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merrlin
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I guess the point that I am trying to make here is that ultra capacitors are not really that far from lead-acid batteries in terms of energy density
in the overall scheme of things. If you are interested in a backup source of electricity, it is going to be difficult to beat a fossil fuel powered
generator. This link provides an interesting table that shows a wide range of energy densities for various energy storage media.
http://wiki.xtronics.com/index.php/Energy_density
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12AX7
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Quote: Originally posted by JohnWW  | | In spite of extensive hydro-electric and geothermal generation, and now wind generation, with tidal generation planned, the cost of electricity in New
Zealand is exorbitant due to ... |
So, in other words...
...You're living in New $ealand?
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not_important
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| Quote: | | I guess the point that I am trying to make here is that ultra capacitors are not really that far from lead-acid batteries in terms of energy density
in the overall scheme of things. |
This is not quite true, as lead-acid batteries have seen recent improvements. These are mostly based on using porous carbon for the electrode base,
with the active lead based material filling to pores. This prevents the growth of large crystals of PbSO5, one of the chief causes of wear out and
failure in lead-acid cells. It also is better at having a supply of acid close to the lead materials, avoiding slow diffusion problems which improves
battery performance. Axion does away with the lead in the negative electrode entirely, having the carbon hold the H+ released in the conversion of
PbO2 to PbSO4.
These and other changes boast the power density to around that of nickle hydride batteries, and increase recharge cycles well past a thousand,
approaching lithium-ion batteries. While still a bit heavy for powering transportation, they look to be quite useful for fixed power storage.
http://www.axionpower.com/profiles/investor/fullpage.asp?f=1...
http://www.allcarselectric.com/blog/1021145_firefly-working-...
A hybrid lead-acid and ultracapacitor
http://www.furukawadenchi.co.jp/english/rd/nt_ultra.htm
http://seekingalpha.com/article/115257-lead-carbon-a-game-ch...
http://seekingalpha.com/article/126053-lead-carbon-batteries...
At this time I'd say that ultracaps are still an order of magnitude less dense (volumetric) than current battery technologies. Their interface
circuitry is more complex as well; while a battery has a fairly unchanging voltage during charge and discharge, capacitors have wide voltage swings.
[Edited on 17-9-2009 by not_important]
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franklyn
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- C L I C K - BELOW FOR VIDEO PREVIEW
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12AX7
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Laff. globalspec. Now it's conclusive you're a kook.
Tim
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franklyn
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In the spirit of this thread
http://www.surplussales.com/PowerSupplies/PowerS-19.html
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franklyn
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It pays to shop around
http://www.invertersrus.com/puresinewaveinverters.html
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franklyn
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A current state appraisal and overview of photvoltaics will presented in this
virtual exhibit industrial fair.
http://www.globalspec.com/events/presentationdetails?eventId...
There are presentations on other technologies too.
http://www.globalspec.com/events/eventdetails?eventid=16&...
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not_important
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| Quote: | | The PHOEBUS demonstration plant supplied energy to part of the Central Library in Forschungszentrum J€ulich, Germany, for 10 years. The technical
feasibility of a self-sufficient energy supply system based on photovoltaic, battery, and hydrogen storage was demonstrated. The overall efficiency
based on the annual energy balance excluding the photovoltaic efficiency varied from 51% to 64%. The battery bank was able to supply energy to the
load for three days in the absence of solar radiation. Around 50–52% of the demands were delivered by the battery. In addition, another 20–25% of
the demand was supplied by the fuel cell, which indicates that the energy should be stored in a long-term storage system. Thus, the highest level of
energetic reliability can be achieved with relatively low battery capacity and hydrogen storage. |
Attachment: solar energy 75 469-478.pdf (826kB)
This file has been downloaded 1033 times
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Contrabasso
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Photovoltaic is perhaps the least profitable source of solar power. Those capacitors make good doorstops  Modern inverters use a HF circuit to raise the voltage and use low current switching devices to chop the DC into AC.
If you are going to be out in the high temperate wilds, a composite system is needed. Solar electric and solar heating come high on the list but a
generation system will be needed and can use the waste heat from the engine and exhaust to supplement the heating. If you are able to redesign the
internal software a UPS of 5+ KVA rating calling the generator the mains, and using solar (PV) also to charge the battery. possibly with a battery
pack say 100x over the usual capacity, will make a system that will be self contained using solar input but can be topped up using the generator when
needed.
The inverters used for off mains power usually fall apart when loaded with a nasty load especially DOL induction motors (Fridge/freezer) or universal
brush motors (vacuum cleaner or power drill) Sometimes generated AC is really necessary.
Once you have a non standard power some extra things need attention 1/Earthing and earth referencing and RCDs, 2/ switching some devices say AC only
because the switches are not suited for interrupting DC.
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