Ultracapacitors - Better than batteries?

Actually, those things seem quite safe. The worst-case scenario seems to be that the whole thing collapses and the system and the stored energy is lost. ... As long as you don't build housing right under it.

Hans
 
MRC_Hans said:
Mmm., that would be quite unliely. Earthquakes, terrorst atfacks, hurricanes, etc.. On the other hand....

Hans
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Without doing any actual analysis, it appears to me that towers (Including cranes) seem to fall over more frequently than mine shafts collapse. Something tall sticking into wind, rain, ice, and snow is much more exposed than dropping a cable into a hole in nice solid stable rock.
 
WhatRoughBeast said:
Rather a long step, actually. I haven't been able to find the weight of the cell discussed in the video, but let's say it's a pound. Then the specific energy is about 16 kJ/kg.

Specific energy of TNT is 14.5 MJ/kg.

Three orders of magnitude in not usually considered "mere".
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Not a bad guesstimate. Manufacture's documentation puts it at 525g or about 1.16lb.

BCAP0010 - Maxwell Technologies, Inc. - iiic.cc


The suffix is A03 not A08 as in the video but I don't expect that to have much bearing on mass.

abaddon said:
I was a student back in the early nineties. A 1F capacitor was amazing to us at the time and purely experimental. Now they are way up in the thousands of Farads. Unthinkable back then. I exploded quite a few back then in first year. And subsequently, TBH. The explosive nature of the devices is...unexpected. Resistors, diodes, even inductors will just smoulder gently. Capacitors will blow in no uncertain terms.

I would have videoed the thing back then, but it was not a thing. Phones could not do it and youtube was 15 years away at that point. I had an Erricson GH198 at the time. Amusingly, my eldest took it to school as a show and tell. Look how dumb old people were.
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It was early 80's for me and when they went it was like a firecracker with bits of wax paper and foil strewn about. I expect in those days it was the wax on the wax paper that vaporized, expanded and blew the capacitor. Don't know what the energy density of the wax was. Haven't had much luck finding it but what I have found suggests that paraffin wax has an energy density similar to fuels like gasoline and diesel. About 46 kJ/g

Firecrackers are currently limited to <50mg of flash powder. At about 9.2 kJ/g. The rest is the casing that holds the expanding gasses together to make a louder bang.

Similarly it is the energy and mass of material burned or converted that needs to be considered not the energy of the material burned and mass of the entire device. Just the mass of the wax or oil itself. Most everything else is just a containment device that eventually fails.
 
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I saw that proposal at some point not too long ago. I did not bother to watch the video past about the 3 minute mark, having muttered silently "why not just pumped storage" fairly constantly until then.

If there was more to the video than that, I apologize for my impatience. I would suggest that if one used gold bricks instead of big concrete blocks the job could be done with fewer cranes and a much smaller tower.

I am thinking of setting up a Gofundme page to enable me to start the gold brick feasibility study.

P.S. I've powered up a couple of aging camera flashes, and can report that though the aging capacitors so far have not erupted through the case when they blow up they tell you they're through with this **** in a very persuasive way.
 
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bruto said:
I would suggest that if one used gold bricks instead of big concrete blocks the job could be done with fewer cranes and a much smaller tower.
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PE = mgh

Potenial energy depends on mass and height.

Gold would reduce the volume, but increase the price, with no energy gain.

Unless, you can explain.
 
bruto said:
P.S. I've powered up a couple of aging camera flashes, and can report that though the aging capacitors so far have not erupted through the case when they blow up they tell you they're through with this **** in a very persuasive way.
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I expect in both abaddon's and my accounts it was simple overvoltage (due to bad circuit calculations) that blew the capacitors not degradation from age and use.
 
Gord_in_Toronto said:
Without doing any actual analysis, it appears to me that towers (Including cranes) seem to fall over more frequently than mine shafts collapse. Something tall sticking into wind, rain, ice, and snow is much more exposed than dropping a cable into a hole in nice solid stable rock.
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On the other hand, drainage is an issue for holes in the ground.
 
MRC_Hans said:
To get back on topic, here is an article I wrote long ago, on conventional capacitors. Super capacitors may use different technologies.

http://www.hans-egebo.dk/Tutorial/electrolytic_capacitors.htm

Hans
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I could have used that when I took Electronics 101 back in 1960. ;) It was mostly about vacuum tubes but we did have a couple of labs with the newfangled transistor thingies.

Without referring back to anything referenced in the thread so far, I would guess the big difference that makes a capacitor a supercapacitor are improvements in the dielectric materials.
 
Gord_in_Toronto said:
I could have used that when I took Electronics 101 back in 1960. ;) It was mostly about vacuum tubes but we did have a couple of labs with the newfangled transistor thingies.

Without referring back to anything referenced in the thread so far, I would guess the big difference that makes a capacitor a supercapacitor are improvements in the dielectric materials.
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In the 80's it was mostly them thar transistor thingies, DIP stuff and even that new finagled 8088 thingamajig. Yet, we still had to learn some tubes, some of the higher powered stuff (commercial radio transmitters and such) still ran off 'em.
 
Gord_in_Toronto said:
Without referring back to anything referenced in the thread so far, I would guess the big difference that makes a capacitor a supercapacitor are improvements in the dielectric materials.
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Not so much 'improved' as different. Capacitance is increased - at the expense of other properties - by making use of the double layer effect, possibly combined with metal oxide or conducting polymer electrodes which have high electrochemical pseudocapacitance.

Another type of supercapacitor becoming popular now is the Lithium Ion capacitor, which uses the anode of a li-ion battery and the cathode of a double-layer capacitor. This gives it higher energy density without compromising power density or cycle life, as well as increasing maximum voltage from 2.5V to 3.8V - but limits the minimum voltage to ~2V (whereas double-layer capacitors can be safely discharged to 0V).

All these methods of increasing capacitance use ions moving in solution, which results in higher losses and a shorter lifespan than conventional capacitors with solid dielectrics. The higher the energy density the more the 'capacitor' acts like a battery, so it's a matter of finding the right balance for the use case.
 
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