Supercapacitors in the Grid
Published: May 28, 2010 Category: Smart Technology

According to NanoMarkets/Smart Grid Analysis, the Smart Grid supercapacitor market will reach $3.8 billion in 2015.  Today, however, the market for these systems is worth only about $0.4 billion with by far the biggest chunk of revenues coming from one specialized application, namely regenerative energy capture with load smoothing for light rail applications.  Our latest report on the topic, however, suggests that new applications , especially those related to power quality and grid instability applications , are likely to be driven significantly forward by the impressive gains that Smart Grid supercapacitors have been able to achieve.


Compared with conventional capacitors, so-called supercapacitors offer much more charge to be stored per volume.  This is achieved through increased electrode surface area and the addition of a liquid electrolyte.  Most supercapacitors on the market today use activated carbon as the electrode material.  The charge is stored via charge separation and alignment of dipoles in the electrical double layer.  The thinness of this layer along with its large electrode surface area allows the super-sized capacity of supercapacitors compared to conventional capacitors.  Unlike batteries, charge is separated, but no electrochemical redox reactions occur.


Although supercapacitors have been little more than a niche product for certain high-priced storage applications for a number of years, recent technology and materials improvements suggests that they will have a growing role in practical large-scale storage applications in the Smart Grid in the future.  While the 100-Farad (F)-and-below-class of supercapacitors are used in many consumer applications, and are not suitable for large-scale electrical storage, the newer class of 1000 to 5000 F and above systems are being examined for possible use in large-scale grid quality and short-term UPS applications.


Supercapacitors versus Batteries


Batteries –using a variety of different technologies -- are also likely to see a growing role in the Smart Grid.  They would usually have higher power densities than supercapacitors.  However, supercapacitors have two advantages over batteries:


· They have very high lifecycle lifetimes; a consequence of the fact that (unlike batteries) supercapacitors have no chemistry going on. They exhibit durability through multiple charge/discharge cycles.  Today’s supercapacitors are rated to last through 500,000 discharge cycles so they are essentially good for the lifetime of the storage system.  Supercapacitors are also durable from the perspective that they do not have any memory effects, or issues with full or partial discharges that effect their overall service lifetime.


· Supercapacitors are extremely high energy devices that can dump the energy very quickly, allowing them to react to power dips and other stability phenomenon,

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