since both active materials react rapidly and because the internal resistance is low, the NAS battery performs well. Because of reversible charging and discharging the NAS battery can be used continuously.

Flow Batteries for Energy Storage

Flow batteries are emerging energy storage devices that can serve many purposes in energy delivery systems. They can respond  within milliseconds and deliver power for hours. They operate much like a conventional battery, storing and releasing energy through a reversible electrochemical reaction with an almost limitless number of charging and discharging cycles. They differ from a conventional battery in two ways 1) the reaction occurs between two electrolytes, rather than between an electrolyte and an electrode and 2) they store the two electrolytes external to the battery and the electrolytes are circulated through the cell stack as required. The great advantage that this system provides is the almost unlimited electrical storage capacity (MWh), the limitation being only the capacity of the electrolyte storage reservoirs.

Flow batteries are essentially comprised of two key elements: cell stacks, where power is converted from electrical form to chemical form, and tanks of electrolytes where energy is stored. These two elements are supplemented with circulation and control systems. An individual cell consists of a negative electrode and a  positive electrode separated by an ion exchange membrane.  The battery uses electrodes that cannot and do not take part in the reactions but merely serve as substrates for the reactions. There is therefore no loss of performance, as in most rechargeable batteries, from repeated cycling causing electrode material deterioration. Banks of these cells can then be linked together to create a bipolar module ‘cell stack’ where the electrodes are shared between the adjacent cells, with the cathode of the first cell becoming the anode of the next cell, etc. Linked in series, sufficient cells in a string can then form the desired voltage for the cell stack.

Firefly Energy's New Lead Acid Batteries

Firefly Energy, a company, spun off from Caterpillar in 2003, has developed a next generation battery using lightweight graphite to replace most of the heavy lead plates contained in traditional batteries. Although no quantitative details could be found at their website the following statements were found:

• The Firefly battery replaces the the heavy, corrosive, traditional positive and negative lead plates, which comprise up to 70% of a typical lead-acid battery's weight, with smaller and extremely low weight non-corrosive composite plate material.
• The composite plates provide more surface area for battery chemistry to occur.
• Firefly's composite plate material will extend battery performance (run time).

  Better high-rate discharge performance.
• Performs whether cold or hot
• Higher number of charge discharge cycles
• Reduced cost-1/10th the cost of NiMH or Li-ion batteries.
• Can be manufactured within the existing lead-acid battery industry's manufacturing infrastructure.
• Firefly's technology can still be put through the existing lead-acid battery's recycling infrastructure, the plate material is simply burned away and remaining lead in the chemistry is recycled.

These advantages of the new battery were confirmed by Mil Ovan, senior vice president and a co-founder of Peoria's Firefly Energy, a speaker at last weeks Energy Independence 2020 Summit held in Chicago. 

Ultracapacitors for Automotive Use

This paper by Maxwell makes the case for ultracapacitors in automotive applications.  The paper is very informative about the uses of ultracapacitors, much moreso than I could be in a post.

Ultracapacitors offer pulse power and power cycling capability for vehicular use far in excess of electrochemical batteries. The migration to electronic control for vehicle applications in safety critical systems such as steer, brake and drive by wire has been delayed due to technical inadequacy in these cost sensitive systems. Similarly, the electrification of key functions like engine cranking and electromechanical valve actuation has also been slowed. This paper re-assesses safety critical and power train systems by exploring the use of distributed energy storage modules in the vehicle electrical distribution system to satisfy the requirements for power supply redundancy.

For the rest of the technical paper, please click here.

Technorati tags: energy storage, ultracapacitors, energy, technology

About Ultracapacitors

Conventional capacitors have enormous power but store only tiny amounts of energy. Supercapacitors offer a unique combination of high power and high energy.  Supercapacitors are capable of very fast charges and discharges, and are able to go through a large number of cycles without degradation.

Batteries are charged when they undergo an internal chemical reaction. They deliver the absorbed energy, or discharge, when they reverse the chemical reaction. In contrast, when a supercapacitor is charged, there is no chemical reaction. Instead, the energy is stored as a charge or concentration of electrons on the surface of a material. The energy can be released in a micosecond, much faster than from a chemical reaction.

