Green Power Research

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Ultra Capacitors in alternative energy applications

by Tony - March 19th, 2012.
Filed under: Electric and Hybrid Vehicles, Ultra-capacitors, Wind Power. Tagged as: , , , , , .

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Image of Ioxus ultracapcitors

Ultra capacitors

Ultra-capacitors (or Super- capacitors) have been getting   attention recently for their use in alternative energy applications.  For my readers are unfamiliar with this technology capacitors  are used in electric devices to store energy. The energy is stored once a power source is connected to the capacitor by depositing a charge onto its two opposing plates with a dielectric material between them. Dielectric materials do not conduct electricity. When the power source is disconnected, the charge remains on the plates within the dielectric material. As soon as a load is attached to the capacitor, the charge flows through the load, providing power. A capacitor stores energy similar to a battery.  The power stored and made available for use when it is needed. Ultra-capacitors are the larger versions of these devices.

One of the properties which allow ultra-capacitors to be useful is the fact they can deliver a large amount of power in a short period of time.

These permit use as power boosters, for instance, when an electric car needs to accelerate rapidly, or wants to crest a steep hill these devices can provide the power while minimizing the use of the battery which will extend life of the battery. Ultra capacitors, used in this fashion in hybrid vehicles, are displacing a good deal of their current battery capacities with safer, lighter energy storage means.  Another key benefit of ultra capacitors is that charging them takes much less time (on the order of 1 percent of the time) than charging a battery.

Wind turbines are another example of an application where ultra-capacitors are used.  Obtaining the maximum energy from the wind requires keeping the blades in the optimal orientation. This is referred to as pitch control. The position of the blade is dynamically adjusted relative to wind speed in order to maximize efficiency for power generation. Ultra-capacitor technology supports the requirement for a quick burst of power to keep up with the rapidly changing speed and/or direction.

Another application related to wind power is Power Conditioning. The practice is intended to improve the quality of power which is delivered from the turbines.  As the contribution of wind power to the electricity generated increases, the grid becomes more susceptible to voltage fluctuations associated with rapid wind speed changes.

Another variation of ultra-capacitors is electric double-layer capacitor (EDLC). EDLC’s do not have a conventional dielectric. Rather than two separate plates separated by an intervening insulator, these capacitors use virtual plates that are in fact two layers of the same substrate. Their electrochemical properties, the so-called “electrical double layer”, result in the effective separation of charge despite the vanishingly thin (on the order of  nanometers) physical distance between of the layers.

The key feature of EDLC’s is their energy density is 10 percent of a typical battery while their power density is generally 10 to 100 times as great. This makes them most suited to an intermediary role between electrochemical batteries and electrostatic capacitors, where neither sustained energy release nor immediate power demands dominate one another.

In practical terms, ultra-capacitors can replace batteries in some applications. Ultra-capacitors won’t necessary supplant batteries in all likelihood; they will be used in conjunction with batteries. The future will require every possible means to extract energy and ultra-capacitors will certainly participate in our alternative energy future once other applications for these devices are discovered.

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