Directory:Capacitors

From PESWiki

Overview

A capacitor is similiar to a battery in that it is a medium for storing electrical energy. However, a capacitor is a much simpler device than a battery, it cannot produce new electrons -- it only stores them. Capacitors that are scaled up to power levels required for deliving power to vehicles and the utility grid are known as ultracapacitors.

Resources

• Hybrid Vehicles > TNO Hybrid Carlab - This Beetle finished 2nd in the 2005 Rallye Monte Carlo for Hybrid Vehicles using < 4 litres/100km (59 mpg US). A 150kW AC Propulsion electrical system powers the front wheels supplied by a generator set based on a VW 1.2 TDI 3-cylinder diesel engine and UQM generator. Peak power is supplied by a supercapacitor pack consisting of 3500F Nesscap cells.
  

• Electromagnetic > Variable Torque Motors - Axial field weakening yields higher efficiency over the rpm range, creating a "built-in" transmission that mechanically enables an operating range up to 10x the motor base speed for electric vehicles. VTM offers hybrid retrofit packages installed on the drive shaft of rear wheel drive vehicles using Maxwell BoostCap™ ultracapacitors for energy storage.
  

• Ultracapacitors Store Energy in a Hybrid Electric Vehicle
• Ultracapacitors - An Explanation from the National Renewable Energy Laboratory

Articles

• A Backup Power System Using Ultracapacitors

• Using Ultracapacitors in Utility Applications

• Carbon Nanotube Enhanced Ultracapacitors - Our analysis shows that the utilization of a matrix of vertically aligned Carbon Nanotubes as electrode structure, can lead to an ultracapacitor characterized by a power density greater than 100kW/kg (three orders of magnitude higher than batteries), a lifetime longer than 300,000 cycles, and an energy density higher than 60Wh/kg.

Businesses

• Will EEStor ceramic battery replace gas engines by 2008? - Texas company is working on an "energy storage" device made from ceramics. It's not technically a battery because it doesn't use chemicals. It can allegedly charge within 5 minutes with enough energy to move a car 500 miles on about $9 worth of electricity -- about 45 cents a gallon.
  

• batScap - Supercapacitors meet applications requiring high power values for short periods (ten seconds) and defined by a very high number of charge / discharge cycles (millions). This technology could replace batteries and fly-wheels and open new prospects for electric and hybrid vehicles.
  

• Canadian Firm Develops Fast-Charge Ultra-Cap 'Battery' - EPOD International is developing a revolutionary new hybrid battery that can be charged in less than one minute and fully cycled over 100,000 times. It combines the high energy density of batteries with the high power density of capacitors, is not made from rare or expensive elements and is environmentally benign. (EV World; May 10, 2007)
  

• NessCap - Ultracapacitor products for portable electronic devices to hi-tech “green‿ cars. Electric Double Layer Capacitors offer high power, long life. Pseudocapacitors have high energy, low cost.
• Maxwell Technologies Ultracapacitors
• High Voltage Ultracapacitors

Research and Development

• Researchers Develop Graphene-Based Ultracapacitors; Potential for Doubling Storage Capacity of Current Materials - University of Texas at Austin developed a new class of carbon material—chemically modified graphene (CMG)—that is made from a 1-atom thick sheet of carbon. CMG materials can be functionalized as needed, and the researchers demonstrated their performance in an ultracapacitor cell. (GreenCar Congress; Sept 16, 2008)
  

• Ultracapacitors Soon to Replace Batteries? - The synergy between batteries and capacitors — two of the sturdiest and oldest components of electrical engineering — has been growing to the point where ultracapacitors may soon be almost as indispensable to portable electricity as batteries are now. (IEEE Spectrum; Nov. 2007) (See also Slashdot)
  

• Capacitor research could increase storage by 7x - Researchers have developed a new type of capacitor which allows up to seven times the electrical storage potential as standard capacitors available today. This is good news for the electric and hybrid car industry, as capacitors are a possible alternative to batteries. (AutoblogGreen; Jul. 4, 2007)
  

• New DESD Capacitor Technology - Researchers are developing Digitated Energy Storage Devices that quickly store and discharge large amounts of power using capacitors built on nano-scale structures, with a capacitance-to-volume ratio that's 10,000 times larger. DESDs would make hybrid vehicles more efficient, and also more environmentally friendly because they don't wear out like batteries. (UANews; Mar. 9, 2007)
  

• Nanotube Super Capacitor Battery - MIT researchers are developing a battery based on capacitors that utilize nanotubes for high surface area, enabling near instantaneous charging and no degradation. Estimating ~5 years to commercialization.

See Also

• PowerPedia:Capacitors - encyclopedic entry at PESWiki
• Batteries Directory at PESWiki
  
• Directory:Flywheels
• Directory:Storage

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