An ultracapacitor or supercapacitor, also known as a double-layer capacitor can be viewed as two nonreactive porous plates, or electrodes, immersed in an electrolyte, with a voltage potential applied across the collectors. In an individual ultracapacitor cell, the applied potential on the positive electrode attracts the negative ions in the electrolyte, while the potential on the negative electrode attracts the positive ions. A porous dielectric separator between the two electrodes prevents the charge from moving between the two electrodes.

Note on Flywheels in Transportation

I caused a little confusion on my post on flywheels by including their use in vehicles under the category of energy reuse, although that was a correct category.  A little further explanation is due however.

Flywheels have been used on engines since their inception and the technology for this application is quite mature.  A possible new application for energy storage has developed with the introduction of hybrid vehicles.  This is because batteries cannot absorb nearly all the power that is available from regenerative braking, the chemical reaction in a battery is much too slow for this.  More than 50% of this energy is wasted.  Flywheels and ultracapacitors can do this job much better.  Flywheels have been used on hybrid subway and hybrid light rail vehicles with success. Their use is being developed for use on hybrid delivery vehicles.  The ultracapacitor has been used on hybrid buses with very good success.  Both of these technologies are expensive and add to the cost of already expensive hybrid vehicles.  Where life-cycle costs are important, as in high mileage commercial vehicles, they can be justified.  One flywheel company is developing a flywheel system aimed at the personal vehicle market, and they are working with on low volume producer.  It is my opinion that flywheels are too heavy and too costly to be incorporated into automobiles with current or near term technology. 

On the other hand ultracapacitors are lightweight, in fact it is claimed that the combined weight and size of an ultracapacitor and battery are reduced compared to the current weight and size of a battery. This is because the ultracapacitor can take over the starting duty of the battery, reducing the size of the battery considerably. (An ultracapacitor with enough capacity for a few starts is state of the art and increases in functionality with decreasing temperature, the capacitor can be recharged in about 15 minutes of driving--ultracapacitors are starting to replace batteries for starting of diesel engines because of these properties) The life of the battery is also increased considerably due to less cycling and no deep discharges.  The cost of ultracapacitors can be reduced significantly with high volume production, so this looks like a much more suitable means of increasing the energy reuse in a car.

It seems to me that a very cost effective "mild hybrid" could be made by putting in an ultracapacitor combined with shutting off the engine when the vehicle is stopped.  If this would increase the mileage by 10 to 15% with little increase in cost it should be a no brainer.  So what is wrong with my reasoning or are the car companies just not motivated.

More blogs about energy reuse, flywheels, batteries, ultracapacitors, energy, technology

About Flywheels

Large metallic flywheels have long been used in many applications as a means of storing and smoothing energy. Flywheels store energy through accelerating a rotor up to a high rate of speed and maintaining the energy in the system as kinetic energy. The flywheel releases its energy by reversing the charging process and slowing down. A flywheel can be designed to either release a large amount of energy in a very short period, or a small amount of energy over a longer period. Flywheels also may be divided into two main types, low speed and high speed. 

Development of flywheels as a stand-alone energy storage unit for electrical power was made possible by advances in power electronics that allowed for the efficient voltage and frequency control of the power output regardless of the rotational rate of the flywheel.  However size and resultant bearing stresses limited the speed and thus the amount of energy that could be stored. Subsequent advances, notably in carbon fiber materials and magnetic bearings allowed for higher energy densities.  Graphic courtesy of Vycon. 

Wind Power Plus Stored Energy

The Iowa Stored Energy Plant (ISEP) will be the first plant in the world that will use energy from a wind farm plus supplemental off peak electricity to produce compressed air to be stored in an underground aquifer until it is need to produce electricity on demand.  When demand for electricity is high, the air will be released and used in combination with a small amount of natural gas to drive combustion turbines to generate electricity.  Wind power is undependable and not always available when needed, compressed air energy storage (CAES) mitigates this intermittency.  This method will save one-third to one-half the natural gas that would otherwise be needed. CAES has been used in Alabama and Germany, but at these locations the energy for storage does not come from wind.

A separate section of the underground aquifer will also be used for storing natural gas. Gas storage will allow the facility and other gas utilities to buy natural gas when prices are lower. This type of gas storage is widely used in the U.S.