page_title: Energy storage
section_title: Supercapacitor
hierarchical_section_title: Energy storage / Methods / Electrochemical / Supercapacitor
caption_attribution_description: English: Expo 2010 in Shanghai: Electric bus at a charging station
context_page_description: Energy storage is the capture of energy produced at one time for use at a later time.
  A device that stores energy is generally called an accumulator or battery.
  Energy comes in multiple forms including radiation, chemical, gravitational potential, electrical potential, electricity, elevated temperature, latent heat and kinetic.
  Energy storage involves converting energy from forms that are difficult to store to more conveniently or economically storable forms.
  Some technologies provide short-term energy storage, while others can endure for much longer.
  Bulk energy storage is currently dominated by hydroelectric dams, both conventional as well as pumped.
  Common examples of energy storage are the rechargeable battery, which stores chemical energy readily convertible to electricity to operate a mobile phone, the hydroelectric dam, which stores energy in a reservoir as gravitational potential energy, and ice storage tanks, which store ice frozen by cheaper energy at night to meet peak daytime demand for cooling.
context_section_description: Supercapacitors, also called electric double-layer capacitors (EDLC) or ultracapacitors, are a family of electrochemical capacitors that do not have conventional solid dielectrics. Capacitance is determined by two storage principles, double-layer capacitance and pseudocapacitance.
  Supercapacitors bridge the gap between conventional capacitors and rechargeable batteries. They store the most energy per unit volume or mass (energy density) among capacitors. They support up to 10,000 farads/1.2 Volt, up to 10,000 times that of electrolytic capacitors, but deliver or accept less than half as much power per unit time (power density).
  While supercapacitors have specific energy and energy densities that are approximately 10% of batteries, their power density is generally 10 to 100 times greater. This results in much shorter charge/discharge cycles. Also, they tolerate many more charge-discharge cycles than batteries.
  Supercapacitors have many applications, including:
  Low supply current for memory backup in static random-access memory (SRAM)
  Power for cars, buses, trains, cranes and elevators, including energy recovery from braking, short-term energy storage and burst-mode power delivery
caption: One of a fleet of electric capabuses powered by supercapacitors, at a quick-charge station-bus stop, in service during Expo 2010 Shanghai China. Charging rails can be seen suspended over the bus.
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