# A power plant that uses more power than it generates

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#### Clausius2

Gold Member
see http://www.energyvortex.com/energydictionary/reactive_power.html

The vectorial sum of Reactive power $$Q(VAr)$$ and True Power $$P(W)$$ gives the Apparent Power$$S(VA)$$. Reactive power is calculated as $$Q=UIsen\phi=XI^2$$ being X the reactance. It is used to magnetize the reactances inside electromagnetic machines, but it hasn't got any capacity of producing mechanical work. At night, when turbines are pumping the water uphill, the synchronous electrical motor acts as an "static compenser", injecting reactive power into the system.

#### willib

Since ultracapacitors use carbon i thought i would google carbon nanotubes and ultra capacitors..interrestingly , a lot showed up..
A matrix of vertically aligned carbon nanotube (CNT) has been investigated as a DLC electrode. Our analysis shows that this configuration can provide a combination of high power density (more than four orders of magnitude greater than fuel cells) and energy density (comparable to Li-Ion batteries). The significant enhancement in the achievable DLC power density derives from the high conductivity obtainable with CNTs, which in the limit of a few microns in length present ballistic conduction. The energy density improvement of a “nanotube enhanced electrode” is due to the higher effective surface area obtainable with a structure based on vertically aligned nanotubes over activated carbon
http://lees.mit.edu/lees/projects/cnt_ultracap_project.htm
Our analysis shows that the utilization of a matrix of vertically aligned CNTs 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.

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#### willib

can lead to an ultracapacitor characterized by a power density greater than 100kW/kg (three orders of magnitude higher than batteries),
pretty cool huh Russ..

Inventing something and mass-producing it are different things, Willi. Your question was, "why wouuld they use Batteries when [ultracapacitors] are available"? The answer is, "Ultracapacitors are not available." However, ultracapacitors may soon be incorporated in a limited capacity in conjunction with batteries since they complement each other well, as the nesscap link you quoted pointed out.
http://www.nesscap.com/prod/Articles/AABC_UCDavis_200102.PDF [Broken]

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The capacitors could provide most of the peak power required from the system and the batteries would recharge the capacitors during periods of relatively low system power demand.
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#### willib

They sure are available, not in the power density i previously listed (from MIT), but they sure ARE available..
http://www.maxwell.com/pdf/uc/datasheets/BMOD2600-16.pdf
and you are correct ultracapacitors at this time , make an excellent complement with batteries..
Because they can absorb the energy from regenerative braking , very quickly..Much more quickly than a battery can..

